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CO2 methanation: recent advances in catalyst development and reaction mechanistic study Junbo TIAN Fangna GU Fabing SU Zhanguo ZHANG Guangwen XU The Chinese Journal of Process Engineering    2023, 23 (3): 375-395.   DOI: 10.12034/j.issn.1009-606X.222027 Abstract （2511）   HTML （116）    PDF （12772KB）（1166）       Knowledge map    Save Choosing a suitable approach for CO2 utilization is crucial to achieving carbon neutrality and carbon peak goals as early as possible. Synthesis of synthetic natural gas (SNG) by methanation of CO2 using hydrogen produced from renewable energy is widely regarded as an efficient and promising carbon capture and utilization technology, which is expected to realize carbon recycling. Considering the importance of CO2 methanation, we provide a systematic review of the latest studies. Firstly, the effect of different reaction conditions on CO2 methanation is introduced from the perspective of thermodynamics. Secondly, the research progress of CO2 methanation catalysts is reviewed from four aspects: active metal, support, preparation method, and assistive technology. In detail, the active components are classified into cheap metal-based (Ni, Fe, Co, and Mo) and noble metal-based (Ru, Rh, Pt, and Pd) materials, and the supports are divided into the conventional oxides (Al2O3, SiO2, TiO2, ZrO2, and CeO2) and the supports with novel structures (e.g., metal-organic frameworks and carbon-based materials), which are all discussed and evaluated in depth. The preparation methods of catalyst are classified as the conventional ones (such as impregnation, coprecipitation, hydrothermal, sol-gel, and solid-phase synthesis) and unconventional ones. The latter includes three technologies such as ultrasound, microwave, and plasma, which can speed up the synthesis and reaction process and facilitate the high dispersion of the active components on the supports. Subsequently, two reaction mechanisms in CO2 methanation (the formate and CO pathways) are discussed. The specific reaction pathway for CO2 methanation is related to the properties of the catalyst surface (e.g., hydroxyl abundance, adsorbed O2- sites) and the reaction conditions (e.g., reaction temperature and pressure). Finally, current research challenges are put forward, and the prospects for future research in this area are made. Related Articles | Metrics

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Review of additives for electrolyte of sodium-ion battery Yuyue GUO Xiaoying ZHAI Ningbo ZHANG The Chinese Journal of Process Engineering    2023, 23 (8): 1089-1101.   DOI: 10.12034/j.issn.1009-606X.223104 Abstract （1762）   HTML （84）    PDF （3494KB）（1764）       Knowledge map    Save With the upsurge of the energy revolution, secondary battery as a new way of energy storage has been widely concerned owing to their efficient energy conversion. As we all know, lithium-ion batteries (LIBs) have high operating voltage and high energy density, they can be used in various application scenarios, such as electrical vehicles (EV), portable electronic devices, and large-scale energy storage systems. However, due to the shortage of lithium resources and rising prices of raw materials, many battery companies are observed to undergo cost pressure and bankruptcy risk. Given this, sodium-ion batteries (SIBs) work similarly to lithium-ion batteries, but they have great advantages in terms of resource reserve, low cost, low temperature, rate performance, and safety, thus have received strong attention from researchers and engineers. In the sodium-ion battery system, it is also composed of the positive electrode, negative electrode, electrolyte, separator, and other key components. The electrolyte, as the intermediate bridge connecting the positive and negative electrode material system, plays a vital role to undertake the transport of sodium ions, which mainly consists of organic solvent, sodium salt, and additives. The introduction of a small number of functional additives can significantly improve the overall performance of the battery because it constructs a solid electrolyte interface (SEI) between electrolyte and electrode. Different kinds of additives can exhibit specific properties to meet different conditions. This review focuses on the use of electrolyte additives, including unsaturated carbonates, sulfur compounds, phosphorus compounds, silicon compounds, inorganic sodium salts, and other types of components. Meanwhile, the research progress and related mechanisms of this addition agent in the electrolyte of sodium-ion batteries in recent years were summarized as a reference for subsequent research. Finally, the future study of electrolyte additives prospects from the science idea and practical application, for example, density functional theory, AI for science, and in-situ analysis method for SIBs. Related Articles | Metrics

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Research progress in the preparation of porous biomass carbon materials and their applications in supercapacitors Xuemin ZHANG Guanyu HE Shaoqi YIN Tingting HUANG Jinping LI Jian ZHENG The Chinese Journal of Process Engineering    2024, 24 (2): 127-138.   DOI: 10.12034/j.issn.1009-606X.223036 Abstract （1635）   HTML （70）    PDF （1013KB）（766）       Knowledge map    Save The biomass carbon material is a kind of green and renewable energy material. Its efficient utilization is of great significance for the sustainable development of the energy environment and the green and low-carbon transition of energy. Biomass carbon materials are widely used in energy storage and conversion, catalysis, adsorption, and many other fields due to their porous nature, abundant functional groups, large specific surface area, excellent electrochemical performance, low cost, and renewable. However, the properties of biomass carbon materials are not only closely related to the microstructure, but also the heteroatom doping has an important impact on the structure and electrochemical properties of biomass carbon materials. The accurate structure regulation of biomass carbon materials is an effective way to improve their electrochemical performance. In this work, the preparation methods of biomass carbon materials and their applications in supercapacitors are comprehensively reviewed, and the relationship between the structure and properties of porous carbon materials is discussed. On this basis, the influence mechanism and rules of different conditions, and different preparation processes (such as material selection, material treatment, and activation mode) on the structure characteristics of biomass carbon materials are analyzed. In this review, the mechanism and rules of the influence of the structure characteristics on the electrochemical properties of porous biomass carbon materials are described in detail, and the preparation process and performance regulation of porous biomass carbon materials need to be perfected and improved. Finally, the main development directions of preparation technology and electrochemical properties of porous biomass carbon materials in the future are pointed out. Related Articles | Metrics

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Research progress of thermal management technology for lithium-ion batteries Jiaxin LI Pengzhao LI Miao WANG Chun CHEN Liangyu YAN Yue GAO Shengchen YANG Manman CHEN Cai ZHAO Jing MAO The Chinese Journal of Process Engineering    2023, 23 (8): 1102-1117.   DOI: 10.12034/j.issn.1009-606X.223094 Abstract （1388）   HTML （64）    PDF （13593KB）（513）       Knowledge map    Save Efficient battery thermal management technology is critical to the safe operation, long cycle life, and overall cost reduction of lithium-ion batteries and is important in promoting the large-scale application of lithium-ion batteries. In this review, several mainstream battery thermal management technologies are discussed in detail, including air cooling, liquid cooling, new phase change material cooling, and thermoelectric cooling technology. The battery heat generation model is briefly described. Finally, the development direction of battery cooling technology is prospected. Air cooling technology is simple in structure, but it is difficult to ensure temperature uniformity of the cells within the battery pack and is not suitable for cooling large lithium-ion battery packs, but is more suitable for small flying electric devices and low-end electric vehicles. Cooling plate liquid cooling technology is more effective, but there is a risk of coolant leakage and the temperature uniformity needs to be further improved. Immersion liquid cooling technology offers significant cooling and temperature uniformity but is expensive and is likely to be used more often in the future in energy storage plants with high cooling requirements, while for most lithium-ion electric vehicles the lower-cost cooling plate liquid cooling technology is more suitable. Phase change material cooling and thermoelectric cooling technologies without moving parts have achieved initial commercial application in electronic equipment and small power plants, but the cooling efficiency is low and needs further refinement. It is worth noting that it is critical to choose the right cooling technology for the user's needs. While there is no perfect cooling solution, a combination of cooling technologies can be used to meet the thermal management needs of a wider range of application scenarios. Related Articles | Metrics

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Surface modification and catalytic performance study of Cu-based carbon dioxide to methanol hydrogenation catalyst Qiang YANG Gang WANG Chunshan LI The Chinese Journal of Process Engineering    2024, 24 (10): 1166-1176.   DOI: 10.12034/j.issn.1009-606X.224059 Abstract （1303）   HTML （28）    PDF （3618KB）（392）       Knowledge map    Save Development of effective copper-based catalyst for CO2 hydrogenation to methanol is of great significance, considering the utilization of this greenhouse gas. In this work, a series of surface promoter-modified (Mn, In, Mo, Mg, Zr) catalyst were synthesized by coprecipitation-post impregnation method and evaluated for CO2 hydrogenation to methanol in fixed-bed reactor. The role of metal modifier on the physicochemical properties of Cu/ZnO/Al2O3 (CZA) were investigated through CO2-TPD, XRD, XPS and H2-TPR. In addition, the catalytic mechanism for CO2-to-methanol hydrogenation was revealed by employing in situ IR. The results showed that the Mn-modified CZA with good reduction behavior, excellent CO2 adsorption capacity and suitable Cu+/Cu0 ratio exhibited the best performance. The metal element loaded on catalyst strengthened the interactions between the copper and support, suppressing the growth of Cu. The appropriate Cu+/Cu0 ratio facilitates the stabilization and conversion of methoxy, resulting in increased methanol production. Compared to the untreated CZA catalyst, the Mn-modified catalyst has more medium strong base sites on the surface, which helps to adsorb more CO2 for further hydrogenation to form formate, methoxyl and other intermediates. The incorporation of metal component in CZA facilitated the catalyst reduction ability. The catalytic mechanism follows the formate pathway and the methoxyl species is the crucial intermediate. The Cu nanoparticles on the catalyst surface showed an increased capacity for H2 dissociation when using Mn-modified CZA catalysts. This is due to stronger metal-carrier interactions. The presence of interstitial H in the carriers contributed to the generation of formate species. The dissociated H atoms from the surface Cu nanoparticles replenished the consumed interstitial H. The modified catalyst's interstitial H presence and enhanced H2 dissociation ability accelerated the formation and conversion of intermediate species, promoting methanol generation. Related Articles | Metrics

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Advances in biosynthesis of diamine as core monomers of new nylon materials Kun LIN Zhuang LI Kun WANG Ying BI Xiuling JI Zhigang ZHANG Yuhong HUANG The Chinese Journal of Process Engineering    2023, 23 (7): 958-971.   DOI: 10.12034/j.issn.1009-606X.223147 Abstract （1194）   HTML （36）    PDF （1140KB）（714）       Knowledge map    Save In the context of carbon neutrality, bio-diamine synthesis is an effective way to achieve the low-carbon production and sustainable development. Using synthetic biology, metabolic engineering, protein engineering strategies, we are able to design and construct efficient key enzymes and pathways for the biosynthesis of diamines. In this work, the progress of diamine synthesis is reviewed around two synthetic strategies: microbial de novo fermentation and whole-cell catalysis. The main diamines include 1,4-butanediamine, 1,5-pentanediamine, and 1,6-hexamethylenediamine. The biosynthesis of butanediamine mainly includes ornithine decarboxylation and lysine decarboxylation pathways, and butanediamine is mainly produced by fermentation. However, the current yield of butanediamine is low and cannot meet the requirments of industrial production. The biosynthesis of pentanediamine depends on the decarbosylation of L-lysine, mainly by de novo fermentation and whole-cell catalysis. The whole-cell catalysis for pentanediamine is more efficient, which has been widely used in large-scale production with the maturity of the technology. Hexamethylenediamine is currently synthesized by constructing artificial pathways. In addition, to address the challenges encountered in the biosynthesis of diamines, such as many by-products, poor strain activity, low yield, difficult separation, and purification, we proposed methods to improve the biosynthesis of diamines by combining metabolic engineering and protein engineering to optimize key enzyme catalysis, exploring the mechanism of cell damage caused by diamine accumulation, enhancing the specificity and activity of enzyme catalysis to improve production intensity, and optimizing the fermentation system to simplify the subsequent separation and purification steps. Finally, we foresee the future direction and development prospect of diamine biosynthesis. Related Articles | Metrics

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Research on the removal process and mechanism of aluminum/iron impurities from wet phosphoric acid through deep extraction Youzhi DAI Ganyu ZHU Ziheng MENG Huiquan LI Chengjin XU Guoxin SUN Fang LI Lei HE Yongfang ZHANG The Chinese Journal of Process Engineering    2024, 24 (10): 1241-1250.   DOI: 10.12034/j.issn.1009-606X.224056 Abstract （1164）   HTML （8）    PDF （4480KB）（192）       Knowledge map    Save The presence of impurities in phosphoric acid hinders its application in downstream processes. The development of wet-process phosphoric acid deep purification technology enables the direct preparation of phosphate-based new energy materials through a simplified process, which represents the mainstream direction for industry advancement. The solvent extraction method was employed for the extraction and separation of Al and Fe impurities in wet-process phosphoric acid. The effects of different extractants, temperature, O/A ratio, time, and extractant content on the separation efficiency of Al and Fe impurities were investigated. Optimal conditions were determined as follows: N,N-N-octyl amine di (methylene phenylphosphonic acid) (OADMPPA) extractant, extractant content of 20wt%, time of 3 min, temperature at 25℃, O/A ratio of 1:1 and 3-stage cross-flow extraction. Under these conditions, the extraction rates for Al and Fe reached 54.5% and 99.6%. Consequently, the contents of Al and Fe impurities in phosphoric acid decreased from 0.857wt% and 0.175wt% to 0.717wt% and 0.015wt%. Additionally, the MER value reduced from 9.037% to 7.227%. Further optimization of stripping process of OADMPPA extractant loaded with Al and Fe was carried out, ammonium oxalate was identified as the optimal stripping agent. The optimized stripping conditions were as follows: 25℃, 5-stage cross-flow stripping, O/A ratio of 2:1, time of 15 min, and concentration of the stripping agent at 0.2 mol/L; the stripping efficiencies for loaded extractant Al and Fe reached 96.4% and 88.3%, effectively achieving their separation from the extractant phase. Finally, the mechanism behind Al or Fe extractants was investigated by stoichiometric calculation and Fourier infrared analysis during the extraction process. It was found that during this process, one molecule of Al combined with one-and-a-half molecules of OADMPPA extractant while one molecule of Fe combined with two molecules of OADMPPA extractant; functional groups involved in these interactions included P=O and P-O-H bonds. A competitive mechanism exists in the extraction process between Al and Fe, where Fe is more easily extracted. Related Articles | Metrics

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Research progress in modification of layered oxide cathode materials for sodium-ion batteries Miaomiao LI Xiangyun QIU Yanxin YIN Tao ZHANG Zuoqiang DAI The Chinese Journal of Process Engineering    2023, 23 (6): 799-813.   DOI: 10.12034/j.issn.1009-606X.222296 Abstract （1151）   HTML （118）    PDF （47402KB）（633）       Knowledge map    Save Sodium-ion batteries (SIBs) have been regarded as the major candidate technologies for large-scale energy storage applications due to the rich abundance of Na sources, low cost and safety. And the development of cathode materials also determines the final performances and commercialization. Layered oxide cathode materials have the advantages of high specific capacity, simple structure and good stability. It is one of the most promising sodium cathode materials at present. However, such materials are still faced with irreversible changes in the electrochemical process, unstable storage in air and poor interface stability, which seriously restricts the development of commercialization of SIBs. In order to solve these problems of materials, researchers modified and optimized them. Accordingly, the modification measures of ion doping, surface coating, nanostructure design and P/O mixing and other related modification measures of sodium electric layered oxide cathode materials, which provides a basis for the modification research of sodium electric layered oxide cathode materials are reviewed in this review. Besides, the future development trend of layered oxides is prospected. Related Articles | Metrics

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Research review in regulating interfacial interaction on MOF-based mixed matrix membranes for gas separation Lili GONG Ju BAI Can WANG Wei LAI Linglong SHAN Shuangjiang LUO Zhichang LIU The Chinese Journal of Process Engineering    2023, 23 (4): 489-500.   DOI: 10.12034/j.issn.1009-606X.223054 Abstract （1129）   HTML （38）    PDF （7406KB）（4025）       Knowledge map    Save Mixed matrix membranes (MMMs) have attracted substantial attention for gas separation, combining the advantages of organic polymers and inorganic fillers, which are expected to solve the Trade-off effect. Metal organic frameworks (MOF), as a kind of innovative filler, provided promising development opportunities for MMMs, thanks to high surface area and porosity, adjustable pores, and low density, etc. These unique physical and chemical properties promoted the application in gas adsorption, separation, and storage. MOF is regarded as good compatibility with the polymer matrix because the organic linkers in MOF are more similar to the organic chain of the polymer compared with traditional inorganic materials (molecular sieve or metal oxide, etc.). Gas separation performance is improved by incorporating MOF into the polymer matrix, which is expected to balance the Trade-off effect. However, the separation performance of MMMs is not simply the sum of the two phases and is far below the predicted theoretical value by the material simulation in most cases. One of the key reasons for these non-ideal morphologies resulting from poor interfacial compatibility, including the non-selective interfacial voids, polymer rigidified, and pore blockage, which reduce the separation performance of MMMs. Therefore, good interfacial compatibility plays a key role in MMMs. Constructing effective interface interactions is a feasible strategy to improve interface compatibility. Thus, in this review, a comprehensive overview of the main technical challenges in developing MOF-based MMMs and a detailed description of the interface issues are provided. And constructing different interface interactions, including hydrogen bonds, covalent bonds, coordination bonds and others, has been expounded through various methods and strategies in the last five years. Finally, it aims to summarize the positive effects on the properties of MMMs through effective and strong interface interactions, guiding the future development of MOF-based MMMs. Related Articles | Metrics

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Research progress of lithium extraction technology from lepidolite Hong YANG Wei ZHONG Faping ZHONG Jiahui ZHAO Dong LI Lei ZHANG Xueyi GUO The Chinese Journal of Process Engineering    2024, 24 (11): 1251-1262.   DOI: 10.12034/j.issn.1009-606X.224019 Abstract （941）   HTML （22）    PDF （1677KB）（253）       Knowledge map    Save Lithium and its compounds are indispensable materials in modern industry and have important applications in the fields of batteries, ceramics and lubricants. China is rich in lithium resources, most of which occur in salt lake brine. However, due to the limitation of resource endowment and geographical location and climate, its production capacity cannot meet the needs of the rapid development of new energy industry in China, and lithium extraction from ores has become an important source of lithium products. Yichun, Jiangxi province has the largest associated lepidolite resources in China, and the development and utilization of lepidolite resources is of great significance to ensure the sustainable development of lithium resources in China. In this review, the principle, advantages and disadvantages of the existing lithium extraction processes from lepidolite are summarized. Based on the understanding of the existing methods, typical lithium extraction processes from lepidolite such as acid method, alkali method and salt method are summarized and evaluated. Among them, the acid method is mature, but there are some problems such as difficulty in impurity removal from leaching solution, low efficiency in lithium extraction and equipment corrosion. Although the alkali process has high efficiency of extracting lithium, its reaction mechanism is not clear, and the waste residue is difficult to use. Although the salt process has high selectivity to lithium and simple process, it also has the problems of high energy consumption and large amount of slag. The development direction of lepidolite extraction technology should focus on the collaborative treatment of multiple technologies to achieve efficient, economical and environmentally friendly extraction of valuable elements. Therefore, some measures to improve the process are put forward, aiming at providing reference for the future research, development, optimization and industrial application of the process. Related Articles | Metrics

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Leaching process and kinetics of niobium-tantalum concentrate by HF-H2SO4 mixed acid Gengyu LIANG Xuebin SU Huiwu LIU Kang LIU Hao CHENG The Chinese Journal of Process Engineering    2024, 24 (4): 470-479.   DOI: 10.12034/j.issn.1009-606X.223211 Abstract （922）   HTML （10）    PDF （2212KB）（186）       Knowledge map    Save As rare precious metals, niobium and tantalum are widely used in the fields of high-precision instruments and military equipment due to their excellent physical and stable chemical properties. China is rich in niobium and tantalum resources, most of which are associated deposits that coexist with various metal minerals and have high comprehensive utilization value. In response to the separation and recovery of uranium, thorium, and rare earth resources in niobium and tantalum concentrates, the HF-H2SO4 mixed acid method is used to preferentially extract niobium and tantalum, while enriching uranium, thorium, and rare earth in the slag. In this research, the one-factor experimental design is applied to study the leaching behavior of niobium and tantalum, meanwhile, the process mechanism and kinetics are discussed. The results show that using high concentration hydrofluoric acid, increasing the amount of hydrofluoric acid and sulfuric acid is beneficial for the leaching rate of niobium and tantalum. Reducing the ore particle size, increasing temperature, and extending leaching time all has favorable effect on the leaching rate of niobium and tantalum. The optimal leaching conditions obtained are as follows: 40wt% HF 1120 g/kg, H2SO4 392 g/kg, average particle size -25 μm (75%), leaching temperature 80℃, and leaching time 4 h. In which the leaching rate of niobium is greater than 98%, and that of tantalum is greater than 97%. Uranium, thorium, and rare earth are retained in the slag, and the enrichment rate in the slag reaches 3.0 to 4.2. The kinetic research has shown that the leaching process of tantalum and niobium conforms to the shrinkage core model and belongs to the chemistry and diffusion mixed control. The apparent activation energy of Nb obtained from the experiment is 34.00 kJ/mol, and that of Ta is 36.26 kJ/mol. This method effectively extracted niobium-tantalum and enriched the other valuable elements, which build the foundation for the design of the separation and purification process. Related Articles | Metrics

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Investigation of phase structure stability and thermal expansion coefficient of ytterbia stabilized hafnia Fei ZHOU Hao LAN Xiaoming SUN Huifeng ZHANG Yonghui SUN Lingzhong DU Weigang ZHANG The Chinese Journal of Process Engineering    2024, 24 (5): 580-588.   DOI: 10.12034/j.issn.1009-606X.223074 Abstract （900）   HTML （6）    PDF （4295KB）（104）       Knowledge map    Save Improvement of the thrust weight ratio of gas turbine engine rely on increased engine operating temperature. At present, it is a priority to find new thermal barrier coating ceramic materials with a higher temperature tolerance than the traditional YSZ (Yttria partially stabilized zirconia) material and match thermal expansion coefficient of Ni-based superalloy matrix. A series of ytterbia stabilized hafnia (YbSH) were prepared with hydrothermal nano-powders by solid-state sintering. Effects of the ytterbia on the microstructure, phase stability, and thermal expansion coefficient of the doped hafnia ceramics were investigated. The microstructure and phase stability mechanism of Yb2O3-doped HfO2 powders and ceramics were analyzed by XRD, Raman, and TEM. DSC-TG and TMA were used to test the high temperature phase structure stability and thermal expansion coefficient of cubic phase structure of YbSH ceramics. The results showed that the grain size of the hydrothermal nano-powder was less than 10 nm, with a uniform distribution and a great crystal state. Most of the powers were cuboid and the density of the sintered ceramics can reach more than 95%. Crystallography analysis revealed that the Yb(III) ion distorted the lattice by replacing Hf(IV) ion position which made the space group of HfO2 from monoclinic phase distortion of P21/c to the cubic phase Fmˉ3m. The hafnia gradually lost its monoclinic phase structure with increasing doping amount of ytterbia, once the doping concentration of ytterbia raised up to 12 mol/mol. By expanding cationic network and generating oxygen vacancy, oxygen overcrowding was effectively alleviated. The cubic phase structure showed good stability from room temperature to 1500℃ by high temperature heat treatment and monitoring enthalpy change of YbSH nanopowders and ceramics during heating process. Average thermal expansion coefficients of YbSH ceramics increased with cubic phase content increasing from 6.016×10-6℃-1 to 10.14×10-6℃-1 (from room temperature to 1500℃). The thermal expansion coefficient of YbSH ceramics doped with 20 mol/mol ytterbia can reach 10.5×10-6℃-1 (from 1000℃ to 1200℃), which was 67.22% higher than that of pure hafnia. Related Articles | Metrics

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Research progress on molding process of catalysts for fixed bed reactor Shanshan LIU Qida DING Tao GUO Yaofeng WANG Baohua XU The Chinese Journal of Process Engineering    2023, 23 (4): 501-511.   DOI: 10.12034/j.issn.1009-606X.222088 Abstract （892）   HTML （32）    PDF （1464KB）（496）       Knowledge map    Save The progresses obtained in the catalytic technology are driven by the social demands, such as environment, energy, chemicals, and fuels. The ultimate goal is to increase the process efficiency for scale-up. The molding catalysts are usually multicomponent material of millimetre-size consisting of the active phases, supports, and various molding additives suitable for commercial applications. Different from the powder catalysts, the molding catalysts should not only possess the catalytic activity of the powder catalyst but also consider the use of binder, lubricant, acid and pore-forming agent to satisfy the required mechanical strength and chemical stability to ensure that they can run smoothly and have a long life in industrial reactors. In addition, the shape and size of the molding catalysts affect the catalytic performance by affecting the flow state of the materials inside the reactor. Therefore, the molding process is complex and full of challenges. This review introduces the influence of molding conditions on both the mechanical and the catalytic properties at the fixed bed. Specifically, the effects of the types and amounts of additives, the addition sequence, the calcination conditions, the pulp ratio, and the shape and size of molding catalysts are focused. Weibull modulus can be used to measure the reliability of mechanical strength of brittle materials, and further judge and predict the reliability of catalyst strength value. In addition, this review also introduces the application of Weibull distribution in the reliability judgment and prediction of catalyst strength value, and the progress of computational fluid dynamics (CFD) simulation in assisting catalyst morphology design. The potential of Weibull distribution and CFD in future applications of molding catalyst are pointed out. Related Articles | Metrics

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A review on current status and carbon accounting of recycling and reusing of spent power batteries Zhiying LAI Wenbin LAI Chuyuan LIN Lingjun HE Hui LIN Fuyu XIAO Qingrong QIAN Jixiang ZHANG Qinghua CHEN Lingxing ZENG The Chinese Journal of Process Engineering    2024, 24 (2): 139-150.   DOI: 10.12034/j.issn.1009-606X.223195 Abstract （820）   HTML （24）    PDF （3821KB）（349）       Knowledge map    Save The booming development of the new energy vehicle industry has ed a significant rise in the amount of end-of-life power batteries, which in turn generates a huge amount of solid waste. Reuse of retired power batteries through laddering utilization and recycling can not only realize the resourceful reuse of valuable metals but also reduce carbon emissions and production costs. As an important part of developing the circular economy and promoting the intensive use of resources, the recycling and the resource utilization of power batteries are of great significance to the implementation of the carbon peaking and carbon neutrality strategy and the promotion of the construction of ecological civilization. Currently, a substantial body of literature and information pertaining to retired batteries has been extensively disseminated across the pertinent domains. Consequently, it is imperative to consolidate the pivotal insights within the industry to furnish industry professionals with a comprehensive point of reference. Overall, based on the current situation of the industry, the main purpose of this review is to discuss the environmental and economic impacts of the different recycling and reusing methods for retired batteries from the perspectives of the recycling process. By analyzing the current situation of recycling and summarizing the progress of research, an accounting method for carbon emissions from decommissioned power batteries is proposed, and then it is pointed out the necessity and feasibility of recycling. The aim of this review is to provide new insights into building waste-free cities and achieving carbon peaking and carbon neutrality target. It is hoped that the battery recycling industry will be able to realize healthy and orderly development in the future under the macro-control of the country, combined with efficient and eco-friendly retired battery recycling technology and relevant standards and norms. Related Articles | Metrics

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Preparation of nano-calcium carbonate intensified by CO2 micro bubble and transfer-reaction analysis Liheng WANG Xiaoping GUAN Ning YANG Zuze MU The Chinese Journal of Process Engineering    2023, 23 (9): 1313-1324.   DOI: 10.12034/j.issn.1009-606X.222450 Abstract （801）   HTML （9）    PDF （2491KB）（626）       Knowledge map    Save Carbonization is one of the common methods to prepare nano calcium carbonate. Controlling the particle size and particle size distribution of calcium carbonate is the key to the preparation of high-quality nano-calcium carbonate by carbonization. Different operating conditions have different effects on the reaction products. The particle size and size distribution of calcium carbonate can be effectively controlled by controlling different reaction conditions to improve the mass transfer and reaction conditions in the slurry. In batch-operated bubble column reactor, gas flow rate and bubble size are factors affecting mass transfer. This study investigates the influences of operation condition (gas flow rate, initial slurry condition), bubble type (ordinary bubble, micro bubble) on carbonation reaction rate and particle size distribution of calcium carbonate. Furthermore, the effects of bubble type on the stable region and abrupt change region in carbonation reaction process are analyzed. The experimental results show that when using ordinary bubble, the increase of CO2 flow rate accelerates the reaction process and reduces the particle size of calcium carbonate, but it does not affect the time of abrupt change region. With increasing the slurry concentration, the particle size first decreases and then increases in small-diameter column with ordinary bubble. However, when using micro bubble, the particle size of calcium carbonate is significantly reduced, and the time of abrupt change region decreases with the increase of gas flow rate. Moreover, the CO2 flow rate is no longer an influential factor on calcium carbonate particle size, which means that the gas-liquid mass transfer process is not the rate controlling step of carbonation reaction. This study provides some references for studying the application of micro bubbles in calcium carbonate crystallization. Related Articles | Metrics

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Progress on resource utilization and second utilization of chloride removal products from Friedel's salt precipitation method Yun GU Peng CHU Dongdong GE Shouqiang HUANG Min JIANG Hongying LÜ Wenxin ZHANG Yangyang LÜ Yang LÜ Yaheng ZHANG The Chinese Journal of Process Engineering    2024, 24 (2): 151-161.   DOI: 10.12034/j.issn.1009-606X.223122 Abstract （786）   HTML （22）    PDF （1474KB）（453）       Knowledge map    Save The high concentration of Cl- in wastewater can seriously corrode industrial equipment, and also pollute the water environment. A series of technologies for removing Cl- from wastewater have been reported, such as membrane separation, concentration, evaporation crystallization, chemical precipitation, adsorption, ion exchange, electrolysis, oxidation, and solvent extraction. Among them, chemical precipitation has significant advantages in equipment investment and operability, Friedel's salt precipitation method of Cl- removal has been intensively studied because of the wide source and low price of raw materials, compared with other methods using silver, copper, or bismuth. After the Cl- removal, a large quantity of chemical sludge is produced, which mainly contains Friedel's salt (3CaO?Al2O3?CaCl2?10H2O), katoite [Ca3Al2(OH)12], and calcium hydroxide, etc. Due to the complex components and the tight binding of Cl- in the interlayer spacing of Friedel's salt, the resultant sludge is difficult to recycle. To promote the application of Friedel's salt precipitation method, it is very important to utilize its Cl- removal products, especially Friedel's salt, as a resource. Based on the introduction of the compositional and structural characteristics of Friedel's salt, this work highlights the advantages of Friedel's salt precipitation method, which cannot only remove Cl-, but also obtain Friedel's salt, by comparing other preparation methods. According to the aluminum and calcium components of Friedel's salt and its layered bimetallic hydroxide structure, effective resource utilization can be carried out, including the removal of various heavy metal cations (i.e., Cu2+, Cd2+, Co2+, Zn2+, and Pb2+) and oxygenated anion complexes [i.e., Sb(OH)6-, AsO43-, SeO42-, and CrO42-], and the preparation of polyaluminum chloride coagulants and as sludge dewatering regulators, etc. These uses have broad application prospects, providing reference and exploration direction for the further development of Friedel's salt precipitation method. Related Articles | Metrics

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Study of flow field characteristics and separation performance of inline cyclone gas-liquid separator Ming ZHANG Huan SUN Qiangqiang WANG Jiaqing CHEN Chao SHANG Xiang LI Chunsheng WANG Lingzhen KONG The Chinese Journal of Process Engineering    2024, 24 (7): 772-782.   DOI: 10.12034/j.issn.1009-606X.223312 Abstract （769）   HTML （13）    PDF （6151KB）（209）       Knowledge map    Save The inline cyclone gas-liquid separator has received much attention because of its high separation efficiency and compact structure, but the ability to adapt to a wide range of inlet gas holdup is the key to its practicality. In this work, the flow field characteristics and separation performance of a inline cyclone gas-liquid separator that can adapt to a wide range of gas holdup changes are investigated by computational fluid dynamics (CFD) and experimental tests in air-water media system. The CFD numerical simulation results show that when the inlet gas holdup changes in the range of 10%~90%, the gas-phase separation efficiency is greater than 80% and the amplitude of change is less than 9.9%, and the liquid-phase separation efficiency is greater than 97% and the amplitude of change is less than 2.2%. The experimental results show that when the inlet gas holdup changes in the range of 9.4%~89.2%, the liquid holdup of the gas-phase outlet gradually decreases and the gas holdup of the liquid phase outlet gradually increases with the increase of the inlet gas holdup. The liquid holdup of the gas-phase outlet is less than 4%, and the gas holdup of the liquid-phase outlet is less than 10% except at liquid flow rate of 12 m3/h. Comparing the gas-phase separation efficiency and liquid-phase separation efficiency under different liquid flow rates, the best separation performance is achieved at a liquid flow rates of 8 m3/h. The CFD numerical simulation results are slightly different from the experimental test results, but the overall trend is consistent, which can be used as an effective tool for the design of structure enlargement. The research results show that the inline cyclone gas-liquid separator adopts the action form of "strong cyclone+weak cyclone+gravity", which has high separation efficiency and good resistance to fluctuations in working conditions. Related Articles | Metrics

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Heat and mass transfer simulation of gas-liquid two-phase flow in a distillation column based on OpenFOAM Yunpeng JIAO Xiaoqing ZHOU Jianhua CHEN The Chinese Journal of Process Engineering    2024, 24 (4): 391-402.   DOI: 10.12034/j.issn.1009-606X.223180 Abstract （767）   HTML （16）    PDF （4117KB）（369）       Knowledge map    Save For multiphase mass transfer processes in distillation columns, computational fluid dynamics can be used not only to simulate the flow phenomena, but also to study the heat and mass transfer processes and their interactions with the flow. Based on previous work on gas-liquid flow simulation in distillation trays, this work applied the multiphase flow solver of the OpenFOAM platform. The energy and species transport equations were considered to construct the heat and mass transfer models for the distillation system. The ideal system of cyclohexane-n-heptane and the non-ideal system of ethanol-water distillation were simulated respectively. The distribution of the gas-liquid two-phase flow, component and temperature on the column trays were analyzed. For the ideal system, the ideal solution mass transfer model can provide accurate predictions for the temperature and concentration fields on the trays. However, for non-ideal systems, it was necessary to introduce the activity coefficient model on the basis of the ideal model. To this end, the effects of two activity coefficient models, UNIQUAC and NRTL, were introduced and compared. In the current simulation framework, the activity coefficient models were able to improve the simulation accuracy of temperature and concentration field. The overall trends predicted by the two models were generally consistent with the results in the literature, and the UNIQUAC model agreed better with the literature. In addition, the comparative analysis of gas-liquid two-phase flow field and concentration field distribution showed that the circulating flow of liquid phase can enhance the local mass transfer efficiency of the column tray, resulting in higher efficiency at the liquid inlet and the weir than the tray center. However, the gas-liquid renewal in the circulating region renewed ly, which led to a reduction in the overall mass transfer efficiency of the column tray. This study can be used for the design and optimization of distillation columns, and it is also valuable for simulations of heat and mass transfer in other gas-liquid two-phase flow systems. Related Articles | Metrics

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Research progress of microreactor technology in gas-liquid two-phase flow systems Xinran YE Zan WU Haiou WANG Jianren FAN The Chinese Journal of Process Engineering    2024, 24 (9): 1001-1015.   DOI: 10.12034/j.issn.1009-606X.224035 Abstract （738）   HTML （26）    PDF （3984KB）（428）       Knowledge map    Save Microreactors possess advantages such as high heat and mass transfer efficiency, strict control of reaction parameters, ease of scale-up, and good safety performance, and hold promises for enabling and accelerating the discovery of flow chemistry towards highly efficient and more sustainable chemical synthesis. Gas-liquid multiphase catalytic reaction is commonly encountered in chemical production process, where the reaction stream enters the microfluidic channel in a continuous flow and undergoes rapid reaction. The combination of microreactor technology and gas-liquid multiphase catalytic reaction facilitates the development of efficient and sustainable chemical production techniques. Gas-liquid multiphase catalytic microreactors can be classified as wall-coated or filled-bed microreactors based on catalyst fixation approaches. By optimizing the geometric structure design of the microreactor, it is possible to further reduce the reaction time, minimize the material retention and suppress the occurrence of undesirable reactions, thus improving the microreactor performance. However, the optimization of microreactor structure requires a comprehensive understanding of various physics including the flow characteristics of gas-liquid fluids, the mass transfer mechanism and reaction kinetics within the microreactor. Both the flow pattern and mass transfer of multiphase fluids in microreactors will affect the reactor performance. Investigating the gas-liquid system in microreactors promotes improved design of practical devices. This review mainly summarizes typical gas-liquid microreactor examples, and hope to provide inspiration and guidance for the design, fabrication, and application of microreactors. The review is organized as follows, first, the features of microreactor technology are introduced and the optimization strategies for microreactor structures are presented, which is followed by a detailed discussion on the flow patterns, mass transfer characteristics and bubble breakup dynamics in gas-liquid multiphase systems within microreactors. Then, examples of multiphase catalytic microreactors in applications (mainly focusing on wall-coated microreactors and filled-bed microreactors) and their limitations are introduced. Finally, the research trends and application prospects in gas-liquid multiphase microreactors are envisaged. Related Articles | Metrics

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Preparation of high-purity copper by electrolytic refining in nitric acid system Mengyang LI Liang XU Tao GE Rui HE Xiaoyu HAN Cheng YANG Zhuo ZHAO The Chinese Journal of Process Engineering    2024, 24 (8): 955-963.   DOI: 10.12034/j.issn.1009-606X.223333 Abstract （736）   HTML （10）    PDF （2577KB）（258）       Knowledge map    Save High-purity copper has been widely used in semiconductor materials, optoelectronics and other fields due to its excellent physical and chemical properties such as ductility, thermal conductivity and electric conductivity. With the rapid development of electronic information industry, the copper product with high purity is pressing needed. Numerous methods such as zone melting, electron beam melting and electrolytic refining have been developed for the preparation of high-purity copper. Among these technologies, electrolytic refining has been investigated extensively and used in the industrial production for high-purity copper owing to its operation flexibility, simple-process and environmental-friendliness. In general, the electrolytic refining methods for the preparation of high-purity copper could be divided into nitric acid system and sulfuric acid system electrolytic refining. The electrolytic refining for high-purity copper preparation in sulfuric acid system has been widely used in industry. However, the high-purity copper prepared in sulfuric acid system generally contains the higher content of impurity elements such as S than in nitric acid system. Therefore, in this study, the 5N purity of copper was prepared from the raw materials of 4N copper in nitric acid system by one-step electrorefining. The effects of H2O2 addition, current density, electrolyte pH, Cu2+ concentration during the electrorefining process were systematically studied. Under the optimum conditions of Cu2+ concentration of 80 g/L, pH of 1.0, H2O2 addition of 0.10 mL/100 mL, and current density of 200 A/m2, the electrolytic product deposited on the cathode surface exhibited the smooth morphology, and the current efficiency during the electrorefining process was over 97%. Furthermore, the impurity elements including S, Ni, Se, As, Sb, Pb, Bi in the electrolytic product were detected by ICP-MS. The results showed that the purity of the copper prepared under the optimum conditions reached the 5N grade, which was consistent with the national standard of 5N high-purity copper. Related Articles | Metrics

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Preparation and properties of piperazine pyrophosphate based flame retardant rigid polyurethane foam Mengru LIU Fulin HUANG Junjie SUN Xiuyu LIU Qingming ZHU Gang TANG The Chinese Journal of Process Engineering    2023, 23 (4): 571-579.   DOI: 10.12034/j.issn.1009-606X.222160 Abstract （718）   HTML （3）    PDF （2204KB）（306）       Knowledge map    Save The energy crisis has led to the development of building materials in the direction of high quality. Rigid polyurethane foam (RPUF) is an insulation material with many excellent performances. However, the rigid polyurethane foam has the defect of being extremely easy to be ignited, and there is a potential safety hazard in the actual use, so it needs to be treated with flame retardant. Piperazine pyrophosphate (PAPP) is a flame retardant that contains both phosphorus and nitrogen flame retardant elements, and it can be added to the RPUF system which can solve the problem of being weak in flame retardancy of RPUF. The limiting oxygen index (LOI), thermogravimetric (TG), and cone calorimetry (CCT) have been used to investigate the flame retardant properties and combustion performance of PPAP/RPUF composites. Scanning electron microscopy (SEM) demonstrated the microscopic vesicle structure of RPUF, and the results showed that the addition of PAPP increased the inhomogeneity and breakage of the vesicle structure. The flame retardant test indicated that the addition of PAPP could effectively inhibit the dripping of the composite, with the highest LOI value of the composite material at 22.7vol% and passing the UL-94 test at V-0 level with the addition of 50wt% PAPP. TG test conducted that the decomposition of PAPP was divided into three stages, and the decomposition rate of its second stage was the largest. The acid substances produced by the decomposition of PPAP made RPUF matrix have a higher char residue rate, in which the char residue of PAPP50/RPUF increased to 34.4wt% at 700℃, and the char residue plays a role in blocking heat and releasing combustible gas in the condensed phase. CCT test confirmed that PAPP could inhibit the release of the heat of combustion from the composite material, and the peak heat release rate (PHRR) and total heat release (THR) generated by PAPP50/RPUF combustion were 54% and 41% lower than those of pure sample. The mechanical properties test demonstrated that the addition of PAPP increased the thermal conductivity and reduced the compressive strength of the PPAP/RPUF composites. Related Articles | Metrics

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Theoretical design of new energy solid-state battery materials and development of battery technology under the background of carbon peaking and carbon neutrality Hongjie XU Guanghui WANG Yujie SU Zhigao ZHANG Haitong LI Zhongzheng YANG Yuchen WANG Linyue HU Guoqin CAO The Chinese Journal of Process Engineering    2023, 23 (7): 943-957.   DOI: 10.12034/j.issn.1009-606X.223113 Abstract （700）   HTML （19）    PDF （4779KB）（683）       Knowledge map    Save Rechargeable lithium metal batteries (LMBs) have attracted wide attention due to their high theoretical energy density and important applications in portable electronic devices, electric vehicles, and smart grids. However, the implementation of LMBs in practice still faces many challenges, such as low Coulombic efficiency, poor cycle performance, and complex interfacial reactions. An in-depth analysis of the physical basis and chemical science of solid-state batteries is of great significance for battery development. To confirm and supplement the experimental research mechanism, theoretical calculation provides strong support for exploring the thermodynamic and kinetic behavior of battery materials and their interfaces and lays a theoretical foundation for designing batteries with better comprehensive performance. In this review, the theoretical and structural design ideas of the Li10GeP2S12 system and argyrodite system in sulfide solid electrolytes are reviewed, including the transport mechanism and diffusion path of lithium ions. The theoretical design ideas of new anti-perovskite Li3OCl and double anti-perovskite Li6OSI2 electrolyte systems are analyzed. The transport mechanism of Li+ in oxide solid electrolyte systems under defect regulation is reviewed. In addition, the theoretical design of new halide electrolyte systems, and the role of computational materials science in the study of battery material properties are also introduced. The key issues such as ion transport mechanism, phase stability, voltage platform, chemical and electrochemical stability, the interface buffer layer, and electrode/electrolyte interface are analyzed by theoretical methods. Understanding the charge-discharge mechanism at the atomic scale and providing reasonable design strategies for electrode materials and electrolytes. Related Articles | Metrics

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Research progress on preparation of magnetic activated carbon and its application in water treatment Qianyu WANG Yuming ZHANG Yanbin CUI The Chinese Journal of Process Engineering    2024, 24 (3): 259-272.   DOI: 10.12034/j.issn.1009-606X.223228 Abstract （698）   HTML （23）    PDF （2257KB）（388）       Knowledge map    Save Activated carbon (AC) has the characteristics of high specific surface area, porosity, abundant surface functional groups and chemical stability, and these advantages make it a widely used adsorbent in water treatment. After being exhausted (saturated adsorption contaminants), the spent AC needs to be separated from aquatic systems and regenerated which is conductive to materials recycling. However, it is difficult to efficiently separate the powder AC saturated adsorption contaminants from aquatic systems by traditional separation methods (gravitational sedimentation, centrifugation, filtration, and flotation), and the disadvantages for these methods root in many aspects including time-consuming, high-cost, and low separation efficiency. These limit the wide application of activated carbon in the field of water treatment to some extent. Magnetic modification treatment on AC can provide a magnetic activated carbon (MAC) which possesses better performances reflecting in higher adsorption capacity, and can be easier, rapid and efficient separation through external magnetic fields. At the same time, MAC has good catalytic activity, which is useful for enhancing the capability of advanced oxidation process to efficiently degrade organic pollutants in aquatic systems. Therefore, MAC has broad application prospects in the field of water treatment. This work mainly introduces the preparation methods (co-precipitation method, thermochemical method, and mechanical milling method), microstructure and physicochemical properties (specific surface area, pore structure, magnetism, crystal and chemical structure, surface charge) of MAC. The research progress of MAC in wastewater treatment in recent years is reviewed, consisting of organic pollutant removal, heavy metal removal and other applications. The adsorption characteristics (adsorption isotherms and adsorption dynamics) and corresponding influencing factors (adsorption temperature, solution pH, and coexisting ions) are summarized in details. And the regeneration methods of AC are investigated comprehensively. In the end, the development and prospect of the application of MAC in water treatment are also discussed. Related Articles | Metrics

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Separation of ethyl formate and ethanol azeotrope by extractive distillation using phosphate salt ionic liquid as extractant Chaoyue YIN Fan YANG Qinqin ZHANG Zhigang ZHANG The Chinese Journal of Process Engineering    2024, 24 (2): 238-247.   DOI: 10.12034/j.issn.1009-606X.223089 Abstract （696）   HTML （8）    PDF （1644KB）（229）       Knowledge map    Save In the process of producing ethyl formate with formic acid and ethanol as raw materials, the unreacted ethanol and ethyl formate will form an azeotrope, which is difficult to separate. In this work, the method of extractive distillation is used to separate the ethyl formate-ethanol azeotrope system with the ionic liquid as an extractant. The ionic liquid is screened by the COSMO-RS model, and the ionic liquid is determined to be 1-ethyl-3-methylimidazole diethyl phosphate ([EMIM][DEP]) and 1-butyl-3-methylimidazole diethyl phosphate ([BMIM][DEP]). The vapor-liquid equilibrium (VLE) data of the ethyl formate+ethanol binary system and the ethyl formate+ethanol+ ionic liquid ternary system are determined, and the experimental data are correlated with the NRTL model. Finally, the separation mechanism is explored by excess enthalpy analysis and σ-profile analysis (probability distribution of surface charge density). The results show that the relative volatility of ethyl formate increases with the increase in the molar fraction of two ionic liquids (ILs). When the ionic liquid concentration is 0.030, the relative volatility of ethyl formate to ethanol is greater than 1, and it can be seen that the separation effect of [EMIM][DEP] is better than that of [BMIM][DEP] ionic liquid. Through excessive enthalpy analysis, it is found that hydrogen bonds and van der Waals forces are more easily formed between ionic liquid and ethanol molecules, and the interaction between molecules is stronger than that between ionic liquid and ethyl formate, which promotes the separation of ethyl formate and ethanol. With the increase in ionic liquid concentration, the interaction between molecules is enhanced. Finally, the σ-profile analysis shows that ionic liquid is more inclined to interact with ethanol to separate ethyl formate, and it can be concluded that the shorter the cationic carbon chain of ionic liquid, the better the separation effect. Related Articles | Metrics

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Research progress on desulfurization technology for blast furnace gas Xindong WANG Tingyu ZHU Yuran LI The Chinese Journal of Process Engineering    2023, 23 (7): 1003-1012.   DOI: 10.12034/j.issn.1009-606X.222334 Abstract （661）   HTML （22）    PDF （1011KB）（414）       Knowledge map    Save The desulfurization technology for blast furnace gas as a source of emission reduction technology is of great significance to promoting ultra-low emission for the whole process in the iron-steel industry. The sulfur-containing components in the blast furnace gas are mainly organic sulfur, coexisting with other complex components. This work discusses the emission limits of sulfur-containing components in various occurrence forms (SO2, H2S, and S), and analyzes their transformation relationship through the mass balance of sulfur. The bottleneck of desulfurization technology for blast furnace gas is to remove the carbonyl sulfur (COS). The aluminum-based catalyst and carbon-based catalyst used for COS catalytic hydrolysis are analyzed in detail, in which γ-Al2O3 is both a carrier and an active component, and activated carbon has the functions of catalyst and adsorbent. The effect mechanism of the complex components O2, and Cl- on the deactivation of hydrolysis catalyst is further elucidated due to the formation of deposition products. For the gaseous H2S formed after the COS hydrolysis, the two kinds of wet removal technology, mainly including the chemical absorption method and catalytic oxidation method, are compared in the reaction mechanism, desulfurizer and product. The difference among the zinc oxide, iron oxide, and activated carbon adsorbent used in the dry removal technology is also concretely elaborated in the reaction mechanism, sulfur capacity, and temperature adaptability. In view of the integrated adsorption of organic sulfur and inorganic sulfur, molecular sieve adsorbent is briefly described in the selective adsorption principle and regeneration process. The "hydrolysis+wet", "hydrolysis+dry", and integrated removal processes have been explored and applied currently, which are preliminarily evaluated. Finally, it is pointed out that the research and development of desulfurization technology focus on how to improve the activity of the hydrolysis catalyst and reduce the influence of complex components in blast furnace gas on catalyst activity and improve the applicability of the technology. Related Articles | Metrics

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Aluminum electrodeposition and refining in ionic liquids Xiaoqing YANG Yong ZHENG Qian WANG Qian YANG Yu LI Tao LI Baozeng REN The Chinese Journal of Process Engineering    2023, 23 (3): 396-410.   DOI: 10.12034/j.issn.1009-606X.222141 Abstract （658）   HTML （18）    PDF （8639KB）（278）       Knowledge map    Save In 2020, China has already committed to peak carbon dioxide emissions before 2030 and achieves carbon neutrality before 2060. Due to the high energy consumption and carbon emission of the traditional Hall-héroult method of the aluminum electrolysis process, China strictly adheres to the production ceiling of 45 million tons of aluminum and actively develops the recycling technology of aluminum, reaching the output of the recycled aluminum up to 11.5 million tons by 2025 from 6.9 million in 2020. At present, both electrolysis and refining of aluminum are processed at high temperature. Thus, the developments of energy saving processes are required. Electrodeposition of aluminum in ionic liquids can proceed at the temperature below 100℃, which is expected to develop into a novel green technique due to its less energy consumption and no emission of carbon dioxide or other pollutants. In this review, the ionic liquids used for aluminum electrodeposition are classified according to the structure of cations, and the related research progress is reviewed respectively. In addition, the application of different anodes with aluminum as main component in electrolytic refining of aluminum in ionic liquids is also summarized. Finally, the characteristics of ionic liquid electrolyte for aluminum electrodeposition are concluded and some existing problems are pointed out. Related Articles | Metrics

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Research process of multivesicular liposomes Xing FAN Hua YUE Xiaojun WANG The Chinese Journal of Process Engineering    2023, 23 (10): 1371-1380.   DOI: 10.12034/j.issn.1009-606X.222431 Abstract （654）   HTML （17）    PDF （2032KB）（306）       Knowledge map    Save Since 1983, multivesicular liposomes (MVLs), as a member of the liposome family, have been of interest in the biomaterials and medical fields. MVLs have multiple aqueous compartments separated by phospholipid bilayers and an internal aqueous phase of up to 90%. They also have the advantages of reducing the number of injections, extending the duration of drug action, and improving patient compliance. So far, most of the MVLs reported in the literature are above 10 μm in size and have made good progress mainly in the encapsulation of analgesic drugs. This review provides an overview of the preparation methods, characterization methods, and drug release mechanisms of MVLs that have been reported in the literature in the last decade. There are relatively several methods for preparing MVLs, including the double emulsification method, spray atomization technique, and electroforming method. Currently, the main characterization methods used for MVLs are optical/fluorescent confocal imaging, scanning electron microscopy imaging, determination of particle size distribution, entrapment efficiency, and determination of zeta potential. Because of the large volume of the internal aqueous phase of MVLs and the high hydrophilic drug encapsulation rate of the internal vesicles, the individual vesicles gradually rupture and the hydrophilic drug gradually gets released during in vitro release, with a three-phase release pattern of sustained release. This review also summarizes the current status of clinical studies and types of commercialized products. At present, the application of MVLs regarding analgesics has reached stages II-IV, and three commercialized formulations have entered the clinic with satisfactory results. Moreover, this review summarizes the current progress in applied research, mainly in the delivery of anticancer drugs, analgesic drugs, and protein peptides. Last but not least, the challenge and prospects regarding small-sized MVLs, diverse biomedical applications, and scale-up strategies are proposed. Related Articles | Metrics

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Study on preparation of sustained release microspheres with octreotide based on hydrophobic ion-pairing method Yu ZHU Yi WEI Donglin SUI Jingxuan LIU Fangling GONG Guanghui MA The Chinese Journal of Process Engineering    2023, 23 (12): 1646-1656.   DOI: 10.12034/j.issn.1009-606X.223064 Abstract （654）   HTML （10）    PDF （3357KB）（215）       Knowledge map    Save Octreotide (OCT) is widely used for the treatment of acromegaly, neuroendocrine tumors such as gastrinoma, and ruptured esophagogastric variceal bleeding in clinical. However, due to the short half-life of octreotide, the patients need frequent dosing in the treatment of diseases requiring long-term medication such as acromegaly, which leads to poor compliance. Therefore, it is urgent to develop a long-acting sustained-release formulation that can improve patient compliance. And since octreotide is a small molecule peptide drug that is extremely soluble in water, it tends to escape to the external aqueous phase during the preparation of microspheres, resulting in low drug loading and encapsulation efficiency. In this study, HIP-OCT complexes were prepared by hydrophobic ion-pairing (HIP) method. The effects of charge ratio, pH value, and temperature on the binding efficiency of the complexes were investigated, and the water solubility and dissociation of the complexes were observed. The sodium dodecyl sulfate-octreotide (SDS-OCT) with 93.77% binding efficiency, 9.31% water solubility, and 92.10% dissociation was screened as the optimal complex from the four HIP-OCT complexes. Due to the formation of HIP complexes, the hydrophilicity of OCT was changed and the difficulty of OCT encapsulation in double emulsion method was overcome. The SDS-OCT complex microspheres were prepared by the O1/O2/W double emulsion method combined with the premix membrane emulsification technique. Finally, the uniform SDS-OCT microspheres with particle size of 28.02 μm, Span value of 0.776, drug loading efficiency of 6.51%, and encapsulation efficiency of 72.00% were prepared under the negative pressure solidification, drug concentration of 80 mg/mL and poly(D,L-lactic-co-glycolic acid) (PLGA) concentration of 200 mg/mL. The in vitro accelerated release of the prepared SDS-OCT complex microspheres was basically in line with the trend of zero-level release, and the cumulative release was close to 100%. In vivo pharmacodynamic experiments showed that the microspheres had stable and long-term sustained release within one month. Related Articles | Metrics

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Recent progress of heterogeneous catalysts towards selective catalytic reduction of NO by CO under oxygen-rich conditions Yaqi LIU Yan LIU Ke WU Liwen XING Dianxing LIAN Mohaoyang CHEN Jianjun JI Yongjun JI The Chinese Journal of Process Engineering    2024, 24 (3): 284-296.   DOI: 10.12034/j.issn.1009-606X.223136 Abstract （651）   HTML （15）    PDF （3784KB）（413）       Knowledge map    Save Nitrogen oxides (NOx), as one of the predominant atmospheric pollutants mainly derived from automobile exhaust and industrial waste gas, have played the role of an inevitable precursor that led to acid rain, photochemical smog, and other environmental contamination issues. In addition to atmospheric pollution, the growing emissions of NOx pollutants also give rise to a serious threat to agricultural production and human health. Thus, it is of urgent need to develop feasible NOx abatement strategies. Selective catalytic reduction of NO by CO (CO-SCR) is a very promising denitrification technology that can simultaneously remove harmful gases of NO and CO, making it one of the most ideal solutions for flue gas treatment. To promote its industrial applications, CO-SCR should have a low operating temperature ranging from 150℃ to 250℃ and superior resistance to oxygen poison. Therefore, there is an urgent need to develop efficient CO-SCR catalysts used under oxygen-rich conditions for abating severe environmental pollution problems. This work provides a comprehensive review of the research progress and latest research findings of CO-SCR under oxygen-containing conditions. The research advances of Pd, Ir, Rh, Mn, and Co-based heterogeneous catalysts were introduced, and the effects of active components, promoters, and supports on the catalytic performance of CO-SCR are described in detail. In this section, the preparation method, doping modification, and reaction conditions are analyzed. Meanwhile, the impact of O2, H2O, and SO2 on the catalytic activity of CO-SCR is discussed, in which the inhibition mechanism of O2 is summarized. Finally, the challenges and future developments of CO-SCR under oxygen-rich conditions are summarized and the corresponding coping solutions are proposed. We hope this review can provide an in-depth understanding and useful guidance for the rational design of efficient heterogeneous catalysts for the CO-SCR reaction in practical applications. Related Articles | Metrics

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Research status and prospect of key installations and flow characteristics of pneumatic conveying Jiawei ZHOU Xiangyu YAN Zebing ZHENG Qinghui WANG Linjian SHANGGUAN The Chinese Journal of Process Engineering    2023, 23 (5): 649-661.   DOI: 10.12034/j.issn.1009-606X.222192 Abstract （648）   HTML （1080）    PDF （3837KB）（226）       Knowledge map    Save Pneumatic conveying has the characteristics of environmentally friendly, operational safety, spatial intensification, flexible configuration, and easy to automate. In addition, this bulk material handling method also has the advantages of quantitative conveying, conveniently dispersing or centralized conveying, and inert gas protection conveying for unstable materials. The aforementioned characteristics pneumatic conveying to a commonly clean conveying technology for bulk materials. At the same time, pneumatic conveying has been widely applied in chemical, food, pharmaceutical, energy industries, and other fields. However, this method also has a few problems, such as high energy consumption, particle degradation, and pipe erosion. The fundamental cause of the disadvantages lies in the complex conveying process, transient state of particle conveying, and difficulty in accurate prediction. Therefore, the multi-means characterization and prediction of material conveying characteristics in different conveying processes have always been the hot points of this technology. It is well known that the equipment composition is the foundation of pneumatic conveying system performance. In addition, the feeding device is one of the most important factors for conveying processes. In this meaning, this work first summarized the structure of the pneumatic conveying system and the structural characteristics of commonly used feeding devices. Then, this work reviews the application and research of the numerical simulation methods including the two-fluid model in the computational fluid dynamics and the coupling simulation of the computational fluid dynamic discrete element method (CFD-DEM). The application conditions, merits, and demerits of the common numerical method are discussed. What is more, the research and application status of measuring devices commonly used in pneumatic conveying are summarized, including electrical capacitance tomography (ECT), pressure determination, and acoustic emission. Meanwhile, the study mainly focuses on flow pattern evolution and pressure loss in the conveying system, as well as some interesting study points of pneumatic conveying, which are well explored. Finally, several thinking points for future research on this technology are discussed. Related Articles | Metrics

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Research advances of slurry bubble column for Fischer-Tropsch synthesis of indirect coal liquefaction technology Li ZHANG Yong YANG Junhu GAO Yu ZHANG Lili ZHANG Chao YANG Yongwang LI The Chinese Journal of Process Engineering    2023, 23 (3): 359-374.   DOI: 10.12034/j.issn.1009-606X.222151 Abstract （644）   HTML （15）    PDF （4445KB）（230）       Knowledge map    Save Coal-to-liquid (CTL) is one of the most promising way to efficiently convert coal into fuels and chemicals promoting the clean and efficient utilization of coal resources. With the successful application of indirect coal liquefaction technology in million-ton commercial demonstration plants, the Fischer-Tropsch synthesis slurry bubble column as its core equipment involves gas-liquid-solid three-phase turbulent flow, heat/mass transfer and reaction that change with the enlargement of the reactor diameter and the structural layout of internals, which in turn affects multiple complex processes of reactor performance, resulting in huge challenges in reactor design, scale-up and operation optimization due to lack of information on hydrodynamics with internals over a wide range of operating conditions of commercial interest. Scientific research and industry still continue to pay attention to it. This work gives a state-of-the-art review of the recent studies on the slurry bubble column for gas-to-liquid Fisher-Tropsch processes. It analyzes the main factors affecting the hydrodynamic performance of slurry bubble column, summaries the research on flow pattern, gas holdup, bubble behavior, and heat transfer, introduces the structural characteristics and development of the internals such as gas distributor, internal filtration, and heat exchanger. The effects of various operating variables, including pressure, temperature, gas velocity, catalyst concentration, and reactor geometry on the hydrodynamic and transport parameters as well as the performance of slurry bubble column are discussed. Unfortunately, little effort has been put on reviewing the experiments and simulations for examining the effect of internals on the performance and hydrodynamics of slurry bubble column for Fischer-Tropsch and significant efforts are still required. The research progresses from basic research to engineering technology of slurry bubble column in coal indirect liquefaction process are reviewed. Perspectives are given on the potential application and future research of slurry bubble column. Process intensification technology using internals to improve the performance and computational fluid dynamics will be the development direction in the future. Related Articles | Metrics

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Research on composition customization strategy and magnetic properties optimization of soft magnetic composite cores based on interfacial solid reaction Rui WANG Hui KONG Haichuan WANG Lejun ZHOU Xi'an FAN Zhaoyang WU The Chinese Journal of Process Engineering    2024, 24 (10): 1196-1207.   DOI: 10.12034/j.issn.1009-606X.223366 Abstract （644）   HTML （3）    PDF （8243KB）（118）       Knowledge map    Save Soft magnetic composite cores (SMCs) are considered the most promising electromagnetic conversion device due to their excellent properties, including high saturation magnetisation, high permeability, and relatively low core loss. However, core loss and permeability, as the key performance parameters for the effective operation of electromagnetic devices, are often restricted. Therefore, by adjusting the distribution characteristics of the powder matrix, the insulating layer, and increasing the ferromagnetic filling factor within the soft magnetic composite core, in-situ coating of the insulating layer can be realised, which helps to simultaneously reduce core loss and improve magnetic permeability. In this work, a novel interface solid-phase reaction strategy was designed. Firstly, calcium acetate was uniformly coated on the surface of Fe-Si-Al soft magnetic alloy powder using hydrothermal method. Subsequently, Fe-Si-Al based soft magnetic composite cores were prepared by hot pressing sintering. The effects of sintering temperature and insulation layer phase transition on the morphology, microstructure, and magnetic properties of the prepared soft magnetic composite cores were studied. The results showed that calcium acetate was successfully coated onto Fe-Si-Al alloy powder surface by hydrothermal method, forming a core-shell heterostructure with the Fe-Si-Al alloy powder as the core and calcium acetate as the shell. This provided powder materials for subsequent preparation of soft magnetic composite cores. Raising sintering temperature eliminated internal pores within soft magnetic composite cores while promoting transition from calcium acetate to calcium carbonate to Al2O3?SiO2?CaSiO3, ultimately providing high-quality insulation. The insulating layer of the soft magnetic composite core prepared by high temperature sintering at 850℃ was dense and uniform, and the magnetic dilution effect was minimised. At 10 mT and 100 kHz, the soft magnetic composite core had the highest permeability (67.2), the lowest core loss (9.24×10-5 kW/cm3), and a relatively higher saturation magnetisation (129.0 emu/g), which had the best comprehensive performance, and provided a solution to restrict the reverse relationship between permeability and loss in traditional soft magnetic materials. Therefore, insulation methods based on thermal decomposition and oxidation of organic salt compounds are expected to be an important supplement to the magnetic property optimisation strategy of soft magnetic composite cores based on interfacial solid phase reaction engineering. Related Articles | Metrics

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Study on preparation and properties of electrospinning nanofiber membrane for air filtration Simin CHENG Fuping QIAN Chen ZHU Lumin CHEN Wei DONG Huaiyu ZHONG The Chinese Journal of Process Engineering    2024, 24 (5): 599-608.   DOI: 10.12034/j.issn.1009-606X.223252 Abstract （638）   HTML （5）    PDF （4750KB）（205）       Knowledge map    Save It has been proved by long-term practice that because the source of atmospheric aerosol particles is very wide, small size, the composition is very complex, the harm to the environment and human health is very serious. Although the government has taken a series of effective measures to control the pollution sources, it still takes a long time to completely solve the PM2.5 pollution problem. If the public wants to reduce the harm caused by particulate matter, specific measures must be taken to conduct individual protection and indoor air purification. At present, the simplest and most effective method for individual protection and indoor air purification is to filter the particles in the air through fiber filtration materials, thus reducing their content in the air. However, traditional fiber filtration materials have the disadvantages of low filtration efficiency, high filtration pressure drop and high energy consumption in the process of use. Meanwhile, filtration fibers with high filtration efficiency are often accompanied by higher filtration resistance. In order to develop high efficiency and low resistance fiber membrane for air filtration, polyacrylonitrile (PAN) electrospinning nanofibers were prepared by electrospinning. In the preparation process, the mass fraction of PAN and the duration of electrospinning were changed, and the electrospinning nanofiber films with different morphologies and filtration properties were obtained. The morphologies and filtration properties of electrostatic spinning nanofibers were tested and analyzed by field emission scanning electron microscopy and filtration test platform, and the preparation parameters of the best performance PAN electrostatic spinning nanofiber membranes were obtained with PAN mass fraction of 9wt%, electrospinning time of 5.0 h. Under the optimum condition, the film thickness of electrospinning nanofibers was 0.0240 mm, the average fiber diameter was 396 nm, the PM2.5 filtration efficiency was 99.99%, the filtration pressure drop was 67 Pa, and the highest quality factor was 0.137 Pa-1. Related Articles | Metrics

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Research progress on liquid bridge fracture in field of micro-nano technology Zhaofei ZHU Yalong CHU Xianming GAO The Chinese Journal of Process Engineering    2023, 23 (6): 814-825.   DOI: 10.12034/j.issn.1009-606X.222287 Abstract （634）   HTML （18）    PDF （4290KB）（526）       Knowledge map    Save Affected by the scale effect, the morphological characteristics of liquid bridges at the microscale determine the changes in liquid bridge forces that are area-related. Liquid bridge forces have an important impact on the formation and fracture of liquid bridges. The liquid bridge fracture mechanism based on liquid bridge morphology is the theoretical basis of biology, chemistry, materials, micro-nano technology, and many other research fields. At present, the study of liquid bridge fracture is an interdisciplinary discipline involving mathematics, fluid mechanics, interface chemistry, materials science, and other disciplines, however there is few review of the research progress focusing on liquid bridge fracture based on liquid bridge morphology. This review mainly summarizes the fracture theoretical models and experimental methods of axisymmetric liquid bridges, non-axisymmetric liquid bridges, and non-Newtonian liquid bridges. It mainly introduces the weak nonlinear behavior of the fluid generated during the tensile and rupture of the liquid bridge under equilibrium or steady state caused by the forced hydraulic bridge. The influences of key factors such as liquid volume, viscosity, surface tension, wettability, roughness of the solid surface, fracture speed, and liquid bridge morphology on the fracture location or liquid distribution rate of the liquid bridge are systematically described. The experimental methods for quantitatively studying the use of different key parameters affecting liquid bridge fracture are analyzed. The structural characteristics of different experimental apparatus and their advantages and disadvantages are compared and discussed. Furthermore, the innovative and high-value research direction of the research is summarized and proposed, which may be used in future research. Finally, the research frontier trends of liquid bridge fracture in the field of micro-nano technology prospected, and it is pointed out that the future research focused on issues including a more comprehensive hydraulic bridge fracture model, the fracture mechanism, and multi-parameter control method of the liquid bridge. Related Articles | Metrics

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Research progress of core monomer separation and purification technology for bio-based materials Kun WANG Xiuling JI Kun LIN Yuhong HUANG The Chinese Journal of Process Engineering    2023, 23 (8): 1137-1149.   DOI: 10.12034/j.issn.1009-606X.222314 Abstract （628）   HTML （19）    PDF （2738KB）（484）       Knowledge map    Save The production of petrochemical-based materials consumes large amounts of non-renewable resources and cause a certain degree of pollution to the environment. The performance of bio-based materials produced by renewable resources can be comparable to that of petrochemical based materials, which is in line with the development concept of green, low-carbon and environmental protection, and provides strong technical support for the realization of the goal of carbon peaking and carbon neutrality. In recent years, with the domestic and international policies tilted to the bio-based materials industry, bio-based materials have become a new material for domestic and international development, providing a good opportunity for the development of bio-based materials industry. The core monomer of bio-based materials produced by biological method has the advantages of mild production conditions, low price, and green environmental protection. But the complex composition within the fermentation broth as well as the low concentration of monomers and the difficulty of separation have seriously restricted the development of the whole industry of bio-based materials. The production of bio-based materials requires high-purity monomers, and a small amount of impurities affect the appearance and performance of bio-based materials. The existing research and application of separation of core monomers of bio-based materials has developed the process of obtaining high purity separation and purification of core monomers of bio-based materials by taking full advantage of chemical separation technology. This review briefly introduces the current status of the production of bio-based materials, reviews the research progress of several widely used separation and purification technologies for core monomers of bio-based materials in recent years, analyzes the advantages and disadvantages of current separation technologies. Finally providing an outlook on the development trend of separation and purification technologies for core monomers of bio-based materials. Related Articles | Metrics

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Forced oxidation of calcium sulfite and the influence of impurities in wet desulfurization by calcium carbide slag Yuewu ZHENG Ziheng MENG Lingxian LIAN Jiliang HAN Liwen ZHAO Xingguo WANG Gang XING Ganyu ZHU Huiquan LI The Chinese Journal of Process Engineering    2023, 23 (12): 1725-1738.   DOI: 10.12034/j.issn.1009-606X.223048 Abstract （620）   HTML （6）    PDF （9117KB）（349）       Knowledge map    Save The main component of calcium carbide slag (CCS) is calcium hydroxide [Ca(OH)2], which can replace limestone ore for wet flue gas desulfurization, but the desulfurization byproducts of calcium sulfite particles are small because of the strong alkalinity of CCS, which may affect the oxidation of calcium sulfite and the crystallization of calcium sulfate (CaSO4). The effects of different process conditions on particle size, oxidation rate, water content, and microcosmic appearance in the process of calcium sulfate oxidation and gypsum crystallization were systematically investigated, and the optimal process condition (calcium sulfate content of 5 g/L, aeration rate of 400 mL/min, initial pH value of 5.5, reaction temperature of 40℃, and reaction time of 4 h) was obtained. The byproduct of desulfurization gypsum (mainly calcium sulfate dihydrate) with large particle size, low water content, high purity, and uniform appearance was obtained under the optimal condition, which is conducive to the subsequent resource utilization of desulfurization gypsum. The leaching sequence of each element in the CCS under the actual operating pH conditions of the CCS slurry (acidic conditions) is Na>Ca>Mg>Si>Fe>Al. The effects of impurities of Na, Mg, Si, Fe, and Al in the CCS on the oxidation process of calcium sulfate and the crystallization of calcium sulfate were investigated under the above optimal reaction condition. The results indicated that Mg, Si, and Fe in the CCS had a significant promotion effect on the oxidation rate of calcium sulfate, while Al and Na in the CCS inhibited the oxidation of calcium sulfate. At the same time, the addition of Si impurity had almost no effect on the crystallization of calcium sulfate, the addition of the impurities of Mg, Fe, and Na had less effect on the crystallization of calcium sulfate, and the addition of Al impurity had a significant adverse effect on the crystallization of calcium sulfate. In this study, the CCS-based calcium sulfate was used as the raw material, and the study of calcium sulfate oxidation and gypsum crystallization was carried out, providing theoretical guidance for the forced oxidation process in the actual industrial desulfurization. Related Articles | Metrics

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Research and industrialization of conductive additive technology in the field of new energy batteries Peiling YUAN Xingxing DING Peng GUO Caili ZHANG Rui HU The Chinese Journal of Process Engineering    2023, 23 (8): 1118-1130.   DOI: 10.12034/j.issn.1009-606X.223115 Abstract （619）   HTML （6）    PDF （2082KB）（250）       Knowledge map    Save Secondary batteries have been widely developed and used in various fields, such as large-scale energy storage, portable electronic devices, and electric vehicles. Conductive additives, as an important component of lithium-ion batteries, could increase and maintain the electronic conductivity of the electrodes by constructing a conductive network, which will effectively improve the electrochemical performance of batteries. Although conductive additives account for a relatively small proportion of the cost of lithium batteries (around 2%), compared to the trillion level lithium battery industry, conductive additives have also become a trillion level industry. At present, the mainstream conductive additives are carbon black, conductive graphite, vapor grown carbon fiber (VGCF), carbon nanotubes, and graphene. They are ideal conductive additives for lithium-ion batteries because of superior properties such as low weight, high chemical inertness, and high specific surface area. Among them, carbon black, conductive graphite, and VGCF are traditional conductive additive materials that form point and line contact conductive networks between active materials; carbon nanotubes and graphene belong to new conductive additive materials, which respectively form wire and surface contact conductive networks between active materials. Compared to a single conductive agent, composite conductive agents create synergistic effects between different conductive agents, thus exhibiting better performance. Therefore, we believe that the new conductive agent has a highly unified relationship with traditional conductive agents. Taking into account both cost and performance, the future conductive agent system will gradually shift from singularity to multiple composites. In addition, China's conductive agents have long relied on imports. In recent years, some excellent enterprises have gradually broken through process barriers in preparation methods and dispersion technologies, accelerating the process of localization. This article will discuss the related work of using carbon nanomaterials as conductive additives in the field of batteries and improving their electrochemical performance. Then, further discuss the industrialization status and prospects of conductive additives. Related Articles | Metrics

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Study on the mechanism of Ni2+ and Mg2+ loss and enhanced separation in sulfuric acid leachate of laterite nickel ore during iron removal using neutralization process Hao JIANG Xin TENG Jun LUO Changye MANG Xinran LI Wenhao SUN The Chinese Journal of Process Engineering    2023, 23 (11): 1558-1567.   DOI: 10.12034/j.issn.1009-606X.223055 Abstract （609）   HTML （9）    PDF （8323KB）（540）       Knowledge map    Save Neutralization precipitation process is often used to remove impurities such as iron, aluminum and chromium from the nickel laterite acid leach solution, however, it accompanied with the loss of nickel and magnesium metal ions. The precipitation behaviors of Ni2+ and Mg2+ ions in nickel laterite acid leach solution during the neutralization precipitation iron removal process was deeply discussed in this work. Furthermore, a novel precipitation mechanism of Ni2+ and Mg2+ with SO42- during the neutralization precipitation iron removal process was proposed. The results showed that under the condition of fixed Ni2+ and Mg2+ concentrations in simulated leachate, the loss rate of Ni2+ and Mg2+ during neutralization and precipitation respectively were 9.13%~23.23% and 9.79%~15.68% with the increase of Fe3+ concentration in simulated leachate. Under the condition of fixed Fe3+ concentrations, the loss rate of Ni2+ and Mg2+ decreased with the increase of the concentration of Ni2+ and Mg2+. According to the results of solution chemical calculation and the characterization of iron hydroxide precipitation by infrared spectroscopy and scanning electron microscopy, both SO42- ions and Fe(OH)3 colloids could co-precipitate in the form of monovalent or binary complex during the neutralization process, in which the lone pair electrons of SO42- in the monovalent complexes bond with Ni2+ and Mg2+ and adsorb, resulting Ni2+ and Mg2+ in the leachate were co-adsorbed with SO42- by Fe(OH)3 colloid and the loss was caused. In addition, it was found that the surfactant such as cetyl trimethylammonium bromide (CTAB), polyethylene glycol (PEG), sodium dodecyl benzenesulfonatecan (SDBS) was added during the neutralization precipitation process can effectively compete for adsorption with neutralizing precipitated products or impede the combination of SO〖_4^(2-)〗 with Ni2+ and Mg2+ ions, which could enhance the selective precipitation of Fe3+ ions during neutralization process. When the dosage of three surfactants was 2×10-5 mol/L, the retention rates of Ni2+ in the process of neutralization and precipitation of iron could reach about 95%, and Mg2+ could reach 100%. Related Articles | Metrics

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Research progress of lithium polysulfide capture in lithium-sulfur batteries Tingting HU Haijian LIU Yunyi CHEN Lingli LIU Chun'ai DAI Yongsheng HAN The Chinese Journal of Process Engineering    2023, 23 (9): 1231-1243.   DOI: 10.12034/j.issn.1009-606X.222413 Abstract （608）   HTML （27）    PDF （6063KB）（463）       Knowledge map    Save Lithium-sulfur battery has an ultra-high theoretical specific capacity (1675 mAh/g) and theoretical specific energy (2600 Wh/kg), which is far higher than commercial secondary batteries. In addition, the sulfur element is rich in the earth, and its price is cheap, the extraction process is environmentally friendly. Therefore, a lithium-sulfur battery is considered as an ideal energy storage unit for the future energy storage system. However, the lithium polysulfide intermediates generated in the charging and discharging process are easily soluble in the electrolyte, resulting in a loss of active materials and an increase in the electrolyte viscosity. In addition, the dissolved lithium polysulfide is inclined to migrate between positive and negative electrodes, and reacts with the lithium negative electrode, causing irreversible loss of active substance sulfur, greatly reducing the battery life and safety. This phenomenon is called the shuttle effect, which hinders the commercialization process of lithium-sulfur batteries. In recent years, researchers have attempted to solve this problem through physical adsorption, chemical action, and external field constraint, and achieved impressive progress. This work summarizes the research progress of capturing lithium polysulfide, and compares the characteristics of each approach and its impact on the electrochemical performance of lithium-sulfur batteries. Whether it is the physical constraint of the porous structure of carbon materials, the chemical interaction between the carrier materials and lithium polysulfide, or the adsorption of electric and magnetic fields on lithium polysulfide, lithium polysulfide is fixed on the positive side and to inhibit its dissolution and diffusion to the negative electrode. Capturing lithium polysulfide by external magnetic field, internal magnetic field induced by magnetic particles, and internal electric field generated by spontaneous polarization of ferroelectric materials is also highlighted. Finally, the challenges in capturing lithium polysulfide and the possible solution are prospected. Related Articles | Metrics

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Gas-liquid flow simulation of a distillation tray based on OpenFOAM Xiaoqing ZHOU Yunpeng JIAO Tianbo FAN Xianfeng HE Jianhua CHEN The Chinese Journal of Process Engineering    2023, 23 (6): 858-869.   DOI: 10.12034/j.issn.1009-606X.222258 Abstract （607）   HTML （15）    PDF （8891KB）（513）       Knowledge map    Save Distillation column with sieve tray is an important separation equipment and widely used in the process industry. The complex behavior of the gas-liquid two-phase flow in distillation columns, especially on the tray, significantly affects the separation performance. With increasing applications of the CFD simulation in multiphase flow, it is interesting to adopt the CFD tools in distillation design and optimization. Traditionally, commercial CFD software has been applied in this field, while they face the problems of black-box feature, limited and expensive license, inflexibility of developing tailored models, etc. Therefore, this work turns to the open source platform of OpenFOAM. By using the Eulerian solver in OpenFOAM, an experimental sieve tray column is studied. The two-phase flow characteristics under different operating conditions are explored, including the height of the clear liquid layer, the gas and liquid velocity, the pressure drop, etc. The predicted trends are consistent with the experimental results. The simulated clear liquid height decreases with increasing gas flow rate and increases with liquid flow rate, and its deviation from the experiments is attributed to the empirical drag correlations which need further study. The influences of sieve holes and liquid inlet conditions on the liquid velocity distribution have been studied. It is found that the number of sieve holes has little impact, and simulations with non-uniform liquid inlet conditions agree with the experiments better. This study verifies the feasibility of using OpenFOAM to simulate distillation columns. The next step is to apply the mesoscale approach to gas-liquid crossing flow systems, construct a new interphase drag model to improve the accuracy of the simulation, and consider the influence of heat and mass transfer on the flow field. This work lays a foundation for the next-step coupling simulations, which is promising for the design and optimization of distillation columns. Related Articles | Metrics