The Chinese Journal of Process Engineering

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The Chinese Journal of Process Engineering. 2026, 26(1): 0.

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Optimization of impeller for gelation process of FCC catalyst

Xin FENG Guoqing ZENG Jie CHEN Xiaoxia DUAN Hui XIAO Ronghua FU Chengqiang WANG Enhui XING

The Chinese Journal of Process Engineering. 2026, 26(1): 1-10. DOI: 10.12034/j.issn.1009-606X.225081

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The rheological properties of the material during the gelation process of fluid catalytic cracking (FCC) catalyst are complex, exhibiting pseudoplastic fluid characteristics with shear-thinning behavior. In order to enhance the mixing efficiency in the FCC catalyst gelation agitated tank, the computational fluid dynamics (CFD) numerical simulation method was used in conjunction with rheological characterization obtained by a rotational rheometer. This method was employed to investigate the influence of different impeller configurations on the mixing effect of high-viscosity, variable-viscosity systems. Due to the difference of rheological properties in different steps of gel process, it needed to be discussed separately and strengthened. By comparing and contrasting the flow field distribution, shear rate distribution and viscosity distribution inside the kettle for different gelation processes, the most appropriate stirring device for each stage can be determined. Based on the design of a new type of folded blade propeller, the multi-layer combination propeller was used in order to achieve the uniform distribution of the flow field and shear rate within the gelation agitated tank. This reduced the high viscosity weak mixing zone in the tank and improved mixing efficiency. The marked grid method was employed to compare the mixing time under different combination structures. The results showed that the optimized multi-layer impeller combination can realize the mixing strengthening of the gelation process. In the mixing process of kaolin, the combined impeller of lower SBT+upper FBT was adopted. In the mixing process of FCC catalyst colloid, the combined impeller of lower SBT+middle FBT+upper PBT was used. Considering the requirements of industrial design, the combined impeller of lower SBT+middle PBT+upper PBT was adopted in industry. This ultimately resulted in a significant reduction in the mixing time required for gelation, which strongly supported energy saving and consumption reduction in factories.

Study on laminar flow heat transfer characteristics of phase change microencapsule suspension based on OpenFOAM-DEM

Jinli LU1, Yaqin WU1, Yafang HAN1, Changlong WANG1, Yanhong SUN1, Xingyu CHEN2

The Chinese Journal of Process Engineering. 2026, 26(1): 11-19. DOI: 10.12034/j.issn.1009-606X.225070

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Microencapsulated phase change materials (MPCM) have the advantages of high energy storage density and small volume expansion rate. A novel heat transfer working medium, microencapsulated phase change materials suspension, can be obtained by mixing MPCM with single-phase heat transfer working medium and adding nanoparticles. It has the advantages of faster heat transfer rate, higher thermal conductivity and lower pumping power, and has broad application prospects in the field of heat energy storage and transport. In this work, the solid-liquid two-phase flow and heat transfer of microencapsulated phase change materials suspension in a long straight tube are numerically simulated based on OpenFOAM-DEM model. The effects of particle mass fraction, wall heat flux and Re number on the flow and heat transfer characteristics are discussed. The result show that, due to the boundary layer effect, the particle concentration is dense near the wall and sparse in the main stream area, and the uneven distribution of particles in the main stream area gradually increases with the increase of particle mass fraction. When the particle mass fraction is 10wt%, the uneven particle distribution is the most obvious. Because of melting heat absorption and particle perturbation, the particle mass fraction has a significant effect on the temperature distribution and heat transfer enhancement of the suspension. With the increase of the wall heat flux, the change trend of the low temperature region of the suspension in the tube is opposite to that of the particle mass fraction, and the low temperature region is gradually shrinking. In other words, the heat flux has a great influence on the melting rate of the phase change materials. The increase of local Nux number in pipe is not synchronized with the increase of Re number, so the synergistic effect of heat flux, flow rate and particle mass fraction should be considered comprehensively in practical engineering applications.

Performance evaluation of highly efficient heat transfer fluid in a TG type static mixer

Yanfang YU Mengqiong ZHANG Huibo MENG

The Chinese Journal of Process Engineering. 2026, 26(1): 20-29. DOI: 10.12034/j.issn.1009-606X.225131

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Effective heat transfer has been a favorite issue in industrial applications as industrial equipment trends towards high performance and density. Although static mixers are widely employed for heat transfer enhancement, research on tongue groove type static mixer (TGSM) remains limited. Thus the TGSM is chosen to examine the thermal and hydraulic characteristics. Both nanoparticles and liquid metal are popular thermal management materials today. As an emerging heat transfer enhancement material, liquid metal avoids common drawbacks of nanoparticles (e.g., agglomeration and precipitation). However, comparative studies between liquid metal and nanofluids remain scarce. Therefore, three hybrid nanofluids (SiC/SWCNT-H2O, Al2O3/SWCNT-H2O, and Al2O3/SiC-H2O) and liquid metal solution are selected to evaluate and analyze the heat transfer and flow characteristics in terms of heat transfer efficiency, energy consumption, and economy. The simulation is carried out using ANSYS fluent 16.1 with SST k-ω and Mixture model selected under turbulent conditions. It is found that the TGSM has a significant pressure drop advantage over the Kenics static mixer (KSM). Although the heat transfer efficiency of TGSM is not as good as that of KSM, the performance evaluation criteria (PEC) is more significant. The addition of liquid metal/nanoparticles improves the convective heat transfer coefficient of the fluid, which increases linearly with Reynolds number (Re). Among the four working fluids, SiC/SWCNT-H2O shows the largest Nusselt number (Nu, strength of convective heat transfer relative to pure thermal conductivity), followed by Al2O3/SWCNT-H2O, Al2O3/SiC-H2O and liquid metal solution. This suggests that SiC/SWCNT-H2O is an effective fluid to increase the heat transfer rate in TGSM. Meanwhile, SiC/SWCNT-H2O also demonstrates the best performance as a working fluid in terms of field synergy and entropy production within the TGSM. The PEC ranges from 4.67~7.33, while increasing the field synergy number by 5.09~6.81 times and reducing entropy generation ST by 87.2%~89.2%.

Preparation and performance study of cerium-modified nanocellulose membranes (Ce-CNF) for lithium batteries

Shuo LOU Yong HUANG Peng KANG

The Chinese Journal of Process Engineering. 2026, 26(1): 30-38. DOI: 10.12034/j.issn.1009-606X.225121

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Nanocellulose has attracted great attention as one of the most promising separator materials owing to the advantage of excellent electrolyte wettability and high thermal stability. It also has excellent natural abundance, biocompatibility and renewability. However, the dispersion of nanocellulose is inadequate, leading to self-agglomeration and other issues. This not only hinders the formation of a uniform porous separator but also diminishes the transport channels for Li+. To overcome this challenge, the rare earth ions Ce3+ were added. The complexation between the rare earth ions and the hydroxyl oxygen atoms of cellulose weakened the original hydrogen bond interactions among cellulose nanofibers, thereby enhancing the dispersion of CNF. In this work, a cerium-modified nanocellulose (0.050% Ce-CNF) separator with excellent thermal stability and high wettability using rare earth metal ions and cellulose nanofibers (CNF) as raw materials was prepared. Compared with conventional nanocellulose, the 0.05% Ce-CNF exhibited better processability for separator manufacturing and the separator obtained in this way possessed high stability in the electrolyte. The contact angle of 0.050% Ce-CNF separator with the electrolyte was smaller (18.7°) compared to that of polypropylene (PP) at 42.3°, and the ionic conductivity was higher. At the same time, due to the high porosity of 67.4% (compared to only 41.8% for the PP separator), batteries using CNF separators showed significantly improved rate performance compared to those using PP separators. In addition, the preparation process of Ce-CNF modified composite separator was environmentally friendly. Therefore, cerium-modified nanocellulose separator is expected to be a strong candidate for the next generation of high-safety and high-performance battery separators.

Effect of solid holdup on microbial activity of refractory gold ore bio-oxidation

Jiale GUO1, 2, Yanzhen CHEN2, 3, Guangji ZHANG2, 3, Chao YANG2, 3

The Chinese Journal of Process Engineering. 2026, 26(1): 39-46. DOI: 10.12034/j.issn.1009-606X.225168

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In order to determine the effect of shear friction caused by different pulp concentrations on the biooxidation performance of leaching bacteria, silica microsphere particles (100 μm) with a particle size close to that of ore particles were used instead of ore as the solid phase to study the biooxidation performance of two moderately thermophilic bacteria Leptospirillum ferrooxidans (L.f) and Acidithiobacillus caldus (A.c). The tolerance of these two moderately thermophilic leaching bacteria to shear friction was preliminarily determined. The density of silica microspheres was close to that of pulp, giving them a similar solid phase sedimentation rate. They were stable in the acidic environment of bioleaching, did not release metal ions or consume nutrient substrates, and can maintain the stable microenvironment required for the metabolism of bioleaching bacteria. In this study, a down-pressure four-pitched impeller stirred tank reactor was used for testing. It was found that for L.f, with the increase of silica solid holdup, the increase rate of redox potential value slowed down, the reaction time extends, and its oxidation performance was reduced by shear friction. When the solid holdup reached 25% (w/v), L.f showed obvious damage. As a sulfur-oxidizing bacteria, an increase in solid holdup also resulted in intensified shear friction within the A.c reaction system, as well as a reduction in bacterial oxygen uptake rate. However, when excessive elemental sulfur powder was initially added, residual sulfur powder remained when the oxidation of A.c was completed. Even at 30% (w/v), where oxidation time was significantly prolonged, the bacteria still maintained good oxidation activity. The addition of the baffle was beneficial to the uniform dispersion of the gas and improved the dissolved oxygen concentration and oxygen mass transfer efficiency, but the shear friction effect was enhanced accordingly, causing further damage to bacteria. As the solid holdup increased to 20% (w/v) and above, the baffles inflicted severe damage on L.f, resulting in a marked increase in oxidation time. For A.c, the baffle improved the mixing uniformity of elemental sulfur powder, and effectively broke up bubbles, which was conducive to the uptake of oxygen by A.c, and exerted a certain compensatory effect on the oxidation reaction. At 30% (w/v), the oxidation time of A.c was not significantly prolonged.

Design and filtration performance of patterned coalescence filter media with non-uniform wettability

Xuesong HUANG Qiling YIN Ying LI Li ZHANG Qianmei LÜ Xiaowei LI Cheng CHANG

The Chinese Journal of Process Engineering. 2026, 26(1): 47-55. DOI: 10.12034/j.issn.1009-606X.225077

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In natural gas pipeline transportation, the deposition of liquid droplets entrained in the gas could lead to an increase in the transportation resistance and other problems, such as equipment damage and corrosion. Liquid impurities in the gas can be effectively separated by coalescing filtration. However, higher efficiency leads to higher resistance for filter media. To meet the demand for developing high-efficiency and low-resistance filter media for industrial processes, glass fiber filter media as the substrate were used in this study. Patterned filter media with non-uniform wettability were prepared via surface modification. The effects of strip pattern arrangement, pattern spacing and number, and the number of filter material layers on the filtration performance were investigated. The results showed that the pressure drop could be reduced for filter media with staggered and overlapped arrangements of the modified areas. More dispersed oleophobic areas led to a more significant reduction of the pressure drop. When the pattern spacing was 5 mm and the number of patterns was 16, the filter media had the lowest saturation and steady-state pressure drop, and the steady-state pressure drop was reduced by 37% compared with that of the untreated filter media. For multi-layer patterned filter media, when the number of layers was the same, the liquid transport path in the filter media with the optimal pattern arrangement was shorter, resulting in a more significant decrease in pressure drop.

Selective lithium extraction technology from spent lithium-ion batteries based on aluminum thermite reduction roasting and lime leaching

Nannan ZHANG Qiong WANG Cheng YANG Wangbing ZHANG Zhenhua DING Yonglin YAO Yongpan TIAN Liang XU Zhuo ZHAO

The Chinese Journal of Process Engineering. 2026, 26(1): 56-64. DOI: 10.12034/j.issn.1009-606X.225144

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The efficient recycling of the spent lithium-ion batteries is of great significance for protecting the environment and promoting the sustainable development of the new energy industry. In view of the problems such as high recovery cost and waste gas emissions in the existing combined process, this study proposes a new method for selective lithium extraction from lithium cobaltate cathode material through thermite reduction roasting followed by lime leaching. The thermodynamic analysis of the thermite reduction process of lithium cobaltate is conducted using HSC Chemistry software to determine the feasible reaction path. Subsequently, the influence laws of roasting temperature and the dosage of reducing agent on selective lithium extraction and the phase composition of the roasted product are systematically investigated, and the effects of leaching temperature, leaching time, and the dosage of calcium oxide on selective lithium extraction efficiency are further studied. The roasted products and leaching residues are characterized by techniques such as XRD, SEM-EDS, and XPS. The research results show that the thermite reduction reaction of lithium cobaltate is thermodynamically feasible. Under the optimal roasting conditions of a roasting temperature of 650℃ and an aluminum powder dosage of 25wt%, LiCoO2 is efficiently dissociated and transformed into LiAlO2 and CoO. Subsequently, under the optimal leaching conditions of a leaching temperature of 70℃, a leaching time of 1.0 h, and a calcium oxide dosage twice the theoretical amount, 94.7% of Li can be selectively and efficiently leached. This innovative method exhibits distinct advantages over conventional processes, including zero exhaust gas emissions during thermal treatment, shortened recovery process, low operational costs, and high recovery efficiency of valuable metals. The proposed technique can provide an environmentally friendly and economically feasible solution for the short-process and low-carbon recovery of lithium from spent lithium-ion batteries, and offer a new idea for the sustainable utilization of secondary resources.

Study on the dynamic control of heat pump-assisted pressure-swing distillation with decanting for separating benzene/n-propanol/water

Qingbo SUN Zekong PENG Jian ZHAI Chunbo HAO Xuefei LENG

The Chinese Journal of Process Engineering. 2026, 26(1): 65-80. DOI: 10.12034/j.issn.1009-606X.225105

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Pressure-swing distillation has demonstrated prominent advantages in separating complex ternary azeotropic systems due to its ability to exploit pressure-dependent azeotropic shifts. This study proposed a novel decanter-assisted pressure-swing distillation configuration (NPSD) for the challenging separation of a benzene/n-propanol/water ternary azeotropic system. Building upon the NPSD framework, thermal efficiency was further enhanced via a vapor recompression heat pump, leading to the NPSD-HP process. Despite these advancements, plantwide dynamic controllability of such hybrid systems remained underexplored. To address this research gap, the controllability of conventional NPSD and heat pump-assisted NPSD-HP processes was systematically investigated through Aspen Dynamics. For the NPSD system, temperature sensitivity analysis employing a slope criterion identified critical control stages, enabling the design of two control configurations: a basic temperature-driven control structure (CS1) and an enhanced structure (CS2) that effectively reduced deviations and offsets of product purity with improved robustness. The NPSD-HP process was evaluated through three progressively sophisticated control schemes (CS3~CS5). The results showed that the component-temperature cascade-feed-forward control structure (CS5) demonstrated superior disturbance rejection capabilities, effectively handling ±20% feed flow and composition disturbances while maintaining favorable dynamic response characteristics. Comparative analysis of integral absolute error (IAE) metrics revealed that cascade control implementation reduced error accumulation through the correction effect of the component loop. This discovery demonstrated that composition control exhibited distinct advantages in complex distillation systems, including shorter response times and reduced overshoot, highlighting its significant application value. These findings underscored extensive research opportunities in dynamic control strategies for ternary azeotrope separation via advanced distillation technologies. Future investigations should focus on intelligent optimization frameworks integrating model predictive control with AI-driven algorithms, multivariable coordinated regulation mechanisms, and intensive energy conservation approaches. Such advancements are expected to further enhance disturbance rejection capabilities and economic performance in heat pump-assisted distillation processes.

Study on performance and mechanism of oxytetracycline degradation with visible-light-driven catalyst CeO₂/ZIS

Huan YU Xinhong GAN Tingting MU Yang XU Jianhua YANG

The Chinese Journal of Process Engineering. 2026, 26(1): 81-91. DOI: 10.12034/j.issn.1009-606X.225120

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The visible-light-driven catalyst CeO2/ZnIn2S4 (CeO2/ZIS) was prepared via a hydrothermal method, and its photocatalytic degradation efficiency and mechanism for oxytetracycline (OTC) in water were explored. The morphological characteristics, crystal structure, thermal stability, specific surface area, and optical properties of the catalyst were analyzed by a series of characterization methods. The results showed that the visible light absorption performance of the spherical CeO2/ZIS composed of flakes was significantly improved compared with that of the monomer CeO2. Under the conditions of an initial content of OTC of 30 mg/L, a catalyst dosage of 0.20 g/L, a catalyst dosage of 7.0, and a xenon lamp power of 500 W, the optimal degradation efficiency of OTC by CeO2/ZIS reached 84%. The photocatalytic degradation of OTC by CeO2/ZIS followed a pseudo-first-order kinetic model, with an apparent rate constant of 0.1148 h-1. The exploration of degradation mechanism revealed that the holes (h+) and superoxide radicals (?O_2^-) played major roles during the degradation process of OTC. By combining experimental results with density functional theory (DFT) simulations, a reasonable photocatalytic mechanism for the system was proposed and the stability of the catalyst was verified. This work provides a preparation method for the visible-light-driven catalyst CeO2/ZIS, which can efficiently photocatalytically degrade oxytetracycline in water. The combination of theoretical calculations and experimental results has certain reference value for fully understanding the degradation process of antibiotic pollutants by visible-light-driven catalysts.

Nucleotide-stabilized semiconductor nanocrystals: case of lead sulfide

Shengrong HUANG Yu ZHANG Jun YANG

The Chinese Journal of Process Engineering. 2026, 26(1): 92-98. DOI: 10.12034/j.issn.1009-606X.225142

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This study systematically investigates the affinities of mononucleotides, i.e., adenine (A), thymine (T), guanine (G), and cytosine (C), and polynucleotides (20 bases, Poly A, Poly T, Poly G, Poly C) for lead sulfide (PbS) nanoparticles by evaluating the stability of mononucleotide- and polynucleotide-modified PbS nanoparticles in aqueous and salt solutions over time. Experimental results reveal distinct affinity trends between mononucleotides and polynucleotides. For mononucleotides, the affinity order is A>G>C>T, with C and T failing to stabilize PbS nanoparticles due to weak interactions. In contrast, the affinity order of polynucleotides differs from that of mononucleotides: Poly C>Poly G>Poly T>Poly A, indicating no direct correlation between the two systems. The discrepancy is attributed to the rigid length of polynucleotides, a critical factor reflecting the rigidity of oligonucleotide chains. Shorter rigid lengths enable more contact points between polynucleotides and the PbS surface, enhancing stability through cumulative interactions, even when individual nucleotide affinities are weak (e.g., Poly T). For example, Poly A's longer rigid length limits contact points, reducing stability despite A's strong single-nucleotide affinity. Transmission electron microscopy (TEM) confirms that Poly A-modified PbS nanoparticles (average size of 9.4 nm) exhibit good dispersibility and crystallinity, while high-concentration Poly G assemblies induce aggregation via intermolecular G-wire formation. These findings highlight the necessity of considering both nucleotide affinity and chain rigidity when designing oligonucleotide-stabilized semiconductor nanoparticles, thus providing a foundation for DNA-guided synthesis of PbS nanoparticles with tailored properties for applications in bioimaging and optoelectronics.

Application of DBN-IWOA-optimized interval type-2 TSK fuzzy logic system for chemical process modeling

Jun LI Pengyuan KANG

The Chinese Journal of Process Engineering. 2026, 26(1): 99-108. DOI: 10.12034/j.issn.1009-606X.225126

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The debutanizer column is a key unit in the naphtha fractionation system, responsible for separating light hydrocarbons such as C3~C5, and plays a crucial role in determining gasoline quality. In particular, the bottom C4 content is a critical quality indicator but is difficult to measure online due to the time delay and high cost of traditional laboratory analyses, limiting the efficiency of real-time control. To overcome this challenge, this work proposes a high-accuracy soft sensor model that integrates a deep belief network (DBN) and an improved whale optimization algorithm (IWOA) into an interval type-2 Takagi-Sugeno-Kang fuzzy logic system (IT2 TSK FLS) with an A2-C1 structure. The DBN is employed for deep feature extraction, enhancing data representation and reducing noise in the input process variables. Subsequently, the IWOA enhanced with cosine adjustment and step-size correction mechanisms is applied to optimize both the antecedent membership functions and the consequent parameters of the fuzzy logic system. This joint approach improves the models prediction accuracy and robustness. To evaluate the effectiveness of the proposed model, a comprehensive set of comparison experiments is conducted. The benchmark methods include support vector machines (SVM), long short-term memory (LSTM) networks, gated recurrent units (GRU), and IT2 TSK fuzzy logic systems optimized using backpropagation (BP), particle swarm optimization (PSO), grey wolf optimization (GWO), whale optimization algorithm (WOA), improved WOA (IWOA), and the proposed DBN-IWOA approach.The model achieves lower RMSE and MAE values, along with higher R2 scores, thereby validating its effectiveness and robustness in practical applications. In conclusion, the proposed approach shows strong potential for advancing soft sensor modeling in complex industrial processes, enabling more accurate and efficient real-time quality prediction and process control.

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