Table of Content

28 April 2026, Volume 26 Issue 4

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Contents

Cover and Contents

The Chinese Journal of Process Engineering. 2026, 26(4):  0. 

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Review

Optimization strategies for thermal transport properties in p-type Mg₃Sb₂-based thermoelectric materials: a review

Di ZHANG Jiawei ZHA Zhiyuan LIU

The Chinese Journal of Process Engineering. 2026, 26(4):  333-343.  DOI: 10.12034/j.issn.1009-606X.225191

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Mg3Sb2-based materials, featuring a unique layered crystal structure, exhibit a favorable combination of low thermal conductivity, high Seebeck coefficient, and decent carrier mobility, establishing them among the most promising mid-temperature thermoelectric systems under active investigation. However, p-type Mg3Sb2 derivatives demonstrate a comparatively lower thermoelectric figure of merit (zT) compared to their n-type counterparts. Enhancing the zT performance of p-type Mg3Sb2 is therefore essential for the development of high-efficiency thermoelectric devices based on this material system. This review systematically summarizes the critical factors governing the thermal transport properties of p-type Mg3Sb2, including intrinsic characteristics such as chemical bonding and crystal structure, as well as extrinsic parameters such as carrier concentration, mobility, point defects, microstructure, and temperature dependence effects. Furthermore, it highlights recent advances in strategies designed to optimize thermal conductivity (κ) and improve zT, mainly including point defect engineering (such as Mg-site doping, Sb-site doping, dual-site co-doping, as well as doping-assisted composite modification), low-dimensional and nanostructural design, and advanced preparation technologies. Experimental studies demonstrate that these targeted strategies, particularly the synergistic introduction of multi-scale defects, can effectively suppress phonon propagation and significantly reduce lattice thermal conductivity (κL). Consequently, substantial improvements in the overall zT of p-type Mg3Sb2-based materials have been realized, providing a robust scientific and technical foundation for accelerating the practical application of Mg3Sb2-based thermoelectric devices.

A review on energy-saving and consumption-reducing technologies for thermal power units based on economic benefit evaluation

Tao JING Quanjie LI Xiannan DU Naimu YANG Zhenshuai YANG Sizheng TONG Bing LI Ye FAN Jinwen SHI

The Chinese Journal of Process Engineering. 2026, 26(4):  344-360.  DOI: 10.12034/j.issn.1009-606X.225184

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With the low-cost advantage of relatively abundant coal resources and the characteristics of ensuring the stable operation of the power system, thermal power units have long occupied a dominant position in our country's energy structure. However, with the increasing global attention to climate change and the proposal of China's carbon peaking and carbon neutrality goals, the environmental pressure caused by the "three wastes" generated during the operation of thermal power units has become increasingly prominent. As a result, thermal power units are facing unprecedented pressure on energy conservation and emission reduction. In this context, the energy-saving transformation and optimization and upgrading of thermal power units have become a research hotspot. At present, the research on energy-saving technology of thermal power units in academia and industry mostly focuses on a single technical field or specific application scenarios, and lacks a systematic combing of the latest progress of mainstream technologies, as well as a comprehensive analysis of the application bottlenecks and research gaps of various technologies, which restricts the coordinated development and large-scale application of energy-saving technologies to a certain extent. In view of this, this work takes the energy-saving technology of thermal power units as the research object, and comprehensively sorts out the current mainstream energy-saving technologies. It includes boiler efficient combustion optimization, heating surface cleaning and transformation, turbine flow part upgrade, waste heat recovery and cascade utilization technology, cold end system optimization and other technologies. In order to evaluate the actual value of various technologies more objectively, this work takes the coal consumption rate as the core economic benefit index, combined with the transformation cases and operation data of typical thermal power units at home and abroad, and deeply analyzes the latest research progress, practical application effects, technical advantages and limitations of different energy-saving technologies. The results show that the energy-saving technology of thermal power units has achieved remarkable results in improving energy efficiency and reducing environmental pollution. However, further research and optimization are still needed in the improvement of multi-objective optimization models, intelligent diagnosis and predictive maintenance, and the application of advanced materials to promote the sustainable development of energy-saving technologies for thermal power units.

Research Paper

CFD simulation and structural optimization of sulfur hexafluoride thermal catalytic degradation reactor

Jingxiang MA Zhonglin XIA Zhiqiang LIU Hongyu LIU Fu YANG Hongtao ZHU Shuangchen MA

The Chinese Journal of Process Engineering. 2026, 26(4):  361-371.  DOI: 10.12034/j.issn.1009-606X.225185

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Through model establishment, grid partitioning, and solution settings (including boundary conditions, chemical reaction mechanisms, porous media and their heat transfer models, turbulence models, solution methods, etc.), numerical simulations were conducted on the thermal catalytic degradation of SF6 in a thermal catalytic reactor. The pressure distribution, velocity distribution, temperature distribution, and concentration distribution of various substances in the reactor were obtained. Pressure, temperature, gas flow rate, and substance concentration all exhibited inconsistency between the central axis and the wall surface. It was found that temperature had the most impact on degradation efficiency of SF6, uneven radial temperature distribution within the reactor lead to a decrease in SF6 degradation efficiency. Based on the analysis results, the optimization design of the reactor was carried out to solve the uneven distribution of the various parameters. The influence of gas flow rate and reaction tube inner diameter size on heat and mass transfer in the reactor was studied. Measures such as reducing reactor diameter and filling inert porous media components with high thermal conductivity were proposed to enhance heat transfer and optimize temperature field distribution to improve SF6 degradation efficiency. After adding porous media at both ends of the catalytic section, the temperature field, reaction rate and substance concentration distribution became more uniform compared to that before optimization. By studying the effect of inlet gas flow rate on reactor performance, it was found that too low or too high inlet gas flow rate can deteriorate effective utilization or heat transfer efficiency in the catalytic zone, resulting in uneven radial distribution of temperature field and reduced degradation efficiency of SF6. The optimal gas flow rate should be controlled between 0.4~0.8 m/s, which can balance the utilization, energy consumption and degradation efficiency of the catalyst. This study provides data support and theoretical guidance for the design, optimization, and practical application of SF6 catalytic degradation reactors.

Gas-liquid dispersion characteristics in a stirred tank equipped with porous aeration tube

Ruiyu SUN Ping XIE Ziqi CAI Xinwei LIU Zhengming GAO Yuyun BAO

The Chinese Journal of Process Engineering. 2026, 26(4):  372-380.  DOI: 10.12034/j.issn.1009-606X.225213

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In chemical production processes, many operations such as oxidation and hydrogenation rely on the mass transfer efficiency of stirred tanks in terms of gas dispersion. Therefore, optimizing gas dispersion characteristics is a key issue. This study aimed to investigate the effects of impeller type, impeller position, and operating parameters on gas-liquid dispersion in a stirred tank by means of porous tube aeration, where two typical wide hydrofoil (WH) and half-elliptical disk turbine (HEDT) impellers were used to investigate the influence of impeller position and rotational speed on the gas dispersion. The critical rotational speed for complete gas dispersion, agitation power consumption, and overall gas holdup were clarified. It was found that for both HEDT and WH impellers, the critical Froude number (Fr) decreased significantly with increasing gas flow number (FlG). Under the same gassing rate, the critical complete dispersion Froude number of the HEDT impeller was generally higher than that of WH impeller, and also the agitation power required for complete dispersion was greater. Additionally, relative power demand (RPD) decreased as FlG increased, and this decreasing trend accelerated at higher L/D ratios. At different impeller positions, the relative power demand of the HEDT impeller was higher than that of the WH impeller, indicating that the agitation power of the HEDT impeller was less affected by the gas than the WH impeller. Notably, the impeller installation height had an obvious impact on gas holdup and power consumption. When the ratio of the vertical distance between the impeller center and the upper edge of the porous distributor (L) to the impeller diameter (D) was 0.75, a higher gas holdup and lower power comsuption were observed. This work provides crucial theoretical and data support for optimizing the design of gas-liquid stirred tanks with gas sparging. It holds clear engineering application value for enhancing mass transfer efficiency and energy-saving operation in chemical processes.

Experimental study on classification performance of multi-arm vortex separator

Binghao YUAN Jiaxu ZHANG Chenglin E Chunxi LU

The Chinese Journal of Process Engineering. 2026, 26(4):  381-389.  DOI: 10.12034/j.issn.1009-606X.225246

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The development of efficient catalyst classification technologies is crucial for optimizing fluid catalytic cracking (FCC) and catalytic pyrolysis coupling processes, where distinct particle size distributions are required for different reaction pathways. In this study, a large-scale cold-model experimental platform of a multi-arm vortex separator is established to explore the influence of operating conditions on classification behavior. Systematic experiments are conducted by changing ejection gas velocity (8~20 m/s), inlet particle concentration (30~70 g/m3), and bed linear velocity (0.15~0.25 m/s). The results demonstrate that ejection gas velocity governs classification sharpness by controlling the entrainment of fines within the coarse fraction. The increase in ejection gas velocity enlarges the upward axial gas velocity inside the device, thereby enhancing the entrainment effect on particles near the vortex arm outlets. Increasing the ejection gas velocity from 12 to 16 m/s reduces proportion of fine particles in coarse components from 14% to 12%. The inlet particle concentration imposes competing effects on classification performance: while higher concentrations promote agglomeration and modify turbulence distribution, and excessive loading intensifies fine-particle entrainment, thereby diminishing classification selectivity. The system maintains stable pressure drop characteristics under different bed linear velocities, with the pressure drop increasing by maximum of about 15% when the bed linear velocity is raised from 0.15 m/s to 0.25 m/s. Analysis of grade efficiency curves reveals classical S-shaped profiles with cut sizes (dc50) shifting under different operating regimes. Higher particle concentrations reduces dc50, favoring fine-particle removal, while higher ejection gas velocities enlarge dc50, moving the classification boundary toward larger sizes. These findings confirm the synergistic effect of ejection gas velocity and inlet concentration, highlighting that rational parameter matching can simultaneously improve efficiency and selectivity. Beyond the experimental findings, this work emphasizes the broader applicability of multi-arm vortex separators in refining and petrochemical processes. By enabling precise adjustment of particle size distribution, the system offers a promising pathway for enhancing catalyst utilization, extending catalyst lifetime, and facilitating process intensification in coupled FCC-pyrolysis units.

Scalable green synthesis of 1-butyl-3-methylimidazolium chloride

Zhiyong LI Jinfa FANG Linming WANG Min LIU

The Chinese Journal of Process Engineering. 2026, 26(4):  390-396.  DOI: 10.12034/j.issn.1009-606X.225227

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Imidazolium-based ionic liquids (ILs) have garnered significant attention as foundational materials in sustainable chemical engineering, owing to their negligible volatility, exceptional thermal stability, and highly tunable structural properties. These characteristics make them particularly valuable for applications such as green solvents, advanced catalysis, and energy storage. This research detailed a comprehensive investigation into the development, optimization, and analysis of an industrial-scale green synthesis pathway for 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), which was prepared through a quaternization reaction using N-methylimidazole and 1-chlorobutane as raw materials.Subsequently, reaction parameters were optimized and the implementation of process intensification strategies to enhance production efficiency and environmental sustainability. Experimental results combined with economic analysis identified the optimal synthesis conditions as a reaction temperature of 76℃, N-methylimidazole to 1-chlorobutane molar ratio of 1∶1.3, and a reaction time of 36 h. Under these optimized parameters, a consistently high single-pass yield of 95.6% was achieved. Kinetic studies revealed that there was a significant correlation between reaction temperature, reactant molar ratio, and conversion efficiency. The calculated activation energy (Ea≈135.7 kJ/mol) indicated a pronounced temperature dependence of the reaction rate. Building upon reaction optimization, a pivotal aspect of this work involved the design and implementation of an advanced closed loop material recycling system. This integrated internal recycling mechanism enabled the near-complete recovery and reuse of unreacted feedstocks and solvents, achieving high recovery rates of 99.5% for 1-chlorobutane and 98.1% for ethyl acetate. By significantly curtailing raw material consumption and waste generation, this approach aligned intrinsically with green chemistry principles and propelled the process toward near zero emissions. In conclusion, this pathway not only offers a scalable model for the manufacture of [Bmim]Cl, but also provides a transferable strategy for the synthesis of other value-added ionic liquids, thereby representing a substantial advancement in the field of sustainable process engineering.

Study on the effect of foaming agent on the performance of phosphogypsum-based lightweight ceramsite

Guangchao WU Kaixuan CHEN Ruiying WANG Haiyang HU Jiamao LI Weihong XU Canhua LI

The Chinese Journal of Process Engineering. 2026, 26(4):  397-405.  DOI: 10.12034/j.issn.1009-606X.225200

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Phosphogypsum is a by-product generated during the wet-process production of phosphoric acid, with enormous annual output. The stockpiling of large quantities of phosphogypsum not only occupies considerable land resources but may also cause environmental and safety issues such as heavy metal leaching, soil salinization-alkalization, and dump collapses. The resource utilization is therefore urgently needed. At present, phosphogypsum is mainly applied in agriculture, industry, and the construction industry. Due to its complex composition, the utilization is challenging owing to the high pretreatment cost. Based on the concept of waste recycling, this study uses phosphogypsum as the main raw material, supplemented by ground granulated blast furnace slag, fly ash, and type II anhydrite. Two foaming agents, sodium bicarbonate and aluminum powder, were adopted to regulate the pore structure, and the effects of different foaming agents on the performance of ceramsites are compared and analyzed. The sample with the highest cylinder compressive strength is further characterized by XRD, SEM, and BET to investigate its micromechanism. The results demonstrate that the type of foaming agent significantly influences the porosity, bulk density, and cylinder compressive strength of ceramsites. Under identical preparation conditions, the 7 d cylinder compressive strength of ceramsites prepared with aluminum powder is higher than that prepared with sodium bicarbonate. With appropriate raw material proportions and a suitable foaming agent, the non-fired ceramsite achieves a maximum cylinder compressive strength of 6.5 MPa, which basically meets the strength requirements for aggregates in lightweight aggregate concrete. This study realizes the green preparation of non-fired ceramsite with favorable environmental and economic benefits, and provides a new way for the large-scale utilization of phosphogypsum.

Synergistic optimization mechanism of microstructure and magnetic properties in M-type strontium ferrite via Ce/La co-doping and pre-sintering temperature regulation

Huilin SHAN Pengjie ZHANG Jiquan WANG Jiajia SI Kuikui SONG Guangqing XU

The Chinese Journal of Process Engineering. 2026, 26(4):  406-417.  DOI: 10.12034/j.issn.1009-606X.225188

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Driven by the urgent demand for green and low-carbon technologies, the development of high-performance and cost-effective rare-earth free permanent magnets has emerged as a key research focus for sustainable energy and advanced electronic applications. Among various candidates, M-type strontium ferrites have attracted considerable attention due to their excellent thermal stability, high magnetocrystalline anisotropy, and abundant raw material availability. In this study, Sr0.41La0.36Ca0.23Fe11.8Co0.2O19 was selected as the base system, and a series of samples were synthesized via a solid-state reaction combined with high-energy ball milling. The synergistic effects of varying CeO2/La2O3 mass ratios (0∶10 to 10∶0) and pre-sintering temperatures (1150~1200℃) on the microstructure and magnetic properties were systematically investigated. Microstructural analyses revealed that moderate Ce substitution effectively induced controlled lattice distortion and promoted densification, which inhibited abnormal grain growth and refined the microstructure. Such structural modulation not only enhanced domain wall pinning but also improved magnetocrystalline anisotropy, leading to a remarkable increase in coercivity. Magnetic measurements confirmed that the composition with a CeO2/La2O3 mass ratio of 2∶8 and pre-sintered at 1180℃, achieved the most balanced magnetic performance, exhibiting enhanced coercivity, sufficient remanence, and stable saturation magnetization.This work provides new insights into the cooperative effects between rare-earth doping ratios and thermal processing parameters, clarifying how lattice defects, grain boundary characteristics, and microstructural evolution collectively govern the magnetic properties of M-type ferrites. The findings establish a practical strategy for tailoring the microstructure-property relationship in rare-earth free permanent magnets, opening an optimized processing window for scalable fabrication of environmentally friendly, high-performance ferrite materials.

Efficient recovery of Li and Co from spent lithium-ion batteries with deep eutectic solvent

Libin TANG Mingqiang CHENG Zhipeng ZHOU Juanjian RU Cunying XU Yixin HUA Ding WANG

The Chinese Journal of Process Engineering. 2026, 26(4):  418-426.  DOI: 10.12034/j.issn.1009-606X.225221

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With the continuous expansion of various electronic equipment markets, lithium-ion batteries (LIBs) are widely used in numerous fields. This trend has also brought about the challenge of recycling a growing number of retired and spent LIBs. Although traditional pyrometallurgical and hydrometallurgical recovery technologies have become relatively mature, several issues remain to be addressed. For example, pyrometallurgical processes suffer from relatively low metal recovery efficiencies, while conventional acid/alkali leaching processes often require the addition of extra precipitants to recover certain metals. In this work, a new strategy is proposed for the clean and efficient recovery of Li and Co from spent LiCoO2 cathode materials using a ChCl-OA-H2O deep eutectic solvent (DES). The method involves the selective separation of Co as cobalt oxalate (CoC2O4?2H2O) via preferential precipitation, followed by the direct recovery of Li by adjusting the water content. The entire recovery process requires no additional reagents and is both simple and environmentally friendly. Under optimal conditions (molar ratio 1∶1∶8, solid-liquid ratio 100 g/L), the leaching efficiency of Li can reach 99.4%, and the recovery efficiencies of Li and Co are 88.3% and 97.8%, respectively, demonstrating excellent metal separation and recovery performance. Furthermore, the DES system exhibited good cycling stability, maintaining Li and Co recovery efficiencies of 78.1% and 92.8% after six cycles, which highlights the sustainability and economic potential of the process for practical applications. This study not only provides an efficient and low-pollution technological pathway for battery recycling, but also offers theoretical support and practical evidence for the sustainable cycling of resources, demonstrating significant environmental benefits and promising industrial application potential.

Improvement of homogeneity for direct cooling battery thermal management system in electric vehicles under dynamic operating conditions

Xijiao ZHU Xiaona MA Huaxia YAN Yi CHEN

The Chinese Journal of Process Engineering. 2026, 26(4):  427-436.  DOI: 10.12034/j.issn.1009-606X.225159

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Lithium-ion batteries are widely used in electric vehicles due to their high energy density, long cycle life, and excellent stability. However, the significant heat generation caused by power fluctuations under dynamic driving conditions poses substantial challenges to the safety and longevity of the battery. These temperature variations, especially during rapid acceleration or deceleration, can accelerate battery degradation and even thermal runaway. Most existing research focuses on the thermal behavior of batteries under fixed ambient temperatures or constant discharge rates, which fail to fully replicate the diverse and fluctuating conditions that batteries experience in real-world dynamic operations. To address this gap, this study investigates the thermal performance of a battery pack under three typical dynamic operating conditions: steady operation, alternating load operation, and progressive acceleration operations. The experimental results show that at an ambient temperature of 35℃, the direct cooling thermal management system meets the temperature control requirements during steady operation and alternating load operation. However, under progressive acceleration operations, the battery pack's maximum surface temperature reaches 49.8℃, accompanied by a significant temperature difference of 16.5℃, both of which pose risks to battery safety and performance. After the installation of fins, the maximum temperature is reduced to 40.9℃, and the temperature difference drops to 5.0℃. The longitudinal temperature difference decreases from 11.2℃ to 4.6℃, and the transverse temperature difference decreases from 5.9℃ to 1.2℃. The addition of fins not only enhances longitudinal heat conduction but also helpes mitigate the transverse temperature imbalance. These findings underscore the importance of optimizing thermal management strategies. This study provides valuable experimental data to guide the development of more effective thermal management systems for lithium-ion batteries in electric vehicles, ultimately contributing to improved battery safety and longevity under real-world driving conditions.

Activation of peroxymonosulfate-based advanced oxidation via Co@Si-A for tetracycline degradation: performance and mechanism

Shihua ZHANG1, 3, Qiao HUANG1, Biming LIU2, 3, Yiyun LIU2, 3, Wenfei WU1, Xiangcheng WU1, Dewei ZHANG4

The Chinese Journal of Process Engineering. 2026, 26(4):  437-452.  DOI: 10.12034/j.issn.1009-606X.225204

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A one-step sol-gel synthesis method was employed to fabricate cobalt-doped silica aerogel (Co@Si-A) catalysts in this study, which were subsequently applied for activating peroxymonosulfate (PMS) to degrade tetracycline (TC). The experimental results demonstrated that the catalyst with a 25wt% cobalt doping ratio (25Co@Si-A) exhibited the most superior catalytic performance, achieving an exceptionally high TC degradation efficiency of 98.97% under the specified test conditions. Brunauer-Emmett-Teller (BET) analysis revealed that the 25Co@Si-A catalyst possessed a high specific surface area and a well-developed porous architecture rich in nano-confined spaces. The synergistic 25Co@Si-A/PMS system displayed outstanding adaptability, effectively operating over a broad pH range from 5 to 9. Furthermore, the system demonstrated strong resistance to interference from sulfate (SO_4^(2-)) and nitrate (NO_3^-) ions. To elucidate the underlying reaction mechanisms, comprehensive analyses were conducted, including electron paramagnetic resonance (EPR) spectroscopy, radical quenching experiments, and probe compound tests. These investigations collectively confirmed that the highly efficient degradation of TC through the 25Co@Si-A/PMS system was attributed to a synergistic combination of radical and non-radical pathways. The primary reactive species involved were free radicals, dominated by sulfate radicals (SO_4^(2-)) with contributions from hydroxyl radicals (?OH), and non-radical singlet oxygen (1O2). The degradation mechanism was further enhanced by the nano-confined effect inherent to the aerogel's structure. This effect promoted several key processes: the concentration and enrichment of reactant molecules (both PMS and TC) within the pores, the increased exposure and accessibility of active catalytic sites, and the enhancement of electron transfer efficiency, which is crucial for the reaction. In conclusion, this research provides a novel and promising strategy for utilizing silica aerogel-based materials to activate PMS for the effective removal of tetracycline. The study offers substantial theoretical insights and crucial technical support for the future development and design of innovative cobalt-based catalytic materials supported on silica aerogels for advanced oxidation processes in water treatment applications.