The Chinese Journal of Process Engineering

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The Chinese Journal of Process Engineering. 2025, 25(1): 0.

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Design and preparation of targeted drug loading systems for treatment of Alzheimer's disease

Jiayuan QIU Xi CHEN Xiaoqian YE Lilong ZHOU Jimmy YUN

The Chinese Journal of Process Engineering. 2025, 25(1): 1-19. DOI: 10.12034/j.issn.1009-606X.224086

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Alzheimer's disease (AD) is a very common progressive and destructive degenerative disease of the central nervous system that affects the quality of life of the elderly and poses a serious risk to their lives, placing a huge economic burden on families, society and the state. There are not many breakthroughs as well as innovations in current medications for the treatment of AD, and there is also the challenge of breaking through the blood-brain barrier, and improper treatment may lead to adverse reactions in patients. Targeted drug delivery system, as an effective therapeutic modality, can significantly reduce the concentration of drugs in the blood, the frequency of drug delivery and the drug toxicity, while increasing the concentration and efficacy of drugs at the target site and drug bioavailability, as well as providing a slow-release effect for drugs. In addition, the targeted drug delivery system is also expected to penetrate the blood-brain barrier, improve blood-brain penetration, realize brain targeting, and deliver drugs precisely, thus providing an efficient and safe way to treat AD. This work reviews the pathogenesis of AD, the non-pharmacological methods of adjuvant drug therapy for the treatment of AD as well as the mechanism of action and side effects of the main drugs targeting amyloid β protein (Aβ) aggregation, acetylcholinesterase inhibition, and receptor antagonism, etc. It also briefly introduces and combs through as well as summarizes the targeting drug delivery systems for the treatment of AD such as magnetic nanoparticles, liposomes, and so forth, points out the problems that exist at the moment, puts forward the possible solutions, and indicates the direction of possible development in the future.

Study of ammonium salt crystallization behavior in high pressure heat exchanger of hydrogenation unit

Jianwen ZHANG Guoqing SU Leilei FENG Yan LI Fan ZHANG Shilin LU Yahui ZHAO Gang SHENG

The Chinese Journal of Process Engineering. 2025, 25(1): 20-33. DOI: 10.12034/j.issn.1009-606X.224129

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The problem of ammonium salt crystallization is very important for the safe production of the heat exchange system in hydrogenation plant, which often leads to blockage, corrosion leakage, and unplanned shutdown of the heat exchange system. It is of great significance to the study of the crystallization process and distribution characteristics of ammonium salt. In order to explore the problem of ammonium salt corrosion failure in the high pressure heat exchanger of diesel hydrogenation plant, the ammonium salt crystallization temperature was determined based on the concentration of components, and the C++ ammonium salt crystallization model and user-defined function (UDF) were written. Through isoparametric modeling of the heat exchanger, numerical simulations of the multiphase flow field, heat and mass transfer processes were carried out using ANSYS Fluent finite element analysis software and embedded UDF to analyze the intrinsic causes of corrosion failure. The mechanism of ammonium salt crystallization can be divided into heat transfer control and mass transfer control. The simulated ammonium chloride crystallization corrosion location and the actual corrosion coincided. The significant factors that influence the ammonium salt crystallization can be get through the orthogonal experimental analysis. The independence of the significant factors were analyzed to get the specific impact on the ammonium salt crystallization. Further, it provides a basis for the optimization of process device operation.

Multi-objective parameter identification method for methanation reaction kinetics combined with process simulation

Zhuohang JIN Xiaoxia HAN Fengyi LIU

The Chinese Journal of Process Engineering. 2025, 25(1): 34-43. DOI: 10.12034/j.issn.1009-606X.224091

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The simulation model of the methanation reactor can guide the optimization of the methanation process, which is of important research significance. However, the construction of the methanation reactor simulation model involves two parts: reactor modeling and reaction kinetics modeling, and the two models are coupled with each other. Neglecting the reactor transferring role and considering the kinetic model alone or solving the reactor model from the chemical equilibrium point of view without focusing on the kinetics will lead to low simulation accuracy, which makes it difficult to guide the optimization of the process effectively. The multi-objective optimization algorithm is used to identify the kinetic parameters of the methanation reactor model built in Aspen Plus, which can achieve high-precision identification of the parameters of the kinetic equation set with fewer data points, and the method can effectively solve the problem of identifying the parameters of the kinetic equation set in the complex reaction process by considering the reactor action and reaction kinetics at the same time. The results show that the multi-objective parameter identification method of the methanation reactor process simulation model can reduce the root-mean-square errors of CO conversion and CH4 selectivity simulation results to 1.96% and 4.59%, respectively, which are lower than those of the existing kinetic models.

Preparation and characterization of abrasion-resistant core-shell alumina support used in fluidized bed reactors

Yinhu ZHANG Zhanguo ZHANG Guangwen XU

The Chinese Journal of Process Engineering. 2025, 25(1): 44-52. DOI: 10.12034/j.issn.1009-606X.224170

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The Ni-based catalyst used in fluidized bed methane dry reforming reaction needs to have both high abrasion resistance and high activity, which requires the catalyst support itself to have both good abrasion-resistance and high Ni loading capacity. Based on the phase transformation mechanism of Al2O3, this study aims to prepare a type of core-shell @Al2O3 support with its shell in abrasion-resistant α-phase and its core in porous γ- or θ-phase Al2O3 through calcination of γ-Al2O3 at high temperatures. For this purpose, commercially available mesoporous γ-Al2O3 particles with a specific surface area of 325 m2/g and an average particle size of 850 μm were used as precursor material and calcinated in a vertical high temperature furnace at different temperatures for different periods of time. For prepared @Al2O3 samples, X-ray diffraction (XRD) analysis and N2 isothermal adsorption-desorption measurement were performed to characterize their phase transformation degree; electron microscopy (SEM) observation of their particles' cross-sections was conducted to confirm the formation of core-shell structure. And cold- and hot-state fluidized bed abrasion tests were carried out to evaluate their abrasion-resistance. The XRD results obtained have shown that the target core-shell @Al2O3 support can be prepared by calcination of porous γ-Al2O3 particles at 1250, 1300, and 1370℃ for different periods of time. SEM and BET characterization results also confirmed that the core-shell @Al2O3 particles with a shell thickness of 30~50 μm, a specific surface area of 86 m2/g and an average pore size of 22 nm were successfully prepared by calcination at 1300℃ for 6 min. The results of the fluidized-bed abrasion tests further confirmed that this core-shell @Al2O3 had the same excellent abrasion resistance as α-Al2O3, and the rate of its weight loss by abrasion at 800℃ was only 0.003wt%/h. At last, with this core-shell @Al2O3 as support, 10wt%Ni@Al2O3 catalyst was prepared in an impregnation approach and its abrasion resistance was evaluated at 800℃ to confirm that it also had the same resistance as α-Al2O3, which strongly suggests that such @Al2O3 supported catalyst has a good application prospect in fluidized bed reactor systems.

Mechanism analysis of COSMO-RS screening ionic liquid to separate isopropanol-acetonitrile

Jungang FAN Yue MENG Mingxin HE Jiarui HAO Wenxiu LI

The Chinese Journal of Process Engineering. 2025, 25(1): 53-61. DOI: 10.12034/j.issn.1009-606X.224115

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The efficient separation of alcohol-nitrile azeotropes produced in chemical production is a difficult problem in the chemical industry, and the widely used extractive distillation techniques in this field have put forward further requirements for the selection of extractants and mechanism analysis. The COSMO-RS model can be used to predict the thermodynamic properties of the fluid through quantitative calculation, and select the ionic liquids (ILs) extractant agent suitable for a certain system from a large number of possible solvents, which can significantly reduce the experimental amount and enhance the research efficiency. By comparing the model prediction value with the experimental value, the accuracy of the COSMO-thermX software in predicting the separation of alcohol and nitrile azeotropes by ionic liquid has been verified. Based on the COSMO-RS model, with the separation selectivity of ILs, the influence of ILs on the relative volatility of isopropyl alcohol (IPA)-acetonitrile (MeCN) near boiling point and the solubility of ILs to IPA as indexes, the effects of 456 ILs composed of 24 cations and 19 anions on the separation of IPA-MeCN azeotrope were calculated and analyzed. The results showed that ammonium tetraethylacetate ([N2,2,2,2][Ac]) was the best extractant. The interaction between IPA-MeCN molecules in the mixture and [N2,2,2,2][Ac] was studied by means of excess enthalpy analysis, interaction energy analysis and weak interaction analysis, and the separation mechanism of [N2,2,2,2][Ac] as an extractant for separating IPA-MeCN at molecular level was discussed, and the results showed that the interaction between [N2,2,2,2][Ac] and IPA was stronger than that with MeCN, thereby accelerating the disruption of the original azeotropic structure. The assistance of the COSMO-RS model in screening ILs extractants and analyzing separation mechanisms provided important information for further understanding the function of ionic liquid in azeotropic system separation, and had important reference value for the development of novel extractive distillation technologies.

Mechanism and kinetics of alkaline leaching for low-grade bauxite activated by pre-roasting

Tianxiang CHEN Haijun MA Kaifeng PANG Yuantao WANG Yifei ZHANG

The Chinese Journal of Process Engineering. 2025, 25(1): 62-69. DOI: 10.12034/j.issn.1009-606X.224137

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In recent years, as the production of alumina in China has sharply increased, the available high-quality bauxite resources have fallen short for alumina in China. Meanwhile, the amount of low-grade bauxite resources, i.e., containing high-sulfur and carbon, with a low aluminum-to-silicon ratio, is underused due to the lack of available technology. The depletion of high-quality bauxite resources and the utilization problem of low-grade bauxite ores have become the main bottlenecks restricting the sustainable development of the alumina industry in China. Therefore, the effective utilization of low-grade bauxite resources is of great significance for the sustainable development of the alumina industry in China. To solve this issue, the present study employed a potential process of sodium nitrate pre-roasting activation coupled with leaching in low-alkali solution for low-grade bauxite. The bauxite and pre-roasted clinker were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), etc. The effects of technical parameters such as the temperature of pre-roasting bauxite alkali leaching, leaching time, and solid-liquid ratio on the leaching of alumina were studied in detail, focusing on the mechanism and kinetics of low-alkali leaching of pre-roasted bauxite. The results showed that after pre-roasting with sodium nitrate, the microstructure of the bauxite became loose, exhibiting a porous and grooved structure. Under the appropriate leaching conditions with a solid-to-liquid ratio of 300 g/L, using a lower concentration of caustic soda solution 160 g (Na2O)/L compared to the traditional Bayer process for 60 minutes at 270℃, 87.22% alumina of the pre-roasted bauxite with an original aluminum-to-silicon ratio of 3.57 was leached, and the aluminum-to-silicon ratio of red mud reduced to 0.88. This method could effectively improve the leaching rate of alumina in the bauxite and overcome the limitation of the theoretical leaching rate of Bayer process. The apparent activation energy for the leaching of alumina in the pre-roasted bauxite was regressed as 23.21 kJ/mol, the leaching process was controlled by mixed mechanisms.

Effect of annealing on microstructure and mechanical properties of cold-rolled 430 ferritic stainless steel

Shuaikang XU Xiaoyu SUN Lin CHEN Jinghui LI Mingya ZHANG

The Chinese Journal of Process Engineering. 2025, 25(1): 70-79. DOI: 10.12034/j.issn.1009-606X.224124

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After cold-rolled deformation of 430 ferritic stainless steel at room temperature with a 55% reduction, the annealing treatments were carried out at 800, 850, 900, 950, and 1000℃ for 15 min, followed by in?situ tensile and nanoindentation tests. The microstructure and mechanical properties of 430 ferritic stainless steel were studied by field emission scanning electron microscopy (SEM), electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM). The results indicated when the annealing temperature increased from 800 to 850℃, the recrystallization proportion of the cold-rolled microstructure of the sample gradually increased, the recrystallization proportion increased from 66% to 68%, and the average grain size decreased significantly, from 9.23 μm to 8.07 μm. At this time, the microstructure of the sample was mainly affected by grain refinement, and the strength and plasticity of the sample were improved to a certain extent. The hardness also showed a certain degree of improvement. When the annealing temperature increased from 900℃ to 1000℃, the recrystallization ratio of the cold-rolled specimens increased from 71% to 89%, the average grain size increased by about 1.5 times, the dislocation density decreased significantly, the strength of the specimens decreased while the plasticity increased, and the hardness decreased significantly. When the sample was annealed at 850℃, the grain size in the structure is small and uniform, the yield strength reached 882 MPa, the elongation reached 17.5%, and the hardness value wass 2.08 GPa, indicating good microstructural and mechanical properties. Therefore, the optimal annealing process of 430 ferritic stainless steel was held at 850℃ for 15 min.

Evolution of cementite in high strength pearlitic steel wires during drawing

Yan WU Jianyu JIAO Fengmei BAI Hongwei ZHOU Gang ZHAO Jun XUE Guangwen ZHENG

The Chinese Journal of Process Engineering. 2025, 25(1): 80-88. DOI: 10.12034/j.issn.1009-606X.224150

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Cold-drawn pearlitic steel wire is widely used because of its high strength and certain toughness. In the process of cold drawing, the evolution of cementite lamellae has an important influence on the strength and toughness of steel wire. In this work, high-carbon steel wire rod with a diameter of 7.81 mm is selected, and the series of high-strength pearlite steel wires with different diameters are obtained by multi-pass cold drawing until the maximum true strain reached to 2.18. The evolution law and microscopic mechanism of cementite lamellae evolution during cold drawing are observed by transmission electron microscope (TEM) and scanning electron microscope (SEM) methods. The results show that during steel wire drawing, the longitudinal fibrous pearlite structure becomes more obvious with the increase of strain, and pearlite lamellae composed of ferrite and cementite are gradually adjusted to the drawing direction, and all of them are parallel to the drawing direction at the strain of 2.18. Complex changes have taken place in the cementite lamellae during drawing, which are characterized by lamellar refinement, bending and fracture in morphology, and polycrystalline, amorphous and nanocrystalline phenomena in microstructure. When the pearlitic lamellar orientation is nearly parallel to the drawing direction, interlamellar spacing gradually decreases, the lamellar arrangement direction gradually turns to the drawing direction, and the cementite lamellae become amorphous and nanocrystalline. When pearlite lamellae are nearly perpendicular to the drawing direction, cementite lamellae are bent, fractured and crystallized. At low drawing strain, dislocations mainly move in ferrite phase with a single slip, forming dislocation lines. At high strain, dislocations transform into multi-slip motions, generating dislocation tangles and dislocation cells, and some dislocations slip across the α-ferrite/cementite interfaces. Dislocation interacts strongly with cementite, and the lattice distortion in cementite increases, which is the main reason for the complex changes of cementite lamellae during cold drawing.

Pilot investigation of catalytic oxidative removal of carbon monoxide from alumina industrial flue gas

Xinglong GU Yang LI Changming LI Zijun GONG Huanyuan NING Ruijian TANG Jian YU

The Chinese Journal of Process Engineering. 2025, 25(1): 89-100. DOI: 10.12034/j.issn.1009-606X.224114

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The calcination process of the alumina industry usually produces nearly 10 000 mg/m3 CO in the flue gas during the combustion process due to low temperature or low excess air coefficient. Direct emissions not only causes energy waste but also causes harm to the local atmosphere. To explore the industrial application feasibility for catalytic elimination of CO from flue gas in alumina calcination, the manganese-cerium particulate industrial catalysts were prepared by co-precipitation method, and the pilot application study with flue gas volume of 1000 Nm3/h was carried out in an aluminum company of Shandong Province. The pilot test results showed that under the condition of low sulfur (<10 mg/m3), when the inlet temperature was 170℃, the CO removal rate was 80%~85%, and the removal rate was above 90% when the temperature was above 200℃. The catalyst was used in the pilot test to run continuously for 500 h at the inlet temperature of 190~200℃. It was found that there was no significant decrease in activity as a whole, indicating that the manganese-cerium catalyst had good stability in the purification of CO gas under actual working conditions. After 500 h of pilot-scale catalyst operation, the catalyst samples at different positions of the fixed bed were analyzed, and it was found that the catalyst performance at the flue gas inlet decreased slightly. The characterization results of typical samples such as XRD, TG, BET, SEM-EDS, and H2-TPR showed that the crystal diffraction peak of the catalyst sample at the flue gas inlet was enhanced, the specific surface area was decreased, and the sulfur deposition was increased, indicating that the local heating sintering and sulfur deposition were the main reasons for the partial deactivation of the catalyst.

Modal visualization of heterogeneous condensation of water vapor on the surface of a single particle

Xiangcheng WU Li LÜ Lijuan QIAN

The Chinese Journal of Process Engineering. 2025, 25(1): 101-110. DOI: 10.12034/j.issn.1009-606X.224142

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Heterogeneous condensation of water vapor on particle surfaces is a highly valuable industrial pretreatment technique for dust removal. Heterogeneous condensation of water vapor on particle surfaces can significantly improve the efficiency of dust removal. To study the dynamic behavior of droplets on the surfaces of particle during the process of heterogeneous condensation, the environmental scanning electron microscope (ESEM) is employed for visual observation of the heterogeneous condensation process of water vapor on particle surfaces. The evolution process of droplet mode is studied, and the contribution of line tension to the Gibbs free energy of the system during the condensation process and the influence of particle size and contact angle on line tension are analyzed. The results indicate that particles first nucleate to form a critical embryo droplet. This embryo droplet continues to grow and rapidly spreads to the equator of the particle. The droplet then remains on the equator, undergoing continuous condensation and growth, gradually transitioning to crossing the equator. With increasing condensation time, the droplet gradually envelops the particle. Once the particle is completely enveloped, the heterogeneous condensation transforms into homogeneous condensation and continuous growth. The entire condensation process can be divided into five modes: nucleation, diffusion, transition, encapsulation, and growth. The line tension of the five modes is analyzed, and it is found that when the droplet is in the upper hemisphere of the particle, the closer it is to the equatorial line, the greater the contribution of the line tension to the Gibbs free energy change of the system, which promotes its movement towards the equatorial line, and when it is in the lower hemisphere, it promotes its encapsulation of the particle. The effects of particle size and contact angle on the line tension are numerically studied, and it is found that the line tension increased with the increase of particle size. The influence of the intrinsic contact angle of the particle on the line tension is small, but the bigger the difference between the particle and the apparent contact angle, the greater the line tension.

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