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Liquid-phase esterification of methacrylic acid with methanol catalyzed by cation-exchange resin in a fixed bed reactor: Experimental and kinetic studies
Junyang Liu, Luming Wang, Yuhang Bian, Chunshan Li, Zengxi Li, Jie Li
Chinese Journal of Chemical Engineering    2023, 58 (6): 1-10.   DOI: 10.1016/j.cjche.2022.10.011
Abstract141)      PDF(pc) (3644KB)(209)       Save
The kinetic behavior of esterification between methacrylic acid and methanol catalyzed by NKC-9 resin was studied in a fixed bed reactor. The reaction was conducted in the temperature range of 323.15 to 368.15 K with the molar ratio of reactants from 0.8 to 1.4 under certain pressure. The measurement data were regression with the pseudo-homogeneous (P-H), Eley-Rideal (E-R), and Langmuir-Hinshelwood (L-H) heterogeneous kinetic models. Independent adsorption experiments were implemented to gain the adsorption equilibrium constants of four components. Among the above three models, the L-H model exhibited the best fitting results. The stability of NKC-9 was evaluated by long-term running with the yield of methyl methacrylate no decrease during 3000 h operation. The structure and physicochemical properties of the new and used catalyst were performed by several characterizations including thermogravimetric analysis (TG), scanning electron microscope (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) and so on.
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Attention-based long short-term memory fully convolutional network for chemical process fault diagnosis
Shanwei Xiong, Li Zhou, Yiyang Dai, Xu Ji
Chinese Journal of Chemical Engineering    2023, 56 (4): 1-14.   DOI: 10.1016/j.cjche.2022.06.029
Abstract125)      PDF(pc) (12718KB)(278)       Save
A correct and timely fault diagnosis is important for improving the safety and reliability of chemical processes. With the advancement of big data technology, data-driven fault diagnosis methods are being extensively used and still have considerable potential. In recent years, methods based on deep neural networks have made significant breakthroughs, and fault diagnosis methods for industrial processes based on deep learning have attracted considerable research attention. Therefore, we propose a fusion deep-learning algorithm based on a fully convolutional neural network (FCN) to extract features and build models to correctly diagnose all types of faults. We use long short-term memory (LSTM) units to expand our proposed FCN so that our proposed deep learning model can better extract the time-domain features of chemical process data. We also introduce the attention mechanism into the model, aimed at highlighting the importance of features, which is significant for the fault diagnosis of chemical processes with many features. When applied to the benchmark Tennessee Eastman process, our proposed model exhibits impressive performance, demonstrating the effectiveness of the attention-based LSTM FCN in chemical process fault diagnosis.
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Preparation of aromatic hydrocarbons from catalytic pyrolysis of digestate
Haodi Tan, Minjiao Yang, Yingquan Chen, Xu Chen, Francesco Fantozzi, Pietro Bartocci, Roman Tschentscher, Federica Barontini, Haiping Yang, Hanping Chen
Chinese Journal of Chemical Engineering    2023, 57 (5): 1-9.   DOI: 10.1016/j.cjche.2022.09.002
Abstract114)      PDF(pc) (18189KB)(350)       Save
Catalytic pyrolysis of digestate to produce aromatic hydrocarbons can be combined with anaerobic fermentation to effectively transform and utilize all biomass components, which can achieve the meaningful purpose of transforming waste into high-value products. This study explored whether catalytic pyrolysis of digestate is feasible to prepare aromatic hydrocarbons by analyzing the thermogravimetric characteristics, pyrolysis characteristics, and catalytic pyrolysis characteristics of digestate. For digestate pyrolysis, an increase in temperature was found to elevate the CO, CH4, and monocyclic aromatic hydrocarbon (benzene, toluene, and xylene; BTX) content, whereas it decreased the contents of phenols, acids, aldehydes, and other oxygenates. Furthermore, the catalytic pyrolysis process effectively inhibited the acids, phenols, and furans in the liquid, whereas the yield of BTX increased from 25.45% to 45.99%, and the selectivity of xylene was also increased from 10.32% to 28.72% after adding ZSM-5. ZSM-5 also inhibited the production of nitrogenous compounds.
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Enhanced ortho-selective t–butylation of phenol over sulfonic acid functionalized mesopore MTW zeolites
Baoyu Liu, Feng Xiong, Jianwen Zhang, Manna Wang, Yi Huang, Yanxiong Fang, Jinxiang Dong
Chinese Journal of Chemical Engineering    2023, 60 (8): 1-7.   DOI: 10.1016/j.cjche.2023.02.014
Abstract107)      PDF(pc) (6063KB)(163)       Save
Novel organo-inorganic hybrid materials (MTW-x-SO3H) have been fabricated by immobilizing 3-mercaptopropyltriethoxysilane onto mesopore MTW zeolites, which is treated via a simple oxidation process with hydrogen peroxide as the oxidant to transform sulfhydryl group into sulfonic acid group. The organic sulfhydryl groups are covalently bonded to the external surface of MTW zeolites through the condensation between siloxane arising from organic fragments with silanol groups on the surface of MTW zeolites, the hybrids contain sulfonic acid group within the external surface of MTW zeolites and an opened mesoporous system in the matrix of MTW zeolites, which provide enough accessible Brønsted acid sites for the alkylation between phenol with tert-butyl alcohol. Through this methodology it’s possible to prepare multifunctional materials where the plenty of mesopores are benefit for the introduction of larger numbers of sulfonic acid groups that contributes to activity during reactions, resulting in high activity (>55%) of MTW-4-SO3H and desired selectivity (>56%) of 2-TBP (2-tert-butyl phenol) in the alkylation between phenol with tert-butyl alcohol.
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Effects of heavy metal ions Cu2+/Pb2+/Zn2+ on kinetic rate constants of struvite crystallization
Guangyuan Chen, Tong Zhou, Meng Zhang, Zhongxiang Ding, Zhikun Zhou, Yuanhui Ji, Haiying Tang, Changsong Wang
Chinese Journal of Chemical Engineering    2023, 57 (5): 10-16.   DOI: 10.1016/j.cjche.2022.06.032
Abstract76)      PDF(pc) (9318KB)(180)       Save
Struvite (MAP) crystallization technology is widely used to treat ammonia nitrogen in waste effluents of its simple operation and good removal efficiency. However, the presence of heavy metal ions in the waste effluents causes problems such as slow crystallization rate and small crystal size, limiting the recovery rate and economic value of the MAP. The present study was conducted to investigate the effects of concentrations of three heavy metal ions (Cu2+, Zn2+, and Pb2+) on the crystal morphology, crystal size, average growth rate, and crystallization kinetics of MAP. A relationship was established between the kinetic rate constant Kt calculated by the chemical gradient model and the concentrations of heavy metal ions. The results showed that low concentrations of heavy metal ions in the solution created pits on the MAP surface, and high level of heavy metal ions generated flocs on the MAP surface, which were composed of metal hydroxides, thus inhibiting crystal growth. The crystal size, average growth rate, MAP crystallization rate, and kinetic rate constant Kt decreased with the increase in heavy metal ion concentration. Moreover, the Kt demonstrated a linear relationship with the heavy metal concentration ln(C/C*), which provided a reference for the optimization of the MAP crystallization process in the presence of heavy metal ions.
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Biological oyster shell waste enhances polyphenylene sulfide composites and endows them with antibacterial properties
Chi-Hui Tsou, Rui Zeng, Neng Wan, Manuel Reyes De Guzman, Xue-Fei Hu, Tao Yang, Chen Gao, Xiaomei Wei, Jia Yi, Li Lan, Rui-Tao Yang, Ya-Li Sun
Chinese Journal of Chemical Engineering    2023, 57 (5): 118-131.   DOI: 10.1016/j.cjche.2022.08.022
Abstract74)      PDF(pc) (30168KB)(32)       Save
To date, there is no research that deals with biological waste as fillers in polyphenylene sulfide (PPS). In this study, oyster shells were recycled and treated to prepare thermally-treated oyster shells (TOS), which were used as PPS fillers to make new bio-based antibacterial composite materials. The effect of varying the content of TOS was studied by means of structure and performance characterization. PPS/TOS composites were demonstrated to have an antibacterial effect on the growth of E coli and S. aureus. Qualitative analysis showed that when the TOS content was ≥ 30% and 40%, the composite materials had an apparent inhibition zone. Quantitative analysis showed that the antibacterial activity increased with the TOS content. Fourier transform infrared spectroscopy indicated the formation of hydrogen bonds between the molecular chains of TOS and PPS and the occurrence of a coordination reaction. At 10% TOS, the composite tensile strength reached a maximum value of 72.5 MPa, which is 9.65% higher than that of pure PPS. The trend of bending properties is the same as that of tensile properties, showing that the maximum property was reached for the composite with 10% TOS. At the same time, the crystallinity and contact angle were the highest, and the permeability coefficient was the lowest. The fatigue test results indicated that for the composite with 10% TOS, the tensile strength was 23% lower than static tensile strength, and the yield strength was 10% lower than the static yield strength. The results of the study showed that TOS not only could reduce the cost of PPS, but also could impart antibacterial properties and enhance the mechanical and, barrier properties, the thermostability, as well as the crystallinity.
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The feasibility for natural graphite to replace artificial graphite in organic electrolyte with different film-forming additives
Shaojun Niu, Guobin Zhu, Kai Wu, Honghe Zheng
Chinese Journal of Chemical Engineering    2023, 56 (4): 58-69.   DOI: 10.1016/j.cjche.2022.06.030
Abstract70)      PDF(pc) (13110KB)(227)       Save
The feasibility for natural graphite (NG) to replace artificial graphite (AG) in organic electrolytes with different additives are investigated. Although the strong film-forming additives contributes to form robust solid electrolyte interphase (SEI) film on graphite particle surface, great differences in gas evolution, lithium inventory loss and other side reactions are observed. Lithium bis(oxalato)borate (LiBOB) and fluoroethylene carbonate (FEC) are found more effective and the combination shows to be more promising. In the optimized electrolyte, natural graphite anode exhibits excellent long-term cycling capability. After 800 cycles at high temperature, the capacity retention is comparable to that using artificial graphite. The mechanisms for the capacity-fading of the full cells with AG and NG anode are investigated by ICP, SEM and polarization studies. The results shows that NG electrode consumes more active lithium due to the rough surface and larger volume expansion. The rapid capacity-fading in the initial 100 cycles is related to the instability of the SEI film aroused from large volume expansion. The systematic analysis is inspiriting for the development of high performance lithium ion batteries with reduced cost.
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Impacts of solid physical properties on the performances of a slurry external airlift loop reactor integrating mixing and separation
Tian Zhang, Qingshan Huang, Shujun Geng, Aqiang Chen, Yan Liu, Haidong Zhang
Chinese Journal of Chemical Engineering    2023, 55 (3): 1-12.   DOI: 10.1016/j.cjche.2022.05.001
Abstract68)      PDF(pc) (2292KB)(187)       Save
Solid physical properties are vital for the design, optimization, and scale-up of gas–liquid–solid multiphase reactors. The complex and interactional effects of the solid physical properties, including particle diameter, density, wettability, and sphericity, on the hydrodynamic behaviors in a new external airlift loop reactor (EALR) integrating mixing and separation are decoupled in this work. Two semi-empirical equations are proposed and validated to predict the overall gas holdup and liquid circulating velocity satisfactorily, and then the individual influence of such solid physical properties is further investigated. The results demonstrate that both the overall gas holdup in the riser and the liquid circulating velocity in the downcomer increase with the contact angle, but decrease with particle size, density, and sphericity. Additionally, the impact of the particle size on the liquid circulating velocity is also profoundly revealed on a micro-level considering the particle size distribution. Moreover, the axial solid concentration distribution is discussed, and the uniformity of the slurry is described by the mixing index of the solid particles. The results show that a more homogeneous mixture can be achieved by adding finer particles other than attaining violent turbulence. Therefore, this work lays a foundation for the design, scale-up, and industrialization of the EALRs.
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KOH-assisted aqueous synthesis of ZIF-67 with high-yield and its derived cobalt selenide/carbon composites for high-performance Li-ion batteries
Kai Xue, Yanchun Xue, Jing Wang, Shuya Zhang, Xingmei Guo, Xiangjun Zheng, Fu Cao, Qinghong Kong, Junhao Zhang, Zhong Jin
Chinese Journal of Chemical Engineering    2023, 57 (5): 214-223.   DOI: 10.1016/j.cjche.2022.09.010
Abstract68)      PDF(pc) (154513KB)(184)       Save
To solve the environmental pollution and low yield during the sythesis of zeolitic imidazolate frameworks (ZIFs) and their derived materials, a KOH-assisted aqueous strategy is proposed to synthesize cobalt zeolitic imidazolate framework (ZIF-67) polyhedrons, which are used as precursors to prepare cobalt selenide/carbon composites with different crystal phases (Co0.85Se, CoSe2). When evaluated as anode material for lithium ion batteries, Co0.85Se/C composites deliver a reversible capacity of 758.7 mA·h·g-1 with a capacity retention rate of 90.5% at 1.0 A·g-1 after 500 cycles, and the superior rate capability is 620 mA·h·g-1 at 2.0 A·g-1. The addition of KOH accelerates the production of ZIF-67 crystals by boosting deprotonation of dimethylimidazole, resulting in rapid growth and structures transition from two-dimensional to three-dimensional of ZIF-67 in aqueous solution, which greatly promotes the application of MOFs in the field of energy storage and conversion.
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Measurements of the effective mass transfer areas for the gas–liquid rotating packed bed
Wen Tian, Junyi Ji, Hongjiao Li, Changjun Liu, Lei Song, Kui Ma, Siyang Tang, Shan Zhong, Hairong Yue, Bin Liang
Chinese Journal of Chemical Engineering    2023, 55 (3): 13-19.   DOI: 10.1016/j.cjche.2022.06.002
Abstract66)      PDF(pc) (2324KB)(270)       Save
Rotating packed bed (RPB) is one of the most effective gas–liquid mass transfer enhancement reactors, its effective specific mass transfer area (ae) is critical to understand the mass transfer process. By using the NaOH–CO2 chemical absorption method, the ae values of three RPB reactors with different rotor sizes were measured under different operation conditions. The results showed that the high gravity factor and liquid flow rate were major affecting factors, while the gas flow rate exhibited minor influence. The radius of packing is the dominant equipment factor to affect ae value. The results indicated that the contact area depends on the dispersion of the liquid phase, thus the centrifugal force of rotating packed bed greatly influenced the ae value. Moreover, the measured ae/ap (effective specific mass transfer area/specific surface area of packing) values were fitted with dimensionless correlation formulas. The unified correlation formula with dimensionless bed size parameter can well predict the experimental data and the prediction errors were within 15%.
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Effects of the original state of sodium-based additives on microstructure, surface characteristics and filtration performance of SiC membranes
Yuling Xie, Qilin Gu, Qian Jiang, Zhaoxiang Zhong, Weihong Xing
Chinese Journal of Chemical Engineering    2023, 63 (11): 1-11.   DOI: 10.1016/j.cjche.2023.05.010
Abstract64)      PDF(pc) (10480KB)(357)       Save
Sodium-contained compounds are promising sintering additives for the low-temperature preparation of reaction bonded SiC membranes. Although sodium-based sintering additives in various original states were attempted, their effects on microstructure and surface properties have rarely been studied. In this work, three types of sodium-based additives, including solid-state NaA zeolite residue (NaA) and liquid-state dodecylbenzene sulfonate (SDBS) and water glass (WG), were separately adopted to prepare SiC membranes, and the microstructure, surface characteristics and filtration performance of these SiC membranes were comparatively studied. Results showed that the SiC membranes prepared with liquid-state SDBS and WG (S-SDBS and S-WG) showed lower open porosity yet higher bending strength compared to those prepared with solid-state NaA (S-NaA). The observed differences in bending strength were further interpreted by analyzing the reaction process of each sintering additive and the composition of the bonding phase in the reaction bonded SiC membranes. Meanwhile, the microstructural differentiation was correlated to the original state of the additives. In addition, their surface characteristics and filtration performance for oil-in-water emulsion were examined and correlated to the membrane microstructure. The S-NaA samples showed higher hydrophilicity, lower surface roughness (1.80 μm) and higher rejection ratio (99.99%) in O/W emulsion separation than those of S-WG and S-SDBS. This can be attributed to the smaller mean pore size and higher open porosity, resulting from the originally solid-state NaA additives. Therefore, this work revealed the comprehensive effects of original state of sintering additives on the prepared SiC membranes, which could be helpful for the application-oriented fabrication by choosing additives in suitable state.
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Growth rate of CO2 hydrate film on water–oil and water–gaseous CO2 interface
Tatyana P. Adamova, Sergey S. Skiba, Andrey Yu. Manakov, Sergey Y. Misyura
Chinese Journal of Chemical Engineering    2023, 56 (4): 266-272.   DOI: 10.1016/j.cjche.2022.07.006
Abstract63)      PDF(pc) (3433KB)(22)       Save
It is known that injection of carbon dioxide into the petroleum reservoir (CO2 flooding) is one of the effective methods for enhanced oil recovery. CO2 flooding may be complicated by formation of CO2 hydrate plugs. It makes topical investigation of CO2 hydrate formation in the system gaseous CO2–oil–water. In this work, the growth rates of carbon dioxide hydrate films at the water–oil as well as the water–gas interface are studied in the pressure range of 2.30–3.04 MPa and at temperatures between –5.4 and 5.0 ℃. It is found that the growth rate for the water–oil interface is 3.5 times lower than that for the water–gas interface with carbon dioxide. It is hypothesised that the observed decrease in the growth rate is related to the mechanical resistance of the oil components adsorbed on the interface to the growth of the hydrate film. The growth rate of the film has been shown to depend on the experimental procedure, most likely due to the different initial concentrations of carbon dioxide in the aqueous solutions.
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Tannic acid/Fe3+ interlayer for preparation of high-permeability polyetherimide organic solvent nanofiltration membranes for organic solvent separation
Haike Li, Xindong Li, Guozai Ouyang, Lang Li, Zhaohuang Zhong, Meng Cai, Wenhao Li, Wanfu Huang
Chinese Journal of Chemical Engineering    2023, 57 (5): 17-29.   DOI: 10.1016/j.cjche.2022.09.014
Abstract62)      PDF(pc) (16514KB)(215)       Save
Organic solvent nanofiltration (OSN) membranes have a great application prospect in organic solvent separation, but the development of OSN membranes is mainly restricted by trade-off between permeability and rejection rate. In this work, a TA/Fe3+ polymer was introduced into polyetherimide (PEI) ultrafiltration membranes crosslinked with hexamethylene diamine as the intermediate layer, and OSN membranes with high separation performance and solvent permeability were obtained through interfacial polymerization and solvent activation. The interlayer with high surface hydrophilicity and a fixed pore structure controlled the adsorption/diffusion of the amine monomer during interfacial polymerization, forming a smooth (average surface roughness < 5.5 nm), ultra-thin (separation layer thickness reduced from 150 to 16 nm) and dense surface structure polyamide (PA) layer. The PA--HDA/PEI membrane retained more than 94% of methyl blue (BS) in 0.1 g·L-1 BS ethanol solution at 0.6 MPa, and the ethanol permeation reached 28.56 L-1·m-2·h-1. The average flux recovery ratio (FRR) of PA--HDA/PEI membrane was found to be 84%, which has better fouling resistance than PA-HDA/PEI membrane, and it was found to have better stability performance through different solvent immersion experiments and continuous operation in 0.1 g·L-1 BS ethanol solution. Compared with thin-film composite nanofiltration membranes, the PA--HDA/PEI membrane can be manufactured from an economical and environment-friendly method and overcomes the trade-off between permeability and rejection rate, showing great application potential in organic solvent separation systems.
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Current advances of biocontainment strategy in synthetic biology
Xueying Zhu, Zhaoyang Zhang, Bin Jia, Yingjin Yuan
Chinese Journal of Chemical Engineering    2023, 56 (4): 141-151.   DOI: 10.1016/j.cjche.2022.07.019
Abstract62)      PDF(pc) (4943KB)(89)       Save
Synthetic biotechnology has led to the widespread application of genetically modified organisms (GMOs) in biochemistry, bioenergy, and therapy. However, the uncontrolled spread of GMOs may lead to genetic contamination by horizontal gene transfer, resulting in unpredictable biosafety risks. To deal with these challenges, many effective methods have been developed for biocontainment. In this article, we summarize and discuss recent advances in biocontainment strategies from three aspects: DNA replication, transcriptional regulation, and protein translation. We also briefly introduce the efforts in the biocontainment convention, such as the recent publication of the Tianjin Biosecurity Guidelines for the Code of Conduct for Scientists.
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Scalability of biomass-derived graphene derivative materials as viable anode electrode for a commercialized microbial fuel cell: A systematic review
Mustapha Omenesa Idris, Claudia Guerrero-Barajas, Hyun-Chul Kim, Asim Ali Yaqoob, Mohamad Nasir Mohamad Ibrahim
Chinese Journal of Chemical Engineering    2023, 55 (3): 277-292.   DOI: 10.1016/j.cjche.2022.05.009
Abstract62)      PDF(pc) (1613KB)(26)       Save
Microbial fuel cell (MFC) is an advanced bioelectrochemical technique that can utilize biomass materials in the process of simultaneously generating electricity and biodegrading or bio transforming toxic pollutants from wastewater. The overall performance of the system is largely dependent on the efficiency of the anode electrode to enhance electron transportation. Furthermore, the anode electrode has a significant impact on the overall cost of MFC setup. Hence, the need to explore research focused towards developing cost-effective material as anode in MFC. This material must also have favourable properties for electron transportation. Graphene oxide (GO) derivatives and its modification with nanomaterials have been identified as a viable anode material. Herein, we discussed an economically effective strategy for the synthesis of graphene derivatives from waste biomass materials and its subsequent fabrication into anode electrode for MFC applications. This review article offers a promising approach towards replacing commercial graphene materials with biomass-derived graphene derivatives in a view to achieve a sustainable and commercialized MFC.
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Mechanistic insights into the active intermediates of 2,6-diaminopyridine dinitration
Junao Zhu, Zhirong Yang, Yuanhan Chen, Mingming Chen, Zhen Liu, Yueqiang Cao, Jing Zhang, Gang Qian, Xinggui Zhou, Xuezhi Duan
Chinese Journal of Chemical Engineering    2023, 56 (4): 160-168.   DOI: 10.1016/j.cjche.2022.06.024
Abstract61)      PDF(pc) (4103KB)(14)       Save
Mechanistic understanding of the active intermediates of 2,6-diaminopyridine (DAP) dinitration in the concentrated nitric-sulfuric acid system is of crucial importance for the selectivity control of target product, i.e., 2,6-diamino-3,5-dinitropyridine (DADNP). The active intermediates determining the product selectivity are theoretically studied. The HSO4--NO2+ complex is proposed as the dominant active nitrating intermediate for the first time, which shows low energy barrier (i.e., 10.19 kcal·mol-1,1 kcal = 4.186 kJ) for direct dinitration of DAP to DADNP. The formed water during the reaction results in not only the formation of less active SO42--NO2+ complex, but also the occurance of DAP sulfonation (DAP-SO3H intermediate) to facilitate the formation of mononitration byproduct. Meanwhile, the accompanied thermal effects cause the generation of undesirable pyridine-NHNO2 intermediate, which is difficult to be rearranged to yield DADNP, inhibiting the reaction and thus giving low DAP conversion. The insights reported here elucidates the importance of thermal effects elimination and water content control, confirmed experimentally in the batch- and micro-reaction systems.
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Prediction of NOx concentration using modular long short-term memory neural network for municipal solid waste incineration
Haoshan Duan, Xi Meng, Jian Tang, Junfei Qiao
Chinese Journal of Chemical Engineering    2023, 56 (4): 46-57.   DOI: 10.1016/j.cjche.2022.06.028
Abstract60)      PDF(pc) (12273KB)(313)       Save
Air pollution control poses a major problem in the implementation of municipal solid waste incineration (MSWI). Accurate prediction of nitrogen oxides (NOx) concentration plays an important role in efficient NOx emission controlling. In this study, a modular long short-term memory (M-LSTM) network is developed to design an efficient prediction model for NOx concentration. First, the fuzzy C means (FCM) algorithm is utilized to divide the task into several sub-tasks, aiming to realize the divide-and-conquer ability for complex task. Second, long short-term memory (LSTM) neural networks are applied to tackle corresponding sub-tasks, which can improve the prediction accuracy of the sub-networks. Third, a cooperative decision strategy is designed to guarantee the generalization performance during the testing or application stage. Finally, after being evaluated by a benchmark simulation, the proposed method is applied to a real MSWI process. And the experimental results demonstrate the considerable prediction ability of the M-LSTM network.
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Research progress on the substrate for metal–organic framework (MOF) membrane growth for separation
Wufeng Wu, Xilu Hong, Jiang Fan, Yanying Wei, Haihui Wang
Chinese Journal of Chemical Engineering    2023, 56 (4): 299-313.   DOI: 10.1016/j.cjche.2022.08.008
Abstract60)      PDF(pc) (14004KB)(48)       Save
During the last decade, metal–organic frameworks (MOFs) have been applied in various fields due to their unique chemical and functional advantages. One of the widespread research hotspots is MOF-based membranes for separations, specifically continuous defect-free MOF membranes, which are usually grown on porous substrates. The substrate not only serves as the MOF layer support but also has a great influence on the membrane fabrication process and the final separation performance of the resultant membrane. In this review, we mainly introduce the progress focused on the substrates for MOF membranes fabrication. The substrate modifications and seeding methods aimed at synthesizing high-quality MOF membranes are also summarized systematically.
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Efficient conversion of CO2 into cyclic carbonates under atmospheric by halogen and metal-free poly(ionic liquid)s
Bowen Jiang, Jia Liu, Guoqiang Yang, Zhibing Zhang
Chinese Journal of Chemical Engineering    2023, 55 (3): 202-211.   DOI: 10.1016/j.cjche.2022.05.018
Abstract60)      PDF(pc) (2114KB)(21)       Save
A novel series of halogen free, hydroxyl group containing poly(ionic liquid)s (PILs) was first synthesized from glycerol dimethyl acrylate (GDA) and 1-vinyl imidazole (1-VIM) through free radical polymerization, follow by an alkylation step and an ion-exchange procedure to form the final imidazolium hydrogen carbonate heterogenous catalyst poly(HCO3-OH-n). The chemical and physical properties were investigated by varying the monomer ratio between GDA and 1-VIM. Among them, poly (HCO3-OH-2) exhibited the highest catalytic activity for CO2 cycloaddition, with the yield of chloropropene carbonate 90% under mild conditions (80 ℃, 0.1 MPa, 12 h, 0.15 g catalyst for 32 mmol epichlorohydrin) in the absence of any cocatalyst, metal or solvent. A range of substrates with good to excellent yields under atmosphere was obtained. The poly(HCO3-OH-n) catalyst is collectable and still remains acceptable catalytic activity after six runs. Finally, a preliminary kinetic is calculated on the basis of poly(HCO3-OH-2) with the activation energy value of 79.5 kJ·mol-1. This study highlights that the poly(HCO3-OH-n) enable to reach efficient CO2 conversion under mild conditions.
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Temperature-induced hydrophobicity transition of MXene membrane for directly preparing W/O emulsions
Yingxiang Ni, Can Yuan, Shilong Li, Jian Lu, Lei Yan, Wei Gu, Weihong Xing, Wenheng Jing
Chinese Journal of Chemical Engineering    2023, 55 (3): 59-62.   DOI: 10.1016/j.cjche.2022.05.006
Abstract60)      PDF(pc) (555KB)(153)       Save
Although hydrophilic membranes are desired for reducing resistance to water permeation, hydrophilic surfaces are not used in the water-in-oil (W/O) membrane emulsification process because water spreads on the hydrophilic surface without forming droplets. Here, we report that a hydrophilic ceramic membrane can form a hydrophobic interface in diesel at a higher temperature; interestingly, the experiments show that the contact angle increases when the temperature rises. The hydrophilic membrane surface evolves into a hydrophobic interface, particularly near the boiling point of water, resulting in a water contact angle of 147.5° ±1.2°. This work established a method for preparing W/O monodispersed emulsions by direct emulsification of hydrophilic ceramic membranes at a temperature close to the boiling point of water. Additionally, it made high flux of membrane emulsification of monodispersed W/O emulsions possible, which satisfied the industrial requirements of fluidized catalytic cracking in the petrochemical industry.
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