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Table of Content
28 January 2022, Volume 41 Issue 1
    Struggling as in past, write a glorious future together—CJChE’s 40th anniversary
    Weiyang Fei, Guangsheng Luo
    2022, 41(1):  1-1.  doi:10.1016/j.cjche.2022.01.006
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    Chen Jiayong: Pioneer in hydrometallurgy and chemical engineering disciplines
    Zai-Sha Mao, Huizhou Liu, Chao Yang
    2022, 41(1):  2-5.  doi:10.1016/j.cjche.2021.06.014
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    Green biomanufacturing promoted by automatic retrobiosynthesis planning and computational enzyme design
    Ziheng Cui, Shiding Zhang, Shengyu Zhang, Biqiang Chen, Yushan Zhu, Tianwei Tan
    2022, 41(1):  6-21.  doi:10.1016/j.cjche.2021.08.017
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    Biomanufacturing, which uses renewable resources as raw materials and uses biological processes to produce energy and chemicals, has long been regarded as a production model that replaces the unsustainable fossil economy. The construction of non-natural and efficient biosynthesis routes of chemicals is an important goal of green biomanufacturing. Traditional methods that rely on experience are difficult to support the realization of this goal. However, with the rapid development of information technology, the intelligence of biomanufacturing has brought hope to achieve this goal. Retrobiosynthesis and computational enzyme design, as two of the main technologies in intelligent biomanufacturing, have developed rapidly in recent years and have made great achievements and some representative works have demonstrated the great value that the integration of the two fields may bring. To achieve the final integration of the two fields, it is necessary to examine the information, methods and tools from a bird’s-eye view, and to find a feasible idea and solution for establishing a connection point. For this purpose, this article briefly reviewed the main ideas, methods and tools of the two fields, and put forward views on how to achieve the integration of the two fields.
    Rational design of heterogeneous catalysts by breaking and rebuilding scaling relations
    Wei-Qi Yan, Yi-An Zhu, Xing-Gui Zhou, Wei-Kang Yuan
    2022, 41(1):  22-28.  doi:10.1016/j.cjche.2021.10.025
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    Various scaling relations have long been established in the field of heterogeneous catalysis, but the resultant volcano curves inherently limit the catalytic performance of catalyst candidates. On the other hand, it is still very challenging to develop universal descriptors that can be used in various types of catalysts and reaction systems. For these reasons, several strategies have recently been proposed to break and rebuild scaling relations to go beyond the top of volcanoes. In this review, some previously proposed descriptors have been briefly introduced. Then, the strategies for breaking known and establishing new and more generalized scaling relations in complex catalytic systems have been summarized. Finally, the application of machine-learning techniques in identifying universal descriptors for future computational design and high-throughput screening of heterogeneous catalysts has been discussed.
    Perspectives on the flexibility analysis for continuous pharmaceutical manufacturing processes
    Wenhui Yang, Wuxi Qian, Zhihong Yuan, Bingzhen Chen
    2022, 41(1):  29-41.  doi:10.1016/j.cjche.2021.12.005
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    Pharmaceutical continuous manufacturing, especially under the context of COVID-19 pandemic, is regarded as an emerging technology that can guarantee the adequate quality assurance and mitigate process risk while guaranteeing the desirable economic performance. Flexibility analysis is one approach to quantitively assess the capability of chemical process to guarantee feasible operation in face of variations on uncertain parameters. The aim of this paper is to provide the perspectives on the flexibility analysis for continuous pharmaceutical manufacturing processes. State-of-the-art and progress in the flexibility analysis for chemical processes including concept evolution, mathematical model formulations, solution strategies, and applications are systematically overviewed. Recent achievements on the flexibility/feasibility analysis of the downstream dosage form manufacturing process are also touched upon. Further challenges and developments in the field of flexibility analysis for novel continuous manufacturing processes of active pharmaceutical ingredients along with the integrated continuous manufacturing processes are identified.
    Layered double hydroxides: Scale production and application in soil remediation as super-stable mineralizer
    Fangqi Mao, Peipei Hao, Yuquan Zhu, Xianggui Kong, Xue Duan
    2022, 41(1):  42-48.  doi:10.1016/j.cjche.2021.09.023
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    Soil contamination by heavy metals has presented severe risks to human health through food chain. As one of the most promising remediation technologies, in-situ immobilization strategy has been widely adopted in practice. However, considering the large quantities of contaminated soil, it is still a huge challenge to design low-cost amendments with strong and long-term immobilization ability. Layered double hydroxides (LDHs) have drawn tremendous attention in fundamental research and practical application because of their unique properties. Moreover, owing to its super-stable mineralization effect to heavy metal ions, LDHs have exhibited great potential in the field of soil remediation. In this work, we mainly focused on the scale production strategy of LDHs with low-cost, and its application in soil remediation. Besides, several key challenges in using LDHs as amendments for immobilization of heavy metal ions are presented. We hope that this mini-review could shed light on the sustainable development of LDHs as amendment for heavy metals in future research directions.
    Reaction kinetics determination based on microfluidic technology
    Zifei Yan, Jiaxin Tian, Chencan Du, Jian Deng, Guangsheng Luo
    2022, 41(1):  49-72.  doi:10.1016/j.cjche.2021.08.023
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    Microfluidic technology has been successfully applied to determine the reaction kinetics relying on its great characteristics including narrow residence time distribution, fast mixing, high mass and heat transfer rates and very low consumption of materials. In this review, the recent progresses about the reaction kinetics measured in microreactors are comprehensively organized, and the kinetic modeling thoughts, determination methods and essential kinetic regularities contained in these studies are summarized according to the reaction types involving nitration, oxidation, hydrogenation, photochemical reaction, polymerization and other reactions. Besides, the significant advances in the innovation of microplatform are also covered. The novel reactor configuration methods were established mainly to achieve rapid and efficient data collection and analysis. Finally, the advantages of microfluidic technology for the kinetic measurement are summarized, and a perspective for the future development is provided.
    Research progress on preparation and purification of fluorine-containing chemicals in lithium-ion batteries
    Xiaobin Liu, Zhenguo Gao, Jingcai Cheng, Junbo Gong, Jingkang Wang
    2022, 41(1):  73-84.  doi:10.1016/j.cjche.2021.09.007
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    With the development of digital products, electric vehicles and energy storage technology, electronic chemicals play an increasingly prominent role in the field of new energy such as lithium-ion batteries. Electronic chemicals have attracted extensive attention in various fields. Characteristics of high-end electronic chemicals are high purity and low impurity content, which requires a very strict separation and purification process. At present, crystallization is a key technology for their separation and purification of electronic chemicals. In this work, the representative fluorine-containing compounds in cathode and anode materials, separator and electrolyte of lithium-ion batteries are introduced. The latest technologies for the preparation and purification of four kinds of fluorine-containing battery chemicals by crystallization technology are reviewed. In addition, the research prospects and suggestions are put forward for the separation of fluorine-containing battery chemicals.
    Computational fluid dynamic simulation of gas-liquid flow in rotating packed bed: A review
    Wen-Cong Chen, Ya-Wei Fan, Liang-Liang Zhang, Bao-Chang Sun, Yong Luo, Hai-Kui Zou, Guang-Wen Chu, Jian-Feng Chen
    2022, 41(1):  85-108.  doi:10.1016/j.cjche.2021.09.024
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    The rotating packed bed (RPB) has been widely used in gas-liquid flow systems as a process intensification device, exhibiting excellent mass transfer enhancement characteristics. However, the complex internal structure and the high-speed rotation of the rotor in RPB bring significant challenges to study the intensification mechanism by experiment methods. In the past two decades, Computational fluid dynamics (CFD) has been gradually applied to simulate the hydrodynamics and mass transfer characteristics in RPB and instruct the reactor design. This article covers the development of the CFD simulation of gasliquid flow in RPB. Firstly, the improvement of the simulation method in the aspect of mathematical models, geometric models, and solving methods is introduced. Secondly, new progress of CFD simulation about hydrodynamic and mass transfer characteristics in RPB is reviewed, including pressure drop, velocity distribution, flow pattern, and concentration distribution, etc. Some new phenomena such as the end effect area with the maximum turbulent have been revealed by this works. In addition, the exploration of developing new reactor structures by CFD simulation is introduced and it is proved that such new structures are competitive to different applications. The defects of current research and future development directions are also discussed at last.
    Chalcocite (bio)hydrometallurgy—current state, mechanism, and future directions: A review
    Shichao Yu, Rui Liao, Baojun Yang, Chaojun Fang, Zhentang Wang, Yuling Liu, Baiqiang Wu, Jun Wang, Guanzhou Qiu
    2022, 41(1):  109-120.  doi:10.1016/j.cjche.2021.12.014
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    There has been a strong interest in technologies suited for mining and processing of low-grade ores because of the rapid depletion of mineral resources in the world. In most cases, the extraction of copper from such raw materials is achieved by applying the leaching procedures. However, its low extraction efficiency and the long extraction period limit its large-scale commercial applications in copper recovery, even though bioleaching has been widely employed commercially for heap and dump bioleaching of secondary copper sulfide ores. Overcoming the technical challenges requires a better understanding of leaching kinetics and on-site microbial activities. Herein, this paper reviews the current status of main commercial biomining operations around the world, identifies factors that affect chalcocite dissolution both in chemical leaching and bioleaching, summarizes the related kinetic research, and concludes with a discussion of two on-site chalcocite heap leaching practices. Further, the challenges and innovations for the future development of chalcocite hydrometallurgy are presented in the end.
    Membrane-based air dehumidification: A comparative review on membrane contactors, separative membranes and adsorptive membranes
    Huaixun Lim, Kunli Goh, Miao Tian, Rong Wang
    2022, 41(1):  121-144.  doi:10.1016/j.cjche.2021.12.018
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    This review compares the different types of membrane processes for air dehumidification. Three main categories of membrane-based dehumidification are identified – membrane contactors using porous membranes with concentrated liquid desiccants, separative membranes using dense membrane morphology with a pressure gradient to drive the separation of moisture from air, and adsorptive membranes using nanofibrous membranes which adsorb and capture moisture to realise dehumidification. Drawing upon the importance of dehumidification and humidity control for urban sustainability and energy efficacy, this review critically analyses and recognizes the three unique categories of membrane-based air dehumidification technologies. Essentially, the discussion is broken into three sections-one for each category-discriminating in terms of the driving force, membrane structure and properties, and its performance indicators. Readers will notice that despite having the same objective to dehumidify air, the polymers used amongst each category differs to suit the operating requirements and optimize dehumidification performance. At the end of each section, a performance table or summary of dehumidifying membranes in its class is provided. The final section concludes with a comparative review of the three categories on membrane-based air dehumidification technologies and draw inspiration from parallel research to rationalise the potential and innovative use of promising materials in membrane fabrication for air dehumidification.
    Hydrogen peroxide and applications in green hydrocarbon nitridation and oxidation
    Yanqiang Shi, Yuetong Xia, Guangtong Xu, Langyou Wen, Guohua Gao, Baoning Zong
    2022, 41(1):  145-161.  doi:10.1016/j.cjche.2021.09.030
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    Basic organic chemicals and high value–added products are mainly produced by hydrocarbon nitridation and oxidation. However, several drawbacks limit the application of the traditional oxidation and nitridation technologies in the future, such as complex processes, poor intrinsic safety, low atom utilization, and serious environmental pollution. The green nitridation and oxidation technologies are urgently needed. Hydrogen peroxide, a well–known green oxidant, is widely used in green hydrocarbon oxidation and nitridation. But its industrial production in China adopts fixed–bed technology, which is fall behind slurry–bed technology adopted by advanced foreign chemical companies, limiting the development of hydrogen peroxide industry and green hydrocarbon nitridation or oxidation industry. This article reviews the industrial production technologies of hydrogen peroxide and basic organic chemicals such as caprolactam, aniline, propene oxide, epichlorohydrin, phenol, and benzenediol, especially introduces the green production technologies of basic organic chemicals related with H2O2. The article also emphasis on the efforts of Chinese researchers in developing its own slurry–bed technology of hydrogen peroxide production, and corresponding green hydrocarbon nitridation or oxidation technologies with hydrogen peroxide. Compared with traditional nitridation or oxidation technologies, green production technologies of caprolactam, propene oxide, epichlorohydrin, and benzenediol with hydrogen peroxide promote the nitrogen atom utilization from 60% to near 100% and the carbon atom utilization from 80% to near 100%. The waste emissions and environmental investments are reduced dramatically. Technological blockade against the green chemical industry of China are partially broken down, and technological upgrade in the chemical industry of China is guaranteed.
    Recent progress on equation-oriented optimization of complex chemical processes
    Yuyang Kang, Yiqing Luo, Xigang Yuan
    2022, 41(1):  162-169.  doi:10.1016/j.cjche.2021.10.018
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    Process optimization in equation-oriented (EO) modeling environments favors the gradient-based optimization algorithms by their abilities to provide accurate Jacobian matrices via automatic or symbolic differentiation. However, computational inefficiencies including that in initial-point-finding for Newton type methods have significantly limited its application. Recently, progress has been made in using a pseudo-transient (PT) modeling method to address these difficulties, providing a fresh way forward in EO-based optimization. Nevertheless, research in this area remains open, and challenges need to be addressed. Therefore, understanding the state-of-the-art research on the PT method, its principle, and the strategies in composing effective methodologies using the PT modeling method is necessary for further developing EO-based methods for process optimization. For this purpose, the basic concepts for the PT modeling and the optimization framework based on the PT model are reviewed in this paper. Several typical applications, e.g., complex distillation processes, cryogenic processes, and optimizations under uncertainty, are presented as well. Finally, we identify several main challenges and give prospects for the development of the PT based optimization methods.
    The development road of ammonium phosphate fertilizer in China
    Dehua Xu, Benhe Zhong, Xinlong Wang, Xue Li, Yanjun Zhong, Zhengjuan Yan, Jingxu Yang, Xiaobin Li, Yumei Wang, Xiaohou Zhou
    2022, 41(1):  170-175.  doi:10.1016/j.cjche.2021.08.015
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    Ammonium phosphate fertilizer is the compounds containing nitrogen and phosphorus that are usually produced through the neutralization reaction of phosphoric acid and ammonia. At present, there are a variety of products, such as slurry monoammonium phosphate (MAP), diammonium phosphate (DAP), industrial grade MAP, water soluble MAP, water soluble ammonium polyphosphate (APP) and so on. After more than 60 years of development, China’s ammonium phosphate fertilizer industry has experienced the road of from scratch and from weak to strong. The successful development of the slurry MAP technology ended the history that the high concentration phosphate fertilizer cannot be produced by using the medium and low grade phosphate ore. The continuous, stable and large-scale production of DAP plant provides sufficient guarantee for DAP products in China. The development of new ammonium phosphate fertilizer products, such as industrial grade MAP, water soluble MAP, water soluble APP, provides technical support for the transformation and upgrading of phosphorus chemical enterprises. In this paper, the production methods, the development history and the latest research progress of ammonium phosphate fertilizers were reviewed.
    Isolated mixing regions and mixing enhancement in a high-viscosity laminar stirred tank
    Qianqian Kang, Jinfan Liu, Xin Feng, Chao Yang, Jingtao Wang
    2022, 41(1):  176-192.  doi:10.1016/j.cjche.2021.11.008
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    Laminar mixing in the stirred tank is widely encountered in chemical and biological industries. Isolated mixing regions (IMRs) usually exist when the fluid medium has high viscosity, which are not conducive to mixing. In this work, the researches on IMRs, enhancement of laminar mixing and the phenomenon of particle clustering within IMRs are reviewed. For most studies, the aim is to destroy IMRs and improve the chaotic mixing. To this end, the mechanism of chaotic mixing and the structure of IMRs were well investigated. The methods developed to destroy IMRs include off-centered agitation, dynamic mixing protocol, special designs of impellers, baffles, etc. In addition, the methods to characterize the shape and size of IMRs as well as mixing effect by experiments and simulations are summarized. However, IMRs are not always nuisance, and it may be necessary in some situations. Finally, the present engineering applications are summarized, and the prospect of the future application is predicted. For example, particle clustering will form in the co-existing system of chaotic mixing and IMRs, which can be used for solid–liquid separation and recovery of particles from high viscosity fluid.
    Stimuli-responsive emulsions: Recent advances and potential applications
    Xue-hui Ge, Liangji Mo, Anhe Yu, Chenzi Tian, Xiaoda Wang, Chen Yang, Ting Qiu
    2022, 41(1):  193-209.  doi:10.1016/j.cjche.2021.11.002
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    Responsive emulsions are the emulsions that can be reversibly switched on-demand between “stable” and “unstable” by environmental stimulus or trigger, which allows a simple and effective adjustment approach to achieve emulsification and demulsification. In recent years, stimuli-responsive emulsions acting as smart soft material are received considerable attention with the advantages of simple manipulation, good reversibility, low cost, easy treatment, and little effect on the system. In this paper, the recent research progress of emulsions that can respond to external stimuli, including pH, light, magnetic field, CO2/N2 and dual responsive are reviewed. Also, the potential applications based on responsive emulsion are discussed, such as catalytic reactions, heavy oil recovery, polymer particles synthesis and optical sensor, aiming to summarize the latest achievements and put forward the possible development trends of responsive emulsions.
    Fluid Dynamics and Transport Phenomena
    Numerical evaluation of virtual mass force coefficient of single solid particles in acceleration
    Zai-Sha Mao, Chao Yang
    2022, 41(1):  210-219.  doi:10.1016/j.cjche.2021.11.014
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    Virtual mass force is an indispensable component in the momentum balance involved with dispersed particles in a multiphase system. In this work the accelerating motion of a single solid particle is mathematically formulated and solved using the vorticity-stream function formulation in an orthogonal curvilinear coordinate system. The total drag coefficient was evaluated from the numerical simulation in a range of the Reynolds number (Re) from 10 to 200 and the dimensionless acceleration (A) between 2.0 to 2.0. The simulation demonstrates that the total drag is heavily correlated with A, and large deceleration even drops the drag force to a negative value. It is found that the value of virtual mass force coefficient (CV) of a spherical particle is a variable in a wide range and difficult to be correlated with A and Re. However, the total drag coefficient (CDV) is successfully correlated as a function of Re and A, and it increases as A is increased. The proposed correlation of total drag coefficient may be used for simulation of solid–liquid flow with better accuracy.
    Molecular insights on Ca2+/Na+ separation via graphene-based nanopores: The role of electrostatic interactions to ionic dehydration
    Yumeng Zhang, Yingying Zhang, Xueling Pan, Yao Qin, Jiawei Deng, Shanshan Wang, Qingwei Gao, Yudan Zhu, Zhuhong Yang, Xiaohua Lu
    2022, 41(1):  220-229.  doi:10.1016/j.cjche.2021.10.023
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    Ca2+/Na+ separation is a common problem in industrial applications, biological and medical fields. However, Ca2+ and Na+ have similar ionic radii and hydration radii, thus Ca2+/Na+ separation is challenging. Inspired by biological channels, group modification is one of the effective methods to improve the separation performance. In this work, molecular dynamics simulations were performed to investigate the effects of different functional groups (COO-, NH3+) on the separation performance of Ca2+ and Na+ through graphene nanopores under an electric field. The pristine graphene nanopore was used for comparison. Results showed that three types of nanopores preferred Ca2+ to Na+, and Ca2+/Na+ selectivity followed the order of GE-COO-(4.06) > GE (1.85) > GE-NH3+ (1.63). Detailed analysis of ionic hydration microstructure shows that different nanopores result in different hydration factors for the second hydration layer of Ca2+ and the first layer of Na+. Such different hydration factors corresponding to the dehydration ability can effectively evaluate the separation performance. In addition, the breaking of hydrogen bonds between water molecules due to electrostatic effects can directly affect the dehydration ability. Therefore, the electrostatic effect generated by group modification will affect the ionic hydration microstructure, thus reflecting the differences in dehydration ability. This in turn affects the permeable and separation performance of cations. The results of this work provide perceptive guidelines for the application of graphene-based membranes in ion separation.
    External mass transfer from/to a single sphere in a nonlinear uniaxial extensional creeping flow
    Anjun Liu, Jie Chen, Moshe Favelukis, Meng Guo, Meihong Yang, Chao Yang, Tao Zhang, Min Wang, Hao-yue Quan
    2022, 41(1):  230-245.  doi:10.1016/j.cjche.2021.11.017
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    This work systematically simulates the external mass transfer from/to a spherical drop and solid particle suspended in a nonlinear uniaxial extensional creeping flow. The mass transfer problem is governed by three dimensionless parameters: the viscosity ratio (λ), the Peclet number (Pe), and the nonlinear intensity of the flow (E). The existing mass transfer theory, valid for very large Peclet numbers only, is expanded, by numerical simulations, to include a much larger range of Peclet numbers (1 ≤ Pe ≤ 105). The simulation results show that the dimensionless mass transfer rate, expressed as the Sherwood number (Sh), agrees well with the theoretical results at the convection-dominated regime (Pe > 103). Only when E > 5/4, the simulated Sh for a solid sphere in the nonlinear uniaxial extensional flow is larger than theoretical results because the theory neglects the effect of the vortex formed outside the particle on the rate of mass transfer. Empirical correlations are proposed to predict the influence of the dimensionless governing parameters (λ, Pe, E) on the Sherwood number (Sh). The maximum deviations of all empirical correlations are less than 15% when compared to the numerical simulated results.
    Separation Science and Engineering
    A novel strategy of lithium recycling from spent lithium-ion batteries using imidazolium ionic liquid
    Hongshuai Zheng, Jiaqi Huang, Tao Dong, Yifan Sha, Haitao Zhang, Jie Gao, Suojiang Zhang
    2022, 41(1):  246-251.  doi:10.1016/j.cjche.2021.09.020
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    In light of the increasing demand for environmental protection and energy conservation, the recovery of highly valuable metals, such as Li, Co, and Ni, from spent lithium-ion batteries (LIBs) has attracted wide-spread attention. Most conventional recycling strategies, however, suffer from a lack of lithium recycling, although they display high efficiency in the recovery of Co and Ni. In this work, we report an efficient extraction process of lithium from the spent LIBs by using a functional imidazolium ionic liquid. The extraction efficiency can be reached to 92.5% after a three-stage extraction, while the extraction efficiency of Ni-Co-Mn is less than 4.0%. The new process shows a high selectivity of lithium ion. FTIR spectroscopy and ultraviolet are utilized to characterize the variations in the functional groups during extraction to reveal that the possible extraction mechanism is cation exchange. The results of this work provide an effective and sustainable strategy of lithium recycling from spent LIBs.
    High-efficiency separation and extraction of naphthenic acid from high acid oils using imidazolium carbonate ionic liquids
    Fenghua Geng, Rui Zhang, Luo Wu, Zheng Tang, Han Liu, Haiyan Liu, Zhichang Liu, Chunming Xu, Xianghai Meng
    2022, 41(1):  252-259.  doi:10.1016/j.cjche.2021.12.012
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    N-alkyl imidazolium carbonate ionic liquids were employed to separate and recover naphthenic acid from model oils. The effects of the cationic and anionic structures of ionic liquids and operating conditions on the deacidification performance were investigated. The deacidification performance of traditional organic solvents was also investigated for comparison. The results indicated that the naphthenic acid could be completely removed from the model oil with a small mass ratio of ionic liquid to oil. The extracted naphthenic acid was regenerated with a recovery of up to 92%. In addition, imidazolium carbonate ionic liquids could be successfully regenerated and recycled. The mechanism of interaction between imidazole ionic liquids and the naphthenic acid molecules were explained by Gauss calculation.
    Two-dimensional MXene hollow fiber membrane for divalent ions exclusion from water
    Guozhen Liu, Yanan Guo, Baochun Meng, Zhenggang Wang, Gongping Liu, Wanqin Jin
    2022, 41(1):  260-266.  doi:10.1016/j.cjche.2021.09.022
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    Two-dimensional material membranes with fast transport channels and versatile chemical functionality are promising for molecular separation. Herein, for the first time, we reported design and engineering of two-dimensional Ti3C2Tx MXene (called transition metal carbides and nitrides) membranes supported on asymmetric polymeric hollow fiber substrate for water desalination. The membrane morphology, physicochemical properties and ions exclusion performance were systematically investigated. The results demonstrated that surface hydrophilicity and electrostatic repulsion and size sieving effect of interlayer channels synergistically endowed the MXene hollow fiber membrane with fast water permeation and efficient rejection of divalent ions during nanofiltration process.
    Charged modified tight ceramic ultrafiltration membranes for treatment of cationic dye wastewater
    Chen Zhao, Yahan Ye, Xianfu Chen, Xiaowei Da, Minghui Qiu, Yiqun Fan
    2022, 41(1):  267-277.  doi:10.1016/j.cjche.2021.11.007
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    Tight ceramic ultrafiltration membranes have been proven to exhibit good rejection performance for reactive dye wastewater at high temperatures because of their high thermal and chemical resistance. However, the application of ceramic membranes for the treatment of cationic dye wastewater is challenging because of their surface charge. In this study, a ceramic membrane is modified by grafting aminosilane (KH-551) to enhance the positive charge of the membrane surface. The rejection performance of the charged modified ceramic membrane toward the methylene blue solution is significantly improved. The modification substance is bonded to the ceramic membrane surface via covalent bonding, which imparts good thermal stability. The modified ceramic membrane exhibits stable separation performance toward the methylene blue solution. Overall, this study provides valuable guidance for the adjustment of the ceramic membrane surface charge for treating industrial cationic dye wastewater.
    Minimising non-selective defects in ultrathin reduced graphene oxide membranes with graphene quantum dots for enhanced water and NaCl separation
    Shi Yuan, Yang Li, Ruosang Qiu, Yun Xia, Cordelia Selomulya, Xiwang Zhang
    2022, 41(1):  278-285.  doi:10.1016/j.cjche.2021.12.009
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    Reduced graphene oxide (rGO) membranes have been intensively evaluated for desalination and ionic sieving applications, benefiting from their stable and well-confined interlayer channels. However, rGO membranes generally suffer from low permeability due to the high transport resistance resulting from the narrowed two-dimensional (2D) channels. Although high permeability can be realized by reducing membrane thickness, membrane selectivity normally declines because of the formation of nonselective defects, in particular pinholes. In this study, we demonstrate that the non-selective defects in ultrathin rGO membranes can be effectively minimised by a facile posttreatment via surfacedeposition of graphene quantum dots (GQDs). The resultant GQDs/rGO membranes obtained a good trade-off between water permeance (14 L·m-2·h-1·MPa-1) and NaCl rejection (91%). This work provides new insights into the design of high quality ultrathin 2D laminar membranes for desalination, molecular/ ionic sieving and other separation applications.
    Fabrication of magnetically responsive anti-fouling and easy-cleaning nanofiber membrane and its application for efficient oil-water emulsion separation
    Yajie Wang, Zhiwei Guo, Yujie Yang, Yanxiang Li, Qingchun Guo, Peilin Cui, Wangliang Li
    2022, 41(1):  286-293.  doi:10.1016/j.cjche.2021.12.013
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    The magnetically responsive anti-fouling nanofiber membrane (MRANM) was fabricated for efficient oilwater emulsion separation, which could be cleaned using oscillating magnetic field. MRANM was prepared by grafting superparamagnetic Fe3O4 nanoparticles onto the surface of electrospun polyacrylonitrile nanofiber membrane (PANM). Compared with PANM, the water contact angle of MRANM decreased from 104° to 0°, indicating that the hydrophilicity of the membrane was significantly improved. For the emulsions of hexadecane, octane and rapeseed oil, the separation efficiency was 98.04%, 96.59% and 92.67%, respectively. After the treatments in oscillating magnetic field, the separation efficiency kept above 95% after 8 times recycling, which indicated that the MRANM had good regenerability and reusability. The as-fabricated membrane with magnetic responsiveness facilitated an effective method for solving the membrane fouling problem during practical applications of separation high viscosity oil-water emulsion.
    Na2SO4–NaCl binary eutectic salt roasting to enhance extraction of lithium from pyrometallurgical slag of spent lithium-ion batteries
    Hui Dang, Zhidong Chang, Xue Wu, Sihang Ma, Yifei Zhan, Na Li, Wenbo Liu, Wenjun Li, Hualei Zhou, Changyan Sun
    2022, 41(1):  294-300.  doi:10.1016/j.cjche.2021.09.008
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    Effectively extracting lithium at a relatively low temperature from the slag produced by the pyrometallurgical treatment of spent lithium-ion batteries remains a great challenge, which limits the acquirement of lithium. Herein, we proposed a eutectic system to roast slag at a lower temperature based on sodium sulfate–sodium chloride (Na2SO4–NaCl) binary eutectic salts. The optimal roasting conditions are as follows: the slag was roasted at 750 ℃ with a (SO42–+Cl)/Li+ molar ratio of 5:1 for 120 min. Followed by aqueous leaching 5 min at room temperature with a water/roasted samples mass ratio of 30:1, it can get 97.07% lithium extraction efficiency.
    Catalysis, Kinetics and Reaction Engineering
    Vacuum residue coking process simulation using molecular-level kinetic model coupled with vapor-liquid phase separation
    Zhengyu Chen, Xinhui Yao, Dong Guan, Suoqi Zhao, Linzhou Zhang, Chunming Xu
    2022, 41(1):  301-310.  doi:10.1016/j.cjche.2021.10.014
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    In this work, a molecular-level kinetic model was built to simulate the vacuum residue (VR) coking process in a semi-batch laboratory-scale reaction kettle. A series of reaction rules for heavy oil coking were summarized and formulated based on the free radical reaction mechanism. Then, a large-scale molecularlevel reaction network was automatically generated by applying the reaction rules on the vacuum residue molecules. In order to accurately describe the physical change of each molecule in the reactor, we coupled the molecular-level kinetic model with a vapor–liquid phase separation model. The vapor–liquid phase separation model adopted the Peng-Robinson equation of state to calculate vapor–liquid equilibrium. A separation efficiency coefficient was introduced to represent the mass transfer during the phase separation. We used six sets of experimental data under various reaction conditions to regress the model parameters. The tuned model showed that there was an excellent agreement between the calculated values and experimental data. Moreover, we investigated the effect of reaction temperature and reaction time on the product yields. After a comprehensive evaluation of the reaction temperature and reaction time, the optimal reaction condition for the vacuum residue coking was also obtained.
    Preparation of Pd/γ-Al2O3/nickel foam monolithic catalyst and its performance for selective hydrogenation in a rotating packed bed reactor
    Hai-Long Liao, Bao-Ju Wang, Ya-Zhao Liu, Yong Luo, Jie-Xin Wang, Guang-Wen Chu, Jian-Feng Chen
    2022, 41(1):  311-319.  doi:10.1016/j.cjche.2021.08.026
    Abstract ( )   PDF (5546KB) ( )  
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    Selective hydrogenation plays an important role in chemical industries, yet its selectivity is usually limited by the mass transfer. In this work, the enhanced hydrogenation selectivity was achieved in a rotating packed bed (RPB) reactor with excellent mass transfer efficiency. Aiming to be used under the centrifugal filed, a monolithic catalyst Pd/γ-Al2O3/nickel foam suiting for the shape and size of the rotor of RPB reactor was prepared by the electrophoretic deposition method. The mechanical strength of the catalyst can meet the requirement of high centrifugal force in the RPB. The hydrogenation selectivity in the RPB reactor using the 3-methyl-1-pentyn-3-ol hydrogenation system was 3–8 times higher than that in a stirred tank reactor under similar conditions. This work proves the feasibility of intensifying the selectivity of hydrogenation process in the RPB reactor.
    Interfacial engineering of transition-metal sulfides heterostructures with built-in electric-field effects for enhanced oxygen evolution reaction
    Shan Ni, Hongnan Qu, Huifang Xing, Zihao Xu, Xiangyang Zhu, Menglei Yuan, Meng Rong, Li Wang, Jiemiao Yu, Yanqing Li, Liangrong Yang, Huizhou Liu
    2022, 41(1):  320-328.  doi:10.1016/j.cjche.2021.09.026
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    Developing highly efficient, durable, and non-noble electrocatalysts for the sluggish anodic oxygen evolution reaction (OER) is the pivotal for meeting the practical demand in water splitting. However, the current transition-metal electrocatalysts still suffer from low activity and durability on account of poor interfacial reaction kinetics. In this work, a facile solid-state synthesis strategy is developed to construct transition-metal sulfides heterostructures (denoted as MS2/NiS2, M = Mo or W) for boosting OER electrocatalysis. As a result, MoS2/NiS2 and WS2/NiS2 show lower overpotentials of 300 mV and 320 mV to achieve the current density of 10 mA·cm-2, and smaller Tafel slopes of 60 mV·dec-1 and 83 mV·dec-1 in 1 mol·L-1 KOH, respectively, in comparison with the single MoS2, WS2, NiS2, as well as even the benchmark RuO2. The experiments reveal that the designed heterostructures have strong electronic interactions and spontaneously develop a built-in electric field at the heterointerface with uneven charge distribution based on the difference of band structures, which promote interfacial charge transfer, improve absorptivity of OH-, and modulate the energy level more comparable to the OER. Thus, the designed transition-metal sulfides heterostructures exhibit a remarkably high electrocatalytic activity for OER. This study provides a simple strategy to manipulate the heterostructure interface via an energy level engineering method for OER and can be extended to fabricate other heterostructures for various energy-related applications.
    Redistributing Cu species in Cu-SSZ-13 zeolite as NH3-SCR catalyst via a simple ion-exchange
    Ben Liu, Nangui Lv, Chan Wang, Hongwei Zhang, Yuanyuan Yue, Jingdong Xu, Xiaotao Bi, Xiaojun Bao
    2022, 41(1):  329-341.  doi:10.1016/j.cjche.2021.10.027
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    The nature and distribution of Cu species in Cu-SSZ-13 play a vital role in selective catalytic reduction of NO by NH3 (NH3-SCR), but existing methods for adjusting the Cu distribution are complex and difficult to control. Herein, we report a simple and effective ion-exchange approach to regulate the Cu distribution in the one-pot synthesized Cu-SSZ-13 that possesses sufficient initial Cu species and thus provides a “natural environment” for adjusting Cu distribution precisely. By using this proposed strategy, a series of CuSSZ-13x zeolites with different Cu contents and distributions were obtained. It is shown that the dealumination of the as-synthesized Cu-SSZ-13 during the ion-exchange generates abundant vacant sites in the double six-membered-rings of the SSZ-13 zeolite for relocating Cu2+ species and thus allows the redistribution of the Cu species. The catalytic results showed that the ion-exchanged Cu-SSZ-13 zeolites exhibit quite different catalytic performance in NH3-SCR reaction but superior to the parent counterpart. The structure–activity relationship analysis indicates that the redistribution of Cu species rather than other factors (e.g., crystallinity, chemical composition, and porous structure) is responsible for the improved NH3-SCR performance and SO2 and H2O resistance. Our work offers an effective method to precisely adjust the Cu distribution in preparing the industrial SCR catalysts.
    Computer generation of detailed reaction networks in hydrocracking of Fischer-Tropsch wax
    Jingjing Wang, Wei Zhao, Kunpeng Song, Hongwei Xiang, Liping Zhou, Yong Yang, Yongwang Li
    2022, 41(1):  342-349.  doi:10.1016/j.cjche.2021.10.007
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    Fischer-Tropsch synthesis (FTS) wax is a mixture of linear hydrocarbons with carbon number from C7 to C70+. Converting FTS wax into high-quality diesel (no sulfur and nitrogen contents) by hydrocracking technology is attractive in economy and practicability. Kinetic study of the hydrocracking of FTS wax in elementary step level is very challenging because of the huge amounts of reactions and species involved. Generation of reaction networks for hydrocracking of FTS wax in which the chain length goes up to C70 is described on the basis of Boolean adjacency matrixes. Each of the species (including paraffins, olefins and carbenium ions) involved in the elementary steps is represented digitally by using a (N + 3)×N matrix, in which a group of standardized numbering rules are designed to guarantee the unique identity of the species. Subsequently, the elementary steps are expressed by computer-aided matrix transformations in terms of proposed reaction rules. Dynamic memory allocation is used in species storage and a characteristic vector with nine elements is designed to store the key information of a (N + 3)×N matrix, which obviously reduces computer memory consumption and improves computing efficiency. The detailed reaction networks of FTS wax hydrocracking can be generated smoothly and accurately by the current method. The work is the basis of advanced elementary-step-level kinetic modeling.
    Importance of metal location in M-H zeolite for synergistically catalyzing dimethyl ether carbonylation
    Shiyue Li, Shouying Huang, Kai Cai, Ying Li, Jing Lv, Xinbin Ma
    2022, 41(1):  350-357.  doi:10.1016/j.cjche.2021.11.019
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    Mordenite (MOR) has shown great potential to catalyze dimethyl ether (DME) carbonylation to methyl acetate (MA) in industry. The synergy between metal species and Brønsted acid sites accelerates DME conversion. Here we designed and prepared two catalysts with different Ag locations by seed-directed growth method and two-step impregnation method (named as Ag@HMOR and Ag/HMOR-out, respectively), to explain the effect of Ag location on catalytic performance. The results of TEM, XPS, CO-IR and UV–Vis showed that Ag species mainly presented as Ag0 species over both Ag@HMOR and Ag/HMOR-out. Meanwhile, Ag0 species mainly located in the micropores of Ag@HMOR, while as for Ag/HMOR-out, Ag0 mainly existed on external surface. After comparing the performance of the catalysts with different Ag positions, we confirmed that the Ag0 species encapsulated in the channels of HMOR promoted the DME carbonylation, which revealed the importance of spatial adjacency on the acid-metal catalysts.
    Controllable synthesis of a hollow Cr2O3 electrocatalyst for enhanced nitrogen reduction toward ammonia synthesis
    Lei Shi, Yu Yin, Hong Wu, Rajan Arjan Kalyan Hirani, Xinyuan Xu, Jinqiang Zhang, Nasir Rafique, Abdul Hannan Asif, Shu Zhang, Hongqi Sun
    2022, 41(1):  358-365.  doi:10.1016/j.cjche.2021.11.016
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    As a fascinating alternative to the energy-intensive Haber-Bosch process, the electrochemically-driven N2 reduction reaction (NRR) utilizing the N2 and H2O for the production of NH3 has received enormous attention. The development and preparation of promising electrocatalysts are requisite to realize an efficient N2 conversion for NH3 production. In this research, we propose a template-assisted strategy to construct the hollow electrocatalyst with controllable morphology. As a paradigm, the hollow Cr2O3 nanocatalyst with a uniform size (~170 nm), small cavity and ultrathin shell (~15 nm) is successfully fabricated with this strategy. This promising hollow structure is favourable to trap N2 into the cavity, provides abundant active sites to accelerate the three-phase interactions, and facilitates the reactant transfer across the shell. Attributed to these synergetic effects, the designed catalyst displays an outstanding behaviour in N2 fixation for NH3 production in ambient condition. In the neutral electrolyte of 0.1 mol·L-1 Na2SO4, an impressive electrocatalytic performance with the NH3 generation rate of 2.72 μg·h-1·cm-2 and a high FE of 5.31% is acquired respectively at -0.85 V with the hollow Cr2O3 catalyst. Inspired by this work, it is highly expected that this approach could be applied as a universal strategy and extended to fabricating other promising electrocatalysts for realizing highly efficient nitrogen reduction reaction (NRR).
    Pt-modulated Cu/SiO2 catalysts for efficient hydrogenation of CO2-derived ethylene carbonate to methanol and ethylene glycol
    Busha Assaba Fayisa, Yushan Xi, Youwei Yang, Yueqi Gao, Antai Li, Mei-Yan Wang, Jing Lv, Shouying Huang, Yue Wang, Xinbin Ma
    2022, 41(1):  366-373.  doi:10.1016/j.cjche.2021.10.024
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    Copper-based catalysts were widely used in the heterogeneous selective hydrogenation of ethylene carbonate (EC), a key step in the indirect conversion of CO2 to methanol. However, a high H2/EC molar ratio in feed is required to achieve favorable activity and the methanol selectivity still needs to be improved. Herein, we fabricated a series of Pt-modulated Cu/SiO2 catalysts and investigated their catalytic performance for hydrogenation of EC in a fixed bed reactor. By modulating the Pt amount, the optimal 0.2PtCu/SiO2 catalyst exhibited the highest catalytic performance with ~99% EC conversion, over 98% selectivity to ethylene glycol and 95.8% selectivity to methanol at the H2/EC ratio as low as 60 in feed. In addition, 0.2Pt-Cu/SiO2 catalyst showed excellent stability for 150 h on stream over different H2/EC ratios of 180-40. It is demonstrated a proper amount of Pt could significantly lower the H2/EC molar ratio, promote the reducibility and dispersion of copper, and also enhance surface density of Cu+ species. This could be due to the strong interaction of Cu and Pt induced by formation of alloyed Pt single atoms on the Cu lattice. Meanwhile, a relatively higher amount of Pt would deteriorate the catalytic activity, which could be due to the surface coverage and aggregation of active species. These findings may enlighten some fundamental insights for further design of Cu-based catalysts for the hydrogenation of carbon–oxygen bonds.
    Development of a new continuous process for the production of 3,5-dimethylpiperidine
    Tao Lin, Xiaoxun Ma
    2022, 41(1):  374-383.  doi:10.1016/j.cjche.2021.07.024
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    This paper developed a new clean continuous process for the hydrogenation of 3,5-dimethylpyridine (DPY) to 3,5-dimethylpiperidine (DPI) without solvent. A series of Ru/C catalysts were prepared by impregnation method, which were characterized by the BET, ICP, CO chemisorptions, XRD, SEM, EDS, TEM and TG. The effect of active species, loading, catalyst support, reaction temperature and pressure on the catalytic performance was investigated. The influence of internal and external diffusion in the trickle-bed reactor (TBR) was basically eliminated by adjusting the particle size and dosage of the Ru/C catalyst. The reaction performance of the hydrogenation of DPY to DPI in the TBR and kettle reactor (KR) was compared, and the superiority of the TBR process was analyzed. The results show that this new continuous process developed in this study is an efficient way to realize the hydrogenation of DPY to DPI, and has a good industrial application prospect.
    Bimetallic PtSn nanoparticles confined in hierarchical ZSM-5 for propane dehydrogenation
    Tianlei Wang, Zhikang Xu, Yuanyuan Yue, Tinghai Wang, Minggui Lin, Haibo Zhu
    2022, 41(1):  384-391.  doi:10.1016/j.cjche.2021.11.020
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    A series of PtSn/hierarchical ZSM-5 catalysts were developed for propane dehydrogenation, in which the PtSn bimetallic particles are confined in the mesopores of hierarchical ZSM-5 zeolite. The synthesis of PtSn/hierarchical ZSM-5 catalysts was achieved via the loading of Pt and Sn species onto the hierarchical ZSM-5 catalysts that are obtained through a desilication of conventional ZSM-5. The PtSn/hierarchical ZSM-5 catalysts were fully characterized by XRD, N2 adsorption, STEM, XPS, and℃O-IR techniques, which reveals that highly dispersed PtSn bimetallic nanoparticles are enclosed into mesopores of hierarchical ZSM-5. The catalytic performance of PtSn/hierarchical ZSM-5 is greatly affected by the concentrations of alkali solution in the desilication process and Sn/Pt ratios in PtSn bimetallic particles. The PtSn1.00/ ZSM-5(0.8) catalyst shows the highest efficiency in propane dehydrogenation, which gives an initial conversion of 46% and selectivity of 98% at 570 ℃. The high efficiency in these PtSn/hierarchical ZSM-5 catalysts for propane dehydrogenation is mainly ascribed to the confinement of PtSn particles in the mesopores of hierarchical ZSM-5 zeolite.
    Synthesis of alumina-nitrogen-doped carbon support for CoMo catalysts in hydrodesulfurization process
    Zhentao Chen, Yaxin Liu, Jian Chen, Yang Zhao, Tao Jiang, Fangyu Zhao, Jiahuan Yu, Haoxuan Yang, Fan Yang, Chunming Xu
    2022, 41(1):  392-402.  doi:10.1016/j.cjche.2021.09.015
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    More stringent environmental legislation imposes severe requirements to reduce the sulfur content in diesel to ultra-low levels with high efficient catalysts. In this paper, a series of CoMo/NDC@alumina catalysts were synthesized by combination of the chemical vapor deposition of nitrogen-doped carbon (NDC) using 1,10-phenanthroline and co-impregnation of Mo and Co active components. The optimal catalyst with additive of 25% 1,10-phenanthroline was screened by a series of property characterization and the hydrodesulfrization (HDS) active test. The amount of “CoMoS” active phase of the optimal CoMo/C3 catalyst increased 5.3% as compared with the CoMo/γ-Al2O3. The introduction of NDC improved the sulfidation degree of Mo by 21.8% as compared to the CoMo/γ-Al2O3 catalyst, which was beneficial to form more active sites. The HDS conversion of the NDC supported catalysts are higher than CoMo/γ-Al2O3 whether for the dibenzothiophene (DBT) or 4,6-dimethyl dibenzothiophene (4,6-DMDBT). Further hydroprocessing evaluation with Dagang diesel revealed that the CoMo/C3 catalyst possessed higher HDS property and the removal rate of DBTs in the diesel increased by 4%–11% as compared to the CoMo/γ-Al2O3 catalyst.
    Surface plasmon resonance metal-coupled biomass carbon modified TiO2 nanorods for photoelectrochemical water splitting
    Yingzhen Zhang, Yonggang Lei, Tianxue Zhu, Zengxing Li, Shen Xu, Jianying Huang, Xiao Li, Weilong Cai, Yuekun Lai, Xiaojun Bao
    2022, 41(1):  403-411.  doi:10.1016/j.cjche.2021.10.022
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    Exploring efficient and stable photoanode materials is a necessary link to realize the practical application of solar-driven photoelectrochemical (PEC) water splitting. Hence, we prepared rutile TiO2 nanorods, with a width of 50 nm, which was growth in situ on carbon cloth (TiO2@CC) by hydrothermal reaction. And then, Ag nanoparticles (NPs) and biomass N,S-C NPs were chosen for the additional modification of the fabricated TiO2 nanorods to produce broccoli-like Ag-N,S-C/TiO2@CC nanocomposites. According to the result of ultraviolet–visible diffuse reflectance spectroscopy (UV–vis) and PEC water splitting performance tests, Ag-N,S-C/TiO2@CC broadens the absorption region of TiO2@CC from the ultraviolet region to the visible region. Under AM 1.5G solar light irradiation, the photocurrent density of Ag-N,S-C/TiO2@CC is 89.8 μA·cm-2, which is 11.8 times higher than TiO2@CC. Under visible light irradiation, the photocurrent density of Ag-N,S-C/TiO2@CC reaches to 12.6 μA·cm-2, which is 21.0 times higher than TiO2@CC. Moreover, Ag-N,S-C/TiO2@CC shows a photocurrent responses in full pH range. It can be found that Ag NPs and N, S-C NPs play key roles in broaden the absorption range of TiO2 nanorods to the visible light region and, promote the occurrence of PEC water oxidation reaction due to the surface plasmon resonance effect of Ag NPs and the synergistic effect of N,S-C NPs. The mechanism demonstrated that Ag-N,S-C/TiO2@CC can separate the photogenerated electron-hole pairs effectively and transfer the photogenerated electrons to the photocathode (Pt plate) in time. This research provides a new strategy for exploration surface plasma metal coupled biomass carbon materials in the field of PEC water splitting.
    Catalyst-modified perovskite hollow fiber membrane for oxidative coupling of methane
    Jian Song, Claudia Li, Shao Zhang, Xiuxia Meng, Bo Meng, Jaka Sunarso
    2022, 41(1):  412-419.  doi:10.1016/j.cjche.2021.11.012
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    The catalytic oxidative coupling of methane (OCM) to C2 hydrocarbons (C2H6 and C2H4) represents one of the most effective ways to convert natural gas to more useful products, which can be performed effectively using La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) perovskite hollow fiber membrane microreactor. In this work, the effects of adding a thin BaCe0.8Gd0.2O3-δ (BCG) catalyst film onto the inner LSCF fiber surface as the OCM catalyst and a porous Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) perovskite layer onto the outer LSCF surface to improve the oxygen permeation were evaluated. Between 700 ℃ and 1000 ℃, methane conversion increased in the order of uncoated, BCG and BSCF-coated, and BCG-coated LSCF hollow fiber while C2-selectivity and C2-yield increased in the order of BCG and BSCF-coated, uncoated, and BCG-coated LSCF hollow fiber. Oxygen permeation flux at the same temperature range, on the other hand, was enhanced in the order of uncoated, BCG-coated, and BCG and BSCF-coated LSCF hollow fiber. This finding demonstrates the complex interplay between oxygen permeation and OCM performance. The BCG and BSCF-coated hollow fiber was also subjected to thermal cycles between 850 ℃ and 900 ℃ for up to 175 hours during which the fiber showed minor degradation in oxygen permeation fluxes and relatively stable OCM performance.
    The self-assembly of gold nanoparticles in large-pore ordered mesoporous carbons
    Chun Pei, Shangjun Chen, Rongrong Song, Fei Lv, Ying Wan
    2022, 41(1):  420-429.  doi:10.1016/j.cjche.2021.10.004
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    Simple encapsulation of 3 nm gold nanoparticles in ordered mesoporous carbon with large pores of 17 nm and thick pore walls of 16 nm was achieved by a metal–ligand coordination assisted-self-assembly approach. Polystyrene-block-polyethylene-oxide (PS-b-PEO) diblock copolymer with a large molecular weight of the PS chain and mercaptopropyltrimethoxysilane were used as the template and the metal ligand, respectively. Small-angle X-ray scattering, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy showed that monodispersed aggregation-free gold nanoparticles approximately 3 nm in size were partially embedded in the large open pore structure of the ordered mesoporous carbon. The strong coordination between the gold species and the mercapto groups and the thick porous walls increased the dispersion of the gold nanoparticles and essentially inhibited particle aggregation at 600 ℃. The gold nanoparticles in the ordered mesoporous carbon are active and stable in the reduction of nitroarenes involving bulky molecules using sodium borohydride as a reducing agent under ambient conditions (30 ℃) in water. The large interconnected pore structure facilitates the mass transfer of bulky molecules.
    Chemical Engineering Thermodynamics
    Ultrasound assisted crystallization of cephalexin monohydrate: Nucleation mechanism and crystal habit control
    Zeren Shang, Mingchen Li, Baohong Hou, Junli Zhang, Kuo Wang, Weiguo Hu, Tong Deng, Junbo Gong, Songgu Wu
    2022, 41(1):  430-440.  doi:10.1016/j.cjche.2021.07.034
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    With the high-quality requirements for cephalexin monohydrate, developing a robust and practical crys-tallization process to produce cephalexin monohydrate with good crystal habit, appropriate aspect ratio and high bulk density as well as suitable flowability is urgently needed. This research has explored the influence of ultrasound on crystallization of cephalexin monohydrate in terms of nucleation mechanism and crystal habit control. The results of metastable zone width and induction time measurement showed the presence of ultrasound irradiation can narrow the metastable zone and shorten induction time. Cavitation phenomena generated by ultrasound were used to qualitatively explain the mechanism of ultrasound promoting nucleation of cephalexin monohydrate. Furthermore, on the basis of classical nucleation theory and induction time data, a series of nucleation-related parameters (such as crystal-liquid interfacial tension, radius of the critical nucleus and etc.) were calculated and showed a decreasing trend under ultrasound irradiation. The diffusion coefficient of the studied system was also determined to increase by 72.73% under ultrasound. The changes in these parameters have quantitatively confirmed the mechanism of ultrasound influence on the nucleation process. In further, the calculated surface entropy factor has confirmed that the growth of cephalexin monohydrate follows continuous growth mechanism under the research conditions of this work. Through the exploration of crystallization conditions, it is found that suitable ultrasonic treatment, seeding, supersaturation control and removal of fine crystals are conducive to improving the quality of cephalexin monohydrate product. Optimizing the crystallization process coupled continuous ultrasound irradiation with fine-crystal dissolution policy has achieved the controllable production of monodisperse cephalexin monohydrate crystal with good performance.
    Solubility of CO2 in nonaqueous system of 2-(butylamino)ethanol with 2-butoxyethanol: Experimental data and model representation
    Yu Dong, Tiantian Ping, Shufeng Shen
    2022, 41(1):  441-448.  doi:10.1016/j.cjche.2021.11.003
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    Nonaqueous amine-based system is an attractive solution to overcome high-energy-intensive CO2 capture process using the conventional aqueous amines. Advanced nonaqueous absorbent of 2- (butylamino)ethanol (BAE) with 2-butoxyethanol (2-BE) has been recently proposed for low-energyconsumption CO2 capture. In this work, Henry’s law constants of CO2 in the BAE/2-BE blend were obtained by N2O/CO2 analogy, and correlated in the temperature range of (283–333) K. Vapor-liquid equilibrium (VLE) data for the BAE + CO2 + 2-BE system at 65.4% (mass) BAE were also determined in a stirred equilibrium cell at temperatures of (313–393) K and CO2 partial pressures up to 275 kPa. A single apparent equilibrium constant KCO2,app was proposed for this system and correlated as a function of temperature, carbonated degree of amine and CO2 loading. Solubility data were well represented by the modified Kent-Eisenberg model with an average absolute relative deviation (AARD) of 13%.
    Biotechnology and Bioengineering
    Characterization and application of a recombinant dopa decarboxylase from Harmonia axyridis for the efficient biosynthesis of dopamine
    Siyuan Gao, Yuanke Guo, Chen Ma, Ding Ma, Kequan Chen, Pingkai Ouyang, Xin Wang
    2022, 41(1):  449-456.  doi:10.1016/j.cjche.2021.12.006
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    Here, a dopa decarboxylase (DDC) from Harmonia axyridis was heterogeneously expressed in Escherichia coli for the efficient biosynthesis of dopamine. For the production of recombinant DDC, the cultivation conditions including IPTG concentration, temperature and induction time were optimized and obtained an optimal specific enzyme activity of 51.72 U·mg-1 crude extracts. After the purification of DDC with a recovery yield of 68.79%, its activity was further characterized. The Vmax, Km, Kcat, and Kcat/Km of DDC for dihydroxyphenylalanine (dopa) were 0.02 mmol·ml-1·s-1, 2.328 mmol·ml-1, 10435.90 s-1 and 4482.77 ml·mmol-1·s-1, respectively. The highest DDC activity was observed at the condition of pH 7.5 and 45 ℃. With the purified DDC, the feasibility to produce dopamine from L-dopa was evaluated. The optimal yield was determined at the following bioconversion conditions: pH of 7.0, the reaction temperature of 40 ℃, 0.4 mmol·L-1 of PLP and 4 g·L-1 of L-dopa. Subsequently, a fed-batch process for the production of dopamine was developed and the effect of oxygen was evaluated. The titer, yield and productivity of dopamine reached up to 21.99 g·L-1, 80.88% and 14.66 g·L-1·h-1 at 90 min under anaerobic condition.
    Catalytic mechanism of manganese ions and visible light on chalcopyrite bioleaching in the presence of Acidithiobacillus ferrooxidans
    Chunxiao Zhao, Baojun Yang, Rui Liao, Maoxin Hong, Shichao Yu, Jun Wang, Guanzhou Qiu
    2022, 41(1):  457-465.  doi:10.1016/j.cjche.2021.10.009
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    The bioleaching of chalcopyrite is low cost and environmentally friendly, but the leaching rate is low. To explore the mechanism of chalcopyrite bioleaching and improve its leaching rate, the effect and mechanism of manganese ions (Mn2+) and visible light on chalcopyrite mediated by Acidithiobacillus ferrooxidans (A. ferrooxidans) were discussed. Bioleaching experiments showed that when both Mn2+ and visible light were present, the copper extraction was 14.38% higher than that of the control system (without Mn2+ and visible light). Moreover, visible light and Mn2+ promoted the growth of A. ferrooxidans. Scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) analysis revealed that Mn2+ promoted the formation of extracellular polymeric substance (EPS) on the surface of chalcopyrite, changed the morphology of A. ferrooxidans, enhanced the adsorption of bacteria on chalcopyrite surface with light illumination, and thus promoted the bioleaching of chalcopyrite. UV–vis absorbance spectra indicated that Mn2+ promoted the response of chalcopyrite to visible light and enhanced the catalytic effect of visible light on chalcopyrite bioleaching. Based on X-ray photoelectron spectroscopy (XPS), the relevant sulfur speciation of chalcopyrite before and after bioleaching were analyzed and the results revealed that visible light and Mn2+ promoted chalcopyrite bioleaching by reducing the formation of passivation layer (Sn2-/S0). Investigation into electrochemical results further indicated that Mn2+ and visible light improved the electrochemical activity of chalcopyrite, thus increasing the bioleaching rate.
    Anodic process of stibnite in slurry electrolysis: The direct collision oxidation
    Yonglu Zhang, Dingfan Qiu, Chengyan Wang, Yongqiang Chen, Zhichao Yao, Xiaowu Jie, Wei Gao, Shufeng Ruan
    2022, 41(1):  466-472.  doi:10.1016/j.cjche.2021.12.011
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    Mineral oxidation leaching in the anode area is the key step in slurry electrolysis. By adopting the slow linear potential scanning method during slurry electrolysis, this study investigated the steady-state polarization curve of a pure stibnite mineral on a graphite anode. In addition, the influence of the mineral particle size, liquid–solid ratio, stirring speed, and temperature on the collision oxidation of the mineral with the anode was studied. Based on the different oxidation reactions, the potential range can be divided into three intervals: the low-potential interval with a potential lower than 0.75 V, an intermediatepotential interval with a potential within 0.75–1.2 V, and a high-potential interval with a potential higher than 1.2 V. The collision oxidation of the mineral with the anode occurred in all three intervals. The oxidation of Sb(III) also appeared in the intermediate- and high-potential intervals, and chlorine evolution occurred in the high-potential interval. Therefore, the low-potential interval was determined to be a suitable potential interval for the slurry electrolysis process. In the low-potential interval, the particle size, liquid–solid ratio, and stirring speed had little effect on the oxidation rate of the minerals. As the temperature increased, the stibnite oxidation rate and exchange current density increased. Overall, the direct collision oxidation rate of stibnite was relatively low and the current densities under all the investigated conditions were lower than 0.4 mA·cm-2. This indicates that it is difficult to realize industrial production while relying solely on this process.
    Performance improvement of ultra-low Pt proton exchange membrane fuel cell by catalyst layer structure optimization
    Jinyan Xi, Kang Meng, Ying Li, Meng Wang, Qiang Liao, Zidong Wei, Minhua Shao, Jianchuan Wang
    2022, 41(1):  473-479.  doi:10.1016/j.cjche.2021.11.013
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    Reducing the loading of noble Pt-based catalyst is vital for the commercialization of proton exchange membrane fuel cell (PEMFC). However, severe mass transfer polarization loss resulting in fuel cell performance decline will be encountered in ultra-low Pt PEMFC. In this work, mild oxidized multiwalled carbon nanotubes (mMWCNT) were adopted to construct the catalyst layer, and by varying the loading of carbon nanotubes, the catalyst layer structure was optimized. A high peak power density of 1.23 W·cm-2 for the MEA with mMWCNT was obtained at an ultra-low loading of 120 μg·cm-2 Pt/PtRu (both cathode and anode), which was 44.7% higher than that of MEA without mMWCNT. Better catalyst dispersion, low charge transfer resistance, more porous structure and high hydrophobicity of catalyst layer were ascribed for the reasons of the performance improvement.
    Ag nanoparticles anchored on MIL-100/nickel foam nanosheets as an electrocatalyst for efficient oxygen evolution reaction performance
    Tao Zhao, Dazhong Zhong, Genyan Hao, Guang Liu, Jinping Li, Qiang Zhao
    2022, 41(1):  480-487.  doi:10.1016/j.cjche.2021.11.011
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    Metal-organic frameworks (MOFs) exhibit excellent application potential in the field of electrocatalysis. In this study, we first prepare MIL-100 nanosheets on nickel foam (MIL-100/NF) and then successfully anchor Ag nanoparticles (NPs) on the nanosheets (Ag@MIL-100/NF) for oxygen evolution reaction (OER) catalysis. This strategy dramatically improves the conductivity of MIL-100 and the Ag NPs are uniformly dispersed on the nanosheets. The Ag@MIL-100/NF catalyst has excellent electrocatalytic performance and long-term corrosion resistance, with a low overpotential of 207 mV and a long-term stability of at least 100 h at a current density of 50 mA·cm-2. The experimental results demonstrate that this high OER catalytic performance is due to the improved charge transfer after loading Ag NPs, the combination of nanosheets and highly dispersed Ag NPs that expose more active sites and the adjusted chemical valence states of Fe and Ni in MIL-100. This work provides a surface decoration approach for the preparation of excellent catalysts directly used in the OER.
    Photocatalytic degradation of tetracycline hydrochloride with visible light-responsive bismuth tungstate/conjugated microporous polymer
    Fenghongkang Pan, Yimeng Wang, Kaiqing Zhao, Jun Hu, Honglai Liu, Ying Hu
    2022, 41(1):  488-496.  doi:10.1016/j.cjche.2021.08.030
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    Conjugated microporous polymer (CMP) is an emerging organic semiconductor with p-conjugated skeletons, and the bandgap of CMP can be flexibly modulated to harvest visible light. Based on the diversity and adjustability of monomers in CMP, we designed and synthesized donor-accepter (D-A) type BTNCMP through Sonogashira-Hagihara cross-coupling polymerization, further in-situ constructing series of inorganic/organic Z-scheme BW/BTN-n composite in the presence of Bi2WO6. After optimization, the tetracycline hydrochloride (C0 = 10 mg·L-1) degradation efficiency reached 84% with BW/BTN-2 as catalyst in 90 min under visible light irradiation, the apparent rate constant k1 is 0.017 min-1, which is 1.7 and 5.7 times higher than bare Bi2WO6 and BTN-CMP. X-ray photoelectron spectra and UV–Vis diffuse spectra showed that the enhanced photocatalytic activity originated from the tight heterojunction between Bi2WO6 and BTN-CMP, which can extend the light absorption range and facilitate the separation and transport of photogenerated charges in the interface of heterojunction. The active species trapping experiments and electron spin resonance technique revealed that h+ was the dominant active species during the photodegradation process of tetracycline hydrochloride (TCH). The present study demonstrated the feasibility to construct inorganic/organic composite for the photocatalytic degradation of environmental pollutants.
    Materials and Product Engineering
    Reduced graphene oxide modified melamine sponges filling with paraffin for efficient solar-thermal conversion and heat management
    Lu-Yue Liu, Zhuang Liu, Han-Yu Peng, Xiao-Ting Mu, Qian Zhao, Xiao-Jie Ju, Wei Wang, Rui Xie, Liang-Yin Chu
    2022, 41(1):  497-506.  doi:10.1016/j.cjche.2021.09.017
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    A novel type of reduced graphene oxide (rGO) modified melamine sponges (rGS) filling with paraffin (rGS-pf) is developed for efficient solar-thermal conversion and heat management. The microstructures, filling and holding capacity of paraffin in porous rGS, solar-thermal energy conversion and energy harvesting efficiency of the prepared rGS-pf have been investigated systematically. The content of rGO nanosheets coated on the skeletons of rGS-pf is only 0.11%, while the loading content of paraffin in the rGS-pf is as high as 97.53%. Based on the solar-thermal conversion property of rGO nanosheets in the rGS-pf and the heat storage ability of paraffin in the rGS-pf, the proposed rGS-pf provides excellent performance for heat management. The efficiency of solar-thermal conversion could reach up to 92.5%. The thermo-regulation provided by the proposed rGS-pf is real-time, repeatable and long-term stable. The results in this study provide valuable guidance for developing functional materials for efficient solarthermal conversion and heat management.