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Selective adsorption of SF_(6) in covalent-and metal-organic frameworks

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Chinese Journal of Chemical Engineering 2021年第11期34卷 88-95页

作者： Xianqiang Zheng Yanlong Shen Shitao Wang Ke Huang Dapeng Cao State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China State Key Laboratory of Laser Interaction with Matter Northwest Institute of Nuclear TechnologyXi’an 710024China

Sulfur hexafluoride(SF_(6))is an extremely severe greenhouse *** is an urgently important mission to find excellent candidates for selective adsorption of SF_(6),in order to reduce the emission of SF_(6) ***,we adopt the molecular simulation method to systematically explore the selective adsorption of SF_(6) in 22 kinds of representative covalent-and metal-organic *** indicate that COF-6 is a promising candidate for the SF_(6) adsorption at low pressure P<20 kPa because of its small pore size,while MOF-180 and PAF-302 are excellent candidates at high pressure P=2×10^(3) kPa due to their large Brunauer-Emmett-Teller specific surface area(BET SSA)and pore *** the two cases of the power industry(X_(SF_(6))=0.1)and the semiconductor industry(X_(SF_(6))=0.002)environments,COF-6 and ZIF-8 are fairly promising candidates for selective adsorption of SF_(6) from the SF_(6)/N_(2) mixtures,because they not only present the high selectivity,but also the large adsorption capacity at ambient environment,which can be considered as potential adsorbents for selective adsorption of SF_(6) at ambient conditions.

关键词： Sulfur hexafluoride(SF_(6)) Metal-organic frameworks molecular simulation Covalent-organic frameworks Adsorption Separation

Understanding the alkyl effect of geminal dinitropropyl ester energetic plasticizers on hydroxyl terminated polybutadiene(HTPB):Simultaneous tuning on low temperature behavior and processability

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Chinese Journal of Chemical Engineering 2023年第2期54卷 364-371页

作者： Baodong Zhao Yinglei Wang Fulei Gao Yajing Liu Weixiao Liu Feng Ding Xi'an Modern Chemistry Research Institute Xi'an 710065China State Key Laboratory of Fluorine&Nitrogen Chemicals Xi'an 710065China

Geminal dinitropropyl ester plasticizers(DNPEPs) possess excellent energetic performances which provide good potentials as insensitive plasticizer. In this study, we design and synthesize DNPEPs with different alkane chain parts, and systematically investigate their structure-property *** show that DNPEPs have impact sensitivities all higher than 25.2 J, thermal decomposition temperatures all higher than 254 ℃, and glass transition temperatures(T_(g)) lower than-90 ℃.Furthermore, the effects of DNPEPs as plasticizer are studied on hydroxyl terminated polybutadiene(HTPB) in detail, including the viscosity, glass transition temperatures and others. It is noteworthy that 2,2-dinitropropyl nonanoate(DNPNc) among these DNPEPs exhibits the most expected simultaneous tuning effects on both viscosity and T_(g) of HTPB systems, providing favorable potentials to replace the conventional plastizers as dioctyl sebacate(DOS) in the HTPB based propellants and explosives.

关键词： molecular simulation Experimental validation Preparation Energetic plasticizer Glass transition temperature Viscosity

Machine learning for molecular thermodynamics

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Chinese Journal of Chemical Engineering 2021年第3期34卷 227-239页

作者： Jiaqi Ding Nan Xu Manh Tien Nguyen Qi Qiao Yao Shi Yi He Qing Shao College of Chemical and Biological Engineering Zhejiang UniversityHangzhou 310027China Chemical and Materials Engineering Department University of KentuckyLexingtonKY 40506USA Key Laboratory of Biomass Chemical Engineering of Ministry of Education Zhejiang UniversityHangzhou 310027China Department of Chemical Engineering University of WashingtonSeattleWA 98195USA

Thermodynamic properties of complex systems play an essential role in developing chemical engineering *** remains a challenge to predict the thermodynamic properties of complex systems in a wide range and describe the behavior of ions and molecules in complex *** learning emerges as a powerful tool to resolve this issue because it can describe complex relationships beyond the capacity of traditional mathematical *** minireview will summarize some fundamental concepts of machine learning methods and their applications in three aspects of the molecular thermodynamics using several *** first aspect is to apply machine learning methods to predict the thermodynamic properties of a broad spectrum of systems based on known *** second aspect is to integer machine learning and molecular simulations to accelerate the discovery of *** third aspect is to develop machine learning force field that can eliminate the barrier between quantum mechanics and all-atom molecular dynamics *** applications in these three aspects illustrate the potential of machine learning in molecular thermodynamics of chemical *** will also discuss the perspective of the broad applications of machine learning in chemical engineering.

关键词： Machine learning Thermodynamic properties molecular engineering molecular simulation Force field

Adsorption of rare earth elements on organic matter in coal

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Journal of Rare Earths 2023年第7期41卷 1108-1115,I0005页

作者： Xiaorui Wang Wei Cheng Renda Xu College of Mining Guizhou UniversityGuiyang 550025China National&Local Joint Laboratory of Engineering for Effective Utilization of Regional Mineral Resources from Karst Areas Guiyang 550025China Guizhou Key Laboratory of Comprehensive Utilization of Non-metallic Mineral Resources Guiyang 550025China

The occurrence modes of rare earth elements(lanthanide and yttrium,abbreviated as REY) in coal are impo rtant both for coal geochemistry studies and the application potential of REY as a by-product of coalbased *** this study,the adsorption behaviors of REY on organic matter in coal were investigated by leaching tests using REY solution and ultra-low ash coal *** this basis,the adsorption mechanism of REY on organic matter in coal was also studied by molecular simulation *** leaching tests show that the organic matter in coal has a relatively strong adsorption capacity for REY,and that the average adsorption rate or the net adsorption amount of heavy rare earth elements(HREY:Gd,Tb,Y,Dy,Ho,Er,Tm,Yb and Lu) is always higher than that of the light rare earth elements(LREY:La,Ce,Pr,Nd,Sm and Eu).A molecular model of humic acid(HA) was constructed and the adsorption amount between REY and HA was *** results show that the theoretical adsorption rate of HREY(84.88%) is higher than that of the LREY(84.00%).The analysis of the adsorption distances between REY atoms and various functional groups on HA molecules shows that the minimum adsorption distance of LREY is 0.372 nm on average,which is larger than that of HREY(0.368 nm),indicating that the adsorption capacity of the latter is *** addition,a coal molecule(C_(18)H_(22)O) was also constructed to investigate the adsorption characteristics of various REY atoms on the *** a result,it is found that the average binding ene rgy and bond length between the hydroxyl functional group and LREY atoms are 0.12469 Ha(Hartree,the unit of energy in the atomic unit system) and 0.1407 nm,respectively,while for HREY,0.12883 Ha and 0.1121 nm,*** confirms that HREY is more stable than LREY in binding on organic matter in *** conclude,both leaching tests and molecular simulation calculations reveal that REY has a strong adsorption affinity for organic matter in coal,and

关键词： Coal Rare earth elements Adsorption characteristics Leaching molecular simulation

Effect of pore size on CH4/N2 separation using activated carbon

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Chinese Journal of Chemical Engineering 2020年第4期28卷 1062-1068页

作者： Gaofei Chen Yaxiong An Yuanhui Shen Yayan Wang Zhongli Tang Bo Lu Donghui Zhang Key Laboratory of Cryogenics Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China The Research Center of Chemical Engineering School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China State Key Laboratory of Coal and CBM Co-mining Jincheng 048000China

In this paper,a model of activated carbon was established by molecular simulation and the separation performance of N2 and CH4 on activated carbon was *** order to evaluate the adsorption selectivity and diffusion selectivity of N2 and CH4,Grand Canonical Monte Carlo and molecular dynamic methods were used to obtain equilibrium adsorption isotherms and mean square displacements of N2 and CH4 on activated carbon with different pore *** results showed that the difference in adsorption isosteric heat of N2 and CH4 at the pore size of 0.46 nm is the largest,which is 5.759 and 7.03 kcal·mol^-1(1 cal=4.184 J),*** carbon with pore size of 0.46 nm has the best N2 and CH4 adsorption selectivity,while its diffusion selectivity is not obvious.

关键词： Activated carbon Coalbed methane GCMC MD molecular simulation

Separation of fuel additives based on mechanism analysis and thermodynamic phase behavior

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Chinese Journal of Chemical Engineering 2023年第12期64卷 168-176页

作者： Mengjin Zhou Yanli Zhang Ke Xue Haixia Li Zhaoyou Zhu Peizhe Cui Yinglong Wang Jingwei Yang College of Chemical Engineering Qingdao University of Science and TechnologyQingdao 266042China

tert-butanol and ethyl acetate,as fuel additives and oxygenated fuels,can improve fuels quality and reduce exhaust ***,the recovery of these compounds from azeotropic systems is of great *** liquids(ILs)are promising green solvents for separating azeotropic *** this study,an efficient extraction strategy based on 1-butyl-3-methylimidazolium acetate([Bmim][AC])is *** mechanism by which ILs enable the separation of binary alcohol-ester azeotropes was revealed by evaluating the lowest conformational energy through combining an independent gradient model based on the Hirshfeld partition(IGMH)and frontier molecular orbitals,to preliminarily screen the *** range of extractants was further reduced by a vapor–liquid phase equilibrium(VLE)experiment,and a modeling method for separating the alcohol–ester system and recovering the solvent using[Bmim][AC]and 1-ethyl-3-methyl-3-imidazolium acetate([Emim][AC])is *** the optimal operating conditions,the use of[Bmim][AC]can reduce the total annual cost(TAC)per year by 17.78%,and the emissions of CO_(2),SO_(2),and NO can be reduced by 10.86%.In this study,a comprehensive method for screening extractants is proposed,and the simulation process is optimized in combination with the economic and environmental *** results have important guiding significance for realizing efficient,energy-saving,and green azeotropic separation systems in industry.

关键词： Ionic liquids Extraction separation Quantum chemistry calculation Azeotrope molecular simulation

Insight into the behavior at the hygroscopicity and interface of the hydrophobic imidazolium-based ionic liquids

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Chinese Journal of Chemical Engineering 2021年第3期34卷 42-55页

作者： Guohui Zhou Kun Jiang Zhenlei Wang Xiaomin Liu School of Chemistry and Chemical Engineering Qingdao UniversityQingdao 266071China

How to completely remove the water from ionic liquids(ILs)is difficult for researchers because of the hygroscopicity of *** order to study the hygroscopicity of ILs,two kinds of ILs,1-Butyl-3-methylimidazolium hexafluorophosphate([Bmim][PF6])and 1-Butyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)([Bmim][NTf_(2)])were investigated by molecular dynamics ***[Bmim][PF6]and[Bmim][NTf_(2)]are hydrophobic,both of the ILs could absorb water molecules from the *** this work,the process of absorbing water from the vapor phase was studied,and the water molecules could disperse into the *** was observed with increasing the water *** the absorbed water increases obviously,the amount of free water and small cluster in the ILs does not change significantly and always stays at a certain *** amount of free water and small cluster in[Bmim][PF6]is more than that in[Bmim][NTf_(2)],which is consistent with their *** addition,the liquid-vacuum and liquid–liquid interfaces of the ILs were simulated and analyzed in *** number density distribution and angle distribution indicated that[Bmim]+cations arrangement regularly at the IL-vacuum *** butyl chain point to the vacuum,while the imidazlium ring is close to the IL phase region and perpendicular to the *** at the IL-water interface,the cations and anions are disordered.

关键词： Ionic liquid molecular simulation Interface Hygroscopicity Cluster

Ionic liquids on uncharged and charged surfaces: In situ microstructures and nanofriction

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Friction 2022年第11期10卷 1893-1912页

作者： Rong AN Yudi WEI Xiuhua QIU Zhongyang DAI Muqiu WU Enrico GNECCO Faiz Ullah SHAH Wenling ZHANG Herbert Gleiter Institute of Nanoscience School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China High Performance Computing Department National Supercomputing Center in ShenzhenShenzhen 518055China Otto Schott Institute of Materials Research(OSIM) Friedrich Schiller University JenaJena 07743Germany Chemistry of Interfaces LuleåUniversity of TechnologyLulea 97187Sweden School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China

In situ changes in the nanofriction and microstructures of ionic liquids(ILs)on uncharged and charged surfaces have been investigated using colloid probe atomic force microscopy(AFM)and molecular dynamic(MD)*** representative ILs,[BMIM][BF_(4)](BB)and[BMIM][PF_(6)](BP),containing a common cation,were selected for this *** torsional resonance frequency was captured simultaneously when the nanoscale friction force was measured at a specified normal load;and it was regarded as a measure of the contact stiffness,reflecting in situ changes in the IL microstructures.A higher nanoscale friction force was observed on uncharged mica and highly oriented pyrolytic graphite(HOPG)surfaces when the normal load increased;additionally,a higher torsional resonance frequency was detected,revealing a higher contact stiffness and a more ordered IL *** nanofriction of ILs increased at charged HOPG surfaces as the bias voltage varied from 0 to 8 V or from 0 to−8 *** simultaneously recorded torsional resonance frequency in the ILs increased with the positive or negative bias voltage,implying a stiffer IL layer and possibly more ordered ILs under these *** simulation reveals that the[BMIM]+imidazolium ring lies parallel to the uncharged surfaces preferentially,resulting in a compact and ordered IL *** parallel“sleeping”structure is more pronounced with the surface charging of either sign,indicating more ordered ILs,thereby substantiating the AFM-detected stiffer IL layering on the charged *** in situ observations of the changes in nanofriction and microstructures near the uncharged and charged surfaces may facilitate the development of IL-based applications,such as lubrication and electrochemical energy storage devices,including supercapacitors and batteries.

关键词： microstructure friction contact stiffness charged surfaces ionic liquids(ILs) molecular simulation

Origin of Modulus Improvement for Epoxide-terminated Hyperbranched Poly(ether sulphone)/DGEBA/TETA Systems

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Chinese Journal of Polymer Science 2018年第8期36卷 991-998页

作者： Xue-Pei Miao Dao-Jian Cheng Ya-Dong Dai Yan Meng Xiao-Yu Li Key Laboratory of Carbon Fiber and Functional Polymers Ministry of Education College of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical Technology Beijing 100029 China Neo Trident Technology Ltd (Beijing) Beijing 100190 China

It has been experimentally shown that epoxide-terminated hyperbranched polyether sulphone （EHBPES） can significantly improve the mechanical properties of traditional diglycidyl ether of bisphenol A/triethylenetetramine （DGEBA/TETA） systems, but the origin of the improvement is still unclear. In this work, we used molecular dynamics （MD） simulations to gain a thorough understanding of the origin of modulus improvement for EHBPES/DGEBA/TETA systems. It is found that the modulus of EHBPES/DGEBA/TETA systems increases with the increase of EHBPES loading. In addition, the crosslinking density, cohesive energy density （CED）, and free volume can be used to understand the modulus for EHBPES/DGEBA/TETA systems. It is shown that the highest modulus is achieved at 7 wt% EHBPES loading due to the highest crosslinking density and CED. When EHBPES loading is below 7 wt%, the higher CED and crosslinking density are responsible for the higher modulus. At higher loadings （〉 7 wt%）, the decreased modulus is closely related to the decreased crosslinking density and increased fractional free volume. It is expected that our results could be of great implications for designing high-performance epoxy materials.

关键词： Modulus molecular simulation Epoxy resin