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Adsorption properties of environmentally friendly insulating medium C_(4)F_(7)N and its common decomposition products in NaA,NaZSM-5,and NaX molecular sieves

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High Voltage 2023年第3期8卷 611-621页

作者： Shuangshuang Tian Zian Yuan Xiaoxing Zhang Yingxiang Wang Weifeng Luo Yang Liu Hubei Engineering Research Center for Safety Monitoring of New Energy and Power Grid Equipment Hubei University of TechnologyWuhanChina Xiangyang Industrial Institute of Hubei University of Technology WuhanChina State Grid HBEPC.Ltd Economic and Technology Research Institute WuhanHubeiChina State Grid Hubei Extra High Voltage Company WuhanChina

Selecting suitable materials to adsorb the C_(4)F_(7)N mixtures decomposition products could not only keep the stable operation of the environmentally friendly insulating gas switch cabinet,but also ensure the safety of operation and maintenance personnel.It is necessary to study the interaction of three types of molecular sieves with the C_(4)F_(7)N mixture and its decomposition products,which could provide a theoretical basis for the selection of adsorbents in the C_(4)F_(7)N gas switch cabinet.In this research,the molecular dynamics simulation was used to study the C_(4)F_(7)N-CO_(2)mixture and its ten kinds of decomposition products CO,CF_(4),C_(2)F_(6),C_(3)F_(6),C_(3)F_(8),CF_(3)H,CF_(3)CN,C_(2)F_(5)CN,C_(2)N_(2),and COF_(2)in three molecular sieves adsorption process(NaA,NaZSM-5,and NaX).The gas concentration distribution curve and interaction energy parameters were obtained by simulation.The interaction energies of C_(3)F_(8)in NaA,C_(4)F_(7)N in NaZSM-5,and C_(3)F_(6)in NaX molecular sieve are the largest,which are−368.35 kJ/mol,−174.93 kJ/mol,and−340.09 kJ/mol respectively.Then,the theoretical results were verified by the fluorocarbon gases adsorption experiment.The adsorption performance of three molecular sieves for all gases was obtained by combining the experimental results and dynamics parameters.The adsorption rate of the NaA molecular sieve for fluorocarbon gas is less than 35%,and its adsorption performance for all gases is weak.NaZSM-5 and NaX molecular sieves show excellent adsorption performance for C_(3)F_(6)and C_(3)F_(8),and the adsorption rates are over 70%.NaZSM-5 molecular sieve shows good adsorption capacity for CF_(3)CN,C_(2)F_(6),C_(2)N_(2),C_(3)F_(6),C_(3)F_(8),C_(4)F_(7)N,and C_(2)F_(5)CN.NaX molecular sieve shows good adsorption capacity for C_(3)F_(6),C_(3)F_(8),C_(4)F_(7)N,and C_(2)F_(5)CN.Both of them have the potential to be used as adsorbents in environmental protection insulated gas switch cabinet.

关键词： sieve adsorption gases

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Selective synthesis of triacetin from glycerol catalyzed by HZSM-5/MCM-41 micro/mesoporous molecular sieve

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Chinese Journal of Chemical Engineering 2019年第5期27卷 1073-1078页

作者： Jiangyong Liu Zihao Wang Yunlin Sun Ruiqi Jian Panming jian Dan Wang School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou225002China School of Medicine Stanford UniversityStanfordCA 94304USA State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China

HZSM-5/MCM-41 molecular sieve (H-ZM) catalysts with well-defined micro/mesoporous structures were synthesized and showed high performance for selective synthesis of triacetin via the esterification reaction of glycerol with acetic acid. The conversion of glycerol was demonstrated to be 100% and the triacetin selectivity was over 91%, which can be attributed to the synergistic effect regarding suitable acidic property, excellent diffusion efficiency and good stability derived from the combined advantages of microporous molecular sieve HZSM-5 and mesoporous molecular sieve MCM-41.

关键词： Mesoscale Porous materials Molecular sieve Triacetin Glycerol esterification

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Sifting for small primes from an arithmetic progression

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Science China Mathematics 2023年第12期66卷 2715-2730页

作者： John B.Friedlander Henryk Iwaniec Department of Mathematics University of TorontoTorontoON M5S 2E4Canada Department of Mathematics Rutgers UniversityPiscatawayNJ 08903USA

In this work and its sister paper(Friedlander and Iwaniec(2023)),we give a new proof of the famous Linnik theorem bounding the least prime in an arithmetic progression.Using sieve machinery in both papers,we are able to dispensh with the log-free zero density bounds and the repulsion property of exceptional zeros,two deep innovations begun by Linnik and relied on in earlier proofs.

关键词： sieve small primes Linnik theorem

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Influence of 3A molecular sieve on tetrahydrofuran (THF) hydrate formation

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Science China Chemistry 2008年第9期51卷 893-900页

作者： ZANG XiaoYa FAN ShuanShi LIANG DeQing LI DongLiang CHEN GuangJin Guangzhou Institute of Energy Conversion Chinese Academy of SciencesGuangzhou 510640China Guangzhou Center for Gas Hydrate Research Chinese Academy of SciencesGuangzhou 510070China Key Laboratory of Renewable Energy and Gas Hydrate Chinese Academy of SciencesGuangzhou 510640China China University of Petroleum Beijing 102249China

Visual observation of the THF hydrate formation process in the presence of a 3A molecular sieve has been made at normal atmosphere and below a temperature of zero by microscopy. The results indicate that a 3A molecular sieve can induce the nucleation of the THF hydrate and promote the THF hydrate growth. With the existence of a 3A molecular sieve, the growth rate of THF hydrate is between 0.01 and 0.05 μm/s. In comparison with the system without any 3A molecular sieve, the growth rate increases about 4 nm/s. After the THF hydrate grows into megacryst, the crystals will recombine and partially change under the same condition.

关键词： molecular sieve tetrahydrofuran (THF) hydrate

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Molding of Molecular sieve Residues and Their Application in Cleaning Oily Wastewater

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Transactions of Tianjin University 2019年第6期25卷 631-640页

作者： Zilu Jin Yuqing Zhang Song Wei Shuai Sun School of Chemical Engineering and Technology Tianjin University

To deeply clean oily wastewater,molecular sieve residues(MSRs)were sufficiently recycled and utilized due to their high specific surface area,porous structure,and outstanding adsorption property.Molding MSRs(MMSRs)were prepared by adding additives(starch,citric acid,and soluble glass)to MSRs and were then filled into a fixed bed for adsorbing and separating the oil in wastewater.Sodium dodecylbenzenesulfonate was used to modify the MMSRs,and their adsorption property was also investigated.In addition,the MSRs were characterized by scanning electron microscopy,energy-dispersive X-ray spectroscopy,Brunauer–Emmett–Teller analysis,and Fourier transform infrared spectroscopy.The results indicated that MMSRs satisfied the filling requirement of fixed bed,and their dynamic adsorption capacity could reach 0.1854 mg g^?1.Furthermore,the static adsorption capacity of MMSRs achieved 1.7346 mg g^?1 in the optimum conditions,and the oil adsorption performance of modified MMSRs was further enhanced.Therefore,this work suggests that MSRs are promising alternatives in cleaning oily wastewater.

关键词： Molecular sieve residues Molding Oily wastewater Adsorption Cleaning

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Investigation of ZSM-5/MCM-41 Composite Molecular sieve for Reducing Olefin Content of FCC Gasoline

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China Petroleum Processing & Petrochemical Technology 2009年第4期11卷 10-17页

作者： Ji Dekun~(1,2) Li Shuyuan~1 Ding Fuchen~2 Chi Yaoling~2 (1.Chemical Engineering School,China University of Petroleum(Beijing),Beijing 102249 2.Department of Chemical Engineering,Beijing Institute of Petrochemical Technology) Chemical Engineering School China University of Petroleum (Beijing) Beijing 102249 China Department of Chemical Engineering Beijing Institute of Petrochemical Technology China

ZSM-5/MCM-41 composite molecular sieve was prepared by the nano-assembling method.The ZSM-5 molecular sieve,the MCM-41 molecular sieve,the ZSM-5/MCM-41 mechanical mixture and the ZSM-5/MCM-41 composite molecular sieve were characterized by X-ray powder diffractometry,N2 adsorption isotherms,temperature programmed desorption of ammonia and scanning electron microscopy and their properties were analyzed.Using FCC gasoline as the feed,activities of different molecular sieves for reducing olefin content were investigated in a continuous high-pressure micro-reactor unit under the following conditions:a reaction temperature of 400℃,a reaction time of 2 h,a weight hourly space velocity of 3h-1,and a reaction pressure of 2.0 MPa.The results showed that the HMCM-41 molecular sieve had low reaction performance,and the HZSM-5 molecular sieve demonstrated high aromatization activity,while the ZSM-5/MCM- 41 composite molecular sieve exhibited a best olefin-reducing performance because of its high isomerization activity and moderate aromatization activity.With a largest olefin-reducmg capability and a reasonable distribution of products,the composite molecular sieve was more suitable for FCC gasoline upgrading compared to other three catalysts.

关键词： ZSM-5 MCM-41 composite molecular sieve FCC gasolin

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Mechanism of selective separation on the surface of ionic sieve of removal of lead

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Chinese Science Bulletin 2002年第10期47卷 814-817页

作者： Linshuang Wang Ping Na Rongshu Wang Tianjin Univ Sch Chem Engn & Technol Tianjin 300072 Peoples R China

This note describes a kind of ionic sieve with high selectivity to remove trace lead in water, in which stannic molybdopyrophosphate is used to be the substrate. The mechanism of selective separation on the surface of ionic sieve of removal of lead was explored by analyzing fourier transformation infrared spectra (FTIR), X-ray photoelectron spectrometry (XPS) and the results of selective adsorptivity experiment. The investigation suggests that in the process of synthesizing ionic sieve the olation reactions occur in solid phase by thermodynamic recrystallization and the adsorption units with special selectivity to lead are formed by chemical modification. After the ion exchange for Pb2+, the oaltion reactions not only keep the microstructures of adsorption units from collapse, but also provide lead cavties with special selectivity to lead ion that are capable of having special binding 'memory effect' to Pb2+ by SnO32- and P2O74- groups on the surface of this ionic sieve. Meanwhile, the selective

关键词： ionic sieve of removal of lead thermodynamic recrystal-lization weak chemical effect selective separation.

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A new sieve for distinct coordinate counting

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Science China Mathematics 2010年第9期53卷 2351-2362页

作者： LI JiYou1 & WAN DaQing2,1Department of Mathematics,Shanghai Jiao Tong University,Shanghai 200240,China 2Department of Mathematics,University of California,Irvine,CA 92697-3875,USA Department of Mathematics Shanghai Jiao Tong University Shanghai China Department of Mathematics University of California Irvine USA

We present a new sieve for the distinct coordinate counting problem.This significantly improves the classical inclusion-exclusion sieve for this problem,in the sense that the number of terms is reduced from 2(k 2) to k!,and reduced further to p(k) in the symmetric case,where p(k) denotes the number of partitions of k.As an illustration of applications,we give an in-depth study of a basic example arising from coding theory and graph theory.

关键词： sieve distinct coordinate counting

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Preparing strong basic zeolite molecular sieve catalytic materials

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Chinese Science Bulletin 1999年第21期44卷 1926-1934页

作者： Jianhua Zhu Yuan Chun Ying Wang Qinhua Xu Nanjing Univ Dept Chem Chem & Chem Engn Coll Nanjing 210093 Peoples R China

Progress on preparing strong basic and superbasic zeolites, mainly obtained in China during last decade has been reviewed. Strong basic sites are difficult to be generated on zeolite by common way, e.g. adjusting the chemical composition of frameworks or loading alkali metal oxides/hydroxides owing to the special structure of zeolite. Through some novel methods

关键词： strong basic molecular sieve solid superbase base catalysis KF modification supporting KNO3 dispersion of MgO by Microwave irradiation.

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On Maximal Large sieve Inequality

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Science China Mathematics 1994年第1期37卷 27-33页

作者：龙瑞麟刘政权 Institute of Mathematics Academia SinicaBeijing 100080PRC Department of Mathematics Hunan Normal UniversityChangsha 410081PR

In this paper it is shown that the maximal weighted large sieve inequality can be implied by a simple weighted Fourier transform inequality.

关键词： Fourier transform maximal function weighted inequality large sieve

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