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Effects of Operating Conditions on the Catalytic Performance of hzsm-5 zeolites in n-Pentane Cracking

China Petroleum Processing & Petrochemical Technology 2021年第1期23卷 67-75页

作者： Hou Xu Zhao Liu Ma Zhenzhou Chen Bochong Feng Jingyuan Cui Tingting School of Chemical Engineering Changchun University of TechnologyChangchun 130012 Advanced Institute of Materials Science Changchun University of TechnologyChangchun 130012 Department of Chemistry Tsinghua UniversityBeijing 100084

In this work,n-pentane catalytic cracking over hzsm-5 zeolites was studied at 650°C under atmosphere pressure.A particular attention was paid to the measurement of n-pentane conversion,light olefins production,product distribution,coke deposit,*** indexes were defined to evaluate the effects of operating conditions on the catalytic performance of hzsm-5 *** was found that decreasing the weight hourly space velocity,increasing the reactant partial pressure,and increasing the carrier gas flow rate could inhibit C-H bond breaking and enhance the C-C bond breaking and hydride transfer reactions,leading to reduced alkenes selectivity,which suppressed the formation of external coke and alleviated the deactivation of hzsm-5 *** was deduced that the catalytic stability of hzsm-5 zeolites was improved at the cost of alkenes *** with decreasing the weight hourly space velocity and increasing the reactant partial pressure,increasing the carrier gas flow rate could enhance the diffusion process and protect alkenes from being consumed in coke formation in order to improve the catalytic stability of hzsm-5 zeolites with less reduction of alkenes selectivity.

关键词： operating conditions hzsm-5 zeolites catalytic performance n-pentane cracking light olefins

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Catalytic activity of phosphorus and steam modified hzsm-5 and the theoretical selection of phosphorus grafting model

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Journal of Natural Gas Chemistry 2008年第2期17卷 142-148页

作者： Renqing Lu Zuogang Cao Xinhai Liu College of Chemistry and Chemical Engineering China University of Petroleum （East China） Dongying 257061 Shandong China College of Mathematics and Computational Science China University of Petroleum （East China） Dongying 257061 Shandong China

The modification of hzsm-5 zeolite with phosphorus and steam has been studied. Results show that 1% phosphorus and steam modified hzsm-5 has the highest catalytic activity for n-heptane. Physicochemical and catalytic properties of 1% phosphorus and steam modified hzsm-5 zeolites have been investigated. The X-ray diffraction （XRD） results exhibit that there is considerable variation in the relative intensity of the individual diffraction peaks. The acidity of the samples decreases with an increase in the steaming temperature, which is determined by the IR of adsorbed pyridine and temperature programmed desorption （TPD） of ammonia. The oxidation state of phosphorus shown by XPS is ＋5, and a model for surface structure modification is proposed. The nitrogen adsorption isotherm for all samples is a combination of type I and type IV, all hysteresis loops resemble the H4-type. The density functional and cluster model methods have been invoked to select the phosphorus grafting model, and it was found that the phosphorus grafting model were more probable in the form of the terminal oxygen coordinating with aluminum.

关键词： hzsm-5 zeolites steam treatment phosphorous acid modification cracking activity cluster model

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Acidity of （CH3）3SiCl-Modified ZSM-5 Zeolite and Its Catalysis in Toluene Disproportionation Reaction

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Chemical Research in Chinese Universities 1988年第2期 72-80页

作者： Li Jieming, Jiang Dazhen, Fan Shuguang and Sun Zhongqi (Department of Chemistry, Jilin University,Changchun)

hzsm-5 zeolites modified by Si(CH3)3 Cl were studied by TPD, IKand 27Al NMR to characterize their surface properties and bycatalytic reaction of toluene *** was found that the concentration of the stronger Bronsted acid sites were decreased and the stronger Lewis acid sites were increased after modifieation with Si(CH3),Cl. The TPD peaks of NH3, presumally attributed to stronger acid sites (peak Ⅱ ) were decreased by the deposition of Si(CH3)3 Cl on the surface of the *** selectivity to the para xylene can be attained not only by controlling the pore opening and channels of the zeolite, hut also by changing the concentration of the stronger acid sites and the acidic type on the surface of the zeolite.

关键词： hzsm-5 zeolites Surface acidity catalysis

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