Adsorption Thermodynamics and Diffusion Kinetics of PX over Na Y Zeolite Synthesized by In-Situ Crystallization from Kaolin Microsphere

查看全文 作　　者：Zhao [1,2]Hua;Song [1,2]Lijuan;Qin [1,2]Yucai;Duan [2]Linhai;Sun [1,2]Zhaolin

机构地区：[1]College of Chemistry & Chemical Engineering, China University of Petroleum Qingdao;[2]Key Laboratory of Petrochemical Engineering, Liaoning Shihua University

出　　处：《China Petroleum Processing & Petrochemical Technology》索引2014年第16卷第4期,共8页

基　　金：financial support from the National Natural Science Foundation of China(20976077,21076100);the National 973 Foundation of China(2007CB216403) 摘　　要：Para-xylene was chosen as the probe molecule to study adsorption thermodynamics and diffusion kinetics on NaY zeolite and composite structured NaY zeolite synthesized by in-situ crystallization from kaolin microsphere(designated as Na Y/kaolin composites) separately, using a high precision intelligent gravimetric analyzer(IGA). The adsorption isotherms showed normal Langmuir type-Ⅰ behaviors. The increased adsorption heat with an increasing p-xylene coverage supported a mechanism of phase transition, diffusion and re-arrangement of p-xylene molecules during the adsorption process. The rearrangement seemed to be most pronounced at an adsorption loading of 2.13 and 2.29 mmol/g for Na Y zeolite and Na Y/kaolin composites respectively. Compared with Na Y zeolite, a 2—3 times higher in the diffusion coefficient of p-xylene was observed on Na Y/kaolin composites when the pressure was more than 50 Pa. Temperature-programmed desorption(TPD) of p-xylene on two samples from room temperature to 450 ℃ at a special loading has also been investigated by IGA. Results showed only single desorption peak appeared for Na Y zeolite, indicating that adsorption can only occur in the super-cage structure. Comparably, there were two different peaks for in-situ synthesized Na Y zeolite, corresponding to the two thermo desorption processes in both super-cage structure and the channels provided by kaolin, respectively.Key words: 关键词：adsorption THERMODYNAMICS diffusion kinetics in-situ crystrallization NAY ZEOLITE PARA-XYLENE

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Adsorption Thermodynamics and Diffusion Kinetics of PX over Na Y Zeolite Synthesized by In-Situ Crystallization from Kaolin Microsphere

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