Entropy considerations in monomolecular cracking of alkanes on acidic zeolites
Entropy considerations in monomolecular cracking of alkanes on acidic zeolites
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DOI：
10.1016/j.jcat.2007.11.003
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发表时间：
2008-01-01
影响因子：
7.3
通讯作者：
Iglesia, Enrique
中科院分区：
文献类型：
--
作者：
Bhan, Aditya;Gounder, Rajamani;Iglesia, Enrique
吸附熵和吸附熵之间的补偿结果在小于2倍的变化在吸附平衡常数为C-3-C-6烷烃在温度下的相关单分子裂化; C-C键活化C3-C6烷烃的大小无关的活化能表明，显着增加单分子裂化周转率与烷烃链的大小，反映了同时增加的活化熵。非理想系统的热力学处理严格地描述了沸石通道内的限制效应，并表明指前因子依赖于沸石-宿主环境的溶剂化效应，通过沸石质子的热力学活性的变化。观察到的速率和选择性的单分子烷烃活化与沸石结构的差异，归一化后的沸石内浓度，反映了内在的速率常数的差异。(C)2007年由Elsevier Inc.出版
Compensation between adsorption entropies and enthalpies results in less than a two-fold variation in adsorption equilibriurn constants for C-3-C-6 alkanes at temperatures relevant for monomolecular cracking; the size-independent activation energy for C-C bond activation in C3-C6 alkanes indicates that the marked increase in monomolecular cracking turnover rates observed with alkane chain size reflects a concurrent increase in activation entropies. Thermodynamic treatments for non-ideal systems rigorously describe confinement effects within zeolite channels and show that pre-exponential factors depend on solvation effects of the zeolite-host environment through variations in the thermodynamic activity of the zeolitic proton. Observed differences in rates and selectivities of monomolecular alkane activation with zeolite structure, after normalization to intrazeolitic concentrations, reflect differences in intrinsic rate constants. (C) 2007 Published by Elsevier Inc.