Role of the Surface Modification on the Transport of Hexane Isomers in ZSM-5†
Role of the Surface Modification on the Transport of Hexane Isomers in ZSM-5†
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DOI：
10.1021/jp106474x
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发表时间：
2011-02
影响因子：
3.7
通讯作者：
Oliver C. Gobin;S. Reitmeier;A. Jentys;J. Lercher
中科院分区：
文献类型：
--
作者：
Oliver C. Gobin;S. Reitmeier;A. Jentys;J. Lercher
通过对正己烷异构体的吸附动力学分析，研究了表面改性对纳米HZSM-5分子筛传输性能的影响。如果初始吸附是限制步骤，即，对于正己烷、2-甲基戊烷和3-甲基戊烷。如果晶内输运是速率决定步骤，即，对于2，2-二甲基丁烷，表面改性导致吸附速率显著降低。传输速率的这种降低是由较低的指前因子引起的;即，它是熵诱导的。由于表面改性，对于空间要求高的分子，一定比例的孔被完全堵塞，从而降低了进入孔的可能性。结果表明，微孔材料的表面改性允许选择性地提高或降低所定义的系统的传输速率。
The role of the surface modification on the transport properties of nanosized HZSM-5 particles was investigated by the analysis of the sorption kinetics of hexane isomers. The rate of diffusion is enhanced by this modification, if the initial adsorption is the limiting step, i.e., for n-hexane, 2-methylpentane, and 3-methylpentane. If the intracrystalline transport is the rate-determining step, i.e., for 2,2-dimethylbutane, the surface modification leads to a significantly decreased sorption rate. This reduction in the transport rate is caused by a lower pre-exponential factor; i.e., it is entropically induced. Due to the surface modification, a certain fraction of the pores is completely blocked for the sterically demanding molecules reducing the probability of entering the pores. The results show that surface modification of microporous materials allows selectively enhancing or decreasing the transport rate of defined systems.