Structure-deactivation relationship for ZSM-5 catalysts governed by framework defects
Structure-deactivation relationship for ZSM-5 catalysts governed by framework defects
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DOI：
10.1016/j.jcat.2011.03.016
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发表时间：
2011-06-13
影响因子：
7.3
通讯作者：
Beato, Pablo
中科院分区：
文献类型：
--
作者：
Barbera, Katia;Bonino, Francesca;Beato, Pablo
沸石是将甲醇转化为碳氢化合物的众所周知的催化剂。通过调整合成程序，ZSM-5沸石在甲醇转化为汽油中的活性和失活可以发生显着变化。我们发现内部骨架缺陷对于 ZSM-5 催化剂的失活行为至关重要。吡啶和2,4,6-可力丁的吸附表明，3745 cm(-1)处的红外波段可归属于外表面上孤立的硅烷醇基团，而3726和3700 cm(-1)处的红外波段可归属于沸石晶体内部的硅烷醇基团。虽然活性与酸位点密度有关，但失活率与测量的 3726 cm(-1) 内部硅烷醇基团和 3745 cm(-1) 外部硅烷醇基团 (I-3726/I-3745) 的红外带的强度比相关。因此，活性和失活取决于不同的物理特性，这意味着它们可以独立变化。 (C) 2011 Elsevier Inc. 保留所有权利。
Zeolites are well known catalysts for the conversion of methanol to hydrocarbons. By adjusting the synthesis procedure, the activity and deactivation of the ZSM-5 zeolite in the conversion of methanol to gasoline can be varied significantly. We found that internal framework defects are crucial for the deactivation behavior of the ZSM-5 catalysts. Adsorption of pyridine and 2,4,6-collidine shows that the infrared band at 3745 cm(-1) can be assigned to isolated silanol groups on the external surface and the bands at 3726 and 3700 cm(-1) to silanol groups inside the zeolite crystals. While the activity is related to the acid site density, the deactivation rate correlates with the measured intensity ratio of the IR bands for internal silanols at 3726 cm(-1) and for external silanol groups at 3745 cm(-1) (I-3726/I-3745). The activity and deactivation, therefore, depend on a different physical property, which means that they can be varied independently. (C) 2011 Elsevier Inc. All rights reserved.