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首页> 外文期刊>Catalysis science & technology >Decoupling porosity and compositional effects on desilicated ZSM-5 zeolites for optimal alkylation performance
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Decoupling porosity and compositional effects on desilicated ZSM-5 zeolites for optimal alkylation performance

机译：对脱胶式ZSM-5沸石的脱钩孔隙率和成分影响，以获得最佳的烷基化性能

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摘要

Desilication of conventional zeolites in alkaline medium generates variable intracrystalline mesoporosity, but inevitably changes other properties such as the Si/Al ratio and aluminium distribution. Assessing the individual effects of porosity and composition on the catalytic performance of desilicated zeolites is relevant for their optimal design. Herein, we decouple the respective impacts in the acid-catalysed alkylation of toluene (or cyclohexylbenzene) with benzyl alcohol. These reactions experience strong accessibility constraints to the micropores, providing high sensitivity to the properties of the developed mesopore surface. Through strategic comparison of alkaline-treated ZSM-5 zeolites prepared with and without subsequent acid treatment, we show that while acidity is important, the alkylation activity is dominated by the mesoporous surface area. The selectivity to (methylbenzyl)benzene does not depend on the available external surface. Excessively large mesopore volumes are detrimental to the activity, and variation in micropore volume has a minimal effect. Acid-treated mesoporous zeolites exhibit higher catalytic activities primarily due to textural enhancements by removal of aluminium-rich amorphous debris. The catalytic results are rationalised on the basis of extensive characterisation (AAS, N2 sorption, XRD, TEM, ~(27)A1 MAS NMR, FTIR, NH3-TPD, and adsorption of toluene and cyclohexylbenzene).
机译：碱性培养基中常规沸石的脱氧化产生可变的晶体内室源性，但不可避免地会改变其他特性，例如Si/Al比率和铝分布。评估孔隙度和成分对脱氧沸石催化性能的单个影响与其最佳设计有关。本文中，我们将甲苯（或环己基苯二苯二酸）用苄醇的酸催化烷基化的影响分离。这些反应对Micropores产生了强大的可及性约束，对发达的中孔表面的性质具有很高的敏感性。通过对碱性处理的ZSM-5沸石进行战略比较，并没有随后的酸处理，我们表明，尽管酸度很重要，但烷基化活性由中端表面积主导。对（甲基苯基）苯的选择性不取决于可用的外表面。过多的中孔体积对活性有害，而微孔体积的变化具有最小的作用。酸处理的介孔沸石表现出较高的催化活性，这主要是由于去除富含铝的无定形碎片的质地增强所致。基于广泛的表征（AAS，N2吸附，XRD，TEM，〜（27）A1 MAS NMR，FTIR，NH3-TPD，以及甲苯和环己基苯乙烯的吸附）。

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