Hierarchically structured ZSM‐5 zeolites (HSZ) were synthesized and used as high‐performance catalysts for para‐xylene (p‐X) production by tuning their pore structures and external surface acidity, which was achieved by two independent passivation approaches: dealumination in oxalic acid solution and chemical liquid deposition of tetra‐ethoxysilane (CLD of TEOS). The mesoporous structures of HSZ were well‐preserved after dealumination or CLD of TEOS, and the external surfaces of HSZ were passivated significantly. Compared to dealumination, CLD is more efficient because not only the external surface could be passivated, but also the pore‐openings of HSZ had been effectively narrowed, which both favored the enhancement of product p‐X selectivity in ortho‐xylene (o‐X) isomerization. The constraint index (CI) of as‐synthesized catalysts derived from the competitive reactions of ethylbenzene (EB) dealkylation and meta‐xylene (m‐X) isomerization and gravimetric adsorption measurements were introduced to investigate the extent of pore‐narrowing by CLD of TEOS. Benefitting from the auxiliary mesopores and surface‐passivation treatments, the optimized catalyst HSZ(Si0.5) showed remarkably enhanced catalytic activity over the microporous ZSM‐5 counterpart in the model reaction of o‐X isomerization.

中文翻译：

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表面钝化的分层结构ZSM5沸石：用于生产对二甲苯的高性能形状选择催化剂

合成了具有层次结构的ZSM-5沸石（HSZ），并通过调节其孔结构和外部表面酸度，将其用作生产对二甲苯（p- X）的高性能催化剂，这是通过两种独立的钝化方法实现的：草酸中的脱铝酸溶液和四乙氧基硅烷（TEOS的CLD）的化学液体沉积。脱铝或TEOS的CLD处理后，HSZ的中孔结构保存完好，并且HSZ的外表面被显着钝化。相比于脱铝，CLD是更有效，因为不仅是外表面可以钝化，也HSZ的孔开口已被有效缩小，这既利于产品的改进p -X选择性邻二甲苯（o- X）异构化。引入了乙苯（EB）脱烷基化反应和间二甲苯（m ‐X）异构化竞争反应和催化吸附测量得出的合成催化剂的约束指数（CI），以研究TEOS的CLD缩小孔隙的程度。得益于辅助介孔和表面钝化处理，优化的催化剂HSZ（Si0.5）在o- X异构化模型反应中显示出比微孔ZSM-5对应物显着增强的催化活性。