Pt-promoted mesoporous Beta zeolite catalysts for n-Hexane isomerization with enhanced selectivity to dibranched isomers

• Published in: Fuel (Guildford) 2024-07, Vol.368, p.131593, Article 131593
• Main Authors: Wang, Pengzhao, Chen, Tingting, Qiu, Zihui, Yao, Wenjun, Liu, Pengpeng, Zhang, Yongze, Song, Yu, Cui, Qingyan, Bao, Xiaojun
• Format: Article
• Language: English
• Subjects: Alkaline etching; Alkane isomerization; Dibranched isomers; Diffusion barrier; Mesoporous Beta zeolite
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2024.131593

[Display omitted] •Mesoporous Beta Zeolite was facilely prepared by alkaline etching and ion exchanges.•Desilication from outer rim of Beta stacking faults enlarged intercrystallite mesopores.•Collapse of microporosity created cylindroid-like intracrystalline mesopores.•Hierarchical micro-mesoporous configurations enhanced the diffusivities of isomers.•Pt/Beta-0.2 M exhibited much higher alkane isomerization selectivity. We report a facile yet effective strategy to prepare hierarchical Beta zeolite with high molecular transport effectivity in catalysis. Alkaline etching involves preferential desilication from Beta framework and collapse of microporosity. The preferential desilication from outer rim of Beta stacking faults enlarged intercrystallite mesopores, while the collapse of microporosity created cylindroid-like intracrystalline mesopore. Part of Altet with lower stability was removed during alkaline etching, leading to a decrease in acid sites density. Alkaline etching of Beta zeolite with 0.2 mol/L NaOH solution greatly improved n-hexane isomerization activity over Pt-based catalysts. The maximum yield of isohexane and dibranched isomers increased by 6.2 % and 38.6 %, respectively. The enlargement of intercrystallite mesopores and the generation of intracrystalline mesopores of Beta zeolite lowered apparent activation energy of reaction. The apparent diffusivities measurements further revealed that Pt/Beta-0.2 M showed much lower transport limitation than Pt/Beta-parent. Our findings provide a promising catalyst for industrial alkane isomerization.