Fabricating self-assembled SAPO-5 with tailored mesoporosity and acidity using a single template

Abstract

The hierarchically structured zeolite with high surface area and a large number of mesoporosities has attracted tremendous attention. Particularly, the morphology and structural tailoring of a diverse mesoporous zeolite with a single template is regarded as a crucial step toward the realization of an environmentally friendly synthesis. Herein, crystalline silicoaluminophosphate (SAPO-5) of the AFI framework type with a bimodal pore system was hydrothermally synthesized using di-n-butylamine (DBA) as a single template. The structural and catalytic properties of the hierarchical SAPO-5 were extensively characterized and compared to those of a conventional SAPO-5 using triethylamine (TEA) as a template. After loading Pt nanoparticles by incipient wetness impregnation, due to the promoting effect of hierarchical SAPO-5 in which the reactant and product were rapidly contacted with the acidity sites and metal sites, the 0.5 wt% Pt/SAPO-5-1.0DBA catalyst exhibits an enhanced hydroisomerization performance, with heptane conversion of 76.1% and iso-C7 yields of 48.4%, compared to a conventional 0.5 wt% Pt/SAPO-5-1.0TEA catalyst. The crystallization evolution under a series of hydrothermal times was also studied here. More importantly, this green, sustainable and economical strategy will extend the application of the synthesis of a silicoaluminophosphate-based zeolite.