Sustainable synthesis of hierarchical MFI zeolite from mesoporous HMS and catalytic application

Constructing hierarchical structure in conventional zeolites is a promising means to overcome intrinsic shortcomings of this type of microporous material. In this research, a novel synthesis strategy for hierarchical zeolite was presented. By utilizing mesoporous HMS as silica source, MFI aluminosilicate with mesoporosity was successfully prepared through sustainable process without organic template or large amounts of solvent. The obtained products were characterized by a series of techniques, including X-ray diffraction, transmission electronic microscopy, N ₂ physical adsorption, X-ray fluorescence and NH ₃ temperature programmed desorption. It has been shown that as-synthesized and calcined HMS had generated MFI zeolite with different mesoporosity, based on which the different synthesis mechanisms for hierarchical products were proposed. The alkylamine dose not impede the sustainable synthesis of MFI zeolite, which endow the availability of HMS for green synthesis of hierarchical zeolite. After loaded with platinum, the obtained hierarchical bifunctional catalysts show higher activity but lower isomers selectivity in hydroisomerization of n -heptane compared to mono-microporous counterpart. In addition, the mesoporosity of the catalysts had led to the higher multi-branched isomers productivity.