Pore-structure-mediated hierarchical SAPO-34: Facile synthesis, tunable nanostructure, and catalysis applications for the conversion of dimethyl ether into olefins

Abstract

Hierarchical cross-like SAPO-34 catalysts with different pore size distributions were obtained via hydrothermal synthesis with polyethylene glycol (PEG) as the mesopore-generating agent. The hierarchical SAPO-34 molecular sieves were characterized using X-ray diffraction, scanning electron microscopy, N2 adsorption–desorption, thermogravimetric analysis, and temperature-programmed NH3 desorption. The cross-like SAPO-34 catalysts exhibited enriched multi-porosity, and the sizes of their mesopores ranged from 10 to 50nm. Both the mesoporous structures and morphologies of the hierarchical SAPO-34 could be further tuned through adjustments of the amount of PEG used. The as-obtained SAPO-34 showed dramatic catalytic performance in the conversion of dimethyl ether into olefins. A maximum selectivity of olefins of 96% was achieved, which was attributed to the rapid transport of the reactants and products in zeolitic micropores through mesopores.