Selective catalytic cracking of n-hexane to propylene over hierarchical MTT zeolite

Catalytic cracking of naphtha over one-dimensional (1D) pore zeolite was targeted by using n-hexane as a model compound. Novel hierarchical H-ZSM-23 (MTT), a 1D pore zeolite, was specially designed to maximize propylene yield from catalytic cracking. Very high propylene-to-ethylene ratio of 2.5 was achieved. The ZSM-23 with mesopores displayed an enhanced deactivation resistance compared to microporous parent crystals. Hierarchical ZSM-23 was synthesized rapidly by applying microwave-assisted hydrothermal synthesis (MAHyS) followed by microwave-assisted alkaline treatment and moderate acid treatment. Pore volume of hierarchical ZSM-23 was improved considerably compared with the ones of parent crystals. Physico-chemical properties of hierarchical ZSM-23 were studied by characterization techniques such as XRD, FE-SEM, N2 adsorption–desorption, 27Al and 29Si MAS NMR, NH3-TPD, and TEM.