Superior ZSM-5@γ-Al2O3 Composite Catalyst for Methanol and Ethanol Coconversion to Light Olefins

This paper proposes a ZSM-5@γ-Al2O3 composite with a core–shell structure for the high-efficiency cocatalytic conversion of a methanol–ethanol system to light olefins. Using ZSM-5 and γ-Al2O3 as sole catalysts for comparison, the effects of physical blending, impregnation, and liquid-phase precipitation coating strategies on the catalytic performance and physicochemical properties of the composite catalysts were systematically investigated. The results indicated that the ZSM-5@γ-Al2O3 composite catalyst prepared by a liquid-phase precipitation coating exhibited excellent catalytic performance. When the ethanol content was 25 wt % and the reaction occurred at 350 °C, the conversion rates of methanol and ethanol were 96.1 and 99.9%, respectively; the selectivity and yield of light olefins reached 92.3 and 89.9%, respectively. The introduction of ethanol into methanol enhanced the selectivity of light olefins as target products. The interfacial composite phase formed by in situ nucleation growth of pseudoboehmite produced distinct Brønsted–Lewis acid synergistic active centers. It also increased the mesopore/micropore ratio in the composite catalyst.