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.