Direct Conversion of the Biomass-Derived Acetone-Ethanol Mixture into Propene over Zr/Beta Zeolite

The conversion of biomass fermentation liquor has garnered significant attention due to its potential for sustainable chemical production. Particularly, the transformation of an acetone-ethanol mixture, derived from the separation of high-value butanol, into other valuable compounds represents a critical advancement in biorefinery processes. Herein, we present a high-efficiency Zr/Beta zeolite catalyst for the conversion of an acetone-ethanol mixture into propene. Through systematic optimization, the optimal catalyst 5%Zr/Beta achieves a high propene yield (37.8%) with a propene selectivity of 67%. Spectroscopic results reveal that the conversion of acetone and ethanol primarily proceeds via the Meerwein-Ponndorf-Verley (MPV) reduction at Zr sites to form the isopropanol intermediate, followed by acid-catalyzed dehydration to propene facilitated by Si-OH groups. The high propene selectivity is due to the minor side reaction of converting acetone to isobutene, accompanied by the accumulation of cyclic unsaturated aldehydes/ketones and aromatic compounds deposited on the Zr active sites, leading to catalyst deactivation. Additionally, the Zr/Beta catalyst demonstrates good regenerability, which could recover to the initial state after a facile calcination process in air. This work offers a promising approach for the synthesis of propene from a biomass-derived acetone-ethanol mixture, contributing to the development of sustainable catalytic processes for biorefinery applications.