Dual-engine-driven synthesis of unsaturated esters over channel-expanding Cu-Cs catalysts

Abstract

This study presents a one-step catalytic synthesis of unsaturated esters (methyl acrylate, MA; methyl methacrylate, MMA) from methanol (MeOH, C1 source) and methyl acetate (MAc) via a Cu-Cs dual-engine-driven (DED) system that integrates four sequential steps—dehydrogenation, aldol condensation, hydrogenation, and secondary aldol condensation. The Cu-engine facilitates proton transfer by capturing protons during MeOH dehydrogenation and donating them in methyl acrylate (MA) hydrogenation, while the Cs-engine activates saturated esters for formaldehyde-mediated aldol condensation. Through systematic optimization of Cu loading methods, deposition sequences, and Cu/Cs ratios, we developed a silicon carrier channel-expanding strategy, enlarging mesopores from 14 nm to 20 nm (30 % specific surface area extension) via copper phyllosilicate-induced corrosion. Catalytic performance hinges on balanced medium-strength acid-base sites, a 10:7 Cs/Cu ratio, and sequential Cu/Cs loading via ammonia evaporation method. The optimized 10Cs/7Cu/Q10 catalyst, combined with a downstream Cs-Al/Q10 system, achieves 64.0 % unsaturated ester selectivity (55.3 % MeOH and 59.8 % methyl acetate conversion). This work establishes a design framework for efficient Cu-Cs catalysts in one-step ester synthesis, emphasizing pore engineering, acid-base synergy, and dual-site cooperativity.