CO2-assisted in situ hydrogen extraction for high conversion dehydrogenation of alcohol over Cu–ZnO–Al2O3 catalyst

Direct dehydrogenation of alcohols to aldehydes is a pivotal transformation in fine chemical synthesis. However, conventional thermal processes often suffer from low efficiency and high energy consumption. Herein, we propose an emerging and sustainable strategy that employs CO 2 -assisted in situ hydrogen extraction to drive the dehydrogenation of alcohols under mild conditions. Specifically, CO 2 as a soft oxidant adsorbs and activates on the Cu–ZnO–Al 2 O 3 composite oxide catalyst surface, generating reactive species (COO*) that selectively abstract hydrogen from the α -C of the alcohol. Combined Langmuir-Hinshelwood kinetic analysis and density functional theory calculations reveal a higher formation rate of the aldehyde product and the lower activation barrier for the key C–H bond activation process under the CO 2 atmosphere. As a result, the CO 2 -assisted dehydrogenation markedly enhances reaction efficiency, achieving a 60.21% conversion of 2-ethylhexanal under a low temperature (240°C), which is nearly twice that observed under the pure N 2 atmosphere. This CO 2 -assisted dehydrogenation strategy in this work exhibits a cooperative catalytic pathway that not only enables efficient aldehyde production but also utilizes CO 2 as a chemical resource.