Density Functional and Coupled Cluster Study on the Conversion of Ethanol to Acetaldehyde on Isolated Zinc Sites Supported on Dealuminated BEA Zeolite

We present a viable mechanism for the conversion of ethanol to acetaldehyde by sustainable heterogeneous catalysis using modified zeolites. The catalytic conversion of ethanol into valuable hydrocarbon compounds is an alternative method for the production of petrochemical feedstock. Here, we calculate the reaction mechanism of the dehydrogenation of ethanol to acetaldehyde over Zn-DeAlBEA by means of density functional theory and coupled cluster calculations. In the reaction mechanisms investigated, high selectivity toward acetaldehyde instead of ethylene is observed, judged by their activation free energies. The zeolite frameworks have a stabilizing effect on all species along the reaction coordinates including intermediates and transition states. The ZnO-DeAlBEA zeolite is compared to Zn-DeAlBEA. With an additional oxygen atom at the Zn surface site, reaction barriers for the ethanol O–H bond dissociation and the acetaldehyde formation become much smaller, while the selectivity toward aldehyde is maintained.