Potassium-mediated control of adsorbed intermediates on CuCoAl layered nanoplates for ethanol synthesis from syngas

A set of K-promoted CuCoAl nanoplates were synthesized via precipitation followed by impregnation method and assessed for syngas conversion. The optimized 1K-CuCo catalyst manifested a relatively higher total alcohols selectivity of 48.4 %, with ethanol comprising 35.4 % of total alcohols. As indicated by in situ CO DRIFT and XPS outcomes, on the 1K-CuCo catalyst surface, a distinct preference was observed for the adsorption of CO on Cu species (non-dissociative CO*) and bridging CO adsorption on Co species (dissociative CO*). A substantial presence of strongly adsorbed formate species, which contributed favorably to the production of CH* intermediates, was also identified on the optimal catalyst surface. More importantly, operando DRIFT characterization confirmed that K-modified CuCo catalyst effectively inhibited the hydrogenation (or coupling) of adsorbed CH* intermediates derived from formate species to generate methane and CH. Instead, the adsorbed CH* intermediates coupled with non-dissociated CO* to form CHCO* species. Therefore, the K promoter can finely regulate the adsorption strength and distribution of intermediates species, thus furnishing sufficient CH* intermediates and CO* species to take part in CH-CO coupling reaction to synthesize ethanol.