In situ topochemical carbonization derivative Co-Ni alloy@Co-Co2C for direct ethanol synthesis from syngas

Abstract

Abstract In this work, Coδ+-Co2C decorated-Co-Ni alloy nanoparticles (NPs) loaded on Mg-Al-O complex oxides were fabricated via an in-situ reduction and topochemical carbonization strategy by using hydrotalcite as the precursor. The Coδ+-Co2C decorated-Co-Ni alloys were obtained via the following process: (I) after reduction, Co-Ni alloy was obtained and Co could donate electrons to Ni in the Co-Ni alloy NPs; (II) in syngas atmosphere, some of cobalt atoms on the surface of Co-Ni NPs reacted with CO and were converted to Co2C. Resultantly, in the reaction process, Co-Ni alloy NPs were transformed into Ni-Co alloy@Co-Co2C, a core-shell structure with Ni-Co alloy core and Co-Co2C shell. When used as the catalysts for direct ethanol synthesis (DES) from syngas, the bimetallic Co-Ni alloy@Co-Co2C catalyst performed excellent selectivity to ethanol, owing to the regulation of dissociatively and associatively adsorbed CO by Coδ+-Co2C active sites formed on the surface of Co-Ni alloy NPs. Moreover, the mutual dilution between Co and Ni in the Co-Ni alloy NPs inhibited the generation of heavy hydrocarbons, further improving the selectivity to alcohols. The total alcohol selectivity of 43.0% and ethanol occupied 45.2\u202fwt% could be reached over the optimal catalyst.