Higher alcohols synthesis from syngas and ethanol over KCoMoS₂-catalysts supported on graphene nanosheets

The comparative study of the catalytic behavior of K-modified CoMoS2-catalysts supported on Al2O3, carbon covered alumina (CCA) and graphene coated alumina (GCA containing 0.4, 1.2, and 1.7% of graphene) in synthesis gas and ethanol conversion (separately) to higher alcohols (HAS) and other oxygenates has been carried out. The supports and catalysts were characterized by N-2 adsorption-desorption isotherms, pyridine adsorption, SEM, EDX, and TEM. In HAS from syngas, the catalyst supported on GCA materials showed better catalytic performances than the catalysts supported on alumina and carbon coated alumina (Cat-GCA > Cat-CCA > Cat-Al2O3). The spectroscopic results have established that the homogenous uniform coating of alumina by graphene nanosheets follows the order: GCA1 (1.7%) > GCA2 (1.2%) > GCA3 (0.4%). The yield of ethanol has a positive correlation with graphene wt. % in GCA. In ethanol conversion, graphene attenuate the interaction of the support/active site KCoMoS2 and with it its selectivity toward dehydrogenation/condensation reactions. The GCA1 supported catalyst exhibits low activity for the water-gas shift (WGS) reaction compared to its counterpart. Explanations of the observed phenomena have been suggested.