Acetone hydrogenation over face-centered cubic and hexagonal close-packed cobalt

Abstract

Acetone hydrogenation is employed for investigating the structure sensitivity of H2 activation over cobalt catalysts while the produced isopropanol garners increasing interest in the sustainable energy context e.g. as H2 storage material and fuel for direct fuel cells. Both hexagonal close-packed (hcp) and face-centered cubic (fcc) Co can produce isopropanol with 100% selectivity below 150 °C with the reaction proceeding almost ten times faster over hcp Co. Hydrogenation rates are even higher over an hcp Co/Co3O4 composite which remains highly selective to isopropanol despite that Co3O4 yields mostly mesityl oxide and related products. The superior performance of hcp Co and its composite are attributed to efficient generation of atomic H on the metal and the presence of stronger sites for acetone activation on XRD-amorphous phases that are formed during reduction of the Co3O4 precursor at 250 °C and 400 °C. These findings provide insight into the optimum structural design of highly active and selective low-temperature cobalt hydrogenation catalysts.