Ni-decorated carbon nanotube-promoted Ni–Mo–K catalyst for highly efficient synthesis of higher alcohols from syngas

Abstract

A type of metallic nickel-decorated CNT-doped Ni–Mo–K oxide-based catalysts was developed, with excellent performance for the selective formation of C1–3-alcohols from syngas. Under reaction condition of 8.0MPa and 558K, the space-time-yield of C1–3-alcohols plus dimethyl ether reached 555mgh−1g−1 over the Ni1Mo1K0.05–11% (5% Ni/CNT) catalyst. The addition of a minor amount of the Ni-decorated CNTs into the NiiMojKk host catalyst caused little change in the apparent activation energy for the higher alcohol synthesis (HAS), but led to the increase of the molar percentage of NiO(OH) and Mo4+/Mo5+ (the two kinds of catalytically active surface-species related closely to selective formation of C1–3-alcohols) and the dramatic decrease of the molar percentage of Ni0 and Mo0 (the two kinds of catalytically active surface-species related closely to selective formation of hydrocarbons, especially methanation of CO). An excellent adsorption performance of the Ni-decorated CNTs for H2 would be conducive to generating a surface micro-environment with a high concentration of H-adspecies in the form of sp2-C–H on the functioning catalyst. In addition, high concentration of H-adspecies on the catalyst would greatly inhibit the water-gas-shift side-reaction. All these factors contribute to an increase in the yield of C1–3-alcohols.