Ternary Cobalt–Copper–Niobium Catalysts for the Selective CO Hydrogenation to Higher Alcohols

Abstract

Novel “CoCuNb” ternary catalysts with bimodal nanosized particle structure, in the absence of a generic support material, were designed and successfully tested in higher alcohol production via CO hydrogenation. The selectivities to primary alcohols with an optimized C2–C5 slate usually exceeded the 50 wt % level, and the combined selectivities to 1-alcohols/1-alkenes reached up to ∼73 wt % for CO conversions ranging between ∼5% and nearly 20%. The bimodal nanosized particle distribution, achieved through oxalate coprecipitation, contained Co–Cu particles with sizes ranging from 25 to 40 nm. Smaller particles between 4 and 8 nm were identified as Nb oxides and played the role of a structural dispersant (“spacer”) and promoter of 1-alcohol/1-olefin production. X-ray photoelectron spectroscopy revealed NbOx to contain major amounts of species with Nb in the 4+ oxidation state.