Bimetallic Ni–Co catalysts supported on Mn–Al oxide for selective catalytic CO hydrogenation to higher alcohols

Abstract

A series of bimetallic Ni–Co catalysts supported on Mn–Al oxide with different Ni/Co molar ratios were synthesized using a sol–gel method and applied for CO hydrogenation to higher alcohols. The physical and chemical properties of the as-prepared catalysts were investigated by various characterization methods such as XRD, N₂ adsorption/desorption, H₂-TPR, TEM, XPS, CO-TPD, H₂-TPD, and CO-TPSR. The results indicated that a stronger interaction between Ni and Co ions led to the formation of a Ni–Co alloy in the reduced catalysts, and CO conversion and alcohol selectivity changed depending on the Ni/Co molar ratio that significantly influenced the properties of the catalysts. The appropriate Ni/Co molar ratio can improve the reducibility, increase the amount of non-dissociated CO on the catalyst surface for CO insertion, and enhance the catalytic performance for higher alcohol synthesis. In particular, a Ni/Co molar ratio of 5/3 was found to be the most suitable for the physical–chemical and catalytic properties of the bimetallic Ni–Co catalysts for CO hydrogenation to higher alcohols.