Boron-promoted Cu/ZrO2 catalysts for hydrogenation of sec-butyl acetate: Structural evolution and catalytic performance

Abstract

Cu/ZrO2 catalysts with or without boron modification were prepared, characterized, and evaluated in the hydrogenation of sec-butyl acetate (SBA) to 2-butanol. Cu/ZrO2 catalysts were active for the hydrogenation of SBA but suffered serious deactivation due to the leaching of Cu. Introduction of boron onto Cu/ZrO2 catalysts improved the dispersion of Cu species, the surface Cu+/Cu0 ratios, and the catalyst stability owing to the enhanced interaction between Cu species and support. However, it decreased the intrinsic activity of Cu towards the hydrogenation of SBA and complicated the reaction network by accelerating acid-catalyzed isomerization and transesterification processes as a result of the strengthened acidity by boron. A further kinetic analysis unravelled that the reaction orders for SBA and H2 are 0.58 and 0.83, respectively, and the apparent activation energy is 47 kJ/mol. Such understanding of the structural evolution of CuB/ZrO2 catalysts and the consequent catalytic performances with the B contents may provide insights useful for the design of Cu catalysts with desirable stability for hydrogenation of SBA and other esters.