Synthesis of Ni5Ga3 catalyst by Hydrotalcite-like compound (HTlc) precursors for CO2 hydrogenation to methanol

Abstract

A Ni5Ga3 catalyst synthesized from hydrotalcite-like compound (HTlc) precursors was examined for CO2 hydrogenation to methanol. HTlc precursors with a nickel atomic percentage of 65 % balanced with gallium were prepared by a urea hydrolysis hydrothermal method, and fully characterized. The HTlc phase in the nickel–gallium precipitant became better crystallized and the structure became more stable as the synthesis reaction temperature increased. Bimetallic alloy Ni5Ga3 was obtained by reducing the as-prepared HTlc precursors in a flow of 5 % H2 balanced with Ar at a temperature of 700 °C. Ni–Ga HTlc precursor prepared at a hydrothermal temperature of 110 °C resulted in the formation of bimetallic alloy, Ni5Ga3, which produces smaller crystal size and a stable structure. Enhanced catalytic performance was demonstrated by an endurance test with a constant CO2 conversion and 100 % methanol selectivity at 200 °C, and a turnover frequency of 0.27 s−1.