Insight into composition evolution in the synthesis of high-performance Cu/SiO2 catalysts for CO2 hydrogenation

Abstract

High-performance catalysts are the key factor for CO₂ activation and conversion. In this paper, we systematically investigate the whole composition evolution process of Cu/SiO₂ catalysts for CO₂ hydrogenation. The precursor gradually evolved from amorphous Cu species to copper phyllosilicate, then to CuO with the increase of calcination temperature from ambient temperature to 700 °C. With the evolution of the precursor, the corresponding species after reduction were gradually evolved from Cu⁰ to Cu⁺, then to Cu⁰ again. The ratios of Cu⁺/(Cu⁺ + Cu⁰) are positively correlated with the catalytic activities. The Cu⁺ species derived from copper phyllosilicate were demonstrated to be crucial in achieving high-performance Cu/SiO₂ catalysts for CO₂ hydrogenation. The composition evolution has been demonstrated to be an efficient strategy to synthesize high-performance catalysts. This strategy of composition evolution can be applied to the synthesis of other high-performance Cu-based heterogeneous catalysts.