Abstract:
Hydrogenation of carbon dioxide to methanol can not only achieve the control of carbon emission, but also reduce the consumption of fossil energy, which is one of the effective ways to realize the utilization of CO
2 resources. Copper-based catalysts are capable of catalyzing the conversion of CO
2 hydrogenation to methanol at high temperature and high pressure, but the traditional copper-based catalysts suffer from the problems of weak CO
2 activation ability, low selectivity of methanol as the target product, and poor stability of oxide-loaded activated copper species, and so on. Therefore, the development of highly efficient, stable and novel copper-based catalysts is an important part of the research in the reaction of methanol synthesis by CO
2 hydrogenation. In this study, four copper-based catalysts supported by zirconium bimetallic oxides, namely Cu/TiZr
4O
2, Cu/ZnZr
4O
2, Cu/GaZr
4O
2, and Cu/CeZr
4O
2, are synthesized and tested in CO
2 hydrogenation experiments for methanol production. The results show that the Cu/TiZr
4O
2 catalysts with TiZr
4O
2 oxides as carriers have good catalytic activity. Characterization analyses show that the H
2 reduced Cu/TiZr
4O
2 catalysts have a large number of unsaturated Cu species (Cu
0) on the surface, which combined with abundant oxygen vacancies and surface alkaline sites to promote the adsorption and activation of CO
2 and H
2. The smaller Cu particle size, larger Cu specific surface area and dispersion combined to promote H
2 activation. The excellent physicochemical properties enable the Cu/TiZr
4O
2 catalyst to exhibit good catalytic activity. In addition the reaction mechanism suggests that formate species are key intermediates in the synthesis of methanol from CO
2 hydrogenation catalyzed by Cu/TiZr
4O
2 catalysts.