Preparation and CO2 hydrogenation catalytic properties of alumina microsphere supported Cu-based catalyst by deposition-precipitation method

Abstract

A series of Cu/ZnO/Al2O3 catalysts with the total weight percentage of Cu and ZnO from 9.94wt.% to 44.5wt.% have been prepared by ammonia deposition −precipitation method and tested for methanol synthesis from CO2 hydrogenation. A Cu/Zn/Al layered double hydroxides (LDHs) precursor can be formed in situ on the surface of microspherical Al2O3 which acts as both support and sole source of Al3+ cations. With increase of total Cu and ZnO loading, the dispersion of copper and reducibility of CuO decline continuously, while the exposed copper surface area increases gradually. In addition, the formation of LDHs results in a stronger both basicity and acid strength on the catalyst surface. It is found that the CO2 conversion increases linearly with increase of the Cu and ZnO loading. The methanol selectivity for the catalyst with low total metal loading (9.94wt.%) is much lower than those for other catalysts, though it increases with increasing loading, which can be mainly assigned to the much smaller Cu particle size (<5nm) and the higher ratio of isolated CuO phase. Moreover, the Cu/ZnO/Al2O3 catalyst with relatively high total metal loading (44.50wt.%) still exhibits a considerable stable catalytic performance due to the formation of LDH structure.