Influence of Support Acidity of Pt/Nb 2 O 5 Catalysts on Selectivity of CO 2 Hydrogenation

In solid acid catalysis, understanding the impact of support acidity on catalytic performance has remained a controversial issue. The selected catalytic systems often rely on mixing different substances to control the degree of acidity, which in turn, also modifies other parameters in the system, making it challenging to perform a definitive study. To specifically investigate the role of support acidity, we performed a systematic study employing Nb 2 O 5 as the catalyst support, which acidity can be controlled by calcination. The catalytic behavior of the fabricated Pt/Nb 2 O 5 catalysts was evaluated using CO 2 hydrogenation to methanol (MeOH) and dimethyl ether (DME). An increase in the acidity of the support resulted in an improvement in the CO 2 conversion owing to the strong interaction between the Pt and the catalyst support, but it was detrimental for the production of MeOH because of the unfavorable adsorption of CO 2 molecules and the formation of carbon-containing species on the surface of the support with high acidity. DME selectivity was enhanced with an increase in catalyst acidity, confirming the role of solid acids for the production of DME from CO 2 reduction. Graphical Abstract By controlling the calcination temperature of Nb 2 O 5 , tunable support acidity was obtained. CO 2 conversion increased while the selectivity of methanol and dimethyl ether decreased with increasing support acidity.