Unraveling the role of basic sites in the hydrogenation of CO₂ to formic acid over Ni-based catalysts

Basic sites profoundly affect the mode and strength of CO2 adsorption in the hydrogenation of CO2 to formic acid (FA), however, the mechanism by which the quantities and strength of basic sites affect the reaction process is not yet clear. Herein, a Ni/MgaAlOx catalyst has been developed and the basic sites of the catalyst can be modulated by simply altering the Mg/Al ratio. Through a series of characterizations and experiments, it was observed that weak and medium basic sites synergistically catalyzed the hydrogenation of CO2 to formic acid, and a reasonable number of weak basic sites can improve reaction performance when a sufficient number of medium basic sites guarantee the fundamental catalytic activity. Moreover, the number and distribution of basic sites are also tightly related to metal-support interactions. This strategy provides theoretical guidance and a feasible scheme for optimizing the performance of non-precious metal heterogeneous catalysts.