Firstly, the formate product is already formed in the absence of gaseous CO2, when only H2 is pressurized. This finding supports the above hypothesis that the bicarbonate serves as a feedstock for the hydrogenation reaction. The addition of gaseous CO2 still accelerates the reaction rate, as it shifts the bicarbonate equilibrium and increases the substrate concentration. Secondly, the hydrogenation reaction is mainly dependent on the hydrogen partial pressure. Thus, the highest activity is obtained at a total pressure of 60 bar, when 50 bar of hydrogen is used. The greater importance of the hydrogen partial pressure is also supported by other works on the base-mediated hydrogenation of CO2 in the aqueous phase, associated with the already increased solubility of CO2 due to the added base.