3.2Reaction Mechanisms of CO2 Hydrogenation to Formic Acid
The reaction mechanism of CO2 hydrogenation to formic acid over Cu-MOF-5 is proposed and systemically investigated via two possible reaction pathways. The first one is called the concerted mechanism in which the reaction occurs in one step without a reaction intermediate. The second one is the stepwise mechanism in which the MOF-5 framework assisted the H–H breaking and the reaction intermediate is formed. The optimized structures are shown in Figures 3 and 4 for both the concerted and stepwise mechanisms, respectively, and selected geometrical parameters are shown in Table 3.