Computational Exploration\non Coupling Formic Acid\nProduction with Propylene Synthesis via Catalytic Transfer Hydrogenation:\nThe Role of <b>CO</b><sub><b>2</b></sub> beyond Reverse\nWater Gas Shift Reaction

CO<sub>2</sub>-assisted propane dehydrogenation (CO<sub>2</sub>–ODHP) is emerging as an alternative route to the direct\ndehydrogenation\nof propane. Previous studies on CO<sub>2</sub>–ODHP have shown\nthat the role of CO<sub>2</sub> is to shift the reaction equilibrium\ntoward the product side by consuming the produced H<sub>2</sub> molecules\nvia reverse water gas shift (RWGS) reaction. Since the ultimate fate\nof CO<sub>2</sub> is to get reduced, we herein propose another pathway\nof CO<sub>2</sub> reduction in the realm of CO<sub>2</sub>–ODHPCO<sub>2</sub> hydrogenation to formic acid (FA). With the objective of\ninvestigating the feasibility of this process, we, for the first time,\ncarry out a computational investigation on coupling propane dehydrogenation\nwith CO<sub>2</sub> hydrogenation using a Ti-alkoxide-functionalized\nUiO-67 metal–organic framework. Analysis using the distortion/interaction\nmodel confirms that CO<sub>2</sub> hydrogenation to FA is a preferred\npathway over the RWGS reaction and hence can be realized in practice.\nOur study also highlights the importance of intersystem crossing,\nwhich provides an opportunity to access nonground state potential\nenergy surfaces while undergoing chemical transformations. Again,\nsubsequent addition of water molecules has shown to ease product desorption\nby 41 kcal/mol. Our study, therefore, hints at an unexplored role\nof CO<sub>2</sub> beyond the RWGS reaction in oxidative propane dehydrogenation.