Heterogeneous Formic Acid Production by Hydrogenation of CO2 Catalyzed by Ir-bpy Embedded in Polyphenylene Porous Organic Polymers

Heterogeneous immobilized molecular catalysis has gained significant attention as a platform for creating more efficient and selective catalysts. A promising type of immobilized molecular catalysts are made from porous organic polymers (POPs) due to their high stability, porosity, and ability to mimic the catalytic activity and selectivity of homogeneous organometallic catalysts. These properties of the POP-based systems make them very attractive as heterogeneous catalysts for hydrogenation of CO2 to formate, where predominately homogeneous systems have been applied. In this study, five POPs were synthesized and assessed in the hydrogenation of CO2 where the active catalysts were made in-situ by mixing IrCl3 and the POPs. One of the Ir/POP catalysts provided a turn-over number (TON) >20,000, which is among the highest for POP-based systems. Thorough characterization (CO2- and N-2-physisorption, TGA, CHN-analysis, XRD, XPS, SEM, STEM and TEM) was performed. Notably, the developed Ir/POP system also showed catalytic activity for the decomposition of formic acid into H-2 enabling the use of formic acid as a renewable energy carrier.

Automated summary

Heterogeneous immobilized molecular catalysis using porous organic polymers (POPs) as catalysts shows high efficiency and selectivity in the hydrogenation of CO2 to formate, with one Ir/POP catalyst achieving a turn-over number (TON) >20,000. This study also demonstrates the catalytic activity of the Ir/POP system in the decomposition of formic acid into H-2, providing potential for the use of formic acid as a renewable energy carrier.