CO2 conversion into formic acid with CO-containing hydrogen gas over a heterogenized Ru catalyst

Abstract

To achieve cost-competitive CO₂ hydrogenation processes, it is desirable to utilize gray hydrogen, which typically contains 1–3 mol% CO. However, previously reported catalysts have been severely affected by CO poisoning, leading to metal aggregation, active site leaching, and structural deactivation. The CO tolerance test of Ru-MACHO-POMP (porous organometallic polymer) confirmed that the catalyst maintained activity during CO₂ hydrogenation to formic acid even under high CO concentrations (12.5 mol%). Through various characterization methods analyzing catalytic active sites, it was found that the catalytic activity was reversibly restored due to reversible binding of CO to Ru active sites, enabling the regeneration of the original active structure. These findings highlight Ru-MACHO-POMP as a sustainable and economically viable catalyst for industrial CO₂ hydrogenation processes.