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

To achieve cost-competitive CO 2 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 CO 2 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 CO 2 hydrogenation processes. • CO-containing gray hydrogen is essential for economically viable CO₂ hydrogenation. • CO poisoning of Ru catalysts was systematically investigated during CO₂ hydrogenation. • Ru-MACHO-POMP maintained catalytic activity under high CO concentrations (12.5 mol%). • Reversible structural changes of the Ru active site were elucidated under CO exposure. • This work establishes key criteria for designing industrially robust CO-tolerant catalysts.