Sustainable synthesis of N-doped carbon to stabilize Ru species for CO2 hydrogenation to formic acid

Abstract

In this study, we developed nitrogen-doped carbon supporting materials from biomass-derived fertilizers, offering a sustainable and eco-friendly approach to heterogeneous catalysis for CO₂ hydrogenation. Three types of fertilizers (AA50, AA80, and FV), derived from different biomass sources, were evaluated there potential to prepare the N-doped carbon structure. The synthesis of fertilizer-based supporting materials resulted in an abundant amount and a specific structure of doped nitrogen, essential for immobilizing atomically dispersed Ru catalysts during CO₂ hydrogenation. The catalytic performance of the Ru catalysts supported on optimized fertilizer-derived materials exhibited a turnover number of 2748 over two hours and maintaining 98 % stability across five recycling tests. Analysis of spent catalysts showed that our fertilizer-based supports effectively prevented the sintering and leaching of the Ru catalysts. Moreover, the capability for industrial application was validated through a continuous flow reactor test, achieving an average formate productivity of 697 mmol•g_cat⁻¹h⁻¹ over 100 hours. These results highlight the synthesized Ru catalyst on fertilizer-derived carbon material as a promising solution for eco-friendly CO₂ hydrogenation to formic acid.