Continuous-flow CO2 hydrogenation to formic acid over Pd-based catalysts on amine-functionalized Zr-SBA-15

The hydrogenation of CO 2 to formic acid (FA) represents a sustainable route for carbon utilization and chemical production, yet it faces challenges in catalytic efficiency, selectivity, and process scalability. Herein, we report a highly efficient catalytic system based on Pd supported on amine-functionalized Zr-SBA-15 (Pd/Zr-SBA-15-AP) for continuous FA synthesis in a fixed-bed reactor. The flake-shaped Zr-SBA-15 support with short mesoporous channels facilitates superior mass transfer. Meanwhile, amine functionalization was identified to serve a dual function: significantly enhancing CO 2 adsorption capacity and modulating the electronic state of Pd to form electron-enriched sites conducive to H 2 activation. The optimized catalyst, 0.3Pd/Zr-SBA-15-AP 3.0 , achieved an exceptional turnover number (TON) of 160 and a turnover frequency (TOF) of 80 h −1 , outperforming the state-of-the-art catalyst under similar continuous-flow conditions. Furthermore, the catalyst demonstrated stable performance over 32 h of continuous operation, underscoring its practical potential. This work provides a scalable strategy for sustainable FA production, effectively bridging laboratory-scale research and industrial application.