Integrative CO ₂ Capture and Hydrogenation to Formate and Formic Acid Separation with a Reusable Ru-POP Catalyst

The hydrogenation of CO2 to formate is a promising method of carbon capture and utilization (CCU) for the production of high-value-added chemicals. Herein, an efficient process for integrating CO2 capture and one-pot hydrogenation to formate catalyzed by ruthenium porous organic polymer (Ru-POP) catalysts in an aqueous solution of amines under relatively mild reaction conditions was developed. Et3N (triethylamine) was selected based on a comprehensive consideration of its boiling point, CO2 absorption capacity, pKa, and formic acid production capability. The catalytic system involving Ru-POPs can realize efficient hydrogenation of CO2 to HCOOH and stable recycling. Furthermore, pure formic acid (HCOOH) was successfully separated from the mixed Ru-POPs/HCOOH/Et3N/H2O system by using trihexylamine (THA) as an extractive agent, which achieved the synthesis and separation of formic acid.