Proximity-independent acid–base synergy in a solid ZrOxHy catalyst for amine regeneration in post-combustion CO2 capture

Abstract

Post-combustion CO₂ capture with amines offers an almost ready-to-use capture technology to assist in the transition towards net-zero carbon emission. However, the technology suffers from a high regeneration cost due to the high process temperatures involved. Utilization of catalysts in the regeneration process was reported to be an elegant solution to lower process temperatures while maintaining high reaction kinetics. Earlier studies were performed under batch conditions and therefore lack practical validation, and a deeper mechanistic understanding of the catalysis is also missing. This study introduces a practical-to-synthesize, highly efficient, stable and recyclable ZrO_xH_y solid catalyst, showing high catalytic CO₂ desorption rates for most common aqueous amine solutions. Kinetic and ex situ/in situ spectroscopic data reveal a proximity-independent acid–base synergistic mechanism between two catalytic cycles. The approach was validated in a fixed-bed continuous reactor, demonstrating sensible contact time shortening (up to 85%), suggesting considerable potential savings in regeneration energy, reactor construction and amine solvent cost.