Improving CO2 desorption performance in monoethanolamine solutions by adding titanium pyrophosphate catalyst

Abstract

Abstract Catalytic CO2 desorption has emerged as a crucial strategy for enhancing the efficiency of CO2 capture and reducing energy requirements, thereby advancing chemical absorption methods. This study examines the catalytic effectiveness of titanium pyrophosphate (TiP2O7) in improving monoethanolamine (MEA)-based CO2 absorption and desorption processes, comparing its performance with other titanium-based catalysts, including titanium dioxide (TiO2), titanium tetrahydroxide (TiO(OH)2), and titanium carbide (TiC). In TiP2O7, Ti ions function as Lewis acid sites by accepting electron pairs (LASs), P2O7 4− anions act as proton carriers, facilitating rapid proton transfer as Lewis base sites (LBSs), and active hydroxyl groups on the surface, resulting from water molecule dissociation or the deprotonation reaction, function as Brönsted acid sites (BASs). These sites work synergistically to accelerate CO2 desorption. TiP2O7 outperforms the other catalysts tested, primarily due to its optimal Brönsted/Lewis (B/L) ratio. This characteristic is particularly advantageous for regenerating RNHCOO−, as the reaction predominantly follows a hydrogen transfer pathway facilitated by the BASs. Consequently, TiP2O7 enhances the CO2 desorption rate by 41.5% at a desorption temperature of 91 °C, while simultaneously reducing the relative heat duty by 13% compared to processes without catalysts.

Keywords

• CO2 capture
• Catalytic desorption
• Energy reduction
• Titanium pyrophosphate