Efficient and eco-friendly carbon dioxide capture with metal phosphate catalysts in monoethanolamine solutions

Abstract

Catalytic carbon dioxide (CO₂) desorption has emerged as a promising approach to enhance the efficiency of CO₂ capture while minimizing energy demands, crucial for advancing chemical absorption methods. This study investigates the catalytic potential of three metal phosphates (aluminium phosphate (AlPO₄), cobaltous phosphate (Co₃(PO₄)₂), and zinc phosphate (Zn₃(PO₄)₂)) in improving the MEA (monoethanolamine) -based CO₂ absorption-desorption performance. Among the catalysts tested, AlPO₄ demonstrated superior performance, enhancing CO₂ absorption capacity by 4.2% to 9.3% and desorption capacity by 12.3% to 22.7% across five cycles. Notably, AlPO₄ increased the CO₂ desorption rate by over 104.4% at a desorption temperature of 81.3 °C, simultaneously reducing the required sensible heat by 12.3% to 22.7%, compared to processes without catalysts. The improved efficiency is attributed to AlPO₄'s ability to effectively transfer hydrogen protons from protonated MEA to carbamate, thereby facilitating the decomposition of carbamate and regenerating CO₂. This research introduces a viable, cost-effective, and eco-friendly solid acid catalyst strategy for CO₂ desorption, contributing to the development of more energy-efficient CO₂ capture technologies.