Renaissance of fly ash as eco-friendly catalysts for rapid CO2 release from amines

Abstract

Catalyst-assisted amine regeneration has emerged as a prominent strategy for enhancing the desorption rate of CO2 from amine solutions at lower temperatures (<100 °C), thereby reducing the massive energy penalty of post-combustion carbon capture process. To make this strategy practical and commercially relevant, it is crucial to develop economically viable, abundant, and eco-friendly catalysts. In this context, we synthesized catalysts from fly ash (FA) through treatment with three acidic solutions of H2SO4, H3PO4, and HNO3 and used them in amine regeneration process with evaluating their catalytic performance in terms of CO2 desorption rate, desorbed CO2 quantity, and regeneration heat duty. The acid treatment increased the BET surface area and generated surface acid sites of the FA, both of which played a vital role in increasing the CO2 desorption from monoethanolamine (MEA) solution at 86 °C. The prepared catalysts increased the CO2 desorption rate by up to 91 % and desorbed CO2 amount by up to 61 %, while reducing the regeneration heat duty by up to 38 % compared to the uncatalyzed amine solution. The studied catalysts could be easily separated and used in successive amine regeneration cycles, which makes them suitable for industrial application.

Keywords

• Amine regeneration
• Fly ash
• Catalytic regeneration
• CO2 capture
• Regeneration heat duty
• Low-cost catalyst