Development of one-step synthesized SO42−/ZrO2-fly ash (SZ@FA) solid acid catalysts for energy-efficient sorbent regeneration in CO2 capture processes.

The use of solid acid catalysts for sorbent regeneration is an emerging approach to improve the energy efficiency of CO2 capture processes. In this study, fly ash (FA), an industrial byproduct rich in acid/base sites, was chosen as a support material for the solid acid SO42−/ZrO2 (SZ) in the preparation of SZ@FA composite catalysts. Three catalysts with different mass ratios between SZ and FA were synthesized and evaluated in the regeneration process at 88 °C of a CO2-saturated MEA solution. Their desorption performance, expressed as CO2 desorption rate, amount of CO2 desorbed, and heat duty, was then compared with that obtained with unmodified FA, ZrO2, and in the absence of catalysts (blank), under identical operating conditions. Compared to the uncatalyzed system, the SZ@FA composite catalysts showed significantly better desorption performance. In particular, SZ@FA-1/2 provided the highest values of desorption rate and cyclic capacity while reducing energy consumption by 45.4% compared to the blank system. It also demonstrated stability over 20 consecutive absorption-desorption cycles. Comparison with other reported catalysts highlighted the high performance of SZ@FA-1/2, particularly in terms of relative heat duty reduction, positioning it as a cost-effective and environmentally friendly choice for post-combustion capture applications.