Low-cost, shapeable solid acid catalysts from binary clay blends for low-energy regeneration of CO2-loaded MEA

Low-cost binary clay catalysts were developed for CO 2 -loaded MEA regeneration. • Binary blending coupled with acid activation enhanced catalyst acidity and porosity. • HAB showed the highest CO 2 desorption performance among the tested catalysts. • HAB enabled lower-energy regeneration of CO 2 -loaded MEA. • HAB retained over 90% of its initial catalytic activity after eight regeneration cycles. Amine-based post-combustion CO 2 capture is a mature technology for industrial decarbonization, but its large-scale deployment remains constrained by the high energy demand of solvent regeneration. Herein, a series of low-cost solid acid catalysts were developed by binary blending of natural clay minerals (attapulgite, bentonite, and diatomite) followed by sulfuric acid activation. Binary blending alleviated clay agglomeration and improved the textural properties of the materials, although the corresponding enhancement in catalytic desorption performance varied among the three binary systems, with AB showing the most evident improvement. Subsequent sulfuric acid activation substantially enhanced the desorption performance of all three binary composites, with HAB exhibiting the best overall performance. Under the evaluated conditions, HAB reduced the relative regeneration heat duty to 65.8% of the blank value, corresponding to a 34.2% reduction in regeneration energy demand. Its superior performance is associated with the combined contributions of favorable pore accessibility and abundant surface acid sites. In situ Raman spectroscopy revealed faster attenuation of the characteristic bands associated with carbamate, bicarbonate, and carbonate in the presence of HAB, supporting its role in facilitating the conversion of major CO 2 -containing species and promoting CO 2 release during MEA regeneration. HAB retained approximately 90% of its initial catalytic activity after eight consecutive absorption-desorption cycles. Furthermore, the shaped HAB-S catalyst retained most of the desorption performance of powdered HAB, with only an approximately 7.1% decrease in CO 2 desorption amount, while exhibiting an average single-pellet crushing strength of 48.8 N pellet −1 . These results demonstrate that acid-activated blended natural clays provide a low-cost, recyclable, and shapeable catalyst platform for reducing the regeneration energy demand of amine-based CO 2 capture.