Synergistic Brønsted–Lewis acid catalysts based on SBA-15 for energy-saving CO2 capture

The high energy demand for monoethanolamine (MEA) regeneration is a major bottleneck in amine-based CO2 capture processes. In this study, sulfonated SBA-15 catalysts functionalized with different metal species (Fe, Al, Zr) were synthesized to promote catalytic CO2 desorption from MEA solutions. The introduction of sulfonic acid groups enriched the Brønsted acidity of the mesoporous support, while metal loading generated Lewis acid sites with tunable properties. Among the tested materials, Fe-SBA-15-SO3H showed the highest performance, reducing the relative heat duty by 46 % at 88 °C compared to the uncatalyzed system. This catalyst also outperformed several benchmark materials reported in the literature. Structural, acidic, and basic features were systematically characterized, and machine learning was employed to identify key descriptors of catalytic performance. Both Brønsted and Lewis acid sites were found to play synergistic roles in facilitating carbamate decomposition and proton transfer. A tentative mechanism was proposed to explain the catalytic pathway. Importantly, Fe-SBA-15-SO3H demonstrated excellent stability and reusability, maintaining its activity over 20 consecutive absorption–desorption cycles. These findings highlight the potential of rationally designed solid acid catalysts to reduce the energy penalty of CO2 capture and contribute to the development of more sustainable and cost-effective solvent regeneration strategies.