Si/Al ratio and its impact on CO2 adsorption in TiO2-Zeolite

Abstract

The aim of this study was to analyze the Si/Al ratio in titanium dioxide (TiO₂) and Zeolite composites (Erionite, Clinoptilolite and Mordenite) and its influence on carbon dioxide (CO₂) adsorption, seeking to optimize materials for greenhouse gas capture. Composites were synthesized by the sol-gel method, varying the proportions of TiO₂ and zeolites (25-75 and 75-25) as a function of weight. They were characterized using techniques such as Energy Efficiency Spectroscopy (EDS) to determine the Si/Al ratio, X-ray diffraction for crystal size, and N₂ adsorption for surface area. The results showed that, in most of the composites, the Si/Al ratio decreases compared to the original zeolites, except in those based on Mordenite, which maintain high values due to their greater chemical stability. The decrease in the Si/Al ratio was correlated with an increase in the CO₂ affinity, especially in the TiO₂-Erionite composites, which presented the lowest Si/Al values (3.29) and higher adsorption capacity. In contrast, composites with Mordenite exhibited a lower CO₂ affinity, but a higher surface area (456 m²/g). In conclusion, the Si/Al ratio is a key parameter to optimize CO₂ adsorption, and the intrinsic properties of each zeolite significantly affect the composite performance. These materials have potential for applications in environmental mitigation technologies.