Nanoporous Metatitanic acid on γ-Al2O3 aerogel for higher CO2 adsorption capacity and lower energy consumption

Abstract

Abstract Carbon dioxide capture has become an important issue in reducing atmospheric heat these days. In this study, adsorption of carbon dioxide by aerogel Gamma Alumina-Metatitanic Acid has been investigated and optimized. Morphological and structural analyses such as BET, FESEM, FT-IR, and XRD have also been conducted. In addition, Response surface methodology has been applied in order to achieve the optimal conditions, using a five-level Central composite design. The highest amount of adsorption, 12.874 (mmol/g), was recorded at a temperature of 20 (°C), pressure of 7 (bar), and 25 (%wt) of Metatitanic Acid. This was approximately 11.46% and 4.84% higher than those of mesoporous MgO and 4Azeolite, respectively. Regeneration of the adsorbent was also studied at different temperatures and process durations. Metatitanic acid, as a catalyst, reduces the temperature and regeneration time of the adsorbent by creating active sites and surface hydroxyl groups. It also lowers the required activation energy and enhances the thermal conductivity of the composite material. The optimal result was achieved at a temperature of 100 (°C) and a duration of 30 (min). Finally, isothermal and thermodynamic experiments were conducted to establish the most accurate predictive model and conditions, including Enthalpy, Entropy, and Gibbs free energy. The results indicate that the Freundlich model aligned well with the laboratory findings. Additionally, the negative values of Enthalpy, Entropy, and Gibbs free energy suggested that the adsorption process was physical, exothermic, and spontaneous.

Keywords

• Aerogel Gamma Alumina
• Metatitanic acid
• Adsorbent regeneration
• CO2 adsorption
• RSM
• Optimization