Density functional theory and reactive dynamics study of catalytic performance of TiO2 on CO2 desorption process with KHCO3/TiO2/Al2O3 sorbent

The high energy required for CO2 desorption process is one of the significant problems that inhibit the development of using potassium-based sorbent for CO2 capture. Proper catalysis should be studied to enhance the desorption kinetics and TiO2 is supposed as the promising catalyst but the catalytic mechanism is not clear. This paper was designed to simulate the catalytic performance of TiO2 with density functional theory (DFT) method and investigate the CO2 desorption performances of KHCO3/TiO2/Al2O3 sorbent. Results showed that, the existent catalyst TiO2 in the sorbent can adsorb the regeneration product (H2O and CO2), which can break the equilibrium of KHCO3 decomposition reaction and lead the equilibrium to move to the right side. Also, the unstable intermediary TiO(OH)(+) and OH-, which formed by the adsorption of H2O on the catalyst TiO2 surface, can accelerate the consumption of HCO3. Therefore, the existence of TiO2 changed the KHCO3 decomposition reaction pathway thus enhanced CO2 desorption reaction kinetics and reduced the activation energy. The absorption energy and reaction barrier of H2O adsorbed on anatase-TiO2 (101) surface is much lower than that of CO2, which means 1-120 is easy to be captured on catalyst TiO2 surface. So, the promising catalyst should perform great H2O adsorption performance. Also, compared with CO2 atmosphere, moisture is thought to be the promising desorption atmosphere in the desired temperature. In addition, some of the calculated results were confirmed with thermos-gravimetric analyzer (TGA) tests. (C) 2017 Elsevier B.V. All rights reserved.