Adsorption\nand Reaction Mechanism of Inert Carriers\n(Al<sub>2</sub>O<sub>3</sub> and TiO<sub>2</sub>) Loaded with Fe<sub>2</sub>O<sub>3</sub> in Chemical Looping Gasification Based on Dens

In the chemical looping gasification (CLG) process, support\nmaterial\nis used to improve the mechanical strength and thermal stability of\nthe oxygen carrier (OC). The presence of a support material can affect\nthe properties and performance of the OC, which influences the synthesis\ngas generation pathways. In this work, the density functional theory\ncalculations were applied to investigate the reaction mechanisms and\nsyngas formation during CLG, while Fe<sub>2</sub>O<sub>3</sub> is\nused with support Al<sub>2</sub>O<sub>3</sub> or TiO<sub>2</sub> as\noxygen material. Adsorption and reaction pathways of C atom and main\nconstituents in syngas (CO, H<sub>2</sub>, and H<sub>2</sub>O) on\nthe surface of the composite carrier were studied. The reaction pathway\nand energy transformation regarding oxidation of C atom and CO on\nthe composite carrier’s surface were calculated and evaluated.\nThe results indicate that CO desorption and COO* formation on the\nFe<sub>2</sub>O<sub>3</sub>/Al<sub>2</sub>O<sub>3</sub> surface were\nthe rate-limiting steps that affect the conversion of C and CO under\nthe studied conditions. In addition, the coadsorption of H<sub>2</sub>O and CO on composite carrier’s surfaces and possible reaction\npathways of them were assessed to compare performance of the two studied\ncomposite carriers. The results indicate that formation of the carboxyl\nintermediate is the dominant pathway during coadsorption of H<sub>2</sub>O and CO and further conversion on the Fe<sub>2</sub>O<sub>3</sub>/Al<sub>2</sub>O<sub>3</sub> surface. On the other hand, formation\nof the formate as an intermediate on surface composite carrier Fe<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> was easier and more direct because\nof its highest energy barrier, which is only 2.01 eV. Therefore, Fe<sub>2</sub>O<sub>3</sub>/Al<sub>2</sub>O<sub>3</sub> can enhance particle\nadsorption and capture, while Fe<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> was more suitable for improving water–gas shift reaction\nperformance. These results are essential to the design and optimization\nof cost-effective composite materials for enhancing performance and\nsustainability in chemical looping processes.