(734d) Mesoporous Silica Supported Metal Oxide As an Efficient Oxygen Carrier for Chemical Looping Partial Oxidation of Methane
Chemical looping partially oxidation of methane is one the most promising techniques to generate syngas. Developing high performance oxygen carriers are the key to this process. In this research, Fe2O3 nanoparticles embedded in mesoporous support SBA-15 (Fe2O3@SBA-15) was synthesized and applied to chemical looping partial oxidation to generate syngas. For comparison, bulk Fe2O3 was also synthesized and characterized. Techniques including XRD, BET, TEM, SEM, and TGA were used to characterize the material before and after reaction. Results showed that Fe2O3@SBA-15 have enhanced stability and reactivity, with a conversion rate 70% higher than bulk Fe2O3. This can be attributed to tube structure of the support SBA-15, which provides large space and surface area for Fe2O3 nanoparticles and prevent the agglomeration of nanoparticles during reaction. In addition, selectivity was also test in TGA. Results showed that very low concentration of CO2 was observed during reaction, indicating high syngas selectivity >99%. This designed material has the potential to generate pure syngas at relatively low temperature. The atomistic thermodynamics methods and density functional theory calculations were carried out to investigate the selectivity enhancement mechanism. It was found activation energy barrier of CHx radicals strongly depends on the particle size, and SBA-15 support has an influence on the surface termination geometry and oxygen vacancy formation, which significantly influences the correlation between the CâH bond activation and the CHx radical adsorption. This study provides guidance on the design of novel oxygen carriers for chemical looping partial oxidation.