Study on the methane-pulsing reduction characteristics of Fe2O3-Al2O3 oxygen carrier

Developing a highly efficient and low-priced iron-based oxygen carrier is the key to the application of chemical looping reforming of natural gas for hydrogen production. In order to explore the basic principle of designing such an oxygen carrier, the methane-pulsing reduction characteristics of Fe2O3-Al2O3 oxygen carriers with different Fe2O3 contents were studied at 800℃ and without the influence of external and internal diffusion by using a self-designed reactor system capable of on-line methane pulsing and synchronized analysis of gaseous reaction products. The results show that the reduction reaction of Fe2O3 proceeds according to a two-stage mechanism, which can stop at Fe2O3 or completely proceed to FeO with the content of Fe2O3 in the oxygen carrier particles. The variation pattern of the molar ratio of CO2 to CO in the gas phase product with the number of CH4 pulses is also closely related to the content of Fe2O3. Pulse reduction results of particles prepared from a mixture of α-Al2O3 powder and powdery 80% (mass) Fe2O3-Al2O3 oxygen carrier further reveal that the reduction degree of Fe2O3 in a single particle as well as in the whole bed is determined by the molar ratio of CH4 entering the particle per unit time to the absolute amount of Fe2O3 in the particle. At last analysis on the correlations of the reduction degree of Fe2O3 and CH4 conversion and CO2 selectivity leads to a conclusion that only limiting the reduction process of Fe2O3 oxygen carries to the stage of Fe3O4 formation could yield a reacted stream of a sufficiently high CO2 concentration for low-cost recovery of high purity CO2 © 2023 Chemical Industry Press. All rights reserved.