LAUSR

Abstract Chemical Looping Hydrogen Generation (CLHG) is promising hydrogen production technology with inherent capture CO 2 and high-purity hydrogen production simultaneously. Although the reactivity and durability of oxygen carriers can be improved by the combination of inert materials. Carbon deposition over oxygen carrier in the reduction period is still a serious problem in the process of CLHG with CH 4 as fuel, and it affects the purity of hydrogen in steam oxidation period and the carbon capture efficiency. In this study, oxygen carriers, Fe 2 O 3 /Al 2 O 3 and Fe 2 O 3 /MgAl 2 O 4 , composed of 60 wt% Fe 2 O 3 , were prepared by mechanical mixing method. Moreover, different contents of K 2 CO 3 were incorporated into the Fe 2 O 3 /Al 2 O 3 oxygen carriers by using impregnation method. Experiments were performed in a fluidized bed reactor by exposing the oxygen carriers to alternating methane reducing, steam oxidizing and air oxidizing conditions. The effects of inert supports and alkali additive on the carbon formation performance of iron oxides with different methane concentration were investigated. Results indicate that carbon was formed on the oxygen carriers Fe 2 O 3 /Al 2 O 3 during the reduction, the cracking reaction of CH 4 on the surface of iron-based oxygen carrier starts as active phase Fe or Fe 3 C formed. However, the methane decomposition promoted the reduction rate of oxygen carriers and it increased with the temperature and CH 4 concentration. Lower carbon deposition rate was found on Fe 2 O 3 /MgAl 2 O 4 compared with Fe 2 O 3 /Al 2 O 3 . Furthermore, the addition of K 2 CO 3 exhibited a beneficial effect on suppressing carbon formation but decreased the reduction activity of oxygen carrier.