Chemical looping dry reforming of methane with hydrogen generation on Fe2O3/Al2O3 oxygen carrier

Abstract

A chemical looping dry reforming process for co-production of hydrogen and syngas was proposed. This process contains four different stages, i.e. reduction, dry reforming, steam oxidation and air oxidation. The partial oxidation of CH4 with lattice oxygen occurred along with dry reforming reaction on the reduced iron oxide in the dry reforming stage, which helps to obtain the flexibility syngas ratio and increase hydrogen yield in the next steam oxidation stages. In this study, Fe2O3/Al2O3 oxygen carrier was used to verify the feasibility of this process in a fluidized-bed reactor at 900 °C and 1.01 bar. Carbon deposition and physical properties of the carrier were studied by using O2-TPO, XRD and BET methods. It was found that the efficient conversion of CO2 and CH4 to syngas can be achieved on the reduced iron oxygen carrier. When the feed ratio of CH4/CO2 was 1 and the reduction extent of iron was 33%, the CH4 conversion and syngas yield (the output of syngas/the input of CH4) reached 98.32% and 3.84 during the dry reforming stage, respectively. Moreover, increasing the feed ratio of CH4/CO2 raised the H2/CO ratio of syngas, but the deposited carbon would form with the available lattice oxygen depleted. Finally, superior redox activity and stability were obtained during the 15 cycles, although slight sintering was observed on the reacted oxygen carrier.