Ce-Fe-Zr-O/MgO coated monolithic oxygen carriers for chemical looping reforming of methane to co-produce syngas and H2

Abstract

Chemical looping steam methane reforming (CL-SMR) is a promising technology for co-producing syngas and pure hydrogen without additional purification processes. As a typical gas-solid reaction, the size and geometry of oxygen carriers strongly influence the dynamic conditions of this process, especially for large-scale application. In the present work, we prepared the monolithic oxygen carrier using Ce-Fe-Zr-O(40 wt%)/MgO as active component and cordieritehoneycomb as structural support by a slurry coating method, and their activity for CL-SMR were compared with the pellet ones. The monolithic oxygen carrier shows higher activity for both methane oxidation and water splitting than pellet oxygen carriers, which results in much higher CH4 conversion (63.2% vs. 52.9%) and yields of syngas (2.85 mol·kg−1) and hydrogen (1.14 mol·kg−1). The honeycomb also enhances the resistance to carbon deposition during methane selective oxidation, which helps to prolong the running cycle of CL-SMR and improve the purity of produced H2. The comparison on the morphology of the cross section of the fresh and cycled monolithic oxygen carriers indicates that the oxygen carrier particles on the inner-surface of honeycomb channels are very stable during the long-term cycling. These results highlight the significance of designing a high-performance oxygen carrier by using a honeycomb support.