Chemical looping preferential oxidation of CO over ceria-supported γ-Fe2O3

A novel chemical looping preferential oxidation (CL-PROX) process is proposed and demonstrated for eliminating trace CO from a H-2-rich stream. The proposed process exhibited an excellent CO removal performance (CO concentration < 100 ppm) and a high H-2 recovery (>similar to 96 %) with a ceria-supported gamma-Fe2O3 oxygen carrier. It was obtained by activating the fresh sample that was synthesized through a co-precipitation method and the innovative activation process comprising a partial reduction step at 400 degrees C followed by an oxidation process at 260 degrees C. The structure and evolution of iron species in the oxygen carrier were investigated through experimental characterizations during activation and redox cycles. TPR characterizations illustrated a significant difference in the reducibility of the active species, gamma-Fe2O3, under H-2 and CO atmospheres, which could be the evidence for its relatively high selectivity to CO oxidation. In-situ FTIR characterization also pointed out that the desorption of reaction intermediates to CO2 is facilitated via the reduction of the surface gamma-Fe2O3, which might contribute to the outstanding CO oxidation performance of the oxygen carrier. The successful application of chemical looping process to selective oxidation of CO in H-2-rich gas not only illustrates a new strategy for H-2 purification, but also provides insights into the redox reaction mechanism with the newly-prepared gamma-Fe2O3-based oxygen carrier.