Chemical looping gasification of biomass using rare earth oxides doped ferric oxide oxygen carrier for hydrogen‐rich syngas production

Abstract

AbstractAn efficient oxygen carrier (OC) is in great demand in the biomass chemical looping gasification (BCLG) process. In the present study, an innovative rare earth oxide doped ferric oxide OC (Fe2O3−REaOb) derived from the Nd‐Fe‐B sintered magnet waste scraps was employed for the BCLG process for hydrogen‐rich syngas production. The critical variables, including the temperature of gasification, the mass ratio of OC/biomass, the mass ratio of steam/biomass, and the cycle performance of the novel OC, were investigated regarding syngas yield and carbon conversion efficiency. Results found that the optimum conditions were achieved at 900°C, with a mass ratio of OC to biomass of 3:1 and a mass ratio of steam to biomass of 0.4, and a syngas yield of 1.19 Nm3/kg with an H2/CO mole ratio of 2.45, and a carbon conversion efficiency of 76.80% was reached. Additionally, a comparison between Fe2O3−REaOb OC, Fe2O3−Al2O3 OC, and Fe2O3−CeO2 OC was also conducted, with Fe2O3−REaOb OC demonstrating a superior performance. The synergistic effects between REaOb and Fe2O3, particularly the generation of perovskite oxide NdFeO3, contributed to the excellent performance of the Fe2O3−REaOb OC during the BCLG process. The outward diffusion of Fe and sintering of the OC reduced the syngas yield and carbon conversion efficiency by about 16.00% and 25.00% over the 20 redox cycles of the BCLG process. In summary, Fe2O3−REaOb can be an efficient and promising OC for hydrogen‐rich syngas production in the BCLG process.