Chemical looping reforming characteristics of methane and toluene from biomass pyrolysis volatiles based on decoupling strategy: Embedding NiFe₂O₄ in SBA-15 as an oxygen carrier

To realize the directional conversion of biomass to produce hydrogen-rich syngas, biomass gasification with a complex reaction system was decoupled into two sub-processes. NiFe₂O₄@SBA-15 was prepared by an embedding strategy via the impregnation method to achieve high reactivity during the volatile chemical looping reforming process. The chemical looping reforming of methane and toluene was investigated based on a fixed-bed reactor and on-line mass spectrometry and gas chromatography. It was found that the selectivity and conversion were improved after embedding, and the conversion of toluene reached 97.5 % at 750 °C. The NiFe₂O₄@SBA-15 maintained good stability after 15 cycles, and the reaction performance had not obviously decreased. Real-time reaction performance showed that the conversion of lattice oxygen could reach 100% above 750 °C. The reaction system belonged to the phase boundary-controlled mechanism based on the conversion of lattice oxygen, and the activation energy was 43.10 kJ·mol⁻¹. In addition, in-situ diffuse reflectance infrared spectroscopy(DRIFTS) study had shown that the dissociation of methane and toluene and the further conversion of formate might be the reaction rate-limiting steps. Although methane and toluene competed in adsorption, the reaction processes were independent.