Chemical looping reforming of toluene as bio-oil model compound via NiFe2O4@SBA-15 for hydrogen-rich syngas production

Hydrogen-rich syngas was a clean energy and an important industrial material. Based on the decoupling strategy of biomass chemical looping gasification process, this paper proposed a strategy of metal oxides embedded into molecular sieves to prepare highly dispersed and nanosized oxygen carriers for producing hydrogen-rich syngas. NiO@SBA-15, Fe2O3@SBA-15, and NiFe2O4@SBA-15 were prepared by the impregnation method, and the re-action conditions on the chemical looping reforming of toluene were investigated. The results showed that NiFe2O4@SBA-15 had the highest toluene conversion rate of 93.4% and a relatively high CO selectivity rate of 80.7%. It was confirmed that the embedding strategy can effectively enhance the nanocrystallization and dispersion of metal oxides in oxygen carriers, which could effectively reduce sintering. The inverse spinel structure of NiFe2O4 made the oxygen carrier have more metal adsorption sites and a closer reaction distance, which were beneficial to the adsorption and reaction of the fuel. After testing, the optimum reaction temperature was 750 degrees C, and the optimum weight hourly space velocity was 1.168 h-1. In the 10 cycles of testing of 20 NiFe2O4@SBA-15, the average conversion rate of toluene was 95.34%, the moderate selectivity of CO in the gaseous product was 94.83%, the average H/C ratio was 1.97, which indicated that the cycle stability is good. It provided a reference for developing and designing future oxygen carriers of biomass chemical looping reforming.

Automated summary

This paper proposes a strategy of embedding metal oxides into molecular sieves to prepare highly dispersed and nanosized oxygen carriers for producing hydrogen-rich syngas. The results showed that NiFe2O4@SBA-15 had the highest toluene conversion rate of 93.4% and a relatively high CO selectivity rate of 80.7%. The embedding strategy effectively enhanced the nanocrystallization and dispersion of metal oxides in oxygen carriers, reducing sintering. The cycle stability of NiFe2O4@SBA-15 was good, indicating its potential for biomass chemical looping reforming.