Chemical Looping Reforming of Toluene as Volatile Model Compound over LaFexM1–xO3@SBA via Encapsulation Strategy

Abstract

Aiming at the problems of large tar influence and low gasification efficiency in traditional biomass gasification, in this paper, a chemical looping reforming (CLR) of volatiles from biomass pyrolysis based on decoupling strategy is proposed to convert macromolecular volatiles into hydrogen-rich syngas. A series of highly active and selective oxygen carrier (OC) SBA-15 encapsulating LaFexM1–xO3 (M = Ni, Cu, Co) for the biomass CLR process was developed. Reaction kinetics and cycling performance of toluene CLR process on LaFe0.6Co0.4O3@SBA-15 OCs were explored. Experimental results showed that the encapsulation effect gave the metal oxide a better dispersion, reduced the sintering, and improved the reaction performance. Compared with LaFeO3, the toluene conversion increased from 52.3% to 79.7%, the CO selectivity improved from 57.0% to 87.4%, and the oxygen release (OR) increased by 100% after encapsulation in SBA-15. Due to the substitution of Ni2+, Cu2+ and Co2+ on Fe3+, more oxygen vacancies in OCs were created, and both conversions of toluene and selectivity of CO were improved. Among them, the incorporation of Co had the best performance, the toluene conversion was 81.6%, and the CO selectivity was 96.8%. The kinetics of the LaFe0.6Co0.4O3@SBA-15 reaction was solved using a gas–solid reaction model with an activation energy of 103.9 kJ mol–1 and a pre-exponential factor of 123.8 s–1. The performance of LaFe0.6Co0.4O3@SBA-15 was tested for 10 cycles, and it was found that conversion of toluene and CO selectivity were well-maintained at 90.0%–92.0% and 93.0%–96.0%, respectively. This study could guide the selection of OCs in reforming macromolecular volatiles from biomass pyrolysis to produce hydrogen-rich syngas.