Reaction kinetics study in direct chemical looping process based on a multi-step reaction scheme.

• A mass balance-based multi-step model was used to study the reaction kinetics of direct chemical looping process. • The mass balance formulated steps required fewer parameters and thus demanded less computational resource. • The activation energy changes were diversified by adding oxygen carrier. • Oxygen carrier altered the yields and distributions of intermediates and products. The investigation into reaction kinetics provides fundamental insights for reactor design in biomass thermochemical conversion. This work studied the kinetics of biomass chemical looping process based on a multi-step model. Cellulose, xylan, and lignin were employed as biomass representatives. The individual step in the multi-step scheme was formulated with a mass-balance equation form, requiring fewer parameters and thus less computational cost. In addition, the decomposition characteristics of different biomass samples in the presence of oxygen carrier (Fe 2 O 3) were analyzed, and the effects of Fe 2 O 3 on the kinetic parameters of reaction steps were investigated. The results revealed that volatiles pyrolyzed from cellulose and xylan were almost not involved with Fe 2 O 3 reduction at high temperatures (∼1000 K) while playing a major role in terms of lignin (∼1050 K). Moreover, adding OC did not always positively affect the activation energy; in particular, it decreased the activation energy of xylan yet elevated the activation energies of cellulose (at low-temperature zone) and lignin to some extent. [ABSTRACT FROM AUTHOR]