Two-step catalytic pyrolysis behavior and product distribution of rice husk impregnated with zinc acetate

Abstract

Two-step pyrolysis (TSP) combined with catalyst was proposed to explore a new effective method of biomass utilization. The pyrolysis behavior and TSP characteristic of rice husk (RH) and RH impregnated with zinc acetate (ZnRH) were investigated by TG (thermogravimetric analyzer) and Py-GC/MS (pyrolysis-gas chromatography/mass spectrometry). The effects of zinc acetate on the pyrolysis kinetics and product distribution were studied. The results showed that the TG process of RH and ZnRH could be both divided into three stages, and zinc acetate decreased the activation energy of pyrolysis process. The kinetic analysis using Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods indicated that the pyrolysis reactions of RH and ZnRH corresponded to one-dimensional shrinking core model (R1). The impregnation of zinc acetate inhibited ring-opening and cleavage reactions and promoted dehydration and cyclization reactions of TSP. Therefore, compared with TSP of RH, ZnRH had higher selectivity of acids and furans in the first step, and obviously higher selectivity of furans and anhydrosugars in the second step. Moreover, the yield of phenols was decreased in TSP of RH by impregnating zinc acetate.