Biochar catalyzing polymerization of the volatiles from pyrolysis of poplar wood

Abstract

In this study, the pyrolysis of poplar wood chips with biochar catalyst produced from gasification of the same poplar wood chips was conducted, aiming to probe its influence on the evolution of the pyrolysis products. From the results, it was concluded that the biochar catalyst enhanced the polymerization of the volatiles produced from the pyrolysis, and thus reduced the yields of the gaseous compounds while increased the yield of char. The carbonaceous deposit on surface of the char was oxygen-rich and more aliphatic, which decreased the thermal stability and crystallinity of the char, while made the char prone to oxidation. The biochar catalyst also promoted the formation of methoxy phenols at the expense of alkyl phenols, and the formation of the phenolics with bigger π-conjugated structures. In addition, the volatile-biochar interaction removed the defective structures in the large aromatic structures in the biochar catalyst. Highlights Biochar catalyzed polymerization, but not cracking, of volatiles in pyrolysis. Biochar catalyst enhances char formation while reduces gas formation in pyrolysis. Char in catalytic pyrolysis is more O-rich and aliphatic and low thermal stability. Biochar catalyzed condensation of volatiles to form bigger fused ring structures. Biochar-volatiles interaction removes defective structure in fused ring of biochar.