Pyrolysis of sawdust impregnated with bio-oil of the same origin: Influence of organics in bio-oil on property of biochar

Abstract

Reactive organics in bio-oil might further react with biochar of the same origin during pyrolysis. This was investigated herein via conducting the pyrolysis of poplar sawdust impregnated with a heavy fraction of the bio-oil from the same biomass at 400 or 600 °C. The results showed that the organics in the bio-oil for impregnation involved in the pyrolysis by enhancing biochar production via cross-polymerization with the organics on biochar and/or the reactive products like aldehydes/furans and some heavy organics. This led to the formation of additional carbonaceous deposit of aliphatic nature on the surface of biochar. This, however, did not enhance the thermal stability of the biochar but lowered activation energy and ignition temperatures for combustion. In addition, the organics in the bio-oil impregnated could also enhance deoxygenation, producing the biochar with the O mass fraction lower than counterpart by 24.1% at 400 °C. Moreover, impregnation of bio-oil also facilitated the formation of mesopores (S > 2nm: 178.6 m2 g−1 versus 117.6 m2 g−1 of counterpart) and created a carbonyls-deficient surface of the biochar.