The effects of char and potassium on the fast pyrolysis behaviors of biomass in an infrared-heating condition

摘要

During the solar pyrolysis of biomass,the heat transfer of biomass is restrained due to uncontrolled heating area and accumulation effect.So the co-pyrolysis reaction behaviors of biomass and char,and the secondary pyrolysis reactions of biomass under co-pyrolysis situation are worth exploring.The effects of char and potassium on fast pyrolysis products distribution by fully mixing and extruding sample materials under various heating rates (5 °C/s,20 °C/s,100 °C/s) and pyrolysis temperature (350 °C,425 °C,500 °C) were discussed.The results showed that high temperature was favorable to the release of vol-atiles,and higher heating rate promoted decomposition of bio-oils into gaseous products.Higher heating rate contributed to the release of O element and the accumulation of C element in bio-char to some extent.The char enhanced the secondary pyrolysis reaction resulting further decomposition of small molecular acids and the conversion of guaiacyl-contained structure into simple phenols and CH_4 by demethylation and demethoxylation reaction.The influences of potassium were concentrated in increasing the reactivity of biomass pyrolysis,which promoted the conversion of bio-oils into gas (especially CO_2) and the demethylation reaction of guaiacyl at low temperature.