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

Abstract

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 volatiles, 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 CH4 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 CO2) and the demethylation reaction of guaiacyl at low temperature.