Capture of released alkali metals and its simultaneously catalytic performance on secondary reactions of volatiles during biomass pyrolysis

Abstract

Limiting the corrosion of alkali metals and making full use of their catalytic activity on biomass pyrolysis are valuable to the development of biomass pyrolysis technology. In this study, γ-Al2O3 was used to capture the released alkali metals and its simultaneously catalytic performance on the secondary reactions was investigated in a special reactor equipped with a vertical baffle. The results showed that a nearly opposite catalytic effect on secondary reactions was presented between gaseous phase and adsorbed KCl. KCl vapor reduced the yield of water, improved the yield of gas and bio-oil, and accelerated the production of CO2, olefins and aldehydes. The adsorbed KCl over γ-Al2O3 limited the formation of CO2 and enhanced the formation of methyl-phenol and water. A possible catalytic mechanism of released alkali metals during biomass pyrolysis was proposed. This study can provide a basis for simultaneous capture of alkali metals and in-situ regulation of volatiles during biomass pyrolysis.