Effect of synergism between biomass and coal during co-pyrolysis in a free fall reactor on tar components

The liquid products from co-pyrolysis of Dayan lignite(DY) and legume straw(LS) and from pyrolysis of the single fuel were classified into asphalts,phenols,aliphatic,aromatics and polar fractions by solvent extraction-column chromatography.Compared with the calculated yield of asphalts,i.e.the mass weighted mean value 19.0% from pyrolysis of the single coal and biomass,the experimental yield from co-pyrolysis decreased to 11.4%,and the aromaticity of the co-pyrolysis asphalts increased.At the same time,the yield of light molecular weight phenols,methylphenol,dimethylphenol and their derivatives increased at about 5% during the co-pyrolysis;while the content of aliphatic hydrocarbons with long chains decreased.The content of decalins was 43.37% in aromatic fraction of the co-pyrolysis tar,whereas it was almost not found in the tars from pyrolysis of the individual fuel.These results verified that the synergy existed during co-pyrolysis of coal and biomass under the experimental conditions.It was contributed to the reactions such as hydropyrolysis and hydrogenation during co-pyrolysis of coal and biomass under the hydrogen atmosphere mainly supplied by biomass pyrolysis.Co-pyrolysis of coal and biomass favors producing low molecular weight compounds and improving the quality of the liquid product.