In order to effectively and widely use low-rank coal and biomass, the co-extracted product was extracted from KL coal and biomass by polar solvent N-2-methyl-2-pyrrolidinone (NMP) at high temperature and high pressure. The structures of the co-extracted product and residues were characterized by element analysis, FT-IR spectra. The effects of temperatures, solid-liquid ratio, and extraction time on the extraction yields of co-extracted product were studied, respectively. Moreover, the extraction mechanism of the co-extracted product at mild conditions is proposed. The results show that the ash contents of the co-extracted products from KL coal and biomass are significantly lower than KL coal, and the volatile contents and H/C are significantly improved. For KL coal, with the increase of biomass/coal ratio, the extraction yield of KL is improved evidently from 56.25 to 71.44% and the ash content is decreased from 0.68 to 0.59% at suitable conditions.
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This work was financially supported by the National Natural Science Foundation of China (NO. 51574023) and National Key Research and Development Program (2016YFB0600701).
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