Interaction between low-rank coal and biomass during degradative solvent extraction

Abstract

A degradative solvent extraction at around 350°C for low-rank coal or biomass wastes upgrading and fractionation was proposed in our previous work. The extraction yield of low-rank coal is relatively lower than that of biomass. In this work the blends of low-rank coal and biomass were treated by this method at 350°C to investigate the interaction between them. The results showed that the yields and elemental compositions of the extracts obtained from the blends were slight different to the calculated results, which were calculated by assuming that there was no interaction between the coal and biomass. The slight promotion of yield was judged to be caused by the catalytic action of the minerals in the coal for thermal decomposition of biomass. It was worth to note that the elemental composition, molecular weight distribution, chemical structure, thermal decomposition behavior and thermoplastic behavior of the extracts obtained from low-rank coal, biomass and their blend, were rather similar to each other, independent of the properties of the raw feedstocks. Overall, the interaction between low-rank coal and biomass during the extraction was not significant. On the other hand, the proposed degradative solvent extraction method was fit not only by single low-rank coal and biomass but also by their blends to produce the product having similar physicochemical properties. This implied that an industrial system of degradative solvent extraction can use coal, biomass or their blends as feedstock at the same time without modification or adjustment.