Research progress in pretreatment method for the quality improvement of biomass pyrolysis products
Biomass are known for its disadvantages,including high water content,low energy density,difficulty in comminuting into small particles and expensive transportation. However,pretreatment is one of the most effective ways to improve the quality of biomass pyrolysis products. The purpose of biomass pretreatment is to optimize certain features of biomass,such as hardness,particle size,density,composition,and chemical properties,to obtain more and higher quality of bio-oil in its pyrolysis liquefaction process. To improve the pretreatment technology with higher economic efficiency,the study onbiomass pretreatment technologies are reviewed in this paper. Many methods for high quality bio-oil have been discussed. In this review,the pretreatment technology,such as drying methods,acid hydrolysis,torrefaction,hydrothermal and biological methods,are analyzed in focus. Among them,drying methods and torrefaction have the potential in comparison. But the current study are still insufficient,we need to seek new pretreatment technology with lower cost,higher yield and less pollution. Suggestions on the development of pretreatment technology are also included. At present,the single biomass pretreatment methods have their defects,the combination of different pretreatment methods is the important direction in future research, in which the structural characteristics and composition of raw material properties are properly combined.