Upgrading of bio-oil from biomass fast pyrolysis in China: A review

Bio-oil is a brown liquid product from biomass fast pyrolysis. The upgrading of bio-oil has been a hotspot due to its contribution to the application of bio-oil. The properties of bio-oil, research progress, advantages and disadvantages of upgrading techniques of bio-oil from biomass fast pyrolysis in China are summarized, with the hope of promoting the development of upgrading and application of bio-oil in China. The upgrading techniques include hydrogenation, hydrodeoxygenation, catalytic pyrolysis, catalytic cracking, steam reforming, molecular distillation, supercritical fluids, esterification and emulsification. Also, the current problems are summarized and several future development directions of bio-oil upgrading are pointed out.