Energy & Fuels, Vol.34, No.7, 7863-7914, 2020
Coke Formation during Thermal Treatment of Bio-oil
Bio-oil is a mixture of organics produced from pyrolysis of biomass. The organics in bio-oil serve as the feedstock for the production of hydrogen, chemicals, biofuels, and carbon materials. In many processes for conversion of bio-oil, heating is required. The thermal treatment of bio-oil induces the polymerization/cracking of the organics in bio-oil, producing coke. Coke could lower the carbon conversion efficiency of bio-oil, clog the reactor chamber, and deactivate the catalyst, imposing the main challenge for the utilization of bio-oil involving the heating of bio-oil. This review investigates the coking issues in the processes for bio-oil upgrading including esterification, hydrotreatment, catalytic pyrolysis, pyrolysis, steam reforming, and the process for the conversion of bio-oil to carbon materials. The properties of coke formed from thermal treatment of bio-oil, the mechanism for coking of bio-oil, and the methods developed for tackling the coking of bio-oil are the focus.