Upgrading Research Of Bio-oil

With the worldwide wanton depletion of fossil energy, the development and utilization of renewable energy have been one of the most urgent affairs. Biomass resource is the only renewable energy which can obtain liquid, gas and solid fuels. Therefore, it is significant to exploit and make use of biomass resources. There are many ways in utilizing biomass resource. Among them fast pyrolysis technology is considered to be the most effective way owing to its quick and efficient to obtain a large number liquid product. However, compared with traditional fossil fuels, the quality of bio-oil prepared by the fast pyrolysis technology is poor for its high viscosity, high oxygen content, high acidity, polarity, low heat value, corrosivity and poor stability. Therefore, it couldn't be used directly as automotive fuel, and must be refined before using. At present, catalytic hydrogenation and catalytic cracking are the two primary ways in refining of bio-oil. However, these methods all have fatal disadvantages, such as low liquid yield, catalytic deactivation, and so on. So we have to develop novel and efficient upgrading methods to obtain bio-oil which can be used as engine fuel or chemicals.This study presents two novel methods on the foundation of the former purification experiences. First, by added 1-octanol as surfactant, the bio-oil was emulsified with 0# diesel fuel and E93# gasoline. The results showed that the emulsified oil had lower acid number and water content, better combustion property and stability, which could be substituted diesel fuel or gasoline. Otherwise, bio-oil could be separated effectually by the emulsification process: most light organic fractions of bio-oil entered into the emulsion phase; meanwhile, most organic acids and heavy fractions of bio-oil such as pyrolitic lignin were retained in water phase. It is a novel way for bio-oil upgrading due to the convenient operations, which makes it possible for the commercialized appliction of bio-oil. Second, through glycerol-assistant distillation technology, bio-oil was separated into three fractions: phenolic fraction, light fraction and the residues. The phenolic fraction and light fraction were upgraded respectively. Phenolic compounds separated from bio-oil were converted into cyclohexanol derivatives, which can be used as high heating-value liquid fuel or fuel additives, in catalytic hydrogenation conditions. The mechanism of catalytic deactivation has also been studied. The quality of light fraction has been improved after catalytic hydrogenation and catalytic esterification. The organic acids in the light fraction have been generally converted into ester compounds, the furfural has been totally eliminated, the amount of unstable functional group such as aldehydes, ketones and alkenes have been greatly decreased, and result in the improvement the stability of light fraction.