Bio-oil Model Compound Catalytic Cracking And Its Fraction Emulsification Research Based On Molecular Distillation

Fast pyrolysis is an important biomass utilization technology which can transform solid biomass to liquid bio-oil efficiently. However, the inferior properties of bio-oil, such as high oxygen content, high water content, low heating value, acidity and instability, limit its utilization as vehicle, fuels. Therefore, it is necessary to upgrade bio-oil for its high-grade utilization. Emulsification and catalytic cracking are promising bio-oil upgrading technologies which can convert the bio-oil to high-grade liquid fuels. Therefore, the emulsification of bio-oil distilled fraction and catalytic cracking of its model compounds from molecular distillation technology are studied in this paper.First, the rice husk bio-oil was separated by molecular distillation technology to obtain its distilled fractions. The rice husk bio-oil distilled fraction had better cracking and emulsification properties because of the removal of the macromolecules like sugars and phenols.In order to investigate the detailed cracking behavior of rice husk bio-oil distilled fraction, hydroxypropanone, cyclopentanone and acetic acid were first chosen to study their co-cracking performance with ethanol, respectively. It was found that they all had good cracking activity, and the oil phase was completely composed of hydrocarbons. Then, in order to simulate the actual composition of distilled fraction, those three typical model compounds were mixed to study their co-cracking performance with ethanol. The influences of reaction temperature and pressure on the conversion of reactants, selectivity and composition of oil phase were investigated. It was found that increasing reaction temperature promoted the conversion of reactants and improved the efficiency of deoxygenation, while increasing reaction pressure would significantly promote the production of hydrocarbons.400℃and2MPa was found to be the optimum condition for bio-gasoline production, under which the selectivity of oil phase was higher and completely composed of hydrocarbons. Then the BET analysis, continuity and regeneration experiments were carried out. It was found that the catalyst had relatively surface area and small amount of carbon deposition under better cracking conditions. As the reaction proceeding, the aromatization capacity and activity of catalyst were decreased significantly. And through the regeneration method of combusting the coke, the catalyst could recover its activity.Then, mechanical and ultrasonic emulsification technologies were used in the emulsification of rice husk bio-oil distilled fraction and diesel to generate emulsion fuels. The influences of different hydrophile and lipophile balance (HLB) values, mechanical agitation speeds, ultrasonic amplitude and different distilled fraction content were investigated. It was found that the emulsion fuels prepared by mechanical technology and ultrasonic technology both had the longest stable time at the HLB value of4.3, and ultrasonic emulsifying effect was significantly better than the mechanical emulsification. In mechanical emulsification, the emulsion fuels prepared by10000r/min had better stability; in ultrasonic emulsification, the emulsion fuels prepared by20Am had the best stability. In addition, with the distilled fraction content increased, the stability of the emulsion fuels was gradually deteriorated. Then the effects of droplet size distribution on the stability of emulsion fuels were investigated. It was found that the emulsion fuels with smaller droplet size and concentrated size distribution had longer stable time.