Upgrading Of Bio-oil Pyrolyzed From Rice Husk

Bio-oil produced through fast pyrolysis of biomass is highly acidic, viscous and corroded and has a high water and oxygen content as well as low heating value, which make it impossible to utilize it as fuel directly. There is a need to upgrade bio-oil through several methods, including physical and chemical methods. In this paper, the method of emulsification was used to upgrade bio-oil. Pyrolysis oil from husk rice was used as raw material, and the heavy fraction and light fraction were got after centrifugation. Then, the heavy fraction and light fraction were upgraded, repectively.The light fraction was mixed with 0 # diesel oil and built emulsifier(Span 80 and Tween 80) to from a steady emulsion. Single factor experiments were conducted to determine the proper emulsification conditions. Some factors, including hydrophile- lipophile balance(HLB) values, temperature, time, speed and co-emulsifier, were explored. The optimal conditions for obtaining a stable emulsion between diesel and bio-oil are with an emulsifier(Span80 and Tween80) dosage of 6% by weight, co-emulsifier(2-octanol) dosage in emulsifier of 30% by weight, HLB value of 7, shear velocity of 15000 rpm, emulsifying time of 5 min, and emulsifying temperature at 40 oC, Under the optimal conditions, the stabilization time of the emulsified oil was up to 384 h. Trioctylamine, 2-octanol and petroleum ether were used as extraction agent, cosolvent, and diluent. Acidic components in the light top fraction were removed to increase the p H value of emulsified oil. S ingle factor experiments and orthogonal experiments were conducted to optimize the extraction experiments. The optimal conditions are with a 4: 1: 5 volume ratio of trioctylamine : 2-octanol: petroleum ether, 1: 0.6 of phrase ratio, 30 oC, 2 min of ultrasonic time, at which conditions the p H of bio-oil is 4.21 after extractinon and the extraction rate is merely 1.81%.The heavy fraction of bio-oil cannot be emulsified with 0 # diesel oil directly duo to its heavy viscosity. Alcoholysis method was used in this paper. The heavy fraction was alcoholyzed over calcium acetate(calcined at 700 oC) at 180 oC and emulsified. The compounds dectecd in the alcoholysis oil are mainly phenol, alcohol, ketone, aldehyde and acid, most of which are phenol(64.10%). Absolute methanol was added into alcoholysis oil to form the syncretic oil. Then, the syncretic oil with a mass ratio(alcoholysis oil: methanol) of 1: 3, 1: 2, 1: 1, 2: 1, 3: 1 were selected to be emulsified with built emulsifier(Span 80, Span 85 and Tween 80) separately to investigate the influence of different HLB value on the stability of the emulsified oil. The result shows that the stability time is up to 96.27 h when alcoholysis oil: methanol mass ratio is 1: 1 and HLB value is 7.The emulsified oil with better stability was selected to detect its flash point, ignition point, density, viscosity, p H and corrosion property, and the result shows that they are close to those of diesel oil.