Ultrasound was adopted to prepare emulsion fuels between bio-oil and 0# diesel. The effects of ultrasound power and treating time on the stability of emulsion fuels were investigated. Excellent stability with stable time as long as 35 hours was obtained under an ultrasound power of 80W and a treating time of 3 minutes. Malvern nanometer particle size analyzer (Zetasizer Nano S90) was used to study the droplet size of emulsion fuels. The emulsion fuels with smaller droplet size had longer stable time. And the droplet size of the optimal emulsion fuel was around 0.4 um.

In the present work, the emulsion fuels from bio-oil heavy fraction and 0# diesel were prepared by mechanical and ultrasound emulsification technologies. The relationship between stable time of emulsions and HLB value of emulsifier was investigated. Results indicated that lower mechanical stirring speeds and lower ultrasonic amplitudes lead to longer stable time of bio-oil heavy fraction emulsions. The stable time of emulsions reduced as HLB values increasing, and it reached a maximal value of 14 minutes under a HLB value of 1.8. Zetasizer Nano S90 was adopted to measure the droplet distribution of emulsions. The major droplet size of emulsions was smaller than 90nm. Meanwhile, the droplet distribution curve of ultrasound emulsions was much complex than those of mechanical emulsions.

In this paper, emulsification study on bio-oil middle fraction and diesel was carried out. Mechanical and ultrasound emulsification technologies were used to prepare emulsion fuels between bio-oil middle fraction and diesel with different hydrophile and lipophile balance (HLB) values. It was found that the stability curve of emulsions had two peaks corresponding to the HLB values of 4.3 and 6, respectively. Comparable to the mechanical emulsions, the ultrasound emulsions had longer stable time. The stable time for ultrasound emulsions at the HLB values of 4.3 and 6 were 215 minutes and 143 minutes, respectively. Then the effects of surface tension and droplet size distribution on the stability of emulsions were investigated. It was found that the emulsion fuels with lower surface tension and smaller droplet size had longer stable time.

Experimental study on the physico-chemical properties of bio-oil and diesel emulsification has been carried out in this paper, which was based on the preliminary experiment. The effect of surface tension and viscosity on the stability of emulsions were particular concerned. It was found that the longest stable time, the lowest viscosity and lowest surface tension can be obtained simultaneously when the hydrophile and lipophile balance (HLB) value was of the optimal value, i.e. 6.5. Experimental results indicated that the stable time of emulsion decreased rapidly with the increase of bio-oil content, while the value of surface tension and viscosity increased. Meantime, it was shown that the most stable emulsions had the lowest value of viscosity and surface tension.

Solid acid catalyst has high catalytic esterification activity but with a free acid excess problem. In this paper, washing pretreatments were adopted in the catalyst preparation processes and their influences on catalytic activity and residual free acid amount were investigated. Residual free acid amount can be reduced by 33% with both washing before calcinations and washing after calcinations pretreatments. But their influences on catalyst activities were different. Washing before calcinations pretreatment reduced the catalytic activity from 80.29% to 57.72% while the other washing pretreatment had little influence on the catalyst activity. In order to describe the influence mechanism of washing pretreatments, catalysts were characterized by FT-IR and XRD. Finally, typical compounds in bio-oil were selected to form a bio-oil model compounds system. The catalyst pretreated by washing after calcinations was used on the esterification research of this bio-oil model system. The volume ratio of propanol to bio-oil model compound was 3:1. The reaction temperature was 90 °C and the amount of catalyst was 2wt% of total liquid mass. Combined with the GC-MS qualitative and quantitative results, carboxylic acids, such as formic acid, acetic acid, propionic acid were converted to esters effectively.