Catalytic Properties Of The Supported Amorphous Catalyst For Hydrotreament Of Bio-oil

With the diminishing supply of fossil fuels and increasing environmental concerns, biomass has great potential to be an alternative source of energy due to its advantages on reproducibility, resources universality and environmental protection. Bio-oil, obtained from biomass by fast pyrolysis, has an irresistible trend applied for transportation fuel. Unfortunately, the bio-oil components are complex, containing mainly oxygenated compounds such as furans, ketones, carboxylic acids, ethers, esters and alcohols, which cause unfavorable properties of high viscosity, thermal instability and corrosiveness. Catalytic hydrotreatment is considered as an attractive technology for bio-oil upgrading to liquid transportation fuels. However, this process is facing a great challenge due to the complex composition of the bio-oil. According to the characteristics of bio-oil to design catalysts with high performance and to develop high efficient hydrotreament technology have become important. Amorphous alloys with superior catalytic activity and selectivity have attracted much attention. However, their practical application is severely limited because of their poor thermal stability and low surface area. One of the most promising methods to solve these problems is to deposit those ultrafine amorphous alloy particles on a support with high surface area.In this paper, Ni B and Ni B/Si O2-Al2O3 amorphous catalysts were prepared by chemical reduction. Firstly, hydrodeoxygenation properties of the catalysts were tested using phenol as the model compound of bio-oil. Our results showed that the supported Ni B/Si O2-Al2O3 catalyst exhibited large specific surface area(383.4m2/g), high thermal stability and excellent HDO properties during the reaction. The conversion of phenol reached 100% and the selectivity of cyclohexane reached up to 98.5% at 250℃. The reaction temperature had great effect on the activity and deoxygenation selectivity of the catalyst.Direct hydrotreatment of bio-oil faces great challenge duo to its complex components and poor thermal stability. So, in this study we developed an efficient method for bio-oil upgrading named emulsion-hydrotreament method. Firstly, the emulsification of bio-oil with decalin and n-butyl alcohol was performed to improve its thermal stability, and then a catalytic hydrodeoxygenation process was carried out to remove the oxygen contained in bio-oil. In this study, the effect of constitute and content of emulsifying agent as well as reaction conditions such as temperature and time were investigated. The results showed that the constitute and content of emulsifying agent had great effect on the properties of upgraded bio-oil. N-butyl alcohol could improve the emulsion of bio-oil and decalin. More emulsifying agent resulted to higher coke rate, when the ratio of bio-oil and emulsifying agent increased from 30:30 to 30:10, the coke rate increased from 3.5% to 10.8%. Reaction emperature and time also had great effect on the hydrotreament of emulsified oil. With the reaction time increasing from 2 h to 4 h, the deoxygen rate increased from 27.5% to 34.6%; with the reaction timperature increasing from 240℃ to 280℃, the deoxygen rate increased from 26.8% to 34.6%. According to the characterization results of GC-MS, the distribution of different kind of compounds changed greatly. The contents of acids and ketones decreased from both 32.5% of crude bio-oil to 7.2% and 5.8% of upgrading bio-oil; the contents of esters and ethers increased greatly from 5.0% and 0 of crude bio-oil to 52.5% and 11.3% of upgrading bio-oil. Emulsion-hydrotreament improved the properties of bio-oil and increased its stability.