Study On Upgrading Bio-oil By Ru/C Catalystic Hydrodeoxygenation

As a clean renewable energy, Biomass energy is the only renewable carbon source. Biomass fast pyrolysis and catalytic hydrogenation of bio-oil is considered one of the most promising application technologies. The properties of bio-oil are similar for different raw materials and pyrolysis conditions where moisture content is 15-40wt%, pH 2-3.5, viscosity (40℃) 20～200 mPa·s and heat value is 14-19MJ/kg. The nature of high viscosity, high corrosion and low heat value limit its application. Recent studies of catalytic hydrodeoxygenation improves the quality effectively,so that the bio-oil can be transformed into high-quality green transport fuel.Firstly, different biomass materials were compared with each other determine their ash, moisture, volatile matter and elemental composition. Pinus sylvestris was chosen as raw material. Fast pyrolysis oil (bio-oil) was produced in our laboratory-developed setup and analyzed by moisture, heat value, viscosity, flash point, pH, GC-MS and so on. Such a bio-oil was chosen as the raw material for catalytic hydrodeoxygenation.Upgraded research of catalytic hydrodeoxygenation of bio-oil was carried out in the Laboratory-designed autoclave using noble metal Ru/C catalyst. By changing the reaction conditions:pressure, reaction temperature and reaction time, it is found that 4h HDO reaction by using 5wt% catalyst at 300℃,13MPa can obtain 35wt% upgraded-oil where water content droped from 38wt% to 2.5wt%, oxygen content reduced from 46.4wt% to 15.2wt% and heat value increased from 18.5MJ/kg to 36MJ/kg. By GC-MS analysis, allyl, which is the most activity in bio-oil, was transformed into alkyl. Ketone was transformed into alkyl ketone, and guaiacol groups were transformed into alkyl phenol. Based on the analysis of products,10wt% water and 2.2wt% CO2 were generated, and the upgraded process is that dehydration is as a main and in decarboxylation as a supplement.Continuous providing hydrogen HDO experiments were carried out in the improved device.40wt% of the oil production rate was obtained with 10MPa at 200-300℃for 4h. At the conditions of 300℃and lOMPa the oxygen removal rate was 84.6wt% and moisture content was 0.2wt%. Heat value was increased from the initial 15.6MJ/kg to 38.5MJ/kg. The acids and ketones were reduced by 50% in the oil phase. Ketone was transformed into alkyl ketone, guaiacol was transformed into alkyl phenols which almost reserved in the oil phase, and a small amount of alkyl benzene was produced. In the conditions of 250℃and 10MPa, the heat value of the upgraded oil can be increased to 39.4MJ/kg and the hydrogen content arrived at 11.6wt%. By GC-MS analysis it is observed that ketones were transformed into the corresponding alkyl alcohol, methoxyl content was relatively high in the phenolic, and a small amount of cyclohexene is formed. Water contain is still 3.7wt% in the oil phase due to the presence of more hydrophilic groups. Such a upgraded oil has better Stability. After HDO process the quality of bio-oil is improved greatly, which has low moisture and corrosive. Mixed with the fossil oil, the upgraded-oil can be applicated in refinery for transportation.