Research On Catalytic In-situ Hydrogenation Of O-cresol And Bio-oil

Along with the growing of crude oil price and the concern about the greenhouse effect, the international community is conducting the research of renewable resource. Bio-oil is derived from biomass, the only renewable carbon containing feedstock that can be used for the synthesis of hydrocarbon transportation fuels. It is considered as an important substitute for fossil fuel, whereas bio-oil has complicate physical and chemical properties including high water content, high viscosity, high corrosion and other serious problems.The paper proposed a new method to combine the methanol aqueous phase reforming(APR) and hydrogenation to refine bio-oil. This work provided a new thought to solve the problem of bio-oil refining.The study detects the effect of reaction parameters, such as Ni loading, temperature, initial pressure, and reaction time on in-situ hydrogenation, the reaction was carried out over Ni/CMK-3 catalysts. The catalysts were characterized by X-ray diffraction(XRD), H2 temperature programmed reduction(H2-TPR) and N2 adsorption-desorption isotherms. The results revealed that the optimal conditions were confirmed as follow: Ni loading of 20%, reaction temperature of 230℃, initial pressure of 0.1MPa, reaction time of 9h for in-situ hydrogenation. The maximum conversion of o-cresol in optimal condition was determined as 50.53%. In the meantime, the study compared the effect of hydrogen donor solvents, formic acid was the best in four kinds of solvents. The comparsion of cresol isomers, recyclability of Ni/CMK-3 were also discussed.O-cresol was using as a probe to test the activity of these catalysts in the condition of 230℃ and 0.1MPa initial pressure of N2. The catalysts were characterized by X-ray diffraction(XRD), H2 temperature programmed reduction(H2-TPR), ammonium programmed desorption(NH3-TPD) and N2 adsorption-desorption isotherms. The results showed that the catalytic performance of Ni/CMK-3(the conversion of o-cresol reached 45.4%) was significantly better than the other three kinds of supports. Across a series of investigated catalysts were modified in the catalytic activity, over 60% conversion of o-cresol was obtained after the addition of Ce(64.6%)and Cu(66.8%) in Ni/CMK-3, whereas the addition of Fe led to a decrease of conversion. In the meantime, Cu changed the products distribution. The appearance of toluene indicated that it existed another pathway in the reaction. Accompanied by the ascension of conversion in both sides, side effects also occurred and got more serious. Reaction pathway, involved three routes, was also mentioned in this study.The results about the in-situ hydrogenation of bio-oil revealed that the main products were acids, esters and phenols, the amount of phenols was small. Ultrasonic agitation was beneficial to the conversion of bio-oil, especially phenols and acids. In addition to this, ultrasonic agitation might be favourable towards preventing catalysts coking.