The Performance Of Hydrodeoxygenation Of Phenol And 4-cresol On Amorphous Catalysts

With the decreasing of coal, petroleum, nature gas, and other mainstream non-renewable energy , biomass, as the only renewable energy that can be converted to liquid fuels, has been attracting more and more attention. Bio-oils were mainly obtained from biomass by fast pyrolysis or high-pressure liquefaction. However, such ways of production make the content of the oxygen in these bio-oils too high, and some of them are even high to 50%, which in consequence lead to high viscosity, thermal instability, poor chemical stability, corrosiveness and immiscibility with hydrocarbon fuels etc, thus the transportation and utilization of the bio-oils are seriously impacted. Therefore, the hydrodeoxygenation (HDO) for bio-oil upgrading and to make it be more widely used became an important research. In this paper, Ni–W–B,Co–W–B,Co–Mo–B,La–Co–Mo–B and La–Ni–Mo–B amorphous catalysts were prepared by chemical reduction, and the catalysts were characterized by BET, SEM, XPS and XRD. The influences of lanthanum in hydrodeoxygenation performances of the Co-Mo-B catalyst were tested using phenol and 4–cresol as the model compound.The results showed that all of these catalysts were amorphous structure. W⁶⁺ was not reduced by NaBH₄ in catalysts, but presented in the form of WO₃, acting as the absorption center of Br?nsted acid. The series of W catalysts exhibited high activity: under the temperature of 548K, the deoxygenation selectivity of phenol by Ni–W–B catalysts could reach 100% in 10 hours. The order of catalytic deoxygenation activity conformed to the following sequence: Ni–W–B–2> Ni–W–B–3> Ni–W–B–1. Under the temperature of 548K, the deoxygenation selectivity of 4–cresol by Ni–W–B catalysts could reached 97.2% in 5 hours. Aromatics were not detected in the productions.Mo⁶⁺ was partially reduced by NaBH₄ in Co–Mo–B and La–Co–Mo–B catalysts, and existed mainly in +4 and +6 valence. Among them, MoO₂ acted as the absorption center of Br(?)nsted acid, and the key of hydrodeoxygenation. By changing the amount of La, it can be found that the hydrogenation activity of the catalyst was improved. When the La: Co= 0.15: 1, the selectivity of deoxygenation on La–Co–Mo–B catalyst was higher than that on Co–Mo–B, which the final conversion of phenol and the selectivity of deoxygenation both could reach 100%. The route of hydrodeoxygenation for phenol trended to direct hydronolysis to form benzene after the addition of lanthanum.After the high temperature treatment of 548K, the amorphous Ni–B in the La–Ni–Mo–B amorphous catalyst with high catalytic activity gradually transformed to crystalline Ni and B. Because of the agglomeration of crystalline Ni on the surface, the surface area of the activity of Ni decreased and the electron transfer between B and Ni reduced. The hydrogenation activity of the catalysts significantly dropped, the relative selectivity of deoxygenation of phenol rised and the total rate of deoxygenation declined. The route of hydrodeoxygenation for phenol trend to direct hydronolysis to form benzene, leading to the increasing content of benzene, which was above the content of aromatic hydrocarbons in the new European regulations (less than 14%).