Hydrodeoxygenation Of Bio-oil Oxygen Compounds Over Amorphous Catalyst

With the continuous depletion of fossil oil resources and the aggravation of environmental pollution, the bio-oil as the environmentally friendly renewable energy has been the focus of attention in all countries. However, the bio-oil pyrolysised from biomass contains a large mount of oxygen compounds including ketones, alcohols, acids and phenols, which contribute to the low heating value, chemical instability and strong corrosion. It is very necessary to improve the quality of the bio-oil via catalytic hydrodeoxygenation.Hydrogenation of the bio-oil model compounds(diacetone alcohol, furfural, phenol and guaiacol) on amorphous Raney nickel catalyst was carried out in an autoclave under mild conditions, aiming to study the hydrotreating characteristics of model compounds and the reaction mechanism. The results showed that high temperature would result in catalyst crystallization and reduce the catalytic activity. Under the optimal conditions of 180℃, 3 MPa, 4 h and 8wt.% amount of catalyst, the conversion of model compounds and the selectivity of saturated alcohols reached 100.00% and 97.74% respectively. For the bio-oil, the yield of saturated alcohols reached 44.00% at the optimal conditions, the pH changed from 4.08 to 5.13. Discussed the reaction mechanism of models, two kinds of hydrogenation ways were concluded, namely different compounds with lone pair electrons of O selectively combined with the two active H( weak absorption of Ni-H, free hydrogen atom) to hydrogenation reaction.Ni-B, Ni-Co-B catalysts were prepared by using chemical reduction method with reducing agent KBH4, and supported catalyst Ni-Co-B/γ-Al2O3 catalyst was also prepared by impregnation reduction method successfully. The prepared catalysts were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM) and specific surface area(BET). And the results showed that the preparation of catalysts were amorphous catalysts, thermal stability of the catalyst order was Ni-Co-B/γ-Al2O3-20% > Ni-Co-B-5/5> Ni-B-3.5. The new fresh catalysts particles were nearly nanometer level, especially the particles of Ni-Co-B/γ-Al2O3-20% was finer and dispersed more uniformity, and exhibited larger specific surface area, which promoted the catalytic activity.The influence of preparation condition of catalysts like Ni Co molar ratio and metal loading,reaction temperature, reaction pressure, reaction time on catalytic activity were investigated by probe reaction with the catalytic hydrogenation of furfural, diacetone alcohol and guaiacol. Under 150℃, 4 MPa, 4 h conditions with the Ni-Co-B-5/5 catalyst, the conversion of furfural and diacetone alcohol were 100.00% and 98.45% respectively, the amount of amyl alcohol and tetrahydrofuran in the products were 10.65% and 14.91% respectively. However, under 210℃, 4 MPa, 4 h, with the Ni-Co-B/γ-Al2O3-20%, the conversion of furfural, diacetone alcohol and guaiacol were 100.00%, 100.00% and 76.82% respectively, the amount of amyl alcohol, tetrahydrofuran and cyclohexane in products were 10.51%, 20.12% and 11.06%, respectively.