Preparation Of Precious Metal Catalyst And Its Hydrodeoxygenation Performance

Biomass pyrolyzed bio-oil is considered to be the best alternative energy source for supplementing gasoline and diesel,but the biggest drawback of this bio-oil compared to fossil fuels is its high oxygen content,which reduces its use as an oil.Therefore,deoxygenation must be performed to improve the quality of the fuel,and catalytic hydrodeoxygenation(HDO)technology can effectively and selectively remove oxygen from the oxygenate.Precious metal catalysts have the advantages of high activity,good stability and long life.They are widely used in the research of HDO.At the same time,the carrier also has an important influence on the activity of supported catalysts.It can change the dispersion of active components and improve the activity of catalysts.In this paper,a series of catalysts were prepared with MCM-41,Al2O3,Co-Al composite oxides and Fe-Ni-Al mixed oxides as supports and Ru,Pt as the main catalytic components.The phenolic compounds were used as probes to test the hydrodeoxygenation performance of the catalysts.The effects of the reduction temperature of the catalyst,the different Co and Fe content in the carrier on the catalytic performance of the catalyst were investigated.When the Ru content of Co-Ru/MCM-41 catalyst was 2%,the Co content was 20%,and the reduction temperature was 350? the best HDO catalytic activity was exhibited.After 2 hours of reaction at 275?,the conversion rate reached 94.7%and the deoxygenation rate reached 94.1%.Co-Ru/Al2O3 catalysts have lower conversion and deoxidation rates.After 2 h reaction at 275 0C and 4 MP,the conversion rate of Ru2/Al2O3-350 catalyst was 29%,and the deoxygenation rate was only 26.7%.When Co is added to the carrier,the activity of the catalyst is significantly increased.With the increase of the content of the Co component,the deoxidation activity of the catalyst is enhanced first and then decreased.A series of Ru/Co-Al-O supported catalysts were prepared using complex oxides formed by calcining Co-Al hydrotalcite as a carrier.The results show that when the mass ratio of Co/Al material is 3:1,the catalyst reduction temperature is 350?,and the reaction temperature is 275? the hydrodeoxygenation activity of the catalyst is the highest,and the catalytic conversion of the hydrodeoxygenation reaction of methyl phenol is catalyzed.Both the rate and deoxygenation rate reached 100%.The larger specific surface area of the catalyst favors the hydrodeoxygenation catalytic activity of the catalyst.After the catalyst is reduced at high temperature,its specific surface area decreases,which results in a decrease in the catalytic activity of the catalyst.The Pt-based catalyst was prepared by using the mixed oxides of Fe-Ni-Al hydrotalcite as the carrier.The results show that the Pt/NiO-Al2O3@Fe3O4 catalyst is magnetic and exhibits high catalytic activity.Aromatic hydrocarbons are produced by a hydrodeoxygenation and dehydrogenation coupling process.The dehydrogenation activity is closely related to the Fe content,which is attributed to the interaction between Pt and Fe.When the 4-ethylphenol was probed at 300? and 2.0MPa in the HDO liquid-phase system,the conversion rate was 99.4%.After 1.5 hours of reaction,the selectivity of toluene was 19.7%.When the reaction time was extended to 8 hours,The toluene selectivity increased to 90.8%.In addition,the magnetic Pt/NiO-Al2O3@Fe3O4 catalyst is easily recovered from the liquid reaction mixture by using an external magnet.