Study Of Performance Of Ni-based Catalyst On Hydrodeoxygenation

With the dramatic increase of economy, the conflict between the lack of petroleum resource and sharply increasing demand for oil become more and more serious, which is crucially important for the continuous development of economy and energy safety of our country. Fischer-Tropsch synthesis, as an alternative method, can covert other carbon sources, such as coal, natural gas and biomass etc, to clean fuel and other chemical feedsocks, and attract the increasing interests of researchers all over the world. The products of Fischer-Tropsch synthesis are very complicated, including mainly hydrocarbon and less oxygenated compounds, such as acid, ester, alcohol, aldehyde and ketone etc, which lower the quality of synthesized oil and cause some problems for downstream treatment, especially the erosion of acids to equipment. In the view points of economy and application, it is crucial important to hydrodeoxygenate the products of Fischer-Tropsch synthesis.Conventional hydroprocessing catalysts, such as Ni-Mo, W-Ni, Co-Mo, Mo-Ni-W, were used most extensively. However, a full understanding of the process and the mechanism for this reaction is still lacking. Thus the detailed study of hydrodeoxygenation shows great interest. In this paper, the hydrodeoxygenation is studied further in term of reaction and catalyst. A serial of Mo(W)-Ni/Al2O3 catalysts were prepared by dipping method with γ-Al2O3 as support. The performances of serial Mo(W)-Ni/Al2O3 catalysts for hydrogenation of the model hydrodeoxygenation were carried out in a continuous fixed bed reactor under conditions, 0-compounds as model oxygenate, were investigated in detail. The results show that the Mo(W)-Ni/Al2O3 catalysts have high activity for oxygenate hydrogenation. Molybdenum or tungsten addition can weaken the interaction of NiO and Al2O3, decrease the reduction temperature of catalysis, and increase the activity of catalysis for hydrodeoxygenation. The results and corresponding conclusion obtained in this work are summarized as follow:1. The optimal reaction conditions attained by changing pressure, LHSV,temperature and content of Ni. The experimental results indicate that with the conditions: NiO content of 6-10%, temperature of 240-280℃, LHSV of 1.5 h-1, catalyst has a optimal performance. Molybdenum addition can weaken the interaction of NiO and Al2O3, decrease the reduction temperature of catalysis, and increase the activity of catalysis for hydrodeoxygenation. Mo-Ni catalysts sulfied with CS2 have better activity for hydrodeoxygenation.2. The effect of calcination temperatures on Mo-Ni catalyst is investigated in detail, and the results show that the suitable calcination temperature for Mo-Ni catalyst is about 400℃. Lower temperature cannot facilitate the precursor to complete decomposition and higher calcination temperature will decline the surface area of the catalyst, which finally declines the yield for desired products.3 .With the same research measures, tungsten addition can increase the activity of catalysis for hydrodeoxygenation in the same way. Catalysts sulfied with CS2 have better activity for hydrodeoxygenation.4. Campared W- Ni and Mo-Ni catalysts in the same operation conditions, the results show that Mo-Ni catalyst has higher activity of hydrodeoxygenation.