Study On Residue Hydrotreating Catalysts And Determination Of Structural Parameters Of Hydrogenation Products

Efficient conversion and optimal utilization of heavy oil relates directly to the domestic energy security,as well as the national economy and the social sustainable development.In recent years,crude oils are more and more inferior and heavier,and the usable light oil is decreasing.On the other hand,the regulations for environmental protection purpose increasingly stringents.while the demand for high quality light oil increases.Thereby,it appears especially important to lower the cost of residuum hydrotreating catalysts and improve the quality of oil products.First,the cost-effective preparation method of the pseudo-boehmite used as the support for residuum hydrotreating catalysts has been investigated.To overcome the shortcomings of the low yield and nonuniform product properties of single batch reaction process,the silicious pseudo-boehmite prepared by the continuous carbonization method and continuous aluminum sulfate method have been developed.The pseudo-boehmite prepared by continuous carbonization method appear to be rodlike,while it seem as filiform prepared by continuous aluminum sulfate method.These two kinds of morphology are beneficial to generate large pore with concentrated distribution and high strength after the shaping process for the support.The catalyst support prepared by continuous aluminum sulfate method has larger pore volume,with high percentage of pore which diameter is larger than 65 nm.Such pore structure is in favor of macromolecule diffusion,particularly the asphaltene diffusion,increasing the availability of the catalyst.Afterwards,the continuous aluminum sulfate method for the preparation of silicious aluminium hydroxide has been further studied,that is,the modified kaolin is used instead of sodium silicate.The as-prepared silicious aluminium hydroxide shows uniform rodlike morphology,and leads to more large pore and higher acidity after calcining,which is suitable for the hydrocracking of heavy oil and residual oil.Secondly,the effect of TiO2-Al2O3 complex support,types of impregnation liquid,additive boron and phosphorus on the synthesis of NiMo residuum hydrotreating catalysts have been investigated.The results show that the introduction of Ti weakens the interaction between the active metal and the support,and decreases the spinel structure phase,improving the HDS performance of the catalysts.Compared to alkaline condition,the HDS catalysts prepared in acidic condition have the advantages of strong acidity,weaker interaction between the active metal and the support and the high dispersion of the active metal.The addition of appropriate amount phosphorus improves the dispersion of the active metal,weakens the interaction between the active metal and the support,promotes the formation of Ni-Mo-S type II phase and enhances HDS performance of the catalysts.However,excess phosphorus will lead to the high agglomeration of the active metal.resulting in low dispersion and low acid.The addition of boron in NiMo/Al2O3 catalyst improves the acidity.enhancing the hydrogenolysis activity of C-S bond in heterocyclic compounds and the performance of aromatics saturation,HDS and HDN.Based on the experimental results.ton industrial scale-up of the boron containing catalyst have been performed.The physicochemical properties of the industrial catalysts meet the relevant technical requirements.It could be seen from the entire running period that the HDS and HDC activities of the boron containing industrial catalyst were excellent,and they still had high catalytic activity and stability after 3000 h operating.The results indicate that the catalysts can meet actual demand of industry,which mean the success of the industrial scale-up.Last,the NMR method for determination of the residual oil average molecular structural parameters has been achieved.The aromatic carbon and hrdrogen content of hydrocarbon oil can be directly measured by this method,so that the catalysts and operating conditions can be optimized accordingly.Similarly,the average molecular structural parameters of residuum hydrotreating products also can be measured by this method.The structure variation law of residuum catalytic hydrogenation can be studied by this method,which improves the understanding of the nature of the residuum hydrotreating process.