Synthesis And Performance Evaluation Of Catalytic Modification And Viscosity Reduction Catalysts For Heavy Oil

With the rapid development of society,the supply of conventional light crude oil can no longer meet the energy demand of people.The efficient and rapid recovery has become a research hotspot in various countries.It is very difficult to exploit and transport heavy oil because of its high viscosity and low fluidity.Catalytic upgrading and viscosity reduction technology is to use catalyst to catalyze the cracking of heavy oil,which can reduce the content of resin and asphaltene and increase the content of saturate and aromatic on the contrary,so as to archive the purpose of permanently reducing viscosity and improving the fluidity of heavy oil.As a result,it can enhance the recovery rate and pipeline transport rate of heavy oil.In this paper,the basic properties of heavy oil A/B in the Karamay oilfield in Xinjiang are analyzed,including viscosity,viscosity-temperature curve,density,water content,SARA and elemental analysis.Three kinds of transition metal elements such as molybdenum,iron and cobalt were selected as the active components of the catalyst,and modified with oleic acid.Finally,three oil-soluble catalysts such as molybdenum oleate,OA-Fe?MoO₄?₃,OA-CoFe₂O₄ were prepared.It was applied to the experimental study on catalytic viscosity reduction of heavy oil in laboratory.In the experiment,the effect of hydrogen donor tetralin on the catalytic viscosity reduction of heavy oil was investigated first.Secondly,the catalytic acticity of the catalyst was researched.Then,the optim conditions were determined by optimizing the dosage of catalyst,reaction temperature and reaction time in order to obtain the best viscosity-reducing ratio.Finally,the SARA,FT-IR,elemental analysis,¹H NMR test were conducted on the heavy oil A/B and its heavy components before and after reaction.In addition,the gas phase analysis of pyrolysis gas produced in the reaction process was carried,so as perliminarily to discuss the reasons for the viscosity reduction of heavy oil A/B.The results analysis indicated that the heavy oil A/B has high asphaltene and resin content,and both oil samples prisent obvious temperature-sensitive properties.The three perpared catalysts have the viscosity-reducing effect on heavy oil,and the optimal conditions were recommended that:the reaction temperature was 240?,the reaction time was 18 h,and the dosage of molybdenum oleic acid was 0.80 wt%,at this point the viscosity reduction rate reached 65.87%of heavy oil A.When the reaction temperature was 240?,the reaction time was 36 h,and dosage of catalyst OA-Fe₂?MoO₄?₃ was 0.40 wt%,the viscosity reduction rate reached 61.21%of heavy oil B.When the reaction temperature was 260?,the reaction time was 24 h,and the dosage of catalyst OA-CoFe₂O₄ was 0.30 wt%,the viscosity reduction rate reached68.79%of heavy oil B.It was found that the viscosity of heavy oil A/B was reduced in various degrees after catalytic modification through the viscosity test.From the perspective of SARA analysis,the heavy component contents in the oil sample A/B showed a significant decrease after the reaction,and the light components content showed a lager increase on the contrary.At the same time,the CO₂,CH₄,and some light hydrocarbon gas were also produced-during reaction process.The results of FT-IR analysis showed that the number of long-chain alkenes in the oil samples increased after the reaction,the C-S bonds,C-N bonds and C-O bonds in the heavy oil molecules showed different degrees of fracture.The content of low-carbon hydrocarbons in the pyrolysis gas increased obviously.Elemental analysis indicated that the S and N contents in heavy oil,resin and asphaltene decreased to some extent after the reaction,and the results were basically consistent with the FT-IR analysis results.In addition,the oil sample and its heavy component H/C ratio also changed to a certain degree.From the ¹H NMR spectrum of asphaltene and resin,it can be seen that the amount of polycyclic aromatic hydrocarbons in resin and asphaltene decreased obviously and the degree of branching of the heavy components after hydrothermal catalytic upgrading.The results of these analyses indicated that there are a series of reactions,including hydrogenation ring opening,hydrodesulfurization and branching cleavage,in the process of viscosity reduction by catalytic modification,which explains the reason for the viscosity reduction of heavy oil A/B.