Preparation Of Nickel-based Catalysts And Research On Aquathermolysis Of Heavy Oil

In the face of the increasing energy demand,the extraction of heavy oil is crucial,however,its high viscosity and low fluidity bring great difficulties to the extraction and transportation work.Therefore,scholars at home and abroad have developed various technologies for the extraction of heavy oil,among which catalytic aquathermolysis viscosity reduction technology is very promising because it can radically reduce the viscosity of heavy oil,improve the quality of heavy oil,and thus enhance the fluidity.At present,the core concern of this technology is the aquathermolysis catalyst,so the development of suitable catalyst is an effective way to improve the viscosity reduction rate of heavy oil.In this thesis,the Ni/C catalysts with spherical shape and radius of about 1μm were prepared and used in aquathermolysis viscosity reduction experiments of heavy oil.The results of XRD,SEM and XPS analyses showed that the active component Ni in the catalyst was mainly distributed on the surface of carbon carrier as a pure metal,and the results of BET and CA analyses indicated that the Ni/C catalysts had good specific surface area and good lipophilicity.By optimizing the viscosity reduction conditions of aquathermolysis of heavy oil,it was found that the catalyst Ni/C could reduce the viscosity of heavy oil by 79.68%at the reaction temperature of 260℃,reaction time of24 h,catalyst amount of 0.6 wt.%,hydrogen donor addition category of tetrahydronaphthalene,and hydrogen donor amount of 1.5 wt.%.The mechanism of viscosity reduction of heavy oil by catalyst Ni/C was analyzed by SARA,EA,GC-MS,FT-IR,~1H NMR.The results indicate that catalyst Ni/C reduced the resins and asphaltenes content by 6.32%and 4.64%,respectively,through hydrocracking,hydrodesulfurization,hydrodeoxygenation,depolymerization,and dealkylation side chain reactions.This is considered to be the radical reason for the viscosity reduction of heavy oil.Next,the Ni Cu/C bimetallic catalysts with spherical shape and radius of about 1μm were prepared and used in aquathermolysis viscosity reduction experiments of heavy oil in order to improve the viscosity reduction ability of the catalysts and bring into play the synergistic effect of multi-metals.The results of XRD,SEM and XPS showed that the Ni Cu in the catalyst was mainly in the form of solid-solution alloy uniformly distributed on the carbon carrier surface,which facilitates the contact of heavy oil macromolecules with it.The results of aquathermolysis viscosity reduction experiments on heavy oil showed that the bimetallic Ni Cu/C catalyst had a better viscosity reduction effect under the same conditions and reduced the viscosity of heavy oil by 82.62%.The reasons for the better viscosity reduction effect of Ni Cu/C catalyst were analyzed by SARA,EA,GC-MS,FT-IR,~1H NMR.The results show that the introduction of Cu element in the bimetallic Ni Cu/C catalyst enhanced the ability of the catalyst to break the side chain alkyl groups in the molecular structure of resins and asphaltenes as well as strengthened the hydrocracking effect of the catalyst on asphaltenes,resulting in a reduction of 7.06%and 6.02%of resins and asphaltenes content,respectively.The feasibility of bimetallic co-catalysis to improve the viscosity reduction effect of heavy oil was confirmed.Finally,the NiCo/C bimetallic catalysts with bulk shape and size around 500 nm were prepared and used in aquathermolysis viscosity reduction experiments of heavy oil,considering that the removal of oxygen-containing functional groups and heteroatoms in heavy oil may be more beneficial to viscosity reduction of heavy oil.The results of XRD,SEM and XPS showed that the NiCo in the catalyst was mainly in the form of solid-solution alloy uniformly distributed on the carbon carrier surface.It can fully contact with the heavy oil macromolecules.The experimental results of viscosity reduction by aquathermolysis of heavy oil show that the bimetallic NiCo/C catalyst has the best viscosity reduction effect under the same conditions and can reduce the viscosity of heavy oil by 87.99%.The reasons for the excellent viscosity reduction effect of NiCo/C catalyst were analyzed by SARA,EA,GC-MS,FT-IR,~1H NMR.The results show that the introduction of Co in the bimetallic NiCo/C catalyst enhances the ability of the catalyst to break C-S,C=O,C-N bonds.The removal of a large number of heteroatoms S,N and O from resins and asphaltenes was promoted,resulting in the reduction of resins and asphaltenes contents by 9.21%and 4.80%,respectively.It supports the view that the removal of oxygen-containing functional groups and heteroatoms is more beneficial to viscosity reduction of heavy oil.In this thesis,the aquathermolysis behavior of heavy oil is studied in terms of aquathermolysis viscosity reduction process conditions,catalyst types,bimetallic synergy,viscosity reduction mechanism,etc.,and some conclusions of practical value were obtained.The conclusions guide the development of aquathermolysis catalysts for heavy oil and contribute to the catalytic viscosity reduction extraction technology for heavy oil aquathermolysis.