Preparation Of Two-dimensional Carbon Supported Iron/Nickel Composites And Their Catalysis In The Viscosity Reduction Of Heavy Oil

Heavy oil, as an abundant unconventional reservoir, is significant in solving the seriously lacks of conventional oil resources. But heavy oil has high viscosity and poor mobility which makes it hard to recovery and transportation. So, reducing the viscosity of heavy oil and improving its mobility become a high-efficiency and economic way to enhance oil recovery. At present, the widely used technology is thermal methods. But this method has low recovery rate, and it can not radically reduce the viscosity of heavy oil. The catalytic cracking is a promising method in reducing viscosity, which can decrease the content of heavy component of the heavy oil with the heating power and proper catalysts, and in this way the viscosity of heavy oil can be irreversibly reduced. Meanwhile, the heavy oil can be promoted due to the formation of light component, such as saturated hydrocarbon and aromatics, which can improve the quality of heavy oil at the same time.In this work, a series of graphene supported iron(Fe/Graphene, abbr. Fe G) and two dimensional(2D) carbon supported nickel(Ni/Carbon, abbr. Ni C) were prepared by high-temperature calcination under inert an atmosphere, with iron chloride and nickel chloride as the precursors. The catalytic activity of the catalysts for the viscosity reduction of the heavy crude oil was investigated. The mechanism of the viscosity reduction was studied through Elemental analysis and compositional analyses( saturates, aromatics, resins, and asphaltenes(SARA) analysis) change of heavy oil and characterization of the retrieved catalyst. The main research contents and results of this paper are as follows:1. Graphene supported iron and 2D carbon supported nickel were prepared by high-temperature calcination. Transmission electron microscopy(TEM) showed that metallic iron and metallic nickel particles are uniformly dispersed in the 2D surface of the carbon material. X-ray diffraction(XRD) characterization results showed the catalysts before and after the reaction have the almost same crystal structure, indicating that these supported catalysts are stable. This two-dimensional carbon material had large specific surface area, which can adsorb more oil, while iron and nickel nanoparticles can provide more catalytically active sites.2. The catalyst with different iron contents, i.e., Fe G2-3, Fe G3-3, Fe G4-3, showed different catalytic efficiencies to the heavy oil from Shengli oilfield. The viscosity reduction ratios of crude oil(80500 m Pa·s) catalyzed by these catalysts are 52.5%, 58.6%, and 64%, respectively. The analysis of the composition changes of SARA before and after reaction, showed that the contents of resin and asphaltene decreased and the contents of saturated hydrocarbons and aromatic hydrocarbons increased. The catalyst Ni C2-3, Ni C3-3, Ni C4-3 showed different catalytic efficiencies to different heavy oils. For the crude oil of 80500 m Pa·s, the viscosity reduction ratios were 52.2%, 49%, and 44.8%,respectively; for the crude oil of 26880 m Pa·s, the viscosity reduction ratios were 16.4%, 9.9%, and 8.6%,respectively. But for the crude oil of 168000 m Pa·s, the viscosity reduction ratios were 30.4%, 24.4%, and 23.3%, respectively. By adding tetrahydronaphthalene(hydrogen donor) to the reaction system, the viscosity reduction ratios of the crude oil(168000 m Pa·s) catalyzed by Ni C2-3 has been greatly improved up to 71%.