Catalytic Effect of Transition Metallic Additives on the Light Oil Low-Temperature Oxidation Reaction

Abstract

Increasing the reaction rate between crude oil and oxygen (oxygen consumption rate) is an effective method for improving the safety of air flooding. The catalytic effect of the transition metallic additives copper chloride, manganese acetate, cobalt chloride, and nickel chloride on the light oil low-temperature oxidation (LTO) was determined through static oxidation experiments. Additionally, the influence of temperature, pressure, and reaction time on the catalytic effect of the additives was investigated. The changes of the oil characteristics due to low-temperature oxidation (LTO) and catalytic low-temperature oxidation (CLTO) were investigated through SARA composition tests, elements analysis, n-alkanes components analysis, and infrared spectrum analysis. In addition, the influence of additives on the kinetic parameters of LTO was also researched. The results showed that the transition metallic additives significantly improved the oxygen consumption rate of light oil LTO, notably the copper chloride. For three oils from different reservoirs, the oxygen consumption rates increased to above 2.2 times the original after the addition of copper chloride at 70 °C and 16 MPa. Besides, the synergistic effect between reaction temperature and catalyst was significant in promoting oxygen consumption. When the reaction temperature reached 130 °C, the oxygen content after reaction reduced to 2.67% from 9.18% after the addition of copper chloride. The oxygen in air reacted with saturate and aromatics, generating resin and asphaltene. The distribution of n-alkanes was shifted to higher molecular weight components during LTO, and the addition of catalyst could enhance the changing trend. In addition, new oxygen-containing groups were generated during LTO and CLTO. The order of the oxygen partial pressure and the activation energy of LTO were all reduced due to the addition of catalyst. This study can provide guidelines to improve the safety and application of air flooding technology.