Study On Removal Of Nickel And Vanadium By Complexation In Crude Oil

Most of the crude oils contains more than 40 kinds of metal,although the content is not high,the metal is harm to oil processing and deep use,especially nickel and vanadium,which may cause pollution to the catalytic cracking catalyst,also they can cause catalyst deactivation in the process of hydrocracking and reactor bed clogging.Nickel and vanadium in crude oils exist in the form of porphyrin compounds,their structures are complex and stable,so they are not easy to remove.In this paper,chelatinge separation method was used to study the removal of metallic nickel and vanadium in crude oils and discuss the process conditions.Chelating separation method uses appropriate reagents to remove nickel and vanadium.In this paper,the equeous solution of chelating reagents was used to be mixed with crude oils to remove the metals in the oils by chelating the metals in the water.According to the ideal metal reagent selection criteria,twenty-four reagents were selected as reagents for removal of nickel and vanadium,including inorganic acids,inorganic acid salts,organic acids,polyacids,amines and other compounds,to examine their demetalization effect under the same experimental conditions.E-1,nitric acid,ammonium dihydrogen phosphate showed better effects,and their optimum process conditions were investigated,respectively,including reaction temperature,reagent concentration,reaction time and reagent oil ratio.The results show that it is beneficial to remove the nickel and vanadium by increasing the reaction temperature,increasing the reagent concentration,prolonging the reaction time and improving the agent oil ratio.Among the reagents,the nickel removal rate of the E-1 can reach 63.33%,and the vanadium removal rate is up to 85.14%.Because the thermal stability of nickel porphyrin and vanadium porphyrin is strong,it is needed to use high reaction temperature to improve the metal removal rate.Selecting fivechelating agents such as E-1 and N-1 as the demetalization reagent to further increase the reaction temperature,to investigate the effect of temperature on the removal rate of nickel and vanadium.The experiments were finished in an autoclave.The results show that most of the reagents exhibit better demetalization effects at high temperatures.For example,the nickel removal rate of N-1 increased from 32.91% to 62.22%,the vanadium removal rate of E-2 rose from 26.62% to 48.35%.But the demetalization reaction is a dynamic equilibrium process,when the temperature is above 160oC,the metal removal rate increased very slowly.In the period of chelation of Ni and V,the calcium is also removed by about more than50%.