Preparation Of Modified Zeolites Adsorbents And Their Dechlorination Performance

As one of the important pillars of national economic life,the consumption of oil continues to rise with the rapid development of China’s economy.At the same time,the quality of crude oil is decreasing,and to increase oil recovery,viscosity reducers,corrosion inhibitors,wax scavengers,and other chloride-containing oil recovery aids are added,resulting in the content of chlorides in petroleum products seriously exceeding the standard.The inorganic chlorides are removed by the electric desalination and dehydration process,but the residual organic chlorides react with hydrogen to form HCl during the catalytic process,aggravating the corrosion of pipelines and equipment,causing catalyst poisoning,blocking pipelines and jeopardizing the normal operation of equipment.Therefore,it is of great practical importance to carry out research on the removal technology of organic chlorides from crude oil and effectively control the content of organic chlorides in crude oil.In this paper,the zeolites were modified by bimetallic treatment to improve the dechlorination effect.The specific research content is as follows:1.Six adsorbents were screened and compared in terms of their dechlorination effect through the principle of shape selection.The effect of three modification methods（constant volume impregnation,excess impregnation and ion exchange method）and different bimetals were investigated by modifying the Na-Y zeolites with the better dechlorination effect,and then the solution concentration of the bimetals and the molar ratio of the bimetals were investigated,and the best dechlorination effect of the Ce-Zn modified Na-Y zeolites adsorbent were found at a solution concentration of 0.1 mol/L,and a bimetallic molar ratio of 1:1.Finally,the effects of different metal ions on the pore structure and acid properties of the Na-Y zeolites were analyzed by XRD,SEM,N₂adsorption and desorption,and NH₃-TPD.2.The ion exchange method was used to modify the 13X zeolites,and the effect of different bimetals on the removal of organic chlorides from the model oil was investigated.It was found that the Zn-Cu/13X adsorbent had the best adsorption effect on organic chlorides,and the best preparation process conditions were as follows:the solution concentration was 0.05 mol/L,the molar ratio of bimetals was 1:0.5,the roasting temperature was 450℃,the roasting time was 4 h,and the dechlorination rate reached 94%.In addition,the regeneration of the adsorbent was also investigated and it was found that the dechlorination performance of the modified adsorbent was still stable up to 80%after three cycles of use.Finally,the changes in pore structure and acid properties were analyzed by XRD,SEM,N₂ adsorption and desorption,and NH₃-TPD characterization of the 13X zeolites adsorbent before and after modification.3.By examining the factors influencing the adsorption process of 1,2-dichloroethane from model oil with Zn-Cu/13X modified adsorbent（adsorption temperature,adsorption time,agent-oil ratio,different initial chlorine content）,at the adsorption temperature of333.15 K,the adsorption equilibrium of organic chlorides in the model oil could be achieved within 6 h.The suitable agent-oil ratio of 1 g:40 m L was determined.The adsorption process of 1,2-dichloroethane by Zn-Cu/13X was fitted separately,and it was found that the Langmuir adsorption isotherm could better describe the adsorption process;finally,by fitting a kinetic model to the adsorption process of Zn-Cu/13X adsorbent,it was found that the proposed secondary kinetic adsorption model was a better fit,which was calculated according to the Arrhenius equation Ea=10.59 k J/mol,indicating that the adsorption process is dominated by physical adsorption and partly involves chemical adsorption.