The Research On Organic Chlorides Removal From Distillates Of Crude Oil

In the past few years,some safety and quality accidents have happened during the crude oil processing in some refineries due to the high concentration organic chlorides in crude oil and its distillates,which hinders normal production of refining enterprises.Organic chlorides in crude oil and its distillates would cause serious corrosion of equipments and pipelines,form ammonium chloride?NH₄Cl?and then block pipeline,which leads to the equipment could not operate smoothly.Therefore,it is necessary to control the concentration of organic chloride in crude oil and/or its distillates,and its premise is the investigation of the distribution and occurrence states of organic chloride in crude oil and/or its distillates.The distribution of chlorine element in Shengli?SL?and Zhongjie?ZJ?crude oil had been identified by using microcoulomb tetrameter and salt content determinator.The species and contents of organic chlorides in light distillates?bp<300??were determined by gas chromatography equipped with an electron capture detector?GC-ECD?.The content of organic chlorine in SL crude oil was as high as 188.68 mg/L,indicating an extra high content of chlorine in crude oil.Carbon tetrachloride,trichloroethylene,tetrachloroethylene,1,2,3-trichloropropene,3-chloro-2-methylaniline,5-chloro-2-methylaniline,and 2,6-dichloro-3-methylaniline were mainly existed in the three types of light distillates of SL crude oil.The content of organic chlorine in ZJ crude oil was 6.33 mg/L,trichloromethane,carbon tetrachloride,trichloroethylene,tetrachloroethylene,1,1,2,2-tetrachloroethane,1,1,1,3-tetrachloropropane,and1,2,4-trichlorobenzene were all identified from three kinds of light distillates of ZJ crude oil.The molecular diameter of sixteen kinds of organic chlorides identified from oil were less than 0.7 nm,which were calculated by using Materials Studio software.Na-LSX zeolite exhibited superior dechlorinate performance than other adsorbents in the batch experiments.Suitable modifying conditions for Y,X,and LSX types of zeolite by using Cu²⁺,Co²⁺,La³⁺,and Ce³⁺ions were that exchange temperature was25?,concentration of ion-exchange solution was 0.05 mol/L,solid to liquid ratio was0.01 g/mL,and exchange time was 36 h.Dechlorinate performance and regenerability of La-Y zeolite was better than Cu²⁺,Co²⁺,and Ce³⁺ions modified Y zeolite.XRD,SEM,BET,TG-DSC,and Py-IR were used to characterize the properties and structures of Na-LSX and La-Y zeolite.The Langmuir isotherm model could be better to describe the adsorption equilibrium of 5-chloro-2-methylaniline onto the Na-LSX and La-Y zeolite.In addition,the pseudo-second-order adsorption kinetic model was suitable to describe the adsorption process of 5-chloro-2-methylaniline onto the Na-LSX and La-Y zeolite.Meanwhile,the intra-particle diffusion model was used to insight the mechanism of adsorption process,indicated the intra-particle diffusion was not the unique rate-determining step for the whole adsorption process,which meant that intra-particle diffusion,external diffusion,and organic chloride adsorption onto inner surface of adsorbent all had impact on adsorption process.At the temperature range of303.15³33.15 K,the enthalpy change of 5-chloro-2-methylaniline adsorption onto Na-LSX and La-Y zeolite were 24.025 and 25.205 kJ/mol,respectively,and the mean?G⁰ was calculated all as negative value.Adsorption activation energy of5-chloro-2-methylaniline adsorption onto Na-LSX and La-Y zeolite were 22.10 and15.68 kJ/mol,respectively,which were calculated by Arrhenius equation.Therefore,adsorption type of 5-chloro-2-methylaniline onto Na-LSX and La-Y zeolite could be mainly catalogued into physical adsorption,and chemisorption might be also involved.The effects of adsorption temperature,initial organochlorine content,and weight hour space velocity?WHSV?on removing organic chlorides from oil by Na-LSX and La-Y zeolite were investigated in a fix-bed adsorber.Breakthrough time and breakthrough capacity of Na-LSX zeolite were 11 h and 19.39 mg/g,respectively,and for La-Y zeolite,they were 32 h and 54.45 mg/g under following conditions,i.e.,the initial concentration was 133.71 mg/L,WHSV was 9.9 h^-1,and adsorption temperature was 323.15 K.And it was proved that La-Y zeolite adsorbent had a better regenerability.Pyridine-IR demonstrated that Br?nsted acid contributed to increasing the dechlorination capacity,while excessive Lewis acidic sites had an adverse effect on the dechlorination performance.Competition adsorption had great influence on removing organic chlorides from kerosene.