Speciation Identification And Transformation Of Organic Chlorides In Crude Oil And Its Fractions

The negative effects of chloride corrosion in crude oil have been extended from primary processing units such as atmospheric and vacuum distillation to secondary processing units such as catalytic cracking.The existing forms and removal methods of inorganic chlorides have been basically clear,but the analysis and identification of organic chlorides are relatively few,and the removal methods are basically blank.With the increase of petroleum exploitation,the harm of chloride to processing units and catalysts is becoming more and more serious.It is of great significance to study the identification and transformation of chloride forms in crude oil and its fractions in order to ensure safety in production and improve the utilization rate of petroleum resources.In this paper,Shengli,Zhongjie crude oil and Changqing crude oil,their atmospheric and vacuum residues after desalination were selected to analyze the chlorine content in each fraction,and to explore the distribution and morphological structure of organic chlorine.The chlorine content of Shengli crude oil is higher than that of Changqing crude oil and Zhongjie crude oil.The chlorine content of Shengli crude oil is lower.The organic chloride distribution of Shengli crude oil is spindle-shaped with high middle and low ends.Zhongjie crude oil is dumbbell-shaped with high,middle and low ends.The relatively low chlorine content of Changqing crude oil is mainly concentrated in heavy fractions.The chemical composition of organic chlorides in light fractions of crude oil was directly analyzed by gas chromatography with electron trap(GC-ECD).The organic chlorides in heavy fractions were enriched by solvent extraction,and the chemical composition and morphological structure of organic chlorides were identified by gas chromatography/mass spectrometry(GC/MS).The results showed that both Shengli crude oil and Zhongjie crude oil contained carbon tetrachloride and ethyl trichloride.Low boiling point organic compounds of alkene and tetrachloroethylene.In addition,Shengli crude oil also contains 5-chloro-2-methylaniline,3-chloro-2-methylaniline,2,6-dichloro-3-methylaniline,2-hydroxy-5-ketoacetone and 4-chloro-2-nitrotoluene,of which 5-chloro-2-methylaniline is the highest,but Zhongjie crude oil does not contain chloroaniline.The chlorides identified in Changqing atmospheric residue are complex,mainly including DL-p-chlorophenylalanine,phthalic acid,2-chlorophenyl ethyl ester,methyl chlorophenyl tetrahydroxazine and so on.Thermodynamic analysis of representative organic chlorides shows that chlorobenzene,5-chloro-2-methylaniline,1-(5-chloro-2-hydroxy-phenyl)ethanone and other organic chlorides can be converted during the secondary processing of crude oil,including delayed coking and catalytic cracking,and hydrogenation.Converted small molecular chlorides are more conducive to the diffusion on the catalyst surface and the catalytic bed,and affect the safety of the unit.Full production operation.Increasing temperature and decreasing pressure are conducive to the conversion of organochlorine.