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A Method to Quantitatively Analyze Conjugated (19) TZZ_ _T (11) EP 1 552 289 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention (51) Int Cl.: of the grant of the patent: G01N 33/28 (2006.01) 28.10.2015 Bulletin 2015/44 (86) International application number: (21) Application number: 03766848.0 PCT/US2003/021458 (22) Date of filing: 08.07.2003 (87) International publication number: WO 2004/013601 (12.02.2004 Gazette 2004/07) (54) A METHOD TO QUANTITATIVELY ANALYZE CONJUGATED DIENES IN HYDROCARBON FEEDS AND PRODUCTS AS AN INDICATOR OF FOULING POTENTIAL VERFAHREN ZUR QUANTITATIVEN ANALYSE KONJUGIERTER DIENE IN KOHLENWASSERSTOFFEDUKTEN UND -PRODUKTEN ALS INDIKATOR DES FOULING- POTENZIALS PROCEDE D’ANALYSE QUANTITATIVE DE DIENES CONJUGUES DANS DES PRODUITS ET DES CHARGES D’HYDROCARBURE EN TANT QU’INDICATEUR DE LA CAPACITE D’ENCRASSEMENT (84) Designated Contracting States: • DOBSON GARY: "Identification of conjugated BE FR GB IT NL fatty acids by gas chromatography-mass spectrometry of 4-methyl-1,2,4-triazoline-3,5- (30) Priority: 06.08.2002 US 401377 P dione adducts", JAOCS, JOURNAL OF THE 10.06.2003 US 458456 AMERICAN OIL CHEMISTS’ SOCIETY 1998 FEB AMERICAN OIL CHEMISTS’ SOC, vol. 75, no. 2, (43) Date of publication of application: February 1998 (1998-02), pages 137-142, 13.07.2005 Bulletin 2005/28 XP002616516, • YOUNG D C ET AL: "Gas chromatography- mass (73) Proprietor: ExxonMobil Research and spectrometry of conjugated dienes by Engineering Company derivatization with 4-methyl-1,2,4-triazoline-3,5- Annandale, NJ 08801-0900 (US) dione", JOURNAL OF CHROMATOGRAPHY, ELSEVIER SCIENCE PUBLISHERS B.V, NL, vol. (72) Inventors: 522, 28 November 1990 (1990-11-28), pages • QIAN, Kuangnan 295-302, XP026487686, ISSN: 0021-9673, DOI: Belle Mead, NJ 08502 (US) DOI:10.1016/0021-9673(90)85199-6 [retrieved on • EDWARDS, Kathleen, E. 1990-11-28] Freehold, NJ 07728 (US) • CHAWLA BIRBAL: "Speciation of Nitrogen • WANG, Frank, C. Compounds in Gasoline and Diesel Range Annandale, NJ 08801 (US) Process Streams by Capillary Column Gas • SISKIN, Michael Chromatography with Chemiluminescence Randolph, NJ 07869 (US) Detection", JOURNAL OF CHROMATOGRAPHIC SCIENCE, PRESTON PUBLICATIONS, NILES, IL, (74) Representative: Mareschal, Anne et al US, vol. 35, no. 3, 1 March 1997 (1997-03-01), ExxonMobil Chemical Europe Inc. pages 97-104, XP009086208, ISSN: 0021-9665 IP Law Europe • CHRISTIE W.W.: ’Mass spectra of methyl esters Hermeslaan 2 of fatty acids - further derivatization’, [Online] 09 1831 Machelen (BE) May 2000, pages 1 - 7, XP002976950 Retrieved from the Internet: <URL:http://www.lipid.co.uk/ (56) References cited: infores/ms/ms04 /file.pdf> Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 552 289 B1 Printed by Jouve, 75001 PARIS (FR) 1 EP 1 552 289 B1 2 Description tography-mass spectrometry of conjugated dienes by derivatization with 4-methyl-1,2,4-triazoline-3,5-dione" BACKGROUND OF THE INVENTION J. of Chromatography Vol 522, 1990, 295-302 discloses thederivatization with MTAD andGC-MS analysisof con- [0001] The present invention is related to a method to 5 jugated dienes, which are described as important in cer- quantify conjugated dienes in hydrocarbon feedstream tain insects as pheromones. and product. In particular, the method determines the molar concentration and/or the carbon number distribu- SUMMARY OF THE INVENTION tion of the conjugated dienes. [0002] Conjugated dienes are a major class of com- 10 [0007] The present invention is a method that detects, pounds in hydrocarbon systems that are responsible for identifies and quantifies conjugated dienes in various hy- deposit formation in refinery conversion units such as drocarbon matrices, such as steam cracked naphtha, hydrocracking and hydroconversion conversion units catalytic cracked naphtha, coker naphthas, and other pe- and fractionators and heat exchangers. They are also troleum distillates. Conjugated dienes are largely respon- responsible for deposit formation in automobile engines. 15 sible for molecular weight growth reactions (fouling) in The information is critical for assessing the potential of various refinery processes. forming deposits in a hydrocarbon system. Knowledge [0008] The invention described herein is based on se- of the concentration and types of conjugated dienes pro- lective and rapid room temperature derivatization of con- vides guidance to the refinery on the necessity of pre- jugated dienes by 4-methyl-1, 2, 4-triazoline-3, 5-dione 20 treating the refinery feed, such as installing a diolefin sat- (MTAD) followed by NO3 Chemical ionization GC/MS urator prior to processing in order to prevent fouling dur- and GC/NCD analyses. The method is highly selective ing processing. In fuel applications, the information may and sensitive to linear, branched and cyclic conjugated be used to determine, e.g. if and how much a naphtha dienes with no interference from other hydrocarbon com- can be blended into fuel or if the naphtha needs to be ponents. The invention has been successfully applied to hydrotreated, etc. 25 the determination of the types and concentrations of con- [0003] There are no reliable established methods to jugated dienes in steam cracked and catalytic cracked identify and quantify conjugated dienes, acyclic and cy- naphthas. clic, in hydrocarbon systems. GC/FID can be used to quantify small conjugated dienes (Less than C6) in low BRIEF DESCRIPTION OF THE DRAWINGS boiling hydrocarbon systems. The identifications were 30 made based on retention times and mass spectral library [0009] matches. The method cannot identify/quantify large con- jugated dienes (Greater than C 6) due to the low concen- Figure 1 shows a GC/MS chromatogram of steam trations of the analytes, severe overlaps with other hy- cracked naphtha (SCN) plus cycloheptadiene inter- drocarbon components and very similar mass spectra 35 nal standard before and after MTAD derivatization. between conjugated and non-conjugated dienes. [0004] Bromination has been widely used to determine Figure 2 shows a GC/MS spectra (electron impact) olefin content (including conjugated dienes) in hydrocar- of MTAD adducts of 2, 4-heptadiene, 2, 4-hexadiene bons. It can not differentiate conjugated dienes from oth- and 1, 3-pentadiene. er olefins. Aromatics, especially phenols, can interfere 40 with the analysis. Figure 3 shows the conjugated diene distributions in [0005] The MAV test is a semiquantitative method de- two steam cracked naphthas (SCN). veloped by UOP and uses maleic anhydride as a deriva- tization agent. The reaction is not selective and cannot Figure 4 shows the conjugated diene distributions in proceed quantitatively. Therefore, only a relative number 45 three heavy catalytic naphthas (HCN). can be obtained. In addition, it cannot provide molecular identifications of different conjugated diene types re- Figure 5 shows a schematic of the reaction of MTAD quired for refinery guidance. with a linear and cyclic conjugated diene. [0006] G. Dobson "Identification of Conjugated Fatty Acids by Gas Chromatography-Mass Spectrometry of 4- 50 DETAILED DESCRIPTION OF THE PREFERRED EM- Methyl-1,2,4-triazoline-3,5-dione Adducts" Journal of the BODIMENT American Oil Chemist’s Society, Vol 75(2), 1998, 137-142 and W.W.Christie, "Mass spectra of methyl es- [0010] The present invention is a method that can de- ters of fatty acids - further derivatization", www.lip- tect, identify and quantify trace levels of conjugated id.co.uk/infores/ms/ms04/file.pdf, pages 1 to 7, each re- 55 dienes in fuel, petroleum feeds and products. These con- late to the analysis of conjugated fatty acids by derivati- jugated structures are largely responsible for the molec- zation with 4-methyl-1,2,4-triazoline-3,5-dione (MTAD). ular weight growth reactions (fouling) in refinery units and D.C. Young, P. Vouros and M.F. Holick, "Gas chroma- deposit formation in automobile engines. Complete iden- 2 3 EP 1 552 289 B1 4 tification/quantification of the conjugated dienes types sion is reached when the molar concentration of MTAD are needed for fouling prevention and management. The to the conjugated diene is between 2 to 10. When the method includes the following: (1) Selective and quanti- ratio is below 2, MTAD reaction is incomplete. When the tative chemical derivatization of conjugated dienes by 4- ratio is greater than 10, self-polymerization of MTAD be- methyl-1, 2, 4-triazoline-3, 5-dione (MTAD); (2) selective 5 comes predominant and results in the reduction of and quantitative determination of MTAD-diene adducts MTAD-conjugated diene adducts. as a function of carbon number by NO3 Chemical Ioni- [0016] The excess MTAD loading becomes a greater zation (Gas Chromatagraph/Mass Spectrometry (CI problem for real sample analyses. It causes formation of GC/MS); and (3) the determination of total conjugated MTAD derivatives that are not due to conjugated dienes. dienes by GC with a nitrogen selective detector, such as 10 It is concluded that the optimum MTAD: conjugated diene Gas Chromatagraph/Nitrogen Chemiluminescence De- ratio is between 2 and 3.5 for quantitative analyses. tector (GC/NCD). Relative Sensitivities General Procedure 15 [0017] We initially evaluated the relative sensitivity of [0011] MTAD stock solution was prepared by dissolv- 12 model compounds of conjugated dienes by GC/NCD, ing 250 mg of MTAD in 5 ml of methylene chloride. The GC/FID and EI-GC/MS. GC/NCD gives quite uniform re- stock solution was directly mixed with hydrocarbon sam- sponses. The molecular ion intensities of EI-GC/MS, ples at room temperature to derivatize the conjugated however, vary significantly. Since CI is a soft ionization structures.
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