Identification of conjugated diolefins in fossil fuel liquids by 1H n.m.r. two-dimensional correlated spectroscopy

Altbach, María I.; Fitzpatrick, Carol P.

doi:10.1016/0016-2361(94)90117-1

Cited by 12 publications

(3 citation statements)

References 6 publications

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“…The uncertainty in the above assignments due to the overlapping of different categories of signals may be insignificant toward the estimation of H . Signals due to two of the possible 4/5 protons of the conjugated double bond generally appear in the region δ 5.9–6.5 ppm ( O 6 ) and the rest spread over the region 5.0–4.5 ppm overlapped with other olefinic protons . As most of the samples contain low (feeds) or insignificant (products) amounts of diolefins, only integral intensities between 5.9 and 6.5 ppm ( O 6 ) have been considered for the estimation of H .…”

Section: Results and Discussionmentioning

confidence: 99%

Dynamic Approach for the Estimation of Olefins in Cracked Fuel Range Products of Variable Nature and Composition by ¹H NMR Spectroscopy

et al. 2019

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A dynamic 1H NMR-based method for the estimation of olefin content in all cracked fuel range products, in general, and in gasoline/naphtha streams, in particular, irrespective of types and composition of olefins and boiling range of samples has been developed. This is in continuation of our earlier works where two methods were described for the determination of hydrocarbon types in straight-run gasoline (no olefins) and cracked full range gasoline/naphtha (with olefins). The average absolute number of unsaturated hydrogen (H) in the olefinic region (4.4–6.5 ppm) was directly estimated with the help of a 1H NMR spectrum using dynamic variables in terms of differential population of various kinds of olefins. The average alkyl chain length (n) was estimated by various methods including 13C NMR and carbon number distribution by a gas chromatography-based detailed hydrocarbon analyzer [DHA, ASTM D6730-01(2016)] and simulated distillation [ASTM D2887-16a] data. The percentage of unsaturated hydrogen (% UH) in an average olefin was then obtained providing a multiplication factor (f o) by which the weight percentage of olefin is estimated using a normalized 1H NMR spectrum. The dynamic estimation of H and n for each sample removes the possibilities of errors in the estimation. The method has efficiently been extended to coker kero and coker diesel range products where there has been no method available for olefin estimation. The method was validated by using DHA following ASTM D6730, by the Reformulyzer-based ASTM D6839 method, and finally by fluorescent indicator adsorption following ASTM D1319. All the methods were compared. Whereas the proposed NMR method is extremely general, free from manual error, the limitations of existing ASTM methods and the old NMR method vis á vis a new NMR method are also discussed.

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Section: Results and Discussionmentioning

confidence: 99%

Dynamic Approach for the Estimation of Olefins in Cracked Fuel Range Products of Variable Nature and Composition by ¹H NMR Spectroscopy

et al. 2019

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“…There are reported methods based on different analytical techniques like GC-FID, GC-MS, and GC-NCD after derivatization of conjugated diolefins, [3] NMR, [4,5] phosphorescence spectroscopy, [6] UV-visible spectroscopy, [7] polarography, [8,9] near infra-red (NIR), [10] voltametric, [11] electrochemical reduction method, [12] HPLC, [13] and supercritical fluid chromatography (SFC) with photo diode array (PDA) detector [14] to determine the conjugated dienes content in gasolines. A beautiful review on the conjugated dienes estimation is written by Miranda et al [15] Ghazvini et al [13] applied an HPLC-UV based method with chromatographic conditions similar to described in IP 391 method.…”

Section: Introductionmentioning

confidence: 99%

HPLC Method for Monitoring the Conjugated Dienes and Olefins in FCC, Coker Gasolines, and their Hydrogenated Products

Yadav

Kagdiyal

Arun

et al. 2015

Journal of Liquid Chromatography & Related Technologies

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The conjugated dienes if present in gasoline have the tendency to polymerize and cause fouling during various refinery processes. Therefore the conjugated dienes need to be reduced. While the conjugated dienes in gasoline are undesirable, the olefins are desirable and act as octane booster. The selective hydrogenation unit selectively reduces conjugated dienes keeping the content of olefins more or less intact. A method based on HPLC-UV-RI has been reported to simultaneously monitor the conjugated dienes and olefins content in the gasoline range samples. The reported method has the detection level of 0.02 (w/W)% for the total conjugated dienes with respect to 2,4-dimethyl 1,3-pentadiene (DMP). The calibration curve for DMP is drawn in the range 0.2-2.5% (w/W) and the R 2 is found to be 0.9972. The method is also applicable for the estimation of olefins content above 10% (w/W) level with respect to 1-octene. The calibration curve is drawn in the range 10-50% (w/W) of 1-octene and the R 2 is found to be 0.9995.

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“…A small number of alternative methods have been reported in literature to determine the diolefins content in gasolines. Techniques such as NMR [3][4][5] and more recently GC-MS and GC-NCD [6] have been applied for detailed characterization of diolefins in gasolines. These analyses are interesting for comprehensive diolefins analyses but they are not practical for daily quantification and furthermore, the diolefins speciation is not necessary for our application.…”

Section: Introductionmentioning

confidence: 99%

Near Infrared Monitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams

López-García¹,

Biguerd²,

Marchal-George³

et al. 2007

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Prédiction de la teneur en dioléfines conjuguées dans les essences de craquage catalytique par PIR -Les essences issues du craquage catalytique (FCC) contiennent des composés indési-rables tels que les dioléfines conjuguées. Ces composés sont très réactifs à la polymérisation, forment des gommes qui bouchent les unités de la chaîne de raffinage et dégradent la stabilité des essences commerciales. Les dioléfines conjuguées peuvent être hydrogénées en oléfines par un procédé d'hydrogénation sélective (Selective Hydrogenation Unit ou SHU). La teneur en dioléfines conjuguées peut être détermi-née par l'intermédiaire de l'indice d'anhydride maléique (MAV) ou son équivalent "Diene Value" (DV). Ces méthodes sont basées sur l'addition stoechiométrique entre les dioléfines conjuguées et l'anhydride maléique selon la réaction de Diels-Alder. Ces analyses sont toutefois très longues (5 à 7 heures par analyse) et laborieuses pour être pratiquées en routine afin de déterminer les performances du procédé SHU. La spectroscopie Proche Infrarouge (PIR) qui est une technique à la fois rapide et répétable a été utilisée pour modéliser par PLS (Partial Least Squares) la teneur en dioléfines conjuguées selon la méthode MAV. La teneur en dioléfines conjuguées dans ces essences est cependant très faible (< 1 % poids) par rapport aux autres hydrocarbures présents dans l'essence, notamment par rapport aux oléfines (20 à 60 % poids) qui absorbent dans des zones très proches des dioléfines. Au lieu de corréler directement la MAV, la modélisation de la variation de la MAV (Delta_MAV) a été testée dans ce travail. La modélisation du Delta_MAV a été possible pour le procédé SHU car, pour une charge donnée, les principales variations de composition en hydrocarbures sont majoritairement dues aux dioléfines conjuguées. Le Delta_MAV a été modélisé à l'aide de soustraction entre spectres. Le modèle PIR développé est en très bon accord avec la méthode par voie chimique : 98 % des échantillons de la base de calibration sont prédits dans l'intervalle de confiance de reproductibilité de la méthode de référence. Des résultats de validation externe du modèle sont aussi présentés avec le suivi d'unités pilote d'hydrogénation sélective des essences FCC. Abstract -Near Infrared Monitoring of Low Conjugated Diolefins Content in Hydrotreated FCC

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Identification of conjugated diolefins in fossil fuel liquids by 1H n.m.r. two-dimensional correlated spectroscopy

Cited by 12 publications

References 6 publications

Dynamic Approach for the Estimation of Olefins in Cracked Fuel Range Products of Variable Nature and Composition by ¹H NMR Spectroscopy

Dynamic Approach for the Estimation of Olefins in Cracked Fuel Range Products of Variable Nature and Composition by ¹H NMR Spectroscopy

HPLC Method for Monitoring the Conjugated Dienes and Olefins in FCC, Coker Gasolines, and their Hydrogenated Products

Near Infrared Monitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams

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Identification of conjugated diolefins in fossil fuel liquids by 1H n.m.r. two-dimensional correlated spectroscopy

Cited by 12 publications

References 6 publications

Dynamic Approach for the Estimation of Olefins in Cracked Fuel Range Products of Variable Nature and Composition by 1H NMR Spectroscopy

Dynamic Approach for the Estimation of Olefins in Cracked Fuel Range Products of Variable Nature and Composition by 1H NMR Spectroscopy

HPLC Method for Monitoring the Conjugated Dienes and Olefins in FCC, Coker Gasolines, and their Hydrogenated Products

Near Infrared Monitoring of Low Conjugated Diolefins Content in Hydrotreated FCC Gasoline Streams

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Dynamic Approach for the Estimation of Olefins in Cracked Fuel Range Products of Variable Nature and Composition by ¹H NMR Spectroscopy

Dynamic Approach for the Estimation of Olefins in Cracked Fuel Range Products of Variable Nature and Composition by ¹H NMR Spectroscopy