Systematic approach to the study of aromatic hydrocarbons in heavy distillates and residues by elution adsorption chromatography

Jewell, D.M.; Ruberto, Raffaele G.; Davis, B. E.

doi:10.1021/ac60322a016

Cited by 34 publications

(10 citation statements)

References 5 publications

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“…The Middle Eastern heavy oil was supplied by General Electric Global Research (Niskayuna, NY), and distillation was performed in a still pot as previously reported . Distillation cuts from South American extra heavy crude (482−533 °C), Middle Eastern heavy crude (510−538, 538−593, and residue 593 + °C) Mackay bitumen (550−600, 600−650, 650−700, and 700 + °C), were fractionated into n -C 7 asphaltenes and C 5–6 asphaltenes as noted below. ,,, High-performance liquid chromatography-grade n -heptane ( n -C 7 ), n -pentane ( n -C 5 ), and toluene (J.T. Baker Chemicals, Phillipsburg, NJ, U.S.A.) and Whatman #2 filter paper (30 μm, 150 mm diameter, GE Healthcare Bio-Sciences, Pittsburgh, PA, U.S.A.) were used as received.…”

Section: Experimental Methodsmentioning

confidence: 99%

Molecular-Level Characterization of Asphaltenes Isolated from Distillation Cuts

et al. 2019

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Asphaltenes challenge nearly all analytical techniques because of their immense polydispersity in molecular composition and structure. This operationally defined fraction of crude oil, insoluble in n-alkanes but soluble in aromatic solvents, is known to concentrate in vacuum residues and islinked to fouling and deposition issues. However, presence and subsequent characterization of asphaltenes are seldom discussed in conventional/unconventional distillate fractions. Here, we isolate asphaltenes from conventional (<593 °C/1099 F) and unconventional (>593 °C) distillation cuts and provide molecular-level characterization by electrospray ionization and atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry as a function of boiling point. Our results indicate that asphaltene molecular composition starts in the vacuum gas oil range and extends into vacuum residues. Moreover, we report that distillable asphaltene composition exists as both highly polar (heteroatom rich), aliphatic (atypical asphaltenes) species as well as condensed aromatic structures (classical asphaltenes). As a function of distillation temperature, asphaltene compounds exhibit structural trends consistent with thermal cracking that starts between 510 and 538 °C, increases between 538 and 593 °C, and is readily observed at temperatures up to 700 °C. Above 600 °C, low molecular weight compounds (expected to boil at much lower temperatures) that are n-heptane insoluble are detected across all heteroatom classes. Results herein suggest that these compounds are formed through structural rearrangement of archipelago asphaltenes because of thermal cracking reactions that occur during distillation and precipitate as asphaltenes. We report the isolation and mass spectral characterization of asphaltenes isolated from distillation cuts and propose that quantification of asphaltenes in distillates is critical to predict and prevent problems related to catalyst deactivation.

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Section: Experimental Methodsmentioning

confidence: 99%

Molecular-Level Characterization of Asphaltenes Isolated from Distillation Cuts

et al. 2019

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“…Products from the reactions were analyzed using a combination of the following: (1) GLC using a 100-ft SCOT capillary column, (2) preparative liquid chromatography using basic alumina (Jewell et al, 1972), (3) preparative HPLC using a 10 mm X 50 cm column packed with Lichrosorb (silica) and the solvent n-hexane, at a flow rate of 9.0 mL/min, (4) 13C NMR using a Varian CFT-20 instrument, and ( 5 ) GLC-mass spectra using a Du Pont 491 instrument. Products from the reactions were analyzed using a combination of the following: (1) GLC using a 100-ft SCOT capillary column, (2) preparative liquid chromatography using basic alumina (Jewell et al, 1972), (3) preparative HPLC using a 10 mm X 50 cm column packed with Lichrosorb (silica) and the solvent n-hexane, at a flow rate of 9.0 mL/min, (4) 13C NMR using a Varian CFT-20 instrument, and ( 5 ) GLC-mass spectra using a Du Pont 491 instrument.…”

Section: Methodsmentioning

confidence: 99%

“…Specifically labeled 13C-octahydrophenanthrene was synthesized by Dr. E. J. Eisenbraun, details of which will be described elsewhere. Products from the reactions were analyzed using a combination of the following: (1) GLC using a 100-ft SCOT capillary column, (2) preparative liquid chromatography using basic alumina (Jewell et al, 1972), (3) preparative HPLC using a 10 mm X 50 cm column packed with Lichrosorb (silica) and the solvent n-hexane, at a flow rate of 9.0 mL/min, (4) 13C NMR using a Varían and (5) GLC-mass spectra using a Du Pont 491 instrument.…”

Section: Methodsmentioning

confidence: 99%

Isomerization and Adduction of Hydrogen Donor Solvents under Conditions of Coal Liquefaction

Cronauer¹,

Jewell²,

Shah³

et al. 1979

Ind. Eng. Chem. Fund.

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Hydroaromatic structures are recognized as "ideal" for liquefying coal due to their ability to readily transfer hydrogen to free radical acceptors. While hydroaromatic hydrogens are preferred, substituted aromatic solvents can compete although the latter are more likely to polymerize or adduct with the acceptors. Hydroaromatic structures rearrange to isomeric forms of enhanced stability which are less likely to transfer hydrogen. Six-membered hydroaromatics such as tetralins and octahydrophenanthrenes contract to fivemembered rings (methylindans, etc.). This isomerization is dependent upon temperature, reactor residence time, and, in particular, the level of acceptor radicals. At relatively low temperatures (300-425 OC), the isomerization process is preceded by the adduction of the original hydroaromatic donor with very stable acceptor molecules. This adduction appears to increase with high organic oxygen and sulfur structures. While rearrangements of the above type have been qualitatively known for several years, the present study has attempted to delineate both the kinetic and structural aspects involved.Periodic or semibatch operation of a continuous stirred reactor produces levels of mixing on the macroscale which are intermediate to the limits of plug flow and stirred tank operation and which can be selected and controlled to any desired level. Such a scheme is an operational alternative to the tanks-in-series or plug flow with recycle system, and provides a means of experimentally producing a desired mixing level or of increasing the yield of desired intermediates in complex reaction schemes. In this work criteria for obtaining desired mixing levels are presented, the resulting degree of segregation, J, is derived, and the influence of segregation or conversion for a second-order reaction is presented. Comparisons to the more familiar tanks-in-series and recycle-plug-flow models are included.

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“…When aromatics from high sulfur vacuum residuals are separated on zero per cent water-alumina by the method of Jewell, et al (1972a), one observes that: (1) only traces of sulfur-free monoaromatics are present; (2) most of the aromatic structures have two or three rings; and (3) the sulfur is concentrated in the di + triaromatic fractions. The cut-points in these aromatic separations are made by on-line UAD at 254, 313, and 365-nm wavelengths.…”

Section: Discussion Of Resultsmentioning

confidence: 99%