Variation in Composition of Subfractions of Petroleum Asphaltenes

Andersen, Simon Ivar; Keul, A; Stenby, Erling Halfdan

doi:10.1080/10916469708949678

Cited by 70 publications

(76 citation statements)

References 23 publications

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“…The temperature of mixing is important. Higher temperatures result in significantly lower asphaltene yields than lower temperatures (Andersen et al 1997). Apparent molecular weights of asphaltenes are a function of measurement conditions such as temperature, solvent, and concentration.…”

Section: Asphaltenesmentioning

confidence: 99%

Residua Upgrading Efficiency Improvement Models: Wri Coking Indexes

Schabron¹,

Rovani²,

Miknis³

et al. 2003

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Pyrolysis experiments were conducted with three residua at 400 °C (752 °F) at various residence times. The wt % coke and gaseous products were measured for the product oils. The Western Research Institute (WRI) Coking Indexes were determined for the product oils. Measurements were made using techniques that might correlate with the Coking Indexes. These included spin-echo proton nuclear magnetic resonance spectroscopy, heat capacity measurements at 280 °C (536 °F), and ultrasonic attenuation.The two immiscible liquid phases that form once coke formation begins were isolated and characterized for a Boscan residuum pyrolyzed at 400 °C (752 °F) for 55 minutes. These materials were analyzed for elemental composition (CHNS), porphyrins, and metals (Ni,V) content.iv

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Section: Asphaltenesmentioning

confidence: 99%

Residua Upgrading Efficiency Improvement Models: Wri Coking Indexes

Schabron¹,

Rovani²,

Miknis³

et al. 2003

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“…The asphaltenes used in this study were n-heptane (nC 7 ) insoluble fractions of a Safaniya vacuum residue. The main properties of the Safaniya VR are summarized in Table 1.…”

Section: Sample Preparationmentioning

confidence: 99%

“…Asphaltenes are the most polar fraction of crude oil that precipitates in the presence of a high excess of a normal alkane (nC 5 , nC 6 or nC 7 ) but are soluble in toluene [1]. The remaining fraction is called maltene.…”

Section: Introductionmentioning

confidence: 99%

“…The first one was the flocculation method, based on the use of a mixture of a good solvent (toluene) and an anti-solvent (normal light paraffins, acetone, methanol), in different proportions [6][7][8][9]. In this work, we succeeded in preparing two different asphaltene fractions, the first one characterized by a low solubility (fraction with a high tendency to association) and the second one by a high solubility (fraction with a low tendency to association).…”

Section: Introductionmentioning

confidence: 99%

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Asphaltenes Size Polydispersity Reduction by Nano- and Ultrafiltration Separation Methods – Comparison with the Flocculation Method

Marques

Merdrignac

Baudot

et al. 2008

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Séparation des asphaltènes par nano et ultrafiltration -Comparaison avec la méthode de floculation -Les asphaltènes contiennent une multitude de composés très polydisperses en terme de composition chimique et en terme de taille, ce qui rend leurs propriétés et leur comportement difficiles à décrire. Afin de mieux caractériser ces espèces, une voie envisagée est de réduire cette polydispersité. Dans cette étude, nous avons proposé deux approches différentes : la floculation (en faisant appel à des solvants et anti-solvants) et la filtration membranaire. Les différentes fractions d'asphaltènes obtenues par chaque méthode sont caractérisées en utilisant les techniques suivantes : la chromatographie d'exclusion stérique (SEC), l'analyse élémentaire, la résonance magnétique nucléaire (RMN-13 C) et la diffusion des rayons X aux petits angles (SAXS). Il a été montré que des agrégats asphalténiques de différentes tailles peuvent être séparés par la filtration membranaire d'une façon plus sélective qu'en utilisant la méthode conventionnelle de floculation. Comparés aux grands agrégats, les petits agrégats asphalténiques présen-tent une aromaticité plus faible et un caractère aliphatique plus élevé. Leurs chaînes alkyles semblent être également plus courtes et plus ramifiées. De plus, l'analyse élémentaire indique que les plus petits asphaltènes contiennent une concentration inférieure en métaux et sont préférentiellement enrichis en vanadium plutôt qu'en nickel. Les effets de la température et de la concentration sur la performance de la séparation membranaire sont étudiés. Abstract

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“…Other factors that affect the weight percent asphaltene value include heating the hydrocarbon and residuum mixture and the manner in which the solvent is removed from the filtered solids. Heptane asphaltene values that were obtained by dispersing a 30:1 (v:w) heptane residuum mixture varied from 20.2 wt % at 24 EC (75.2 EF) to 16.6 wt % at 50 EC (122 EF) and 14.7 wt % at 80 EC (176 EF) (Andersen et al 1997). The precipitate was dried with air flow under a vacuum.…”

Section: Asphaltene Determinationmentioning

confidence: 99%

Residua Upgrading Efficiency Improvement Models: Coke Formation Predictability Maps

Schabron¹,

Pauli²,

Rovani³

2002

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The dispersed particle solution model of petroleum residua structure was used to develop predictors for pyrolytic coke formation. Coking Indexes were developed in prior years that measure how near a pyrolysis system is to coke formation during the coke formation induction period. These have been demonstrated to be universally applicable for residua regardless of the source of the material. Coking onset is coincidental with the destruction of the ordered structure and the formation of a multiphase system. The amount of coke initially formed appears to be a function of the free solvent volume of the original residua. In the current work, three-dimensional coke make predictability maps were developed at 400 EC, 450 C, " and 500 EC (752 EF, 842 EF, and 932 EF). These relate residence time and free solvent volume to the amount of coke formed at a particular pyrolysis temperature. Activation energies for two apparent types of zero-order coke formation reactions were estimated. The results provide a new tool for ranking residua, gauging proximity to coke formation, and predicting initial coke make tendencies.iv

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Variation in Composition of Subfractions of Petroleum Asphaltenes

Cited by 70 publications

References 23 publications

Residua Upgrading Efficiency Improvement Models: Wri Coking Indexes

Residua Upgrading Efficiency Improvement Models: Wri Coking Indexes

Asphaltenes Size Polydispersity Reduction by Nano- and Ultrafiltration Separation Methods – Comparison with the Flocculation Method

Residua Upgrading Efficiency Improvement Models: Coke Formation Predictability Maps

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