Kenneth A. Gould

Oxidative demetallization of petroleum asphaltenes and residua

Abstract Cold Lake asphaltenes, Arabian Heavy asphaltenes, and Cold Lake vacuum residuum were treated with a variety of oxidizing agents. Of these, reagents such as air/100 °C and NaOH/air were found to have no appreciable demetallization activity while oxidants such as sodium hypochlorite and peroxyacetic acid exhibited high demetallization activity coupled with the ability to remove or destroy petroporphyrins. The sodium hypochlorite, however, was found to suffer from the disadvantage of causing chlorine incorporation into the feed. This oxidative demetallization appears to be a rather unselective reaction with both metals and porphyrin removal being proportional to the amount of oxidant used. Various peroxy acids were found to be effective.

Chemical depolymerization of petroleum asphaltenes

Abstract The acid-catalysed phenol depolymerization of three petroleum asphaltenes has been investigated. Asphaltenes from Cold Lake, Arabian Heavy, and Tia Juana Medium residua were subjected to depolymerization conditions using phenol and para -toluenesulphonic acid, and the products were examined by a variety of instrumental and chemical methods. The treatment resulted in reduced average molecular weights, increased oxygen contents, formation of toluene-insoluble fractions, increased aromatic to aliphatic hydrogen ratios, and increased hydroxyl contents. These observations, when coupled with the finding that silylation resolubilized the toluene-insoluble material, have led to the conclusion that insolubility resulted from phenol incorporation into the asphaltene structure and a concomitant increase in polarity and hydrogen bonding. Since it has been shown in the literature that this treatment can depolymerize coal by breaking the alkyl-aromatic bonds which link aromatic units, the present observations are consistent with the presence in petroleum asphaltenes of condensedring systems linked by alkyl bridges. An additional implication is that the size of the individual condensed-ring systems is smaller than would be the case in the absence of bridging since the resulting molecules are composed of smaller condensed systems linked by aliphatic bridges as opposed to one large condensed unit.

A new technique for the acid/base separation of petroleum and coal-derived fractions

Abstract A new method for the acid/base fractionation of asphaltenes and other petroleum and coal-derived materials has been developed. This technique, which employs a strong, solid acid, has been shown to separate on the basis of acidity or basicity and to fractionate in a fashion similar to hydrogen chloride precipitation. In addition, the yields of fractions were shown to depend on the acidity of the separating medium. Basic and non-basic fractions were characterized by elemental analysis, e.s.r., n.m.r., interfacial tension, mass spectrometry, molecular weight, u.v.-visible spectrophotometry, and silylation. These data provide detailed information on the elemental distributions, functional group types, carbon and hydrogen types, and vanadium environments in the two fractions. The findings indicate that basic nitrogen is concentrated in the basic fraction while non-basic nitrogen and hydroxyl are mainly in the non-basic fraction. Although total nitrogen was concentrated in the basic fraction from coal asphaltenes, this was not the case for petroleum asphaltenes.

Influence of thermal processing on the properties of Cold Lake asphaltenes. 2. Effect of steam treatment during oil recovery

Abstract Cold-bailed (untreated) Cold Lake crude asphaltenes have been compared to steam-stimulated Cold Lake crude and Cold Lake vacuum residuum asphaltenes by elemental analysis, vapour pressure osmometry, gel permeation chromatography, infrared spectroscopy, and thermogravimetric analysis. The results of these analyses indicate that the steam stimulation procedure used to produce Cold Lake crude asphaltene results in significant changes in all of the measured characteristics except molecular weight. These changes include a decreased H C ratio, alterations in the carbon skeleton and functional groups, an increased percentage of aromatic carbon (as determined by 13 C n.m.r.), and decreased volatiles evolution during thermogravimetric analyses. The changes occurring during steam stimulation, which are implied by these physical measurements, include side-chain dealkylation and/or aromatization of hydroaromatic rings and loss or alteration of some heteroatomic functional groups. Polymerization leading to high-molecular-weight materials was not observed.