Douglas S. Montgomery

Oxidation studies on coking coal related to weathering. 4. Oxygen linkages influencing the dilatometric properties and the effect of cleavage of ether linkages

Abstract Samples of a vitrinite concentrate of Balmer 10, medium-volatile bituminous coal (433) and high-volatile Moss 3 coal (535) were oxidized in air at 85°C for four days to partially destroy the swelling characteristics as measured by the Ruhr dilatometer. Similar samples were oxidized at 100°C for three days to completely destroy the swelling properties. These artificially weathered coals were then treated with reagents to remove peroxides, keto and aldehyde groups. The hydroxyl groups were also blocked to prevent condensation reactions. The result of the removal of these functional groups and the blocking of the hydroxyl groups had little influence in restoring the swelling properties. This suggested that the swelling properties were largely destroyed by ether-type cross-links which form at low temperature. The cleavage of these ether linkages in the Balmer coal using potassium in tetrahydrofuran resulted in the lowering of the melting point and a large increase in dilatation. The values of these properties after cleavage were essentially the same for the fresh and oxidized coal indicating that no significant amount of polymerization through carbon-carbon bond formation occurred during the low-temperatureoxidation step. Indications were obtained that the large increase in dilatation after cleavage was due to steam formation resulting from condensation reactions occurring at the temperature of the dilatation measurements. After the cleavage of the ether linkages, the dilatation could be reduced by blocking the hydroxyl groups or removing water by heat treatment under vacuum.

Oxygen distribution and hydrogen bonding in Athabasca asphaltene

Abstract The oxygen distribution in the Athabasca asphaltene has been investigated. On the average, 75% of the oxygen is present in the form of hydroxyl groups. I.r. studies indicate that these hydroxyl groups exist almost entirely as hydrogen-bonded complexes which do not dissociate in carbon tetrachloride. The decrease in the molecular weight of the acetylated, methylated and silylated asphaltene suggests that the hydrogen bonding is intermolecular in character. The i.r. spectra of the asphaltene fractions extracted with polar solvents showed the presence of free OH, NH and carbonyl groups. The strong hydrogen-bonding properties of the Athabasca asphaltene were confirmed in i.r. measurements of the interaction with phenol, and molecular weight determinations of asphaltene 2,7-naphthalenediol and 4,4′-dihydroxy-3,3′-dimethyldiphenyl mixtures.

Sulfides in petroleum

Abstract The homologous series of terpenoid sulfides previously reported to be present in Athabasca bitumen have been detected in a variety of petroleums from the Western Hemisphere. All 22 samples examined, ranging in age from Devonoan to Cretaceous, contained the terpenoid sulfides. A method is described for the isolation of sulfides from petroleums based on the selective oxidation of sulfides to more polar sulfoxides which are easily removed from the mixture and their subsequent reduction to sulfides. The sulfide content in the petroleum maltenes examined ranged from 0.3 to 16.1% w/w. In addition to the bicyclic and tetracyclic terpenoid sulfides a new series of tricyclic terpenoid sulfides has been identified, and the details of the isoprenoid side chain have been elucidated for all three homologous series. The distributions by carbon number of the bicyclic and tetracyclic homologous series of terpenoid sulfides show pronounced variations which are attributed to thermal maturity and degree of water washing of the petroleum, thus the ability to identify terpenoid sulfides should provide a useful tool for oil-oil and oil-source rock correlation studies. The bicyclic and tricyclic terpenoid sulfides have the same carbon framework as the carotenoids which suggest that these sulfides were accessory pigments in photosynthesis.

Hydrocarbon-type separation of heavy petroleum fractions

Abstract In this investigation the US Bureau of Mines — API method for the separation of heavy petroleum hydrocarbons into structural types — saturates, monoaromatics, diaromatics and polyaromatic-polar material — has been modified. The time of analysis is reduced drastically by applying pressure on the column and eliminating a time-consuming pretreatment of the samples with ion-exchange resins to remove the acidic and basic components of the oil. The polyaromatic-polar material, forming a substantial amount of the high-molecular-weight fractions of heavy oils, has been further separated into three concentrates of different composition, by using an additional two eluents. This step allows better characterization of the high-molecular-weight components of heavy oils and bitumens. The sample size, column volume and the weight of the adsorbing gels have also been scaled down first by a factor of 10 — for quantitative preparation of hydrocarbon classes in research laboratories for further analysis by Chromatographic or spectroscopic methods — and then 100 for chemical characterization of drill core extracts.

Absorption and emission spectra of Athabasca asphaltene in the visible and near ultraviolet regions

Abstract Absorption, excitation and emission spectra in the visible and ultra-violet region were recorded at room temperature for Athabasca (Alberta, Canada) asphaltene and five of its fractions separated according to molecular weight (MW) by gel permeation chromatography (g.p.c.) on Bio-Beads SX-1. Strong concentrations effects were observed on the profiles of all the excitation and emission spectra at concentrations higher than 5.0 mg l−1. The proper excitation and emission spectra were taken at concentrations lower than 5.0 mg l−1 where the profiles are independent of concentration. All the spectra obtained were broad, structureless bands with the exception of that of the lowest MW fraction, which shows the sharp Soret band characteristic of the vanadyl porphyrin complex. The absorbance of the whole asphaltene was found to be equal to the weighted sum of absorbances of the fractions at a given wavelength and a given weight concentration. This additive property was not observed among the intensities in the emission spectra. The profiles of all the excitation and absorption spectra are identical throughout the asphaltene fractions, suggesting that the basic absorbing chromospheres are the same throughout the fractions and independent of MW of the fractions. In addition the absorption spectra are not significantly affected by the Tyndall scattering. From the examination of absorptivity and the position of the absorption band, the average number of aromatic rings in the average absorbing chromophores throughout the fractions was found to consist of approximately two to three. The fluorescence spectra, on the other hand, show a very rapid decrease of intensity at a constant weight concentration and a gradual shift of the band maxima toward longer wavelength with increasing number average MW. The origin of the fluorescence band is considered to be exciplexes. The average rate of non-radiative processes decreases steadily with decreasing MW from fraction 1 to fraction 5. The influence of various solvents was explored on the absorption, excitation and emission spectra of the lowest MW (1200) asphaltene fraction.

Novel terpenoid sulfoxides and sulfides in petroleum

Abstract Homologous series of novel and unexpected biological markers, bicyclic and tetracyclic terpenoid sulfoxides and sulfides, have been identified in the Athabasca bitumen.

Chemical composition of gases in Athabasca bitumen and in low-temperature thermolysis of oil sand, asphaltene and maltene

Abstract Athabasca oil sand on degassing in vacuo releases gases volatile at −78 °C which are composed of neopentane, methane, acetaldehyde, propane and propylene. At elevated temperature, 70–210 °C, additional quantities of these materials are produced by thermolysis along with other C2C5 hydrocarbons, CO2, CO, H2S, COS, CS2 and SO2. The activation energies of product formations were determined: they all have unusually low values, pointing to a catalytic effect of the mineral matter present. These results clearly suggest a thermal rather than a microbial origin for the volatile materials present in the oil-sand formations. The separated asphaltene and maltene yield similar products but with considerably higher activation energies. If the values obtained are representative of the entire formation then the amounts (on bitumen reserves of 1012 bbl) of neopentane and methane produced are 2.1 × 106 and 1.05 × 104 tpa, respectively.

A homologous series of novel hopane sulfides in petroleum

Abstract A homologous series of hexacyclic sulfides ranging from C 30 to C 35 and containing the 17α(H), 21β (H) hopane carbon skeleton, III , have been identified in the heavy oils of Northern Alberta.

Oxidation studies on coking coal related to weathering. 3. The influence of acidic hydroxyl groups, created during oxidation, on the plasticity and dilatation of the weathered coking coal

Abstract A high-volatile bituminous coal possessing a high Gieseler fluidity and large dilatation was subjected to slight oxidation in air under chosen conditions. The resultant ‘oxycoal’ was treated with various chemical reagents in order to determine to what extent the original caking properties of this coal, as measured by Gieseler fluidity and dilatation, could be restored. Treatment with aqueous barium hydroxide or barium acetate solutions succeeded in doing so to a considerable degree. It is tentatively concluded that certain acidic hydroxyl groups formed in the course of oxidation are indirectly responsible for the deterioration of fluidity and dilatation — possibly via condensation reactions involving the hydroxyl groups — during subsequent pyrolysis of oxycoal. The presence of carboxyl groups appears to have no effect.

Separation and characterization of clay from Athabasca asphaltene

Abstract Athabasca bitumen separated from the associated mineral matter by Soxhlet extraction contains fine clay particles and inherent ash. Empirical relations have been developed to estimate the percentage of clay and inherent ash present in the asphaltene fraction which concentrates in large measure the mineral constituents present in the bitumen. The ash level, Y , of the asphaltenes is related to the weight per cent of clay, C t , by an expression of the form Y = 0.872 C t + 0.582. The ash level of the asphaltene fraction is also correlated with the infrared absorbance. A , at 1032 cm −1 which gives an approximate empirical relation of the form A = 0.0648 Y + 0.294. Greater accuracy at low ash levels can be achieved by measuring A at 1040 cm −1 above the base line drawn from 960 to 1140 cm −1 . This results in the equation A = 0.0709 Y + 0.0124 when a standard KBr pellet thickness of 0.833 mm and concentration of 2 mg asphaltene per 300 mg KBr is used. X-ray diffraction used to characterize the clay minerals shows decreasing crystallinity as the particle size diminishes. The infrared absorbance of this mineral matter indicates decreasing intensity of the band at 2930 cm −1 , associated with adsorbed and occluded organic matter, relative to the two characteristic clay bands at 3697 and 3620 cm −1 as the particle size decreases. Trace element analysis of the asphaltene inherent ash, by inductively coupled argon plasma, shows the major metallic constituents to be vanadium, nickel and iron with minor amounts of calcium, potassium, aluminium and sodium.