Isolation and f.i.m.s. analysis of saturated hydrocarbons from tar sand bitumens

Saturated hydrocarbons in two Utah tar sand bitumens were determined via compound-type isolation and mass spectral analyses. Four analytical methods for isolating saturated hydrocarbons were evaluated:

• 1.1) dewaxing,
• 2.2) modified deasphaltening,
• 3.3) adsorption and complexation chromatography,
• 4.4) desorptive Soxhlet extraction followed by complexation chromatography.

The latter method was preferred for concentrating the greatest amount of saturated hydrocarbons without overlap from aromatic or heteroatom-containing species. Field ionization mass spectrometry (f.i.m.s.) adequately profiled these hydrocarbons by molar mass (m/z) and by Z-series type. The sample of Northwest Asphalt Ridge bitumen was comprised of a wax of mostly acyclic and monocycloalkanes; whereas, the saturates from the sample of Asphalt Ridge bitumen were mostly tetracyclo- and penatcycloalkanes. Based upon a comparison of the saturate distributions in the samples of bitumen, the sample from the Northwest Asphalt Ridge deposit was found to have undergone less biodegradation. This wax-like sample of bitumen may have migrated to the deposit at a later time than the major bitumen generation and/or resulted from physicochemical segregation of waxy organic matter in the reservoir.     

Characterization of polynuclear aromatic hydrocarbons in bitumen,heavy oil fractions boiling above 350 °C by g.c.-m.s.

The separation and characterization of polynuclear aromatic hydrocarbons of five fractions of bitumen, heavy oils and synthetic fuels boiling > 350 °C were performed using a combination of Chromatographic techniques. The polynuclear aromatic hydrocarbon fractions were obtained by liquid-solid chromatography and prior to the high performance liquid chromatography and gas chromatography/mass spectrometry techniques, the fractions were subjected to an acid/base extraction procedure to remove polar material. In total, 97 polynuclear aromatic hydrocarbons were tentatively identified by a correlation of their mass spectra and retention indices with those of 25 model polynuclear aromatic compounds.     

Investigations on Romashkino asphaltic bitumen. 1. Use of ion-exchange and adsorption chromatography for the separation of maltenes

Use has been made of ion-exchange resins to remove acid and base fractions from maltenes originally separated from Romashkino asphaltic bitumen. The effect has been studied of the ion-exchange resin treatment on the group-type composition of maltenes using adsorption chromatography through alumina. Yields, elemental and densimetric analyses of sub-fractions obtained have been given. Data from the separation will aid in the characterization of the nonhydrocarbon materials generally described as resins.     

Molecular characterization of statistical copolymers: 1. Potential and limitations of full adsorption–desorption procedure in separation of statistical copolymers

Dynamic integral desorption isotherms for a series of poly(methyl methacrylate) homopolymers and poly(methyl methacrylate)–polystyrene statistical copolymers were measured. Nonporous silica was the full adsorption–desorption (FAD) column packing and various adsorption‐promoting and desorption‐promoting liquids were used. The aim of this study was to evaluate the applicability of the FAD approach for separation of statistical copolymers. The effects of the adsorbing liquid and desorbing liquid nature were demonstrated on the positions and shapes of desorption isotherms. The desorption isotherms also strongly depended on both (co)polymer molar mass and copolymer chemical composition. This indicates large fractionation potential of the FAD procedure. Simultaneously, the interference of both above parameters prevents the direct use of FAD for fractionation of the copolymers. It is anticipated that the fractionation and/or reconcentration potential of the FAD procedure can be very effectively utilized in combination of FAD with size‐exclusion chromatography and/or with gradient elution liquid adsorption chromatography. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 857–864, 2000     

Trace constituents in milk fat: Isolation and identification of oxofatty acids

Ca. 1% of the glycerides of milk fat contain oxofatty acids. The isolation, fractionation, and characterization of oxofatty acids were accomplished using the following sequence of steps: (A) transmethylation, (B) conversion into 2,4-dinitrophenylhydrazones, (C) adsorption of the 2,4-dinitrophenylhydrazones on magnesium oxide to eliminate the colorless lipid, (D) fractionation of the 2,4-dinitrophenylhydrazones into non-oxofatty acid and oxofatty acid fractions on alumina, (E) separation of the oxofatty acid 2,4-dinitrophenylhydrazones into saturated and unsaturated classes by argentation column chromatography, (F) separation of these classes by chain length using liquid-liquid column and thin layer partition chromatography, (G) resolution of positional isomers by thin layer chromatography, (H) regeneration of the positional isomer 2,4-dinitrophenylhydrazones, and (I) analysis of the parent oxofatty acids by gas liquid chromatographymass spectrometry. In this manner, 36 saturated and 11 unsaturated oxofatty acids were identified tentatively or positively. The saturated oxofatty acids ranged in chain length from C₁₀–C₂₄, predominantly C₁₈ and C₁₆, and generally contained an even number of carbon atoms. The unsaturated oxofatty acids ranged from C₁₄–C₁₈, with C₁₈ predominating.     

Adsorption parameters for strongly adsorbed hydrocarbon vapours on some commercial adsorbents

High-temperature measurements of the adsorption properties of strongly adsorbed hydrocarbon vapours on a wide range of commercially available adsorbents are presented. These adsorbents include various cationic forms of the type A, X and Y zeolites, activated alumina and carbon, and some clays. The studies are based upon pulse chromatography experiments using low concentrations of hydrocarbon vapours (toluene and methylcyclohexane) in nitrogen carrier gas. The temperature range of investigation was chosen as 400–700 K, which is typical for the catalytic dehydrogenation of methylcyclohexane to toluene. Even at these temperatures, the relatively strong adsorption properties of the hydrocarbons necessitated the use of high carrier gas flow rates. As a consequence, significant deviation from isobaric operation existed. In this work, non-isobaric pulse chromatography theory was applied to the first moment data, and found to describe accurately the adsorption trends. Furthermore, the temperature dependence of the adsorption equilibria parameters could be determined. The data provide a useful reference in the design and assessment of processes in which the simultaneous operations of high-temperature chemical reaction and adsorptive separation take place, as in chromatographic and pressure swing based reactors.     

Gas-solid chromatography of hydrocarbons on activated alumina. II. Alkane,alkene, alkyne separations and subtractive adsorption

Various alkanes,-enes and-ynes of molecular weights below C₁₀ are rapidly separated by gassolid adsorption chromatography on untreated activated alumina. Solid silver nitrate coated on alumina removes alkenes and alkynes through oxidative degradation. Silver-nitrate concentration and column temperature markedly affect olefin removal. At about 300C some of the C₈ and higher molecular weight saturated hydrocarbons are destroyed. Conditions for this subtractive chromatography are detailed, and the fate of unsaturated hydrocarbons is explained. Presented at AOCS Meeting in Los Angeles, Calif., April 1966. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Compositional and structural variations of bitumen and its interactions with mineral matters during Huadian oil shale pyrolysis

Thermal bitumen is an important intermediate derived from kerogen decomposition during oil shale pyrolysis. In this study, free bitumen (FB) and bound bitumen (BB) were obtained by extracting oil shale chars (300–550 °C) before and after demineralization, and then analyzed by liquid chromatography fractionation, Fourier transform infrared spectroscopy, and gas chromatography/mass spectrometry. The FB yield first increased and then decreased with increasing temperature, and the maximum value was 2.10% at 400 °C. The decarboxylation of acids and decomposition of esters at 350–450 °C decreased the content of these compounds. Meanwhile, the intense cracking reactions of aliphatic compounds and alkyl chains at 400–450 °C decreased the carbon chain lengths and molecular weights of these compounds. From the analytical results obtained for the BB fractions, we suggest that some carboxylic acids or carboxyl group-containing compounds may be trapped on carbonate particles by the formation of Ca₂₊COO_? bonds, whereas other oxygenated compounds (e.g., esters and phenols) can be adsorbed preferentially by clay minerals through Lewis acid-base interactions.     

Effect of catalyst deactivation on the chemical composition and biological activity of catalytic two-stage coal liquefaction process materials

Samples of pressure filter liquid (PFL), the solids-free portion of the recycle slurry oil, were taken each day of the 25-day demonstration run No. 227-20 of the catalytic two-stage direct coal liquefaction (CTSL) process operated by Hydrocarbon Research Inc. (HRI). Selected samples were chemically characterized by fractionation into chemical classes by adsorption column chromatography using neutral alumina and picric acid-coated alumina adsorbents followed by high resolution gas chromatography, g.c.-m.s. and low voltage probe-inlet mass spectrometry. Selected samples were tested for biological activity using the standard histidine reversion microbial mutagenicity assay with S. typhimurium, TA 98 and an initiation/promotion assay for mouse skin tumorigenicity. Chemical analysis results indicated that there were increased concentrations of heteroatomic components in the PFL as catalyst age increased; the nitrogen-containing polycyclic aromatic compound fraction and hydroxy-substituted polycyclic aromatic hydrocarbon fraction contents of the PFL both increased with increasing pilot plant operation time. In addition, the aliphatic hydrocarbon and hydroaromatic fraction contents of the PFL decreased and the heavier molecular weight PAH compound content increased as the catalyst aged during the demonstration run. Biological testing results indicated that the mutagenic activity increased and that the skin tumour initiating activity of the PFL, as determined by total number of tumours per mouse, also tended to increase with catalyst age and deactivation.     

Fractionation of low molecular weight polyethylene by high-pressure soxhlet extraction

The use of quantitative, high-pressure Soxhlet extraction for the fractionation of low molecular weight polyethylene samples is described. Liquid carbon dioxide was found to be a suitable solvent for the lowest molecular weight hydrocarbons but failed to solubilize hydrocarbons with molecular weights greater than C-40—C-50. Liquid pentane was found to be an effective solvent for hydrocarbons that were insoluble in liquid CO₂. Careful, stepwise adjustment of the extraction solvent temperature produced polymer fractions with molecular weight distributions substantially narrower than those of the parent materials. Polymer fractions with molecular weights up to C-90 were analyzed by high-temperature gas chromatography. These analyses demonstrated the effectiveness of the technique in fractionating polymers according to molecular weight. Further evidence was provided by thermal analysis of the fractions that indicated melting-point transitions that were much sharper than those of the parent materials. High-pressure Soxhlet extraction offers considerable potential as a general method for purification and fractionation of synthetic and natural polymers. © 1993 John Wiley & Sons, Inc.     

The hydrocarbons of anhydrous butterfat: Influence of technological treatments

The hydrocarbons of butter oil were isolated after saponification of the oil by thin layer chromatography and then analyzed by gas liquid chromatography. The influence of such treatments of butter oil as fractionation, passage over Fuller’s earth, and hydrogenation on the nature and relative proportions of of the hydrocarbons was studied. Passage of butter oil over Fuller’s earth causes the formation of cholesta-3,5-diene, probably from cholesterol. Hydrogenation of butter oil passed over Fuller’s earth progessively transforms cholestadiene into cholestene.     

Gas-solid chromatography of hydrocarbons on activated alumina

Volatile hydrocarbons representative of those in autoxidizing fats were analyzed on a single column of activated alumina by gas-solid adsorption chromatography (GSC). Mixtures of C₁ to C₈ paraffins anda-olefins were readily separated from one another, and from several branched hydrocarbons in less than 40 min. Semilog plots of carbon number versus log retention time for these individual mixtures indicate that good separations may be expected when all components are present simultaneously. Alumina is a unique chromatographic substrate for these separations. Since no liquid phase is employed, wide temperature ranges may be applied, column bleeding is eliminated and the system becomes ideal for temperature programming even on single column instruments. This system of GSC offers a convenient and direct method for hydrocarbon analysis since more polar materials such as aldehydes, ketones and esters are irreversibly adsorbed on alumina. It shows promise not only for the analysis of volatiles in the flavor evaluation of edible oils, but also as an aid in solving many other food and biological problems. Presented at AOCS meeting in Houston, Texas, 1965. A laboratory of the No. Utiliz. Res. and Dev. Div., ARS, USDA.     

Determination and mutagenic activity of nitrogen-containing thiophenic compounds in coal-derived products

Polycyclic aromatic compounds containing both nitrogen and sulphur heteroatoms in aromatic rings were determined in a coal-derived liquid and a coal tar by capillary column gas chromatography and gas chromatography-mass spectrometry. G.c. with a flame photometric detector was used to analyse the nitrogen-containing polycyclic aromatic compound fraction obtained by adsorption chromatography on neutral alumina. The four possible isomers of the azadibenzothiophenes, and various other azathiophenic compounds, were positively identified by comparison with retention data of newly synthesized standard compounds. The aminodibenzothiophenes were the major nitrogen/sulphur-containing heterocycles in the coal liquid, while the azathiophenic compounds were the major ones in the coal tar. The differences between the two coal-derived products were related to the reaction conditions during their production. The four isomers of the azadibenzothiophenes were assayed for mutagenicity using the Ames test and compared with the mutagenicities previously reported for the aminodibenzothiophenes. It was found that the azadibenzothiophenes were not mutagenic, as opposed to the aminodibenzothiophenes.     

Separation and characterization of bitumen from Athabasca oil sand

Separation and chemical analysis was investigated using bitumen samples from Athabasca oil sand in Alberta. Fractionation according to solubility and polarity has been used to separate bitumen into its fractions. The solvent de-asphaltening was performed by n-pentane solvent (solubility fractionation), and the polarity fractionation using Fuller’s earth allows maltene to separate into SARA components (saturates, aromatics, resins and asphaltenes). The SARA components are analyzed comprehensively using elemental analysis (EA), Fourier-transformed infrared (FTIR), ultraviolet-visible spectroscopy (UV-vis), high performance chromatography (HPLC) and thermogravimetric analysis (TGA). EA (C, H, N, S), heavy metals (Ni, V) concentrations, FT-IR and UV-vis tests provided the explanation of chemical composition. From IR spectra, maltene and saturates/aromatics (sat/aro) contained more aliphatic compounds than resin or asphaltene. Also, IR spectrum of sat/aro was similar to crude oil and VGO (vacuum gas oil). Different UV signal data clearly indicates the contribution of aromatic constituents in the fractions. Using optimized analysis conditions of HPLC, we successfully separated the peaks for bitumen and its fractions. The characteristic peak pattern of SARA (saturates, aromatics, resins, asphaltenes) fractions was observed, and also the peak pattern of sat/aro was similar to that of crude oil and VGO. However, TGA results revealed that thermal behavior for sat/aro was similar to that of crude oil but different from that of VGO. Also, from the comparison between decomposition temperature of TGA and boiling point, their correspondence was found.     

Physico-chemical analysis of five hard bitumens: Identification of chemical species and molecular organization before and after artificial aging

The present paper focuses on a physico-chemical analysis of five different types of bitumens, both before and after aging. These bitumen samples were chosen based on: the original crude oil (straight-run bitumens with different asphaltene and crystallized fraction contents), mode of refining (straight-run vs. half-blown bitumen), and modifier characteristics (straight-run vs. polyphosphoric acid (PPA)-modified bitumen). The aim of this study is to determine both the aging effect on chemical species and the chemical organization as a function of the type of bitumen sample.In order to obtain information on bitumen chemistry, n-heptane precipitation (Standard NF EN 12591), IATROSCAN chromatography (coupling between a thin-layer liquid chromatography on a silica gel and a flame ionization detector), FTIR spectroscopy and differential scanning calorimetry (DSC) have all been used. Size exclusion chromatography under “high-speed” conditions (HS-SEC), which yields information relative to asphaltene associations, was also introduced. Several years of road aging were simulated through 25 h of a pressure aging vessel (PAV) test.The coupling of IATROSCAN chromatography and n-heptane precipitation made it possible to identify and quantify polar resins.In accordance with previous studies, the use of HS-SEC combined with IATROSCAN chromatography indicates that a modification by PPA leads to an increase in asphaltene content and a more dispersed asphaltene structure than that found in pure bitumen. This same conclusion can be drawn from observations of the half-blown bitumen sample. The half-blown bitumen actually contains less asphaltene than one of the straight-run bitumens in the study; furthermore, its asphaltenes are more highly agglomerated. These results demonstrate that asphaltene association does not systematically depend on quantity alone, as its chemical type also enters into play. Moreover, during aging, even though asphaltene content is increasing for all bitumen samples, its agglomeration is still highly dependent on the type of bitumen. It would therefore appear that the presence of crystallized fractions exerts a major influence on this process.     

Reverse osmosis separation of binary organic mixtures using cellulose acetate butyrate and aromatic polyamide membranes

A systematic investigation has been conducted to demonstrate applicability of reverse osmosis (RO) fractionation of organic liquid mixtures by laboratory-prepared cellulose acetate butyrate (CAB) and aromatic polyamid (PA) membranes. The determination of preferential sorption was also conducted by using liquid chromatography technique. It was found that reverse osmosis was applicable to the fractionation of organic liquid mixtures. It was also found that the component of the binary mixture that is enriched in the membrane permeate can be predicted by considering the preferential sorption and Stokes' radius for each constituent of the feed mixtre.     

Prediction of bitumen content in oil sand based on FT-IR measurement

FT-IR spectra of bitumen are utilized to propose simple prediction method of bitumen content in oil sand. Analysis and fractionation of Athabasca oil sand were carried out by standard method. A fraction of bitumen dissolved in tetrahydrofuran (THF) was 9.1 wt% and insoluble fraction was found as concomitantly clean clay (sand). The asphaltene fraction of oil sand was 1.42 wt%, which has higher sulfur content and lower H/C molar ratio than that of maltene. The clean clay and bitumen were used to prepare clay/bitumen composites. FT-IR spectra of different clay/bitumen composite were measured and compared. From analysis of the absorbance data, the empirical equation to predict bitumen content in oil sand was acquired using linear least square fitting. Using this equation, bitumen content of Athabasca oil sand was predicted to have a value of 10.5 wt% which is similar to 9.1 wt% of bitumen content extracted by THF solvent from oil sand.     

Release of bitumen from mature fine tailings in the presence of a polymeric dispersant

The effect of the addition of a polymeric dispersant, sodium lignosulphonate (LS), on the dispersion of mature fine tailings (MFT) was studied using zeta potential and total organic carbon measurements. Three different types of LSs were investigated to determine the importance of molecular weight and level of anionicity of LSs on the treatment of MFT. The presence of two fractions of bitumen was identified in the tested MFT sample. A small portion of bitumen was found to occur in the form of weakly held aggregates between bitumen and fine solids. This fraction was easily dispersed by small dosages of LS, resulting in bitumen liberation to the tailings surface. A much larger amount of bitumen was found to be strongly attached to the solids, and only very high dosages of LS were capable of partly liberating this fraction. The zeta potential promoted an understanding of the mechanism of adsorption of LS on the particles and liberation of bitumen from MFT. Carbon measurements facilitated determination of the adsorption density of the selected types of LS on solid particles.     

Beeswax Fractions Used as Potential Oil Gelling Agents

The objective of this work was the fractionation of beeswax to investigate the phase behavior of binary blends of the fractions and their potential use as gelling agents in edible oleogels. We have extracted seven distinctive fractions, using preparative flash chromatography with eluents permitted to be used in the processing of food raw materials. The odor profile of the fractions was characterized. The high purity of collected fractions was shown through thin-layer chromatography, Fourier-transform infrared spectroscopy, and high-performance liquid chromatography with an evaporative light scattering detector methods for hydrocarbons (94.8%), monoesters (97.6%), and mixed mono-, di-, and triesters fraction (98.7%). Free fatty acids and fatty alcohol fractions had lower purity which equals 82.6% and 39%, respectively. The analysis of the binary pseudo phase diagram revealed that all fractions combined with hydrocarbons express eutectic behavior. Combinations of all other fractions resulted in the formation of solid solutions. This study shows that the texture of oleogels can be improved by using a combination of various fractions of beeswax instead of native wax.     

The Chemical and Physical Structure of Peat Bitumens

Peat bitumen obtained by solvent extraction of Irish high moor peat was subjected to chemical, structural and rheological characterisation. The bitumen was fractionated on the basis of solubility in n-heptane, toluene and ethyl acetate into wax, resin and asphaltene; each of these major constituent groups was further separated into sub-fractions by column chromatography using solvents of increasing polarity. All materials were chemically characterised by C, H, N and O content and infra-red spectroscopy. Molecular size distribution of the materials was determined by gel permeation chromatography and vapour pressure osmometry. Heats of fusion, measured using the differential scanning calorimeter, indicated that crystalline species were concentrated in the wax fraction. The rheological properties of the bitumen were investigated between 10 and 50°C, and the fractions were examined at 20°C. Following analysis as yield pseudoplastic fluids, flow behaviour was described in terms of yield stress, flow and consistency indices. The measured flow parameters were examined in the light of the structural implications of the calorimetry and the results of the chemical analysis. Carboxylic acids and esters which are found principally in the wax fraction are considered to be the dominating rheological influence in the bitumen, affecting physical behaviour through their ability to crystallise at low temperature and thus mechanically hinder flow, and through secondary bonding increasing viscosity in the liquid phase.