Supercritical fluid extraction of bitumens from Utah oil sands

The supercritical fluid extraction (SFE) of bitumens from four major Uinta Basin (Utah) oil sand deposits was studied with propane solvent. The deposits studied included Whiterocks, Asphalt Ridge, PR Spring and Sunnyside. The bitumens from these deposits differed widely in physical and chemical properties. The volatilities (components with boiling point <811 K) were 46.6, 53.5, 45.4 and 40.9 wt.%; the molecular weights were 653, 426, 670 and 593 kg/kg mol; and the asphaltene contents (n-pentane insolubles) were 2.9, 6.8, 19.3 and 23.6 wt.% for the Whiterocks, Asphalt Ridge, PR Spring and Sunnyside bitumens, respectively. The SFE experiments were carried out at five conditions, combinations of three different pressures (5.6 MPa, 10.4 MPa, and 17.3 MPa) and three temperatures (339 K, 380 K and 422 K). The cumulative extraction yield increased with increase in solvent density at all operating conditions for the four bitumens. A maximum yield of 45 wt.% was obtained at the highest solvent density with the Whiterocks bitumen. The extraction products were significantly upgraded liquids relative to the bitumens. Comparatively lighter fractions were extracted in the earlier stages of extraction for all the four bitumens, whereas heavier extracts were obtained at higher extraction-solvent densities. The asphaltene contents of the residual fractions were significantly higher than the asphaltene contents predicted on a prorated basis for all four bitumens. This trend was due to the extraction of cosolubilizing components that kept the asphaltenes in suspension in the bitumen. It was concluded that solute polarity played a significant role in the extraction yields of the four bitumens. The Whiterocks bitumen, which was the least polar bitumen based on asphaltenes content, gave higher extraction yields compared to the bitumens from the other three deposits at all five operating conditions. The Sunnyside bitumen with the highest asphaltene content gave the lowest extraction yield at all five conditions. The Asphalt Ridge and PR Spring bitumens with intermediate polarity (based on asphaltene content) gave intermediate extraction yields with the Asphalt Ridge bitumen extraction yields higher than the PR Spring bitumen. Preliminary modeling of the extraction process using the Peng–Robinson cubic equation of state and a pseudocomponent lumping scheme provided a reasonable match with the experimental data for Whiterocks and PR Spring bitumens.     

Rheological properties of bitumen modified with ethylene butylacrylate glycidylmethacrylate

This article presents experimental results related to rheological viscoelastic properties of polymer modified bitumens, PmBs. Experiments were performed by a dynamical shear rheometer before and after thermo‐oxidative aging. Two types of bitumens with different asphaltene contents were modified by the addition of two types of reactive ethylene terpolymers, Elvaloy AM, and Elvaloy 4170, with a different percentage of reactive functional group, glycidylmethacrylate, GMA. Results of the investigation indicate that the degree of reactive polymer modification is a function of bitumen type, bitumen‐polymer compatibility, and polymer concentration. Polymer modification improves the following physical properties of the base bitumen: penetration, softening point, temperature susceptibility, and elastic recovery. Reactive polymers are effective binder modifiers that improve the susceptibility to high temperature of asphalt mixes, and also their rutting resistance, contribute to their good storage stability and make them less sensitive to aging. This is a result of the formation of a chemical bond between the polymer and molecules of asphaltenes. POLYM. ENG. SCI., 54:1056–1065, 2014. © 2013 Society of Plastics Engineers     

A method for evaluating the kinetics of n-heptane-induced asphaltene precipitation from various Saskatchewan crude oils during light hydrocarbon flooding

A molar n-heptane programmed titration technique has been developed for evaluating the kinetics of n-heptane-induced asphaltene precipitation from three Saskatchewan crude oils during light hydrocarbon flooding. Results from the technique show that asphaltene precipitation kinetics can be modeled semi quantitatively in terms of a power law rate model. Values for the reaction order for n-heptane (35.8–43.3) were much larger than those for asphaltene (1.0–2.5) showing that asphaltene precipitation is more sensitive to the n-heptane added than the asphaltene content of the oil. Also, the large activation energies obtained (32–185 kJ/mol) confirms experimentally that n-heptane asphaltene precipitation is not just a mere physical process.     

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.     

The Conductivity and Dielectric Behavior of Solutions of Bitumen In Toluene

The conductivity and dielectric constant of solutions of bitumen in toluene were determined for bitumens of differing asphaltene content. The results show that the conductivity is primarily controlled by the asphaltene content while the dielectric constant can be described in terms of the polarity and concentration of the various fractions of the bitumen. It is demonstrated that it is possible to determine bitumen content of a solution of bitumen in toluene by measuring the conductivity.     

Influence of poly(phosphoric acid) on the properties and structure of ethylene–vinyl acetate‐modified bitumen

Ethylene–vinyl acetate (EVA) modified (EM) bitumen was modified further by the addition of poly(phosphoric acid) (PPA). Owing to the gelation and acidification effect of PPA, the high‐temperature properties and compatibility of EM bitumen were improved greatly. Part dissolution of EVA after acidification was confirmed by the viscous behavior of EVA/PPA‐modified (EPM) bitumen in rheological tests to some extent. Morphology observation illustrated the decomposition of EVA in bitumen after PPA modification and ageing. Fourier transform infrared analysis proved that the hydrolysis reaction took place between the vinyl acetate segment of EVA molecule and the extra hydrogen protons of PPA. Thermal analysis displayed the thermodynamic behaviors of EM and EPM bitumens before and after ageing and confirmed the part dissolution of EVA further after PPA acidification. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46553.     

The zeta potential and surface properties of asphaltenes obtained with different crude oil/n-heptane proportions

We have investigated some surface properties of asphaltenes precipitated from crude oil with different volumes of n-heptane. According to the crude oil/n-heptane proportions used, asphaltenes are identified as 1:5, 1:15 and 1:40. Zeta potential results indicate that the amount of n-heptane determines the electrokintetic behaviour of asphaltenes in aqueous suspensions. Asphaltene 1:5 exhibits an isoelectric point (IEP) at pH 4.5 whereas asphaltenes 1:15 and 1:40 show an IEP at about pH 3. Surface charge on asphaltenes arises from the dissociation of acid functionalities and the protonation of basic functional groups. The presence of resins remaining on the asphaltene molecules may be responsible for the different IEP of asphaltene 1:5. Both sodium dodecyl sulfate (an anionic surfactant) and cetylpyridinium chloride (a cationic surfactant) were found to adsorb specifically onto asphaltenes. They reverse the sign of the zeta potential under certain conditions. These surfactants may be potential candidates to aid in controlling the stability of crude oil dispersions. Critical micelle concentration, interfacial tension measurements, and Langmuir isotherms at the air-water interface confirm the different nature of asphaltene 1:5, which also showed more solubility and a larger molecular size.     

Compound types and properties of Utah and Athabasca tar sand bitumens

Properties and compound types were examined in detail for tar-sand bitumens representative of four major deposits in Utah and Alberta. Methods for bitumen extraction, separation, and compound type (functional group) analysis are presented. Results of the analyses are compared with each other and with results in the literature for tar-sand bitumens and petroleum. Comparison of the results of Utah bitumens with the Athabasca bitumen provides a basis for evaluation of the Utah bitumens because considerable information about the processing characteristics of the Athabasca bitumen has been reported. Simulated distillation and Chromatographic separation data indicate that, in general, the tarsand bitumens most closely resemble Wilmington petroleum with respect to hydrocarbon/non-hydrocarbon distribution, especially in the non-distilling portion (the distillable portions, mainly hydrocarbons, are similar for all samples). Tar-sand bitumens were also shown to differ significantly from one another, principally in the amounts and kinds of heteroatomic compound types present. This information is important because of the effects that composition has on recovery and refining processes. Analyses of the chemical functionalities also provide a basis for developing correlations between bitumen composition and the recovery and processing characteristics of the bitumen.     

Artificial aging of polymer modified bitumens

This paper presents an investigation of artificial aging of polymer modified binders, prepared from three base bitumens and six polymers. Aging of the binders was performed using the Thin Film Oven Test (TFOT), the Rolling Thin Film Oven Test (RTFOT), and modified RTFOT (MRTFOT). The binders were characterized by means of infrared spectroscopy, different types of chromatography, and dynamic mechanical analysis. It was found that the effect of aging on the chemistry and rheology of the modified binders was influenced by the nature of the base bitumens and was strongly dependent on the characteristics of the polymers. For styrene–butadiene–styrene (SBS) and styrene–ethylene–butylene–styrene (SEBS) modified binders, aging decreased the complex modulus and increased the phase angle. Aging also increased the temperature susceptibility of these modified binders. The rheological changes of SBS modified bitumens were attributed to polymer degradation and bitumen oxidation. However, for SEBS modified bitumens, the mechanisms of aging are unclear. In the case of ethylene vinyl acetate (EVA) and ethylene butyl acrylate (EBA) modified binders, the process of aging increased the complex modulus and elastic response (decreased phase angle), and reduced temperature susceptibility. These changes were mainly due to the oxidative hardening of the base bitumens. The study also showed statistically significant correlation between TFOT, RTFOT, and MRTFOT. However, no definite conclusions could be drawn regarding the difference in severity of aging between these methods. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1811–1824, 2000     

Extraction of bitumen with sub- and supercritical water

The sub- and supercritical water extractions of Athabasca oil sand bitumens were studied using a micro reactor. The experiments were carried out in the temperature range of 360–380 °C, pressure 15–30 MPa and water density 0.07–0.65 g/cm³ for 0–2 hrs. The extraction conversion of bitumens increased with solvent power and temperature. A maximum conversion of 24% was obtained after 90 min extraction at the supercritical condition. Hydrogen and carbon mono-oxide were not detected in sub-critical region but in the supercritical region. The supercritical condition was favorable to the hydrogen formation for bitumen extraction. The extraction products were upgraded relative to the original bitumens due to direct hydrolysis of low-energy linkage and H₂ formed by water gas shift reaction in supercritical condition. 18% of initial sulfur in bitumen can be removed at maximum conversion condition. The asphaltene contents of the residue were significantly higher than that of original bitumen due to preferential extraction of aromatic compounds in supercritical condition.     

Effect of montmorillonite on properties of styrene–butadiene–styrene copolymer modified bitumen

Clay/styrene–butadiene–styrene (SBS) modified bitumen composites were prepared by melt blending with different contents of sodium montmorillonite (Na‐MMT) and organophilic montmorillonite (OMMT). The structures of clay/SBS modified bitumen composites were characterized by XRD. The XRD results showed that Na‐MMT/SBS modified bitumen composites may form an intercalated structure, whereas the OMMT/SBS modified bitumen composites may form an exfoliated structure. Effects of MMT on physical properties, dynamic rheological behaviors, and aging properties of SBS modified bitumen were investigated. The addition of Na‐MMT and OMMT increases both the softening point and viscosity of SBS modified bitumens and the clay/SBS modified bitumens exhibited higher complex modulus, lower phase angle. The high‐temperature storage stability can also be improved by clay with a proper amount added. Furthermore, clay/SBS modified bitumen composites showed better resistance to aging than SBS modified bitumen, which was ascribed to barrier of the intercalated or exfoliated structure to oxygen, reducing efficiently the oxidation of bitumen, and the degradation of SBS. POLYM. ENG. SCI., 47:1289–1295, 2007. © 2007 Society of Plastics Engineers     

Isolation and characterization of various types of organic matter in oil sands tailings sludge

In bitumen extraction of oil sands by hot water, the problem of sludge accumulation is, at least partially, attributable to the presence of unrecovered bitumen as well as acetone solubles and so called ‘insoluble organic matter’ (IOM) on the surfaces of inorganic particles. A comparative study of the bitumens separated from both sludge and the original oil sands feed suggested that the former was depleted in high molecular weight fractions. Examination of the organic matter extracted from sludge with acetone indicated that asphaltene constituents, as well as long chain fatty acids, could report with the acetone solubles. The structural parameters of the IOM derived from sludge were, in general, similar to those for oil sand IOM.     

Characterization of the viscoelastic behavior of the pure bitumen grades 10/20 and 35/50 with macroindentation and finite element computation

In this article, we present an identification procedure that allows the determination of the viscoelasticity behavior of different grades of pure bitumen (bitumen 35/50 and bitumen 10/20). The procedure required in the first stage a mechanical response based on macroindentation experiments with a cylindrical indenter. A finite element simulation was performed in the second stage to compute the mechanical response corresponding to a viscoelasticity model described by three mechanical parameters. The comparison between the experimental and numerical responses showed a perfect matching. In addition, the identification procedure helped to discriminate between different bitumens characterized by different asphaltene and maltene contents. Finally, the developed procedure could be used as an efficient tool to characterize the mechanical behavior of the viscoelastic materials, thanks to the quantified relationship between the viscoleastic parameters and the force–penetration response. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3440–3450, 2013     

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.     

Thermal and kinetic analyses of pure and oxidized bitumens

The thermal behaviour of pure and oxidized bitumens was studied by both DSC from ?60 to +80 °C and TGA at different heating rates in flowing nitrogen from 100 to 600 °C. The determined crystallised fractions FC of pure and oxidized bitumens were successively 5.19% and 3.90% and the determined glass transitions T_g of pure and oxidized bitumens were successively ?41.43 °C and ?28.36 °C. The kinetics parameters (n, k, E_a, A) were calculated from the experimental results using a differential method. The TGA/DTG data showed that the thermal degradation of bitumen is a one stage process for pure bitumen and a two stage process for oxidized bitumen.     

The application of compound-type analyses to the correlation of product distributions and yields from the fluidized-bed pyrolysis of oil sands

The production of liquids from Utah (Uinta Basin) oil sands in a fluidized-bed reactor was investigated. The product distributions, yields, and product qualities were determined as a function of operating variables: temperature (698–973 K), sand retention time (15–35 min) and fluidizing gas velocity (50–150 cm s⁻¹). The quality of the liquids was assessed by gradient elution chromatography. Temperature appeared to be more significant than sand retention time in determining the compound-type distribution for oil sands containing moderate-viscosity bitumens; the distribution was approximately constant as the retention time changed at constant temperature. The predominant aromatic structure in the Uinta Basin bitumens appeared to be a naphthalene. The asphaltene content of bitumens was found to be an excellent correlating parameter for predicting product distributions and yields for pyrolysis of oil sands.     

Ageing by UV radiation of an elastomer modified bitumen

Laboratory methods to simulate the short- and long-term ageing occuring during the service life of pure and polymer modified bitumens in a pavement are standardized but none of them takes into account the influence of UV radiations. If the impact of thermal ageing on the degradation of SBS elastomers in bitumens has been extensively studied, there is not study dealing with the photo-oxidation of these copolymers in a bituminous matrix. So, the aim of our study was to investigate, by FTIR spectrometry and SEC chromatography, whether the architecture of elastomers (linear or radial) might have any influence on their ageing by UV radiation in a bituminous matrix. The results show that the elastomers oxidation kinetic, unlike the disappearance kinetic of trans-butadiene double bond, does not depend on their architecture. But, when putted into the same base bitumen, the two copolymers show exactly the same oxidation kinetic and the same decreasing kinetic of trans-butadiene double bond. So, this study has revealed that inside the bituminous matrix, on the one hand, the elastomers architecture does not influence on its degradation when submitted to UV radiation and, on the other hand, there is a “protection” of the elastomers by the studied bitumen towards UV radiation.     

Evaluation of physical,rheological, and structural properties of vulcanized EVA/SBS modified bitumen

In this study, the performance and modification mechanism of EVA (ethylene‐vinyl‐acetate) modified (EM), EVA/SBS (Styrene‐Butadiene‐Styrene) modified (ESM), and EVA/SBS/sulfur modified (ESSM) bitumens were evaluated. The physical, rheological, morphological, and structural properties were determined before and after aging, and compared with those of base bitumen. These properties were evaluation using conventional physical methods, Fourier transform infrared spectrometer, optical microscopy, dynamic shear rheometer, and bending beam rheometer, respectively. The results showed that sulfur was useful in bitumen, EVA, and SBS modification by forming a vulcanized crosslinking polymer network. The vulcanization improved most of the physical properties of ESM bitumen, especially high‐ and low‐temperature performance, and toughness and tenacity (previously not evaluated in the literature). Meanwhile, vulcanization improved the compatibility between polymers and bitumen and increased the aging resistance of ESM bitumen. Vulcanization reactions took place without new functional groups being presented in the infrared spectrum. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44850.     

Composition of natural bitumens and asphalts from Iran: 2. Bitumens from the Posteh Ghear valley,south-west Iran

Vein, lens and stratiform natural sedimentary bitumen deposits were analysed by combined geochemical and micropetrographic techniques. Reflectances in oil, air and water, fluorescence spectral properties, solubility in dichloromethane, elemental analysis and bulk chemical composition of soluble fractions by chromatographic separation indicate that these materials are generally gilsonite bitumen, although some, showing evidence of significant alteration and weathering, are closer to albertite in composition. Optical properties show that the bitumens are immature and fall within the field of asphaltites on the bituminization curve. Fluorescence spectra generally show two maxima, again a feature associated with immature gilsonite bitumen. Capillary-column g.c. of saturates fractions indicates the absence of normal and acyclic isoprenoid alkanes, these fractions being dominated by a series of C₂₇-C₃₄ pentacyclic triterpanes of the hopane family. The saturates fraction composition is characteristic of biodegraded crude oils, and molecular biomarker stereochemistry indicates a moderately mature petroleum source. All the bitumens are shown to have a common genetic origin and are thought to be the result of in situ alteration and biodegradation of oil infillings in joints, fractures and bedding planes, resulting from fracturing and faulting of reservoir and overlying cap rocks associated with a period of Neogene tectonism.     

Molecular size of asphaltene fractions obtained from residuum hydrotreatment

Previously, fluorescence depolarization techniques (FD) have been shown to measure asphaltene molecular size, thereby establishing the substantial difference between asphaltenes derived from crude oil vs from coal. Here, FD is used to track the changes of the asphaltenes from a petroleum atmospheric resid feedstock that has been subjected to increasing thermal severity of catalytic hydrothermal cracking. Changes in asphaltene properties with increasing cracking are readily observed and understood. In addition, asphaltene molecular size is measured for various asphaltene solubility fractions in binary solvent mixtures of toluene with either n-heptane or acetone; a strong dependence is found of asphaltene properties on the particular solvent mixtures in accord with recent publications.