EFFECTS OF THE BITUMEN POLAR FRACTIONS ON THE STABILITY OF BITUMEN AQUEOUS DISPERSIONS

The flocculation of aqueous bitumen emulsion during transportation and processing depends mostly on the electrical properties of bitumen-water interface. The aim of this study is to show how such interface is affected by the resins/asphaltenes ratio (r/a) of the bitumen. Our results indicate that the r/a controls the interfacial composition and the stability of the bitumen droplets in a water-continuous medium. Moreover, it is shown that the r/a is primarily responsible for maintaining diffusion of polar components inside the bitumen droplet. Such non-equilibrium behavior of various bitumen polar components takes place during the dispersion manufacturing and/or maturation phase. In this work, the asphaltenes and resins contents of a bitumen series were determined. In addition, the acid-base properties of the same bitumen series were studied by non-aqueous potentiometric titration method. The nature and the amount of acidic and basic functionaliti present in the bitumen were evaluated by comparison with the acid-base model compounds such as carboxylic acid, benzoic acid and pyridine. Furthermore, the interfacial properties of the acidic aqueous bitumen dispersions were studied by contact-angle and zeta potential measurements. The overall results indicate that stable bitumens dispersions are obtained with bitumens having high values of the resins/asphaltenes ratios.     

PHYSICO-CHEMICAL AND COMPOSITIONAL ASPECTS OF BITUMEN BEARING CRUDES AND THEIR INSTRUMENTAL CHARACTERISATION

In India the production of bitumen is primarily based on middle-east crude oils which normally have a right balance of bitumen constituents (i.e. asphaltenes and maltenes). In general, bitumens obtained from such crude oil sources have a good balance of rheological and physico-chemical properties at both low and high temperatures.

Bitumen is a complex mixture consisting of compounds ranging from non-polar aliphatic and naphthenic hydrocarbons to highly polar aromatic molecules containing heteroatoms such as oxygen, nitrogen, and sulfur; and, several attempts have been reported to fractionate and characterise bitumens into broadly defined compound groups. The separation method adopted in the present study is based on the polarity of the constituent compounds comprising the bitumen. The separated groups of compounds which progressively increase in their polarities are saturates, aromatics, resins and asphaltenes. In the present study three important (middle-east) bitumen bearing short residues have been selected and their detailed physico-chemical as well elemental compositions have been reported. Each short residue has been characterised by NMR and FT-IR spectroscopy methods and the information obtained from these analyses have been used to estimate several average structural parameters. Ultimate compositions have been determined for deducing the average molecular formulae.     

EFFECT OF INTER-MOLECULAR ASSOCIATION ON BITUMEN OXIDATION

The hypothesis that inter-molecular associations between species in petroleum bitumens affects the rate of air oxidation of the bitumens was examined using infrared spectroscopy, gel permeation chromatography and viscosity measurements. Experiments were carried out in which the rate of oxidation of two different bitumens and their fractions (maltenes, resins, asphaltenes) were measured in terms of carbonyl group formation. In THF solution at 30°C the rates of reaction of the maltene and asphaltene fractions were the same when oxidised separately or as a mixture. Although the presence of inter-molecular associations were confirmed by gel permeation chromatography, the results indicated that such effects were unimportant to the rate of the reaction. Further experiments were performed in which neat bitumen, resin and maltene (n-heptane) factors and reconstituted mixtures were oxidised under 2069 kPa of oxygen or air at 40°C or 60°C. Again, no evidence for the effect of inter-molecular association on oxidation rate was obtained. Another experiment in which a bitumen, rejuvenating oil (RO), and a mixture of the two was oxidised (2069 kPa air, 60°C) again showed that the reaction rate of the bitumen and RO were the same when oxidised separately or in the mixture. However, in contrast, the rate of increase of viscosity of the bitumen was significantly affected by the RO and was attributed to dispersal of polar oxidation products by the RO.     

EFFECT OF INTER-MOLECULAR ASSOCIATION ON BITUMEN OXIDATION

ABSTRACT

The hypothesis that inter-molecular associations between species in petroleum bitumens affects the rate of air oxidation of the bitumens was examined using infrared spectroscopy, gel permeation chromatography and viscosity measurements. Experiments were carried out in which the rate of oxidation of two different bitumens and their fractions (maltenes, resins, asphaltenes) were measured in terms of carbonyl group formation. In THF solution at 30°C the rates of reaction of the maltene and asphaltene fractions were the same when oxidised separately or as a mixture. Although the presence of inter-molecular associations were confirmed by gel permeation chromatography, the results indicated that such effects were unimportant to the rate of the reaction. Further experiments were performed in which neat bitumen, resin and maltene (n-heptane) factors and reconstituted mixtures were oxidised under 2069 kPa of oxygen or air at 40°C or 60°C. Again, no evidence for the effect of inter-molecular association on oxidation rate was obtained. Another experiment in which a bitumen, rejuvenating oil (RO), and a mixture of the two was oxidised (2069 kPa air, 60°C) again showed that the reaction rate of the bitumen and RO were the same when oxidised separately or in the mixture. However, in contrast, the rate of increase of viscosity of the bitumen was significantly affected by the RO and was attributed to dispersal of polar oxidation products by the RO.     

STUDY OF COMPOSITION OF NIGERIAN TAR SAND BITUMEN

Compositional characterization techniques developed for high-boiling heavy ends of petroleum have been applied to Nigerian tar sand bitumen. The bitumen was subjected to ion-exchange and ferric chloride coordination chromatography to separate acids, bases and neutral nitrogen compounds. The remaining Hydrocarbon plus fraction was separated into saturates, monoarmatics, diaromatics and polyaromatic plus polar compounds on dual packed column of silica - alumina gels. Simulated distillation data were also obtained for the bitumen and were used to plot a boiling point distribution curve.

Results of the characterization are compared with results in literature for tar sand bitumens and petroleum. Comparison of the results with the Utah and the Athabasca bitumens provides a basis for the evaluation of the Nigerian bitumen because considerable information about the processing characteristics of the Athabasca bitumen have been reported by many researchers.

Simulated distillation and chromatographic separation data indicate that the bitumen used in this present study closely resembles the Athabasca and the Utah tar sand bitumens with respect to hydrocarbon/non-hydrocarbon distribution, and the high-boiling petroleum fraction with respect to non-distilling portion. Information about the composition of bitumens and heavy oils is needed because of the prospect of using heavy oils including bitumens as energy sources.     

STUDY OF COMPOSITION OF NIGERIAN TAR SAND BITUMEN

Abstract

Compositional characterization techniques developed for high-boiling heavy ends of petroleum have been applied to Nigerian tar sand bitumen. The bitumen was subjected to ion-exchange and ferric chloride coordination chromatography to separate acids, bases and neutral nitrogen compounds. The remaining Hydrocarbon plus fraction was separated into saturates, monoarmatics, diaromatics and polyaromatic plus polar compounds on dual packed column of silica - alumina gels. Simulated distillation data were also obtained for the bitumen and were used to plot a boiling point distribution curve.

Results of the characterization are compared with results in literature for tar sand bitumens and petroleum. Comparison of the results with the Utah and the Athabasca bitumens provides a basis for the evaluation of the Nigerian bitumen because considerable information about the processing characteristics of the Athabasca bitumen have been reported by many researchers.

Simulated distillation and chromatographic separation data indicate that the bitumen used in this present study closely resembles the Athabasca and the Utah tar sand bitumens with respect to hydrocarbon/non-hydrocarbon distribution, and the high-boiling petroleum fraction with respect to non-distilling portion. Information about the composition of bitumens and heavy oils is needed because of the prospect of using heavy oils including bitumens as energy sources.     

UV/VIS SPECTROPHOTOMETRY FOR THE EVALUATION OF BINDER-AGGREGATE INTERACTIONS

ABSTRACT

UV/VIS absorption spectra of a few bitumens and their main generic fractions obtained by liquid chromatography have been recorded. Major or minor differences have been found depending on the nature of the bitumen and the generic fraction considered. Those differences are a valuable help in interpreting measurements of binder-aggregate affinity. A spectrophotometry technique has been tried in order to assess this affinity from a physicochemical point of view. It is baaed on the adsorption equilibria in solution between the bitumen or one of its generic fractions and a ‘and’ grading fraction of the aggregate. Both the asphaltenes of the bitumen and the nature of the aggregate play a considerable part in binder-aggregate interactions. The influence of the nature of the aggregate depends mainly on the specific surface of the ‘sand’ fraction used in the tests: with a 0.15 to 0.4?mm fraction this specific surface may vary by a factor up to more than 10, according to the nature of the original aggregate. Orientation tests to obtain more information about the generic fractions have been positive. The asphaltenes can be separated into cyclic-like and resin-like asphaltenes and the resins can be divided into resins with an ‘acid’ or ‘basic’ behaviour     

UV/VIS SPECTROPHOTOMETRY FOR THE EVALUATION OF BINDER-AGGREGATE INTERACTIONS

UV/VIS absorption spectra of a few bitumens and their main generic fractions obtained by liquid chromatography have been recorded. Major or minor differences have been found depending on the nature of the bitumen and the generic fraction considered. Those differences are a valuable help in interpreting measurements of binder-aggregate affinity. A spectrophotometry technique has been tried in order to assess this affinity from a physicochemical point of view. It is baaed on the adsorption equilibria in solution between the bitumen or one of its generic fractions and a 'and' grading fraction of the aggregate. Both the asphaltenes of the bitumen and the nature of the aggregate play a considerable part in binder-aggregate interactions. The influence of the nature of the aggregate depends mainly on the specific surface of the 'sand' fraction used in the tests: with a 0.15 to 0.4 mm fraction this specific surface may vary by a factor up to more than 10, according to the nature of the original aggregate. Orientation tests to obtain more information about the generic fractions have been positive. The asphaltenes can be separated into cyclic-like and resin-like asphaltenes and the resins can be divided into resins with an 'acid' or 'basic' behaviour     

A CORRRELATION OF UNITED STATES TAR BAHD BITUMEN VISCOSITIES WITH EMR SPECTROSCOPIC PARAMETERS

Many physicochemical properties of bitumens must be known in order to mathematically model and simulate the processes used for the recovery of bitumen from tar sands. One fundamental property is the temperature dependence of viscosity. This property determines the heat transfer and flow characteristics of a bitumen through a porous media.

A method has been developed whereby the viscosity of a tar sand bitumen at any temperature can be calculated from nuclear magnetic resonance parameters. The method is semiempirical but is based upon some fundamental theoretical concepts for molecular mobility and intermolecular interactions. Using this method, the viscosities of three United States tar sand bitumens have been correlated to the weighted average spin-spin relaxation rates for the semiliquid, solidlike mobile, and solidlike rigid phases of the bitumens. The results indicate that bitumens with a high viscosity have a greater amount of solidlike rigid phase and lesser amounts of solidlike mobile and semiliquid phases than do the bitumens with low viscosity. It is also shown that the viscosity of a tar sand bitumen over a 100 degree temperature range can be determined from a single NMR experiment conducted near room temperature.     

A CORRRELATION OF UNITED STATES TAR BAHD BITUMEN VISCOSITIES WITH EMR SPECTROSCOPIC PARAMETERS

ABSTRACT

Many physicochemical properties of bitumens must be known in order to mathematically model and simulate the processes used for the recovery of bitumen from tar sands. One fundamental property is the temperature dependence of viscosity. This property determines the heat transfer and flow characteristics of a bitumen through a porous media.

A method has been developed whereby the viscosity of a tar sand bitumen at any temperature can be calculated from nuclear magnetic resonance parameters. The method is semiempirical but is based upon some fundamental theoretical concepts for molecular mobility and intermolecular interactions. Using this method, the viscosities of three United States tar sand bitumens have been correlated to the weighted average spin-spin relaxation rates for the semiliquid, solidlike mobile, and solidlike rigid phases of the bitumens. The results indicate that bitumens with a high viscosity have a greater amount of solidlike rigid phase and lesser amounts of solidlike mobile and semiliquid phases than do the bitumens with low viscosity. It is also shown that the viscosity of a tar sand bitumen over a 100 degree temperature range can be determined from a single NMR experiment conducted near room temperature.     

REACTION OF PHOSPHORIC ACID WITH THERMAL RESIDUES AND BITUMENS

The purpose of the work was to study the effect of the addition of small quantities of phosphoric acid (or P₂O₅), on the physical and chemical behaviour of petroleum residues and bitumens.

Phosphoric acid (and P₂O₅) reacts only with thermal products such as visbreaker (VB) residues and bitumens, and do not react with straight run (SR) products.

The unstable constituents of VB residues, i.e. carbonaceous material and part of the asphaltenes, contain significant amounts of free radicals which easily share electrons with phosphorous.

The resulting condensed particles are higher molecular wighht, polar material no longher soluble in the bitumen, and flocculate.

This reaction confirms the presence of stable free radicals in thermal bitumens and residues, suggests a way to neutralize their destabilizing effect.     

ANALYSIS AND PHYSICO-CHEMICAL CHARACTERIZATION ON CHINESE OIL SAND BITUMENS

The extraction of four Chinese oil sands from Sinjiang and Inner Mongolia Autonomous Regions with Dean-Stark extractor were investigated. The mineral composition and sand grain distribution were determined and the bitumens were separated into saturates, aromatics, resin-I and resin-II, asphaltenes. The structure parameters and molecular model were made for the bitumens. Elemental analysis, molecular weight, FTIR, 1H-NMR were made for the bitumen fractions. The results show that the molecular structure of Mongolia bitumens have more polycyclic aromatics than that of Sinjiang bitumen. It is believed that the extraction of Sinjiang oil sand bitumen by hot alkaline water is much easier than Mongolia oil sand due to the difference of the viscosity of bitumen, the molecular structure and other physico-chemical properties of the bitumens.     

ANALYSIS AND PHYSICO-CHEMICAL CHARACTERIZATION ON CHINESE OIL SAND BITUMENS

Abstract

The extraction of four Chinese oil sands from Sinjiang and Inner Mongolia Autonomous Regions with Dean-Stark extractor were investigated. The mineral composition and sand grain distribution were determined and the bitumens were separated into saturates, aromatics, resin-I and resin-II, asphaltenes. The structure parameters and molecular model were made for the bitumens. Elemental analysis, molecular weight, FTIR, 1H-NMR were made for the bitumen fractions. The results show that the molecular structure of Mongolia bitumens have more polycyclic aromatics than that of Sinjiang bitumen. It is believed that the extraction of Sinjiang oil sand bitumen by hot alkaline water is much easier than Mongolia oil sand due to the difference of the viscosity of bitumen, the molecular structure and other physico-chemical properties of the bitumens.     

辽河原油沥青质及胶质油水界面化学性质初探

对由辽河原油中分别提取的沥青质组分,胶质组分配成的模型油与水的界面性质进行了研究,还考察了油相芳香度对涸青质,胶质模型油油水界面粘度的影响及当模型油中沥青质与胶质共存时的油水界面性质。结果表明,含沥青质的模型油的油水界面粘度较高,界面老化现象严重;而仅含胶质的模型油的油水界粘度较小。     

界面扩张流变法研究有机碱与原油活性组分的界面相互作用

从胜利油田渤61原油中分离得到胶质和沥青质,通过滴外形分析方法研究了两种原油组分模拟油（质量分数0.5%,由航空煤油配制）与乙醇胺溶液间的界面张力及界面扩张流变性质。结果表明,乙醇胺与胶质中脂肪酸反应,形成脂肪酸和皂的混合吸附膜,有利于界面张力的降低,但对界面扩张模量影响不大。乙醇胺与沥青质中芳香酸的反应能促进芳香酸的吸附,降低界面张力,同时增加膜强度;但随着乙醇胺浓度的进一步增大,芳香酸皂扩散交换作用对界面膜的影响增强,界面膜黏性部分增加,膜强度有所降低。     

道路沥青条形试件的缩裂试验

介绍了一种沥青条形试件的收缩试验方法,条形试件模拟沥青路面低裂缝发生情况,它的开裂与路面实际开裂相似,用七种沥肝进行了试验,结果表明,这种方法比较直观,有参考价值。     

VISCOSITY AND SOLUBILITY OF MIXTURES OF BITUMEN AND SOLVENT

The solubilities of three bitumen samples (Suncor, Syncrude and Lloydminster) in five solvents were examined and prediction on the various bitumen-solvent mixture viscosities were made with Cragoe equation. By calculating the Cragoe constant 'a' for each mixture and using the average value in the Cragoe equation the prediction accuracy of the equation was improved by over 60%. Bitumen-naphtha mixtures showed the best viscosity prediction characteristics.

The solubility of the asphaltenes in the bitumen was highest in toluene among the five solvents However, naphtha, showed a moderate solvating power, which negligibly varied over the range of composition studied. Therefore naphtha, a solvent derived from bitumen was recommended as the most appropriate solvent for reducing the viscosity bitumen.     

CHARACTERIZATION OF VARIOUS BITUMEN SAMPLES FROM TAR SANDS

We have investigated twenty three bitumen samples obtained using different separation methods such as: ultracentrifugation, Dean-Stark extraction, solvent extraction employing vigorous agitation, hot water separation and the Solvent Extraction Spherical Agglomeration technique. These samples were extracted from oil sand feedstocks of different grades, Suncor sludge pond tailings and mineral agglomerates obtained from the Solvent Extraction Spherical Agglomeration process. All of the bitumen samples were examined on a comparative basis using various analytical techniques. These included: fractionation into asphaltenes and maltenes; elemental analyses; molecular weight determination using vapour pressure osmometry and gel permeation chromatography, infrared, proton and 13C nuclear magnetic resonance spectroscopy. Proton and ¹³C n.m.r. spectroscopic data were used to determine the distribution of various types of hydrogens and carbons in the samples. These data were also used to derive various molecular parameters in order to investigate average molecular structures of different bitumen samples and some of their asphaltene fractions.     

乙醇胺与胜坨油田坨28 区块原油活性组分 相互作用对动态界面张力的影响

为明确胜坨油田坨28区块原油中活性组分与有机碱乙醇胺间的相互作用对动态界面张力的影响,采用SARA四组分分离方法对坨28区块原油进行分离,获得饱和分、芳香分、胶质和沥青质等组分;利用醇碱萃取法获得酸性组分;通过旋转滴界面张力仪测定了乙醇胺与坨28区块原油活性组分模拟油间的动态界面张力。研究结果表明:酸性组分是原油的主要活性组分,其质量分数及结构对有机碱与原油间界面张力的行为具有关键性影响,体系动态界面张力的最低值可达10-2m N/m数量级;酸性组分质量分数越大,低界面张力维持时间越长。对于坨28区块原油,与乙醇胺作用的难易顺序为:酸性组分最强,胶质次之,沥青质、饱和分和芳香分与之作用比较微弱。     

REACTION OF PHOSPHORIC ACID WITH THERMAL RESIDUES AND BITUMENS

ABSTRACT

The purpose of the work was to study the effect of the addition of small quantities of phosphoric acid (or P₂O₅), on the physical and chemical behaviour of petroleum residues and bitumens.

Phosphoric acid (and P₂O₅) reacts only with thermal products such as visbreaker (VB) residues and bitumens, and do not react with straight run (SR) products.

The unstable constituents of VB residues, i.e. carbonaceous material and part of the asphaltenes, contain significant amounts of free radicals which easily share electrons with phosphorous.

The resulting condensed particles are higher molecular wighht, polar material no longher soluble in the bitumen, and flocculate.

This reaction confirms the presence of stable free radicals in thermal bitumens and residues, suggests a way to neutralize their destabilizing effect.