Multivariate Screening Analysis of Water-in-Oil Emulsions in High External Electric Fields as Studied by Means of Dielectric Time Domain Spectroscopy

The effect of crude oil resins with various polar characters on the stability of w/o model emulsions containing asphaltenes is investigated using a mixture design. The resins were extracted using an adsorption-desorption technique. One asphaltene fraction and four different resin fractions from one European crude oil were used. The stabilities are measured using time-domain dielectric spectroscopy in high external electric field. It is found that resins with different polar character have different effects on the emulsion stability. At asphaltene/resin ratios of 1 and 5 : 3 the resins in some cases lead to an emulsion stability higher than that of a similar emulsion stabilized by asphaltenes only, while at low asphaltene/resin ratios ( approximately 1 : 3) the emulsion stability is reduced by the resins. The effect on emulsion stability of combining two different resin fractions depended on the resin types combined as well as the relative amount of resins and asphaltenes. Also, an increase in the stability of some of the emulsions containing resins and asphaltenes for a period of 50-300 min after the emulsification was observed. This time-dependence of emulsion stability is attributed to the mobility of resins at the oil-water interface and the slow buildup of a stabilizing interfacial film consisting of resins and asphaltenes. Copyright 2000 Academic Press.     

Heat Treatment Condition Influence on Novokuibyshevsk Vacuum Residue Component Composition

The article presents the information about thermal degradation of Novokuibyshevsk vacuum residue and change of products composition during this process. The optimal conditions for the thermal destruction of vacuum residue components were established. The regularities of material balance composition change, S_general were determined depending on cracking conditions. The basic directions of resin-asphaltene component transformations were identified, changes in their structural-group parameters in the process of initiated cracking were analyzed. Conducting of Novokuibyshevsk vacuum residue thermolysis leads to deep resins-asphaltenes average molecules structure characteristic changes. Developed alkyl and naphthenic moieties, which are presented in initial molecule, undergo degradation, amount of structural blocks in resins and asphaltenes molecules reduces, their average size decreases. Also the reduction in total content of the rings (saturated and aromatic) was established in average structural unit, at the same time decrease of rings substitution and length of the aliphatic fragments can be observed. In general the process of vacuum residue thermal cracking causes partial degradation of saturated (aliphatic and naphthenic) fragments and, partially, aromatic rings, which contain heteroatomic elements.     

Film forming properties of asphaltenes and resins. A comparative Langmuir– Blodgett study of crude oils from North Sea, European continent and Venezuela

 Asphaltenes and resins were separated from different crude oils, dissolved in different paraffinic and aromatic solvents and studied by means of Langmuir technique. It was found that the resin films are more compressible and more polar than the corresponding asphaltene films. Intermolecular aggregation between asphaltene molecules was more prominent than between resin molecules, and the size of the final aggregates depended on the nature of the solvent and the bulk concentration of the aggregating species. Even when present in smaller amounts than asphaltenes on the surface, the resins dominate the film properties. Received: 19 January 1998 Accepted: 15 April 1998     

Quantitative Determination of Asphaltenes and Resins in Solution by Means of Near-Infrared Spectroscopy. Correlations to Emulsion Stability

Near-infrared (NIR) spectroscopy in the range 1100-2250 nm together with a latent-variable regression technique is used to analyze the content of asphaltene and resins in solution. It is shown that this technique is capable of determining the amount of these components individually. w/o emulsions were prepared from the separated components of asphaltenes and resins from crude oils. The stability was directly determined with the critical voltage in a dielectric instrumentation. The emulsion stability decreased linearly with an increase in the resin/asphaltene ratio. A final linear model correlating the critical voltage and the analytical concentrations (from the NIR spectra) could be established for this model system. Copyright 2000 Academic Press.     

Preparation of ion exchange resins from carbonaceous adsorbents

Carbonaceous adsorbents are obtained by thermolysis of sulfonated macroreticular polystyrene ion exchange resins at 300-500°C. The hard, spherical, carbonaceous particles react exothermally with elemental chlorine to form products containing up to 38% Cl. The chlorinated particles react readily with polyamines to form anion exchange resins with capacities of up to 2.2 meq/g dry resin. Less than 60% of the nitrogen atoms in the particles are utilized as ion exchange sites. The carbonaceous particles can also be chloromethylated with chloromethyl methyl ether or chlorinated with sulfuryl chloride and then aminated with polyamines to form anion exchange resins, sulfonated with sulfuric acid or chlorosulfonic acid to form strongly acidic cation exchange resins, or chlorosulfonated and then aminated with polyamines to form anion exchange resins. Model structures of the thermolyzed resins containing polycyclic aromatic hydrocarbon fragments are proposed to explain their chemical reactivities.     

褐煤蜡树脂中多环芳烃组成的研究

采用气相色谱法对云南寻甸褐煤蜡树脂和吉林舒兰褐煤蜡树脂,进行了多环芳烃分布特征的研究,从树脂中鉴定出６８个化合物的同系物。两个树脂样均以菲系化合物占有优势,舒兰树脂中菲系列量约三倍于寻甸树脂的相应量     

钌离子催化氧化法研究大港减压渣油组分化学结构

利用钌离子催化氧化方法对大港减压渣油芳香分、胶质和庚烷沥青质进行了选择性降解，通过GC、GC-MS等分析手段对降解反应产物中一元正构脂肪酸、α,ω-二元正构脂肪酸和苯二～六元羧酸的含量和分布分别进行了定量分析。结果表明，芳香分、胶质和庚烷沥青质中的芳香结构上都存在大量烷基取代基和桥接不同芳碳的聚亚甲基桥。烷基取代基碳数最大约为33，聚亚甲基桥最大碳数约为24，而且这两种结构单元的含量均随碳数的增加而减少，并呈现出了偶碳优势。庚烷沥青质C12以下侧链相对较多而C16＋较少，与芳香分的分布相反；正构烷基侧链的浓度按庚烷沥青质、胶质和芳香分的顺序递减。降解产物中都检测到了苯二甲酸到苯六甲酸等一系列的苯多酸，表明三个组分中都存在稠环芳香结构。庚烷沥青质中缩合程度较高的迫位缩合结构含量最高，芳香分渺位缩合结构最多，胶质介于两者之间。     

A quartz crystal microbalance study of the adsorption of asphaltenes and resins onto a hydrophilic surface

The adsorption of extracted and purified samples of asphaltenes and resins onto gold surfaces has been studied as a function of bulk concentration using a quartz crystal microbalance with dissipation measurements (QCM-D). With this device, which works equally well in transparent, opaque, and nontransparent samples, the adsorbed amount is measured through a change in resonant frequency of the quartz oscillator. The measured change in dissipation reports on changes in layer viscoelasticity and slip of the solvent at the surface. The results show that the adsorbed amount for resins from heptane corresponds to a rigidly attached monolayer. The adsorbed amount decreases with increasing amount of toluene in the solvent and is virtually zero in pure toluene. Asphaltenes, on the other hand, adsorb in large quantities and the mass and dissipation data demonstrate the presence of aggregates on the surface. The aggregates are firmly attached and cannot be removed by addition of resins. On the other hand, resins and asphaltenes associate in bulk liquid and the adsorption from mixtures containing both resins and asphaltenes is markedly different from that obtained from the pure components. Hence, we conclude that preformed resin aggregates adsorb to the surface. These results are compared and discussed in relation to adsorption from crude oil diluted in heptane/toluene mixtures.     

煤基和石油基C7-沥青质的结构特征及缔合行为

采用核磁(NMR)、小角散射分析(SAXS)、X射线光电子能谱(XPS)、改进的B-L法等手段,研究了煤基C7-沥青质(CT-asp)和石油基C7-沥青质(M-asp)两类沥青质的化学组成、官能团和分子结构等组成结构特征以及差异性,进而通过极性溶剂中沥青质稳定参数研究两类沥青质的缔合行为和聚集体尺寸以及两者之间的氢键和酸碱作用。结果表明,CT-asp分子芳香环数较少且有较多短烷基侧链,且芳香度较高,较高含量氧杂原子以芳香醚和酚羟基赋存形态为主;而M-asp的芳香核尺寸和平均相对分子质量明显高于CT-asp,芳香环数虽较多且有较多长烷基支链,且芳香度较小;两类沥青质缔合聚集程度关联物质的量比(n_(CT-asp)/n_(M-asp))及其分子结构特征,源于杂原子官能团的氢键和酸碱作用是两类沥青质缔合的主要作用力。     

Effects of petroleum resins on asphaltene aggregation and water-in-oil emulsion formation

Asphaltenes from four crude oils were fractionated by precipitation in mixtures of heptane and toluene. Solubility profiles generated in the presence of resins (1:1 mass ratio) indicated the onset of asphaltene precipitation occurred at lower toluene volume fractions (0.1–0.2) than without resins. Small-angle neutron scattering (SANS) was performed on solutions of asphaltene fractions in mixtures of heptane and toluene with added resins to determine aggregate sizes. Water-in-oil emulsions of asphaltene–resin solutions were prepared and separated by a centrifuge method to determine the vol.% water resolved. In general, the addition of resins to asphaltenes reduced the aggregate size by disrupting the π–π and polar bonding interactions between asphaltene monomers. Interaction of resins with asphaltenic aggregates rendered the aggregates less interfacially active and thus reduced emulsion stability. The smallest aggregate sizes observed and the weakest emulsion stability at high resin to asphaltene (R/A) ratios presumably corresponded to asphaltenic monomers or small oligomers strongly interacting with resin molecules. It was often observed that, in the absence of resins, the more polar or higher molecular weight asphaltenes were insoluble in solutions of heptane and toluene. The addition of resins dissolved these insolubles and aggregate size by SANS increased until the solubility limit was reached. This corresponded approximately to the point of maximum emulsion stability. Asphaltene chemistry plays a vital role in dictating emulsion stability. The most polar species typically required significantly higher resin concentrations to disrupt asphaltene interactions and completely destabilize emulsions. Aggregation and film formation are likely driven by polar heteroatom interactions, such as hydrogen bonding, which allow asphaltenes to absorb, consolidate, and form cohesive films at the oil–water interface.     

Adsorption isotherms of associating asphaltenes at oil/water interfaces based on the dependence of interfacial tension on solvent activity

In the Gibbs adsorption equation, the application of solvent activity for the calculation of the surface/interfacial excess is proposed for nonideal or associating or pseudocomponents such as asphaltenes. For the aforementioned systems, only the mass-based phenomenological interfacial excess can be determined based on interfacial tension versus activity data. The use of the mole fraction is compared to the use of the activity when the adsorbed amount of associating asphaltenes is calculated at a water/toluene interface. Langmuir-type isotherms describe the adsorption of asphaltenes at toluene/water interfaces. Asphaltenes were treated to remove the resins and natural surfactants using cyclic precipitation and dissolution of asphaltenes at a fixed aliphatic/aromatic ratio. Different fractions of asphaltenes were obtained by changing the aliphatic/aromatic ratio of the precipitating solvent. The limiting molar masses of asphaltenes measured by vapor pressure osmometry are different for fractions precipitated at different heptane to toluene ratios. The mass-based adsorbed amounts at the water/toluene interface, at a 0.1 asphaltene-to-toluene mass-ratio, varied in the range of 0.8-2.8 mg/m(2), depending on the molar mass of asphaltenes.     

Radiation-induced effects on alternative fuels

Solvent refined coal (SRC) produced from Indiana V feed coal was X-ray irradiated at different doses. The gases evolved from the irradiated sample consist mainly of methane, whose concentration is shown to depend on the irradiation dose. The condensed matter left after gas extraction was fractionated by column liquid chromatography into five non-polar fractions (saturated, monoaromatic, diaromatic, triaromatic and polyaromatic hydrocarbons); one of intermediate polarity (resins); and two polar (asphaltenes and asphaltols) fractions. The relative distribution of these radiolytic products depends upon the dose delivered with the concentration of hydrocarbons increasing remarkably with the dose.     

Aldehyde separation by polymer-supported oligo(ethyleneimines)

Chlorosulfonated styrene (10%) divinylbenzene resin beads reacted with an excess of ethylenediamine (EDA), diethylenetriamine (DETA), and triethylenetetramine (TETA) to give the corresponding sulfonamides with pendant oligo(ethyleneimines). The resulting modified resins are useful in the separation of aldehydes from hydrocarbon mixtures. Sorption of aldehydes occurs through formation of both Schiff base and five-membered (imidazoline) rings. Sorbed aldehydes can readily be stripped from the resins by treating with dilute acid solutions. Since the sulfamide bond has a reasonable stability toward acid-base hydrolysis, the loaded resins can be regenerated and recycled by simple acid-base washings, without losing their activity. In the present study, sorption and desorption kinetics of acetaldehyde, benzaldehyde, and salicylaldehyde have been investigated under different conditions. The aldehyde sorption obeys second-order kinetics. The method presented is applicable for all aromatic aldehydes. However, in the case of aliphatic aldehydes carrying an α-hydrogen, aldol condensation products form in solution. So aliphatic aldehydes and their aldol products are sorbed together by the resins. This limits the recovery of aliphatic aldehydes. Consequently, the resins described are cost effective sorbents for the removal and recovery of aromatic aldehydes from various mixtures. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2857–2864, 1997     

Effect of Asphaltenes and Resins on Asphaltene Aggregation Inhibition,Rheological Behaviour and Waterflood Oil-Recovery

This study presents an investigation about the influence of resins and asphaltenes, extracted from two Mexican crude oils (light and heavy oil samples), on the asphaltene aggregation inhibition, rheological behavior, and waterflood oil-recovery. Resins and asphaltenes were characterized by means of elemental analysis, metals analysis by atomic absorption, ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy, and electrospray ionization mass spectrometry (ESI-MS) in order to evaluate the effect of their structural parameters on the phenomena studied. Efficiency of the resins fraction as natural inhibitors of asphaltene aggregation was evaluated trough ultraviolet–visible (UV–vis) spectroscopy. Results showed better efficiencies of resins on asphaltene aggregation inhibition at resin/asphaltene (R/A) ratios close to unity and at high temperature. In addition, efficiencies were influenced by structural characteristics of the asphaltene–resin system. Rheological behavior of the heavy crude oil sample was significantly influenced by the presence of asphaltenes and resins. Finally, asphaltenes and resins played an important role on wettability and waterflood oil-recovery.     

大港常压渣油临氮与临氢热反应过程中胶体稳定性变化研究

对比了大港常压渣油临氮和临氢热反应过程中的胶体稳定性变化。结果表明,随着反应时间的延长,在热反应生焦诱导期内,渣油样品的胶体稳定性迅速下降;开始生焦后,胶体稳定性缓慢下降。从组分组成和组分性质角度,对大港常压渣油样品在热反应过程中胶体稳定性变化原因进行了分析。结果表明,随着反应时间的延长,沥青质含量先上升、后下降,在生焦诱导期结束时达到最大值,与体系胶体稳定性的变化特征相一致。随着热反应的进行,饱和分和轻芳烃组分的含量在上升,重芳烃、轻胶质、中胶质、重胶质含量下降,临氮热反应过程中轻胶质、中胶质、重胶质含量的下降更为显著。对渣油样品各组分的数均相对分子质量和平均偶极矩进行了研究。结果表明,随着热反应的进行,轻、中、重胶质组分的数均相对分子质量和平均偶极矩呈下降趋势,而沥青质的数均相对分子质量和偶极矩先增大后减小,从而使沥青质和胶质的分子性质差别先增加后减小,与体系胶体稳定性的变化趋势一致;同时沥青质的偶极矩变化表明,强极性的沥青质优先聚集生焦、临氢热反应过程中,氢与催化剂的作用有助于抑制沥青质分子量增大和极性增强,从而有助于抑制生焦。     

DPD Molecular Simulations of Asphaltene Adsorption on Hydrophilic Substrates: Effects of Polar Groups and Solubility

Adsorption of asphaltenes onto a polar substrate (e.g., a mineral) was modeled with dissipative particle dynamics (DPD) simulations, using continental asphaltene models. The adsorption mechanisms in 10–20% wt, of asphaltene in toluene/ heptane solutions were studied (well above the solubility limit). The structure in the adsorbed layer was highly sensitive to the presence of polar groups in the alkyl side chains and heteroatom content in the aromatic ring structure. Four types of asphaltene models were used: completely apolar (zero adsorption), apolar chains and polar heteroatoms, polar chains and no heteroatoms, and polar chains and heteroatoms (maximum adsorption). One hundred asphaltene monomers were distributed homogeneously in the solvent initially, in a ～(10 nm)³ domain.

Asphaltene monomers adsorbed irreversibly on the substrate via the polar group in the side chains, resulting in an average perpendicular orientation of the aromatic rings relative to the substrate. More frequent π–π stacking of the aromatic rings occurred for less solubility (more heptane), as in aggregates. With apolar side chains, only the heteroatoms in the aromatic ring structure had affinity to the substrate, but the ring plane did not have any preferred direction.

An important finding is that the aromatic ring assemblies “shielded” the substrate and polar groups that were anchored to the substrate, resulting in an effective non-polar surface layer seen by asphaltenes in the bulk, leading to much lower adsorption probability of the remaining asphaltenes. This “adsorption termination” effect leads to mono-layer formation. Continued adsorption with multilayering and reversible nanoaggregate adsorption occurred when both side chains in the model asphaltene (located on opposite sides of the aromatic sheet) contained polar groups, with a higher probability of exposing further polar groups to the bulk asphaltene. The general conclusion is that the number and position of the polar groups in side chains determine to a large degree the adsorption and aggregation behavior/efficiency of (continental) asphaltenes, in line with experimental evidence. The heteroatoms in the aromatic ring structure plays a more passive role in this context, only by providing organization via more π–π stacking in the adsorbed layer, and in aggregates.     

Synthesis and properties of biobased epoxy resins. part 1. Glycidylation of flavonoids by epichlorohydrin

Biobased epoxy resins were synthesized from a catechin molecule, one of the repetitive units in natural flavonoid biopolymers also named condensed tannins. The reactivity of catechin toward epichlorohydrin to form glycidyl ether derivatives was studied using two model compounds, resorcinol and 4‐methylcatechol, which represent the A and B rings of catechin, respectively. These model molecules clearly showed differences in reactivity upon glycidylation, explaining the results found with catechin monomer. The reaction products were characterized by both FTIR and NMR spectroscopy and chemical assay. The glycidyl ether of catechin (GEC) was successfully cured in various epoxy resin formulations. The GECs thermal properties showed that these new synthesized epoxy resins displayed interesting properties compared to the commercial diglycidyl ether of bisphenol A (DGEBA). For instance, when incorporated up to 50% into the DGEBA resin, GEC did not modify the glass‐transition temperature. Epoxy resins formulated with GEC had slightly lower storage moduli but induced a decrease of the swelling percentage, suggesting that GEC‐enhanced crosslinking in the epoxy resin networks. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Water‐in‐Crude Oil Emulsions in the Burgan Oilfield: Effects of Oil Aromaticity,Resins to Asphaltenes Content (R/(R+A)), and Water pH

Asphaltenes and resins separated from emulsion samples collected from Burgan oil field were used with heptane‐toluene mixtures as model oil to study the effect of oil aromaticity, resin content, and pH of the aqueous phase on the stability of water in model emulsions. It was confirmed that, as long as the asphaltenes are completely solubilized, increasing aromaticity leads to less stable emulsions. A consistent correlation between emulsion stability and relative resin mass content (R/(R+A)) was observed for all three of the field samples. There was a sharp decrease in stability when the R/(R+A) value exceeded 0.75. Emulsion stability was enhanced at high pH and possibly at very low pH (<2).     

大港常压渣油各组分平均偶极矩的研究

将大港常压渣油利用液相色谱法分成六个组分，测定了各组分的平均偶极矩。结果表明，渣油分子具有极性，饱和分和轻芳烃组分、重芳烃、轻胶质、中胶质、重胶质、沥青质的偶极矩依次增大，分别为1.19、2.88、3.79、4.92、6.36、11.70 Debye。元素分析表明，从饱和分和轻芳烃组分到沥青质组分，H/C原子比逐渐下降，表明H/C原子比减小与平均偶极矩增大有关；从饱和分和轻芳烃组分到沥青质组分，S/C、N/C原子比总体呈现上升趋势，渣油组分的杂原子含量与其极性有一定的关系，但两者并不完全一致，渣油组分分子的平均偶极矩还受到其他因素的影响。     

热改质过程中渣油结构及其重组分溶剂化变化规律研究

以委内瑞拉减压渣油为原料,采用微型反应釜,研究了其在410℃、2.0 MPa氮气初压下,不同反应停留时间的热改质过程生成油的化学结构组成及其重组分溶剂化变化规律。通过1H-NM R技术研究了热改质过程生成油中沥青质和重胶质不同化学位移归属氢的转化路径;并结合改进的Brown-Ladner法分析了热改质过程生成油中沥青质和重胶质的平均分子结构参数变化;采用蒸汽压渗透法考察了热改质过程生成油中沥青质和重胶质在甲苯溶液中所形成的复合超分子结构的平均相对分子质量。结果表明,随着热改质程度的加深,沥青质和重胶质的H/C原子比减小,供氢能力逐渐下降,沥青质和重胶质的芳香环共轭程度和fA在体系生焦后(45 min)显著提高;沥青质的聚集趋势相关值在热改质15 min前变化不大,15 min后显著增强,而重胶质在整个热改质过程中,其聚集趋势相关值的增势较为缓和;沥青质和重胶质的聚集趋势相关值差异逐渐增大,15 min时增加了1.5%、25 min时增加了50.8%、45 min时增加了142.3%,表明沥青质和重胶质的结构差异越来越明显;重胶质溶剂化沥青质的能力逐步减弱,体系的溶剂化参数从0时的32.9%逐步降到15 min时的29.5%、25 min时的14.1%和45 min时的9.6%;热改质生成油的斑点实验等级逐渐增加,体系的胶体稳定性逐渐降低。