STUDY OF SERIAL REACTION KINETICS AND CHANGES OF GROUP COMPOSITIONS OF PETROLEUM ASPHALTS IN CONTINUOUS HEAT AND AIR AGING

ABSTRACT

The serial reaction kinetics and the changes of group compositions of Shengli petroleum asphalt(SPA) and Huansanlian petroleum asphalt(HPA) were studied during continuous heat and air aging(CHAA) at 120 ～ 180°C. The test results show that at given temperature the contents of saturate constituents of two asphalts change very little, aromatic constituents decrease clearly and asphaltenes increase gradually during CHAA. At lower temperatures(120 ～ 140 °C) the contents of resins increase slowly and no toluene insolubles form obviously, but at higher temperature(180°C) the resins increase at first and then decrease and the toluene insolubles increase much quickly with the CHAA time. The higher the CHAA temperature, the more evidently the change of asphalt group compositions would change. The apparent aging rate constants and the apparent aging activation     

Influence of Chemical Composition on the Physical Characteristics of Paving Asphalts

Abstract

The simplest general compositional model considers asphalt to be made up of asphaltenes, heavy oils, and resins. In the present study the extent of similarity between the properties and composition of various types of asphalt obtained from different sources has been carefully explored. It shows how ductility, penetration, and softening point are related to the chemical nature of paving asphalts in the range 41–58 softening points. Asphalt properties are found to be a direct function of its chemical constituents. The relationship between softening point and asphaltene content was found to be linear while asphalts of the same softening point are easily distinguished by the content of the resins. Evaluation of the two asphalt indices—the asphaltene index (I _A ) and the Gaestel index (I _C ), reveals that they both vary linearly with the composition of asphaltenes and resins thus confirming their suitability in the characterization of asphalts. Comparison of the two indices shows that IC is more suitable in estimating the colloidal stability of different groups of asphalts. The observed correlations can be found useful in the areas of asphalt blending and rejuvenating through the appropriate selection of asphalt components.     

Study and Evaluation of Aging Performance of Petroleum Asphalts and Their Constituents During Oxygen Absorption. I. Oxygen Absorption Behaviors and Kinetics

Abstract

The oxygen absorption behaviors and kinetics of Shanjiasi, Shengli, and Renqiu petroleum asphalts and their constituents including saturates, aromatics, resins, and asphaltenes were successfully studied at 50°C, 0.133 MPa (O₂) and 1 mm sample film in darkness by means of precise measurement of oxygen pressure changes in reactor. The experimental results that the resin and the asphaltene can easily absorb oxygen and they are more active constituents in petroleum asphalt, while the saturate hardly absorbs oxygen, which is the most stable constituent of petroleum asphalt. The better the antiaging performance of straight run petroleum asphalt, the more stable its constituents and the less oxygen they absorb generally. The oxygen absorption rate of asphaltene diluted with the lower viscous saturate is obviously higher than that of pure asphaltene. The resin constituent of Shanjiasi asphalt could remarkably improve the antiaging ability of Shengli asphalt by the constituent substitution. The kinetic model of maximum combined oxygen presented in this paper could satisfactorily explain the oxygen absorption behaviors of petroleum asphalts and their constituents, and the oxygen absorption quantities calculated by the model are very identified with the test ones.     

A six-lumped kinetic model of pyrolysis of heavy oil in supercritical methanol

The product distribution of pyrolysis of heavy oil in the supercritical methanol (SC-MeOH) was studied. It could be found that the pyrolysis reaction rate enhanced with the increase of temperature. Compared with reaction in N₂, the coking formation was promoted in SC-MeOH. It was attributed to “cage effect” caused by methanol. The aromatics and resins which can dissolve asphaltenes were isolated by cages. Therefore, more coke was formed by condensation of asphaltenes. A lumped reaction kinetic model modified by equilibrium mass fraction of aromatics and resins was established, which could describe and predict the products distribution in SC-MeOH.     

CHANGES IH CHEMICAL COMPONENT TYPE COMPOSITION AND EFFECT ON RHEOLOQICAL PROPERTIES OF ASPHALTS

ABSTRACT

Component type compositions were changed by blending with fractionated materials and the effects of these changes on the Theological properties were studied. Thus, saturated hydrocarbons, naphthene aromatics, propane precipitated asphalts and waxes were blended with both good and poor paving asphalts. Changes in penetration index, low temperature stiffness, ductility and glass transition temperature were examined. The composition of a number of asphalts including air blown and visbroken asphalts and their Theological properties were also examined in these studies to obtain correlations     

PREPARATIVE SIZE-EXCLUSION CHROMATOGRAPHY SEPARATION OF SHRP ASPHALTS: CORRELATION WITH YISCOELASTIC PROPERTIES

ABSTRACT

Eight core asphalts and eleven other asphalts selected for study in the Strategic Highway Research Program have been separated into two or more fractions by means of preparative size-exclusion chromatography. The first fraction obtained by this technique is believed to consist of materials that form associations and correspond roughly to asphalt dispersed phases. This phase is polar, aromatic, and of high apparent molecular weight. Subsequent fractions obtained by size exclusion chromatography of the asphalts are of progressively lower molecular weight. When the asphalts were separated into nine fractions, the weights of each fraction were plotted versus elution volume to give distinctive bimodal chromatograms, with one exception.

The first eluted size exclusion fractions consist of the major viscosity-building components of the asphalts. When these fractions are removed from asphalts, the weight fractions of the residual materials correlate with tan δ (ratio of viscous to elastic moduli)s of the whole asphalts at 26° (77°F). Gel-type asphalts have low values of tan δ and large amounts of material in their initially eluted size-exclusion chromatography fractions. For sol-type asphalts, the reverse is true. For the nineteen asphalts studied size-exclusion chromatography fractionation patterns, which are a fundamental chemical property, correlate with the aforementioned fundamental physical property     

CHANGE IN COMPOSITION AND STRUCTURE OF REDUCED CRUDES DURING CONVERSION ON CONTACT MATERIAL

ABSTRACT

Four Chinese 350°C+ reduced crude feedstocks were heated thermally in the presence of a contact material at 480–540°C in a fixed bed reactor. The feed and products were fractionated into eight fractions using normal pentane precipitation and alumina adsorption chromatography and average molecular parameters calculated with a modified Brown-Ladner method. The results obtained show that the conversion of various fractions of the reduced crudes was quite different. The conversion of asphaltic substances was much higher than those of saturates and aromatics. It is shown that the CH₂/CH₃ ratio, aromaticity and the numbers of aromatic, naphthenic and total ring of heavy products were obviously lower than those of reduced crudes. The effect of temperature on metal, sulfur, nitrogen removal has been also investigated. The data indicate that the removal of weak polar non-porphyrin nickel was larger than that of middle and strong polar nickel complex.     

Group Type Analysis of Asphalt by Column Liquid Chromatography

An improved analysis method for characterization of asphalt was established. The method is based on column chromatography technique. The asphalts were separated into four groups: saturates, aromatics, resins, and asphaltenes, quantitatively. About 0.1 g of sample was required in each analysis. About 20 mL of n-heptanes was used to separate out saturates first. Then about 35 mL of n-heptanes/dichloromethane (1/2.5, v/v) mixture was used to separate out aromatics. About 30 mL of dichloromethane/tetrahydrofuran (1/3, v/v) mixture was used to separate out resin. The quality of the separation was confirmed by infrared spectra (IR) and ¹H NMR analysis. The model compounds, tetracosan for saturates, dibenz(ah)anthracen for aromatics, and acetanilide for resins were used for verification. The IR and ¹H NMR analysis of the prepared fractions from the column liquid chromatography were in good agreement that of pure reagents.     

Study on product distribution and catalytic performance of ZSM-5 in methanol conversion to gasoline-range hydrocarbons (MTHC)

Precise product distribution data is very important for kinetic modeling of chemical reactions and chemical reactor design. In this work, H-ZSM-5 catalyst was hydrothermally synthesized and characterization tests including XRD, XRF, BET, and NH₃-TPD revealed its physicochemical properties. Then, methanol conversion into hydrocarbons over ZSM-5 was investigated with WHSV of 4 h^?1 at reaction temperature 410°C. Product distribution result indicated that C₃-C₅⁺ and C₂⁼-C₄⁼ were the major products in gaseous phase, and in liquid phase xylenes, three methyl benzene and C₁₀⁺ aromatics were the main components. It was also observed that the synthesized ZSM-5 had good performance in the methanol to hydrocarbons process and gave rise to highest activity (100%) during 10 h of operation approximately.     

热反应对辽河重油胶质及沥青质性质的影响

辽河重油于高压反应釜中分别在350,375,400 ℃下加热反应2 h。对油样的饱和分、芳香分、胶质和沥青质进行了分离。并对其沥青质和胶质进行了元素分析,VPO相对分子质量测定,IR分析和H-NMR分析。结果表明：反应温度升高,(沥青质+饱和分)/(胶质+芳香分)比值上升,胶体的稳定性下降。热反应中,沥青质、胶质的分子骨架结构未发生破坏,但是侧链发生断裂;反应温度375 ℃后,沥青质、胶质等重组分分子侧链的断裂变化较小,而缔合程度增强。     

CHANGES IN ASPHALT CHEMISTRY AND DURABILITY DURING OXIDATION AND POLYMER MODIFICATION

The Gulf Countries' environmental conditions are very severe. The temperature zoning study indicate that more than half of Gulf areas experience a maximum seven consecutive days pavement temperature of 76°C (Al-Abdul Wahhab et al., 1997). This has resulted in damage to the road networks in the form of cracking, rutting and deformation. Polymer modification of asphalt is required to increase the resistance to permanent deformation at relatively high temperatures without adversely affecting the properties of the asphalts at low temperature. In this work chemical and performance-related properties of fresh, oxidized, and polymer modified asphalts were evaluated. The physical properties and performance characteristics of asphalts were found to depend on the chemical composition of asphalt. The interactions of polar functionalities actually present or formed during oxidative aging or due to polymer modification, influence the viscosity and related flow properties. The changes in composition of fresh, oxidized and polymer-modified asphalts can be clearly identified from Infrared spectroscopy. NMR spectroscopy enables detailed information about the Carbon-and-hydrogen-types and average molecular/structural parameters of asphalt without separating it into different components.     

用催化裂化重质芳烃制备多环芳烃树脂

以催化裂化回炼油中抽提出的重质芳烃为原料，在酸性催化剂作用下，与交联剂多聚甲醛反应制备多环芳烃树脂，对多环芳烃树脂进行了初步评价，结果表明：两种后处理工艺路线（溶剂沉降过滤法和减压蒸馏拔头法）得到的多环芳烃树脂平均相对分子质量较低，具有较好的热稳定性。与催化裂化重质芳烃原料相比，未反应芳烃油显示了较好的安定性，将多环芳烃树脂掺入聚氨酯系涂料中，试制的改性双组分聚氨酯系防腐涂料性能良好，具有一定的开发应用价值。     

Structural Changes of Sub-fractions in Residue Hydrotreating Products by Ruthenium Catalyzed Oxidation

Abstract

Structure of aromatics, resins, and asphaltenes in petroleum residue was undertaken by using ruthenium ion catalyzed oxidation. The distribution of alkyl side chains and bridges connected to aromatic rings was quantified, and the condensed type of aromatic rings was deduced. The structural changes of fractions in residue during hydrotreating were discussed. The results showed that fractions have abundant alkyl side chains (C₁–C₂₇), mainly n-alkyl side chains, attached to aromatic carbons, and polymethylene bridges connected to at least two aromatic ring systems are also present. The molar concentrations of these alkyl groups are declined as the increase of chain length. Cata-condensed, peri-condensed, and biphenyl-type aromatic unit structures coexist in fractions, while the proportion of biphenyl type structure is relatively small. The aromatic structure of aromatics is mostly cata-condensed, while for resins the proportion of cata-condensed and peri-condensed type aromatic structures is comparable, and structure of asphaltene is mostly peri-condensed. The chemical structure of fractions in residue changed due to the increase of hydrotreating degree. The enrichment of large aromatic units made asphaltene have more aromatic structures and higher condensed degree.     

STRUCTURAL CHARACTERIZATION OF ARABIAN HEAVY CRUDE OIL RESIDUE

ABSTRACT

The residue (370°C+) from Arabian Heavy Crude Oil was separated into four fractions, asphaltenes, resins, aromatcis and saturates. The four fractions were found to be free of artifacts and analytically significant in themselves. Each fraction was further characterized by elemental analysis, infrared spectroscopy, n.m.r. spectroscopy and mass spectroscopy. The aromatics are the major constituent of the residue and the ratio of asphaltenes, resins, aromatics and saturates is about 2:3:8:3. The strucutral characterization study led to the conclusion that asphaltene fraction is maximum hydrogen deficient followed by resins, aromatics and saturates thus suggesting larger degree of ring condensation in the structure of asphaltenes than resins and aromatics.     

Blending modification of Tahe vacuum residuum using Chunfeng vacuum residuum

Abstract

Utilization of vacuum residue resources has been receiving extensive research interests in order to maximize the economic benefits of refineries. In present work, Tahe vacuum residuum (THVR) was blended with Chunfeng vacuum residue (CFVR). The influences of addition of CFVR on properties of THVR were investigated and the average molecular structures of SARA (referring to saturates, aromatics, resins and asphaltenes) of base and modified THVR were determined by using experimental and simulation methods. The results show that CFVR has better low-temperature performance but worse temperature susceptibility as compared with THVR. The blending TH-CF-40 sample containing 40% CFVR can meet the standard of 60# road petroleum asphalt. The saturate of TH-CF-40 has the L of 14.44, which is smaller than that of THVR. Moreover, the aromatic, resin and asphaltene have f_A of 0.29, 0.42 and 0.46, R_A/R_N of 1.24, 2.65 and 2.93, and L of 6.78, 6.09 and 5.40. CFVR shows the similar molecular structure to THVR, therefore, contributes to the improved low-temperature ductility of blending TH-CF-40. Present results can provide theoretical guidance on the optimization utilization of vacuum residue resources.     

Generation of adamantanes and diamantanes by thermal cracking of polar components of crude oils of different genotypes

The thermal cracking of polar petroleum compounds—resins and asphaltenes—isolated from crude oils of different genotypes was carried out, with C₁₀-C₁₃ adamantanes and C₁₄-C₁₆ diamantanes being produced as a result. It was assumed that resins and asphaltenes contain the adamantane and diamantane moieties in their molecular structure. An explicit relation between the distribution of C₁₀–C₁₃ adamantanes in crude oils, thermal cracking products of high-molecular-mass (bp >350°C) saturated fractions, and the products of thermal cracking of resins and asphaltenes was revealed. The distributions of C₁₄–C₁₆ diamantanes in the cracking products of resins and asphaltenes are close to one another and correlate well with their distribution in the products of thermal cracking of high-molecular-mass (>350°C) saturated fractions, but differ from the distribution in oils. The products of thermal cracking of resins and asphaltenes almost completely lack cyclic hydrocarbons and contain only a small amount of remaining n-alkanes and isoprenanes.     

SIZE EXCLUSION CHROMATOGRAPHY STUDIES OF AGED SHRP ASPHALTS

Abstract

One of Ihe objectives of the Strategic Highway Research Program is the development of a test procedure that accurately predicts pavement aging. In order to accomplish this goal, the nature and mechanism of oxidative-aging of asphalts must be known.

Eight asphalts were aged in a pressure-oxidation vessel at 60°C (140°F) and 2.07 x 10⁶ Pa (300 psi) for 144 hours (6 days) after a preliminary thin-film oven treatment. The tank asphalts and aged asphalts were separated by preparative size exclusion chromatography into two fractions: one consisting of large molecular size, associated molecules and the other consisting of smaller molecules with less tendency lo associate. The amount of the large molecular size fraction is greater in an aged asphalt compared with its parent tank asphalt. Number-average molecular weights of this large molecular size fraction increase substantially in some aged asphalts but not in others. Viscosities of smaller molecular size fractions (which comprise the bulk of both aged and unaged asphalts) of aged asphalts are not greatly different from viscosities of corresponding fractions of parent tank asphalts. Viscosities of the small molecular size fractions are much lower than viscosities of whole asphalts. Oxygen-containing functional groups were observed in both size exclusion chromatography fractions of all eight aged asphalts.

The above results can be rationalized by invoking a model of asphalt structure in which complex structural units composed of polar and/or aromatic molecules arc dispersed in a less polar solvent phase. The aping process causes buildup of more polar molecules, which increases the relative amounts of asphalt components that engage in associative behavior.     

RESIDUUM HYDROTREATING APPLICATION OF IH AND QUANTITATIVE CARBON-13 NMR SPECTROSCOPY FOR THE STUDY OF HYDROTREATED PRODUCTS

ABSTRACT

Bai-Hassan reduced crude (350^°C + ) was hydrotreated in fixed bed reactor with commercial Ni-Mo-alumina catalyst. H and quantitative C NMR are used to derive statistical average structure parameters of feedstock and hydrotreated products. The main aromatic hydrocarbons (of type C_ar,H + C_ar,CH₃ + C_ar,n + C_ar,I) of hydrotreated products decreases by temperature, (at mild conditions) particularly at lower space velocity. The severe operating conditions increases the main aromatic hydrocarbons. An approximate inverse correlation is observed between the behaviour of saturated hydrocarbons and the aromatics of type C_ar,H + C_ar,CH₃ + C_ar,n + C_ar,I during hydrotreating process. Higher temperatures show an increase in the percentage of alkyl aromatics of type C_ar,alkFurthermore, the severe operating conditions promotes the formation of the alkyl aromatics with H_α(ArCH₃) while it decreases the alkyl aromatic having H₈ and H₈ The kinetic study of napthenes formation indicates that this reactin is well correlated with a first-order kinetics. The apparent activation energy lpar;E rpar;, enthalpy lpar;? H rpar;and entropy lpar;? s?lpar; of activation are 23.630 KJ mol 18.390 kJ mol ^-1 and -225.95 J mol^-1 k^-1 respectively.     

Production of High-Grade Asphalt from Liaoshu Crude Oil

Abstract

The high viscous crude oil for Shuguang No. 1 zone of Liaohe oilfield has the characteristics of high density (ρ₂₀ = 0.9977 g.cm^?3), high viscidity (ν₁₀₀ = 1,223.9 mm².s^?1), and high solidifying point (SP = 48°C), which belongs to low sulfur naphthene-base crude oil. The comprehensive evaluations indicate that this oil has no gasoline fraction and the diesel oil is only 7.19%. In addition, the lubricating oil distillate is not suited to produce lubricating oil and heavy oil is not good feedstock for catalytic cracking. However, the low wax and high resin, as well as asphaltene content, make it an ideal raw material for producing paving asphalt. The vacuum residue of this crude acted as base oil and three kinds of waste oil with high aromatics and low wax content were selected as blenders. Various brands of high-grade paving asphalts meeting GB/T15180-94 (China) specification were produced by blending method. The blending effects were investigated and corresponding mathematics models were set up.     

油基钻井液天然岩沥青降滤失剂的环保性能

为了解决环保油基钻井液中低成本降滤失剂环保问题,采用致癌多环芳烃含量和急性生物毒性检测对天然岩沥青降滤失剂进行环保性能评价。结果表明,天然岩沥青降滤失剂中未检出致癌多环芳烃,掺入3%天然岩沥青的白油基钻井液体系污染后的岩屑EC₅₀值为104 751 mg/L,达到环保无毒标准。沥青族组成分析结果表明,天然岩沥青中不含低分子量的饱和分和芳香分,可变形的胶质组分含量为13.83%,其余为刚性的沥青质,所有组成均可参与封堵泥饼空隙,起到降滤失效果。天然岩沥青在油基钻井液体系中150℃高温高压滤失量不大于3.7 mL,200℃高温高压滤失量不大于4.0 mL。天然岩沥青降滤失剂绿色环保、降滤失效果稳定,可用于环保油基钻井液体系。