THE EFFECT OF ASPHALT COMPOSITION ON THE FORMATION OF ASPHALTENES AND THEIR CONTRIBUTION TO ASPHALT VISCOSITY

Interactions among asphalt components have significant effects on the performance of asphalt binder. To understand those interactions, four asphalts, SHRP AAA-I, AAD-I, AAF-I, and AAG-I, were fractionated into three generic fractions according to Corbett's procedure and reblended into asphaltenes/aromatics/saturates ternary mixtures in various ratios. Mixtures were oxidatively aged with atmospheric air at temperatures of 87.7, 93.3, and 98.8°C for 5 to 33 days. The changes in chemical composition and physical properties were monitored using fourier transform infrared spectroscopy (FT-IR) and dynamic mechanical rheometry

The formation of asphaltenes is a major factor in the hardening of asphalt with aging. The data collected in this study indicate that the saturate content in the maltene phase has a profound impact on the contribution that asphaltenes have on the viscosity of aged asphalt. The data also suggest that the aromatics fraction is solely responsible for the formation of asphaltenes as an asphalt oxidizes.     

EFFECT OF EXPERIMENTAL CONDITIONS AND SOLVENTS ON THE PRECIPITATION AND COMPOSITION OF ASPHALTENES

The ASTM D 3279 test method for “n-Heptane Insolubles” is being currently used to determine the asphaltene content of fuel oils as defined by insolubility in normal (n) heptane solvent. Precipitation of n-heptane insolubles can produce sediments which vary in color, morphology and composition. The SEM analysis of n-heptane insolubles indicated that the sediments were heterogeneous containing some large particles >300 μ and the majority of particles to be small, <10 μ, “chained” together forming agglomerates. Significant fractions of n-heptane insolubles were found insoluble in toluene indicating their non-asphaltenic nature (“solids”). FTIR and XRF analyses of “solids” indicated the presence of multiring aromatics, Ni and carboxylate and sulfate salts. FTIR analysis of toluene soluble asphaltenes showed the presence of multiring aromatics. GC/MS analysis of toluene soluble asphaltenes indicated desorption of alkylbenzenes and O-containing molecules but no desorption of N- and S-containing molecules was observed. The tendency for N- and S-containing molecules to remain in the nonvolatile residue during the GC/MS analysis indicates that the N- and S-containing compounds have higher stability. The XRF analysis of the toluene soluble asphaltenes indicated that the molecules are similar to asphaltenes found in crude oils in terms of C, H, N and S contents, however, no presence of V- and Ni-containing molecules was found.     

EFFECT OF PRECIPITATION TEMPERATURE ON THE COMPOSITION OF N-HEPTANE ASPHALTENES

Petroleum asphaltenes were separated from Boscan and Kuwait crude oils by n-heptane at constant temperatures ranging from -2 to 80 ° C. A decreased yield with increase in temperature was observed. The precipitated material was characterized using infrared spectroscopic functional group analysis, HPLC-size exclusion chromatography, vapor pressure osmometry, and elemental analysis. The change in vanadium porphyrin content was estimated for Boscan using UV-Vis. With elevated temperature the asphaltenes are more aromatic (lower H/C) and have higher apparent molecular weight, whereas the pattern of changes in functional groups and heteroatoms (NSO) are more complex and apparently dependent on the crude oil. Porphyrins and low molecular weight types were seen to stay in solution at increased temperature, and a specific extraction of these takes place above 40 ° C. Asphaltene solubility is seen to approximate the Flory-Huggins theory as small molecules go into solution before large molecules. Several other mechanisms may, however, be involved in the phase separation. The molecular size distribution curves obtained by HPLC-SEC were found to explain the trends found in the molecular weights by VPO.     

沥青降粘剂对沥青性能影响研究

针对沥青热拌和施工过程中的环保问题,以基质沥青为原料,研究分析了中国石化齐鲁分公司研究院自主开发的沥青降粘剂VR-Q1对沥青的降粘效果及对沥青各项性能的影响。试验结果表明,该沥青降粘剂降粘效果好,能够提高沥青高、低温性能。与国内外两种市场性能较好的降粘剂相比较,VR-Q1对沥青高温降粘、低温增粘效果显著,同时表现出优异的高、低温性能。     

EFFECT OF PRECIPITATION TEMPERATURE ON THE COMPOSITION OF N-HEPTANE ASPHALTENES Part 2

ABSTRACT

Petroleum asphaltenes precipitated by n-heptane at temperatures between ambient and 80^°C from two crude oils have been characterized regarding hydrocarbon structures using ¹H and ¹³C nmr, and fluorescence spectroscopy. This indicates a very complex and apparently very small change in structural features except for a molecular weight increase as more material stays in solution at elevated temperature. Aromaticity increase and apparently alkyl chains diminish. The latter trend is however affected by the structural equation used. According to the fluorescence spectroscopy the content of large and complex chromophores increases but a significant effect of the presence of porphyrins on the spectra is also observed. The data is analyzed in combination with previous characterizations of the same asphaltenes presented in the first part of this work (Andersen, 1994). This indicates that as smaller molecules are extracted at elevated temperature the precipitated asphaltenes tend to associate more. This implys that these small molecules block association sites which therefore become available for further association at elevated temperature. For Boscan part of the smaller easy to extract porphyrins may have this behavior.     

EFFECT OF PRECIPITATION TEMPERATURE ON THE COMPOSITION OF N-HEPTANE ASPHALTENES Part 2

Petroleum asphaltenes precipitated by n-heptane at temperatures between ambient and 80^°C from two crude oils have been characterized regarding hydrocarbon structures using ¹H and ¹³C nmr, and fluorescence spectroscopy. This indicates a very complex and apparently very small change in structural features except for a molecular weight increase as more material stays in solution at elevated temperature. Aromaticity increase and apparently alkyl chains diminish. The latter trend is however affected by the structural equation used. According to the fluorescence spectroscopy the content of large and complex chromophores increases but a significant effect of the presence of porphyrins on the spectra is also observed. The data is analyzed in combination with previous characterizations of the same asphaltenes presented in the first part of this work (Andersen, 1994). This indicates that as smaller molecules are extracted at elevated temperature the precipitated asphaltenes tend to associate more. This implys that these small molecules block association sites which therefore become available for further association at elevated temperature. For Boscan part of the smaller easy to extract porphyrins may have this behavior.     

30号硬质道路沥青组成结构对使用性能影响的机理研究

30号硬质道路沥青对提高路面高温稳定性能有显著效果,为探索影响沥青质量的内在因素,以溶剂脱沥青工艺制备的阿曼30号沥青和沙中30号沥青为研究对象,研究组成结构对使用性能的影响机理。结果表明,两种30号沥青均满足GB/T 15180—2010的要求,相比沙中30号沥青,阿曼30号沥青具有较好的高低温性能、抗老化性能和感温性能。组成结构研究表明,沥青的使用性能与其组成结构有着重大关联,不仅与组成存在比例关系,同时也与其内部结构紧密相关。相对于沙中30号沥青,阿曼30号沥青中各组分相对分子质量分布较宽,同时平均相对分子质量较高,各组分之间f_A,H/C,R_A/R_N,H_(AU)C_A等结构参数的差异性较小,胶体稳定指标I_c较高,主要组分芳香分、胶质和沥青质具有较长的侧链。高胶体稳定系数、较宽的相对分子质量分布、较小的组分结构差异性和具有长侧链等特点有利于形成稳定的胶体结构,进而使30号沥青体现出良好的高低温性能和抗老化性能。     

RELATIONSHIPS BETWEEN ASPHALTENES,HEITHAUS COMPATIBILITY PARAMETERS,AND ASPHALT VISCOSITY

ABSTRACT

Historically, asphalt rheology has been described in terms of a colloidal model, which depicts asphalts as dispersions of asphaltenes in petrolenes (maltenes). The model leads to a classification of asphalts into sol, gel, or intermediate categories. Sol and gel type asphalts exhibit differences in physical and chemical behavior. Sol asphalts also are described as compatible, while gel asphalts are described as non-compatible. The relative viscosity of an asphalt, defined as the quotient of the viscosity of the whole asphalt divided by the viscosity of the n-heptane soluble maltene fraction at a given temperature and rate of shear is one measure of asphalt compatibility. Based on this definition of compatibility, asphalts with low values of relative viscosity are designated as compatible and higher values of relative viscosity are designated as incompatible. Asphalt compatibility is also related to the asphaltene content, where asphalts with low asphaltene content are designated as compatible. It is claimed that the Heithaus parameters also are measures of asphalt compatibility. Therefore there should be a relationship between relative viscosities (π_rel), Heithaus parameters, and n-heptane asphaltene volume fractions ( φn-heptane)- Such a relationship has been derived assuming that the Heithaus p_a parameter is numerically equivalent to α in the Pal-Rhodes equation.     

THE INFLUENCE OF PRESSURE ON THE ASPHALTENES CONTENT AND COMPOSITION IN OILS

The objective of this work was to investigate the effect of pressure on the concentration of the dissolved asphaltenes in a heavy oil. The asphaltenes content was determined in oil samples, produced at reservoir temperature and different pressures ranging from the initial reservoir pressure to the atmospheric one, using the standard IP143/90 method. Additionally, the content of nine trace metals in the asphaltenes, produced at each pressure step was studied by Total Reflection X-Ray Fluorescence (TXRF). It was found that the amount of the dissolved asphaltenes in oil decreases as pressure falls from the initial reservoir pressure down to bubble point pressure and subsequently increases as the pressure is reduced further. A positive correlation was observed between the concentration of several metals (Ni, V, Cr, Mn) and the dissolved asphaltenes content.     

THE INFLUENCE OF PRESSURE ON THE ASPHALTENES CONTENT AND COMPOSITION IN OILS

The objective of this work was to investigate the effect of pressure on the concentration of the dissolved asphaltenes in a heavy oil. The asphaltenes content was determined in oil samples, produced at reservoir temperature and different pressures ranging from the initial reservoir pressure to the atmospheric one, using the standard IP143/90 method. Additionally, the content of nine trace metals in the asphaltenes, produced at each pressure step was studied by Total Reflection X-Ray Fluorescence (TXRF). It was found that the amount of the dissolved asphaltenes in oil decreases as pressure falls from the initial reservoir pressure down to bubble point pressure and subsequently increases as the pressure is reduced further. A positive correlation was observed between the concentration of several metals (Ni, V, Cr, Mn) and the dissolved asphaltenes content.     

盆地形成演化对粘土矿物组成和分布的影响

物源、古气候、沉积环境和成岩作用是控制含油气盆地内泥岩粘土矿物分布特征的4个主要因素,这4个因素均与盆地形成的大地构造背景和构造发育史密切相关.我国东、西部含油气盆地的大地构造背景、形成机制和构造发育史明显不同,文中研究了这些因素对泥岩粘土矿物分布特征的影响.     

EFFECT OF DISPERSANTS AND FLOCCULANTS ON THE COLLOIDAL STABILITY OF ASPHALTENES

Since the traditional deasphalting process is expensive, a more economical approach would be to use dispersants or flocculants to control the colloidal stability of asphaltenes. The asphaltene content of fuel oils is defined by testing the n-heptane insolubles following the ASTM D 3279 method. In the presence of dodecylbenzenesulfonic acid, a decrease in n-heptane insolubles precipitation was observed indicating an increase in their colloidal stability. No significant change in n-heptane insolubles precipitation was observed in the presence of dodecylphenol and nonylphenol. Poly(maleic anhydride-1-octadecene) polymer was found to be an effective flocculant. The flocculation of n-heptane insolubles varied depending on the polymer-to-asphaltenes weight ratios. The FTIR results indicate that the flocculation occurs through the H-bonding between the asphaltenes and the polymer molecules. Maleic anhydride was found to continuously increase the n-heptane insolubles precipitation with an increase in its treat rate. The FTIR analysis showed the presence of an acidic C=O group and no presence of an anhydride functional group. The results indicate that the presence of an anhydride and unsaturation makes the maleic anhydride too reactive leading to chemical changes and the precipitation of asphaltenes and other aromatic molecules found in fuel oils.     

EFFECT OF DISPERSANTS AND FLOCCULANTS ON THE COLLOIDAL STABILITY OF ASPHALTENES

Since the traditional deasphalting process is expensive, a more economical approach would be to use dispersants or flocculants to control the colloidal stability of asphaltenes. The asphaltene content of fuel oils is defined by testing the n-heptane insolubles following the ASTM D 3279 method. In the presence of dodecylbenzenesulfonic acid, a decrease in n-heptane insolubles precipitation was observed indicating an increase in their colloidal stability. No significant change in n-heptane insolubles precipitation was observed in the presence of dodecylphenol and nonylphenol. Poly(maleic anhydride-1-octadecene) polymer was found to be an effective flocculant. The flocculation of n-heptane insolubles varied depending on the polymer-to-asphaltenes weight ratios. The FTIR results indicate that the flocculation occurs through the H-bonding between the asphaltenes and the polymer molecules. Maleic anhydride was found to continuously increase the n-heptane insolubles precipitation with an increase in its treat rate. The FTIR analysis showed the presence of an acidic C=O group and no presence of an anhydride functional group. The results indicate that the presence of an anhydride and unsaturation makes the maleic anhydride too reactive leading to chemical changes and the precipitation of asphaltenes and other aromatic molecules found in fuel oils.     

实验温度对沥青质热解的影响

本项研究主要是通过不同温度条件下的沥青质热解实验,研究热解温度对生物降解原油中生物标志物的恢复可能产生的影响。研究结果表明 340℃时,沥青质组分具有最大的产油率。另外,300℃之前,热解温度对沥青质热解产物中生物标志物的组成分布影响较小。因此,对于采用生物标志物恢复的方法来进行油/油对比时,300℃是沥青质热解实验较合适的温度。     

油品组成对废橡胶改性沥青性能的影响

以催化裂化油浆(FCC)和糠醛抽出油(FEO)为原料,利用溶剂萃取法来减少油品中的饱和分质量分数。分别以萃取前后的油品作为改性沥青相容剂,对比了在预混工艺下经四种相容剂制备的改性沥青的性能。采用凝胶色谱、元素分析和核磁共振分析手段,对油品的相对分子质量、元素组成和组成结构进行了表征。实验结果表明,胶粉经两种萃取油预处理后制备的改性沥青的5℃延度和高温存储稳定性显著得到改善。FEO的萃取油中因含有相对较多与沥青相容性好的稠环芳烃以及对橡胶有较好溶胀作用的大环烷烃,采用其所制备的改性沥青的高温存储稳定性最好。     

沥青粘滞性对混合料蠕变特性的影响

从解决沥青路面的车辙、拥包等问题出发，研究了沥青混合料的蠕变特性、沥青结合料的剪切蠕变，以及沥青混合料的劲度模量与沥青粘度的关系。研究结果认为，现行的马歇尔试验方法不足以评价沥青混合料的热稳定性；蠕变试验能充分反映沥青混合料的粘流性质，说明沥青路面产生车辙的机理；沥青结合料的粘度对混合料的抗永久变形能力有直接影响，因此抗车辙沥青结合料必须具备足够的粘度。     

道路石油沥青中蜡对沥青性质的影响

测定了大庆和辽河１００号道路石油沥青中蜡的分布,并将其中的饱和蜡,芳香蜡,总蜡分离出来,用其与脱蜡沥青调制成蜡含量不同的系列样品,考察了饱和蜡,芳香蜡对沥青物理性质的影响,总蜡对沥青路用性能的影响,对沥青质量指标中否应设置蜡含量指标进行了讨论．     

微生物对沥青集料间粘附作用的影响

沥青混合料的剥离是沥青路面几种常见破坏现象之一。通常认为沥青混合料水稳性主要依靠沥青与集料间的粘附程度，它同沥青集料间的物理化学作用密切相关。本文分析了微生物对沥青集料粘附作用的影响，这对改善沥青路面水稳性有重大意义。     

燃气组分变化对重整燃烧器燃烧过程及炭粒生成的影响

采用数值模拟方法对连续重整加热炉燃烧器的流动和燃烧过程进行研究,分别考察氢气、甲烷、乙烷、丙烷和丁烷五种不同的气体燃料对燃烧过程的影响,重点研究在燃烧不同气体燃料时的燃烧状况和火焰形状的变化情况及形成原因,同时考察燃气组分变化对炭粒生成的影响。结果表明,较轻的燃料燃烧迅速,具有较短的刚直火焰,辐射段出口烟气温度较低,燃烧充分,炭粒生成较少;较重的燃料与空气混合慢,火焰较长,辐射段出口烟气温度较高,未完全燃烧的燃料在很大区域存在,炭粒生成较多,并可能形成结焦。     

乙醇胺对聚丙烯酰胺溶液黏度的影响

针对如何提高聚丙烯酰胺(HPAM)黏度的问题,考察了有机碱乙醇胺对HPAM黏度和渗流特征的影响。实验发现,乙醇胺对HPAM具有明显的增黏效果,随着热老化时间的延长,增黏效果越显著;乙醇胺可以提高HPAM的阻力系数和残余阻力系数,乙醇胺-HPAM体系具有更优的流度控制能力。此外,通过对乙醇胺-HPAM体系开展微量热,剪切流变和冷冻蚀刻电镜研究,发现乙醇胺与HPAM分子在溶液中存在较强的分子间相互作用,HPAM分子之间借助有机碱反离子形成松散的网络结构导致体系黏度增加。