Thermal Degradation of Asphaltene and Infrared Characterization of Its Degraded Fractions

Petroleum asphaltene and its thermally degraded fractions are characterized using thermal analysis and infrared spectrometry, respectively. Thermal analysis of asphaltene has demonstrated that heating rate is important in studying thermal degradation of asphaltene. Asphaltene goes through three stages of mass reduction under thermogravimetric analysis from 25 to 1,000°C at a heating rate of 1°C/min and below. The products from thermal degradation of asphaltene at three different temperature intervals are collected. The collected fractions are characterized using a Fourier transform infrared spectrometer. The fraction collected between 220 and 350°C demonstrates similar infrared spectrum to that of asphaltene, however, with less aromatic properties. The fraction collected between 350 and 450°C resembles the undegraded asphaltene most based on the infrared spectra obtained. The fraction collected between 450 and 650°C demonstrates a spectrum that is totally different from those of the undegraded asphaltene and the other two fractions. In addition, a high degree of oxidation is observed on all of the three degraded fractions of asphaltene.     

Characterization of Thermally Degraded Asphaltene Fractions Using Gel Permeation Chromatography

Abstract

Petroleum asphaltene goes through three stages of mass reduction under thermogravimetric analysis from 25°C to 1,000°C at a heating rate of 1°C/min. The products from thermal degradation of asphaltene at three different temperature intervals are collected. Two residual fractions left in the sample cup are also obtained at two specific temperatures. The collected fractions and the residual fractions are characterized using gel permeation chromatography. The fraction collected between 25°C and 350°C demonstrates similar molecular weight distribution to that collected between 350°C and 450°C, with both fractions showing a typical molecular weight distribution for polymeric material. The fraction collected between 450°C and 650°C illustrates three different molecular weight distributions. The chromatogram of the residual fraction obtained at 350°C resembles that of the undegraded asphaltene. The residual fraction obtained at 450°C also demonstrates three different molecular weight distributions. The experimental data indicate that the mass reduction of asphaltene heated from 25°C to 350°C is mainly due to the evaporation of low boiling point and/or low molecular weight substances in asphaltene. Thermal decomposition and coke production occur significantly in the 350°C–450°C temperature interval. Thermal degradation continues to finish until 650°C.     

Characterization of Thermally Degraded Asphaltene Fractions Using Gel Permeation Chromatography

Petroleum asphaltene goes through three stages of mass reduction under thermogravimetric analysis from 25°C to 1,000°C at a heating rate of 1°C/min. The products from thermal degradation of asphaltene at three different temperature intervals are collected. Two residual fractions left in the sample cup are also obtained at two specific temperatures. The collected fractions and the residual fractions are characterized using gel permeation chromatography. The fraction collected between 25°C and 350°C demonstrates similar molecular weight distribution to that collected between 350°C and 450°C, with both fractions showing a typical molecular weight distribution for polymeric material. The fraction collected between 450°C and 650°C illustrates three different molecular weight distributions. The chromatogram of the residual fraction obtained at 350°C resembles that of the undegraded asphaltene. The residual fraction obtained at 450°C also demonstrates three different molecular weight distributions. The experimental data indicate that the mass reduction of asphaltene heated from 25°C to 350°C is mainly due to the evaporation of low boiling point and/or low molecular weight substances in asphaltene. Thermal decomposition and coke production occur significantly in the 350°C-450°C temperature interval. Thermal degradation continues to finish until 650°C.     

沥青质热等离子体裂解热力学的分析

针对重油溶剂脱沥青过程中产生的大量沥青质,提出利用热等离子体超高温的极端反应条件,实现沥青质高效处理的热化学转化方案。采用热力学分析的方法,分析额外加入氢气、清焦气体(水蒸气或二氧化碳)和共裂解烃类(甲烷、乙烷、丙烷)对于沥青质热等离子体裂解制乙炔过程气相体系的影响。分析结果表明,在2 MW热等离子体裂解中试装置上,沥青质的最优处理量约为407 kg/h,并可获得约210 kg/h的乙炔;额外加入氢气和清焦气体不利于生成乙炔,额外加入的氢气量应低于15 kg/h;清焦气体的加入量应低于50 kg/h;加入共裂解烃类,可显著提高裂解气中乙炔的含量。裂解气温度的提高、气相有效碳氢质量比的增大和惰性因子的减小是提高裂解气中乙炔含量的有效手段。     

沥青质热裂解、临氢热裂解和临氢催化裂解反应动力学

 实验考察了1种正戊烷不溶解的沥青质在703 K下的热裂解、临氢热裂解和由 NiMo/γ-Al₂O₃催化的临氢裂解反应。3种沥青质转化反应都能较好地吻合二级反应动力学,得到的表观速率常数分别为1.704×10^-2、 2.435×10^-2和9.360×10^-2。建立三集总动力学模型,用于求解沥青质裂解转化生成液体油反应速率常数(k₁)和与之平行的生成焦炭＋气体反应速率常数（k₃）,以及由液体产物继续转化生成焦炭＋气体的反应速率常数（k₂）。对沥青质热裂解、临氢热裂解和临氢催化裂解反应,速率常数 k₁分别为1.697×10^-2、 2.430×10^-2和9.355×10^-2, k₂分别为3.605×10^-2、 2.426×10^-2和6.347×10^-3, k₃分别为6.934×10^-5、 5.416×10^-5和4.803×10^-5。     

沥青质裂解反应选择性分析

在703 K 下,考察了1种正戊烷不溶的沥青质的热裂解、临氢热裂解和 NiMo/γ-Al₂O₃存在时的临氢催化裂解反应。结果表明,在相同的反应物转化率水平下,3种裂解反应按液体产物选择性从大到小的排列顺序为临氢催化裂解、临氢热裂解、热裂解反应,而按焦炭的选择性的排列顺序则相反。在热裂解反应中,沥青质中大量的硫被转化生成高硫焦炭;在临氢热裂解反应中,氢气分子对高硫焦炭的生成只起到有限的抑制作用;在临氢催化裂解反应中,催化剂充分激活氢气分子,使其有效地对沥青质及中间产物发生“加氢”（氢化）作用,显著地抑制了焦炭的生成,提高了液体产物的稳定性、选择性和品质（低相对分子质量和低硫含量）。     

Spectroscopic Characterization of Asphaltene Fraction of Nigerian Bitumen

This research article offers data on the spectroscopic elucidation of the asphaltene fraction of Nigerian bitumen in order to establish its features that might aid the developmental processes of the fossil fuel. Bitumen was extracted from the oil sands obtained from six locations where there were oil sand out-crops in Southwestern Nigeria using toluene via Soxhlet extraction and then deasphalted using n-pentane. The organic components of the precipitated asphaltenes were investigated using Fourier transform infrared spectrometry, while the elemental contents were determined using Inductively coupled plasma atomic emission spectroscopy and carbon/nitrogen analyzer. The results revealed that the average content (29.15 wt%) of Nigerian bitumen asphaltenes was less than that of Athabasca (40.10 wt%) but slightly higher than that of Cold Lake bitumen (24.40 wt%). The IR spectra of the asphaltenes indicated the presence of various organics and heteroatoms corroborating that asphaltenes composed of high molecular weight polycyclic constituents comprising of nitrogen, sulfur, and oxygen heteroatoms. The results indicated that the values of Cr, Cu, Fe, Mn, Ni, S, V, and Zn were comparatively higher in the asphaltenes than the parent bitumen due to the presence of comparatively high levels of porphyrins in the asphaltenes than the bitumen, while the concentrations of all the elements were higher in the Nigerian bitumen asphaltene than Nigerian crude oil asphaltene (except S and C). Cross plot analysis result between the asphaltenes and bitumen using their elemental mean concentrations as variables indicates that significant and positive correlation (R² = 0.975) exists between them, indicating very strong interelement and geochemical relationships between them. The elements showed close clustering, indicating similar sources because the elements were known to associate with petroleum hydrocarbon formation. Also, apart from N, S, and C, other elements are transition metals with similar chemical affinity.     

沥青质组分轻质化转化的分子结构基础探索

渣油资源高效轻质化转化为轻、中质馏分原料,化工轻油,甚至直接产化学品,是提高渣油资源利用率的重要途径。渣油及沥青质组分的轻质化转化,实质是要大幅降低渣油的馏程范围使其从重变轻,以及降低沥青质沉淀析出倾向使体系相容性提高。研究发现,降芳环反应无论是对降低原料分子的沸点还是对减少原料分子的聚集倾向都具有显著正向效果。基于此,对沥青质组分的多环芳烃体系开展分子表征。结果表明：所研究的减压渣油沥青质分子以孤岛型结构为主,含有多个噻吩环且噻吩环主要处在分子结构内部位置,而噻吩环位于结构外围位置及湾型的含硫沥青质分子相对较少。基于分子表征结果探讨比较不同结构类型沥青质分子的降芳环反应路径,提出具有桥键或内部杂环的沥青质分子(群岛型Ⅰ、群岛型Ⅱ、群岛型Ⅲ和孤岛型Ⅰ)通过断桥键及加氢脱内部杂环反应可大幅度降低芳环数,从而显著降低沸点和聚集活性,实现轻质化目标,并且需要的氢耗较低。     

Estimating Methyl/Methylene Groups in Asphaltene and Other Fractions of Asphalt

Abstract

Infrared is the most widely used analytical method for interpreting the structure of petroleum fractions. In this study, IR spectra of standard normal nonadecane were used to get ε for methyl and methylene groups. A linear relationship was obtained by plotting the peak intensities at 2,954, 2,926, 2,854, 1,466, and 1,376 cm^?1 against different amounts of N-nonadecane. The R ² obtained for most of the plots was in the range of 0.988–0.997. The Beer-Lambert's law was used for the first time to quantitatively estimate the weight percent of methylene and methyl groups present in the different fractions of asphalt.     

塔河超稠油胶质、沥青质形貌分析

用环境扫描电子显微镜观察稠油非烃组分胶质和沥青质的形貌,分析结果表明,胶质分子之间、沥青质分子之间以及二者之间可以发生相互作用,形成结构较大的颗粒,胶质颗粒之间连接紧密,沥青质颗粒之间较分散。胶质和沥青质的含量和平面堆砌结构是影响稠油粘度的因素。     

Study of Resin Adsorption onto Asphaltene and Silica-Asphaltene Particles

Abstract

We present a methodology to study the adsorption behavior of resins on asphaltenes, which we call silica-asphaltene complex methodology (SACOM), and compare it to a methodology regularly used by many researchers (Acevedo et al., 1995 Acevedo, S., Ranaudo, M., Escobar, G., Gutiérrez, L. and Ortega, P. 1995. Adsorption of asphaltenes and resins on organic and inorganic substrates and their correlation with precipitation problems in production well tubing. Fuel., 74: 595–598. [Crossref], [Web of Science ®] , [Google Scholar]; González et al., 2003 González, G., Neves, G., Saraiva, S., Lucas, E. and Anjos de Sousa, M. 2003. Electrokinetic Characterization of Asphaltenes and the Asphaltenes-Resins Interaction. Energ. Fuel., 17: 879–886. [Crossref], [Web of Science ®] , [Google Scholar]; León et al., 2002 León, O., Contreras, E., Rogel, E., Dambakli, G., Acevedo, S., Carbornani, L. and Espidel, J. 2002. Adsorption of Native Resins on Asphaltene Particles: A Correlation between Adsorption and Activity. Langmuir, 18: 5106–5112. [Crossref], [Web of Science ®] , [Google Scholar]; Marczewski et al., 2002 Marczewski, A. and Szymula, M. 2002. Adsorption of asphaltenes from toluene on mineral surface. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 208: 259–266. [Crossref], [Web of Science ®] , [Google Scholar]; Pereira et al., 2007 Pereira, J. C., López, I., Salas, R., Silva, F., Fernández, C., Urbina, C. and López, J. C. 2007. Resins: The Molecules Responsible for the Stability/Instability Phenomena of Asphaltenes. Energ. Fuel., 21: 1317–1321.  [Google Scholar]) that we call traditional methodology. Three isotherms of resins adsorbed on the complex substrates (asphaltene and its colloidal fractions A₁ and A₂ adsorbed on silica) were built, analyzed, and then compared with two isotherms built by applying a traditional methodology where resins were adsorbed on two organic substrates: asphaltene and its fraction A₁.     

An Investigation of Asphaltene Precipitation During Natural Production and the CO2 Injection Process

Some of Iranian oil reservoirs suffer from operational problems due to asphaltene precipitation during natural depletion, so widely investigation on asphaltene precipitation is necessary for these reservoirs. In this study, a reservoir that is candidate for CO₂ gas injection process is selected to investigate asphaltene precipitation with and without CO₂ injection. In this case, asphaltene precipitation is monitored at various pressures and reservoir temperature. Then, a series of experiments are carried out to evaluate the amount of precipitated asphaltene by injection different molar concentrations (25%, 50%, and 75%) of CO₂. The results show that during primary depletion the amount of precipitated asphaltene increases with pressure reduction until bubble point pressure. Below the bubble point the process is reversed (i.e., the amount of precipitated asphaltene at bubble point pressure is maximum). The behavior of asphaltene precipitation versus pressure for different concentrations of CO₂ is similar to primary depletion. Asphaltene precipitation increases with CO₂ concentration at each pressure step. In the modeling part, solid model and Peng-Robinson equation of state are employed which show a good match with experimental results.     

中低温煤焦油沥青质的分析表征

采用XPS、XRD、FT IR、13C NMR、元素分析等手段分析表征了中低温煤焦油正庚烷沥青质(CT C7沥青质),系统研究了CT C7沥青质表面元素的赋存状态、相对含量以及其晶体结构。结果表明,该沥青质的主要结构为多环稠合芳香烃并富含杂原子,其芳香度(fa)明显大于一般原油沥青质;烷基链间距和芳香片层直径值较小,其芳环上烷基侧链短而少且难以形成堆积结构;表面C主要以sp2和sp3碳的形式存在,二者摩尔分数之和达699%,以C=O和COO-基团存在的C较少。该沥青质表面的杂原子以O原子为主,N和S原子较少,其中含氧官能团主要是酚羟基和醚氧基,摩尔分数达619%。含氮官能团主要以吡啶氮(N 6)和吡咯氮(N 5)为主,二者摩尔分数之和为805%;含硫官能团中,噻吩硫、烷基硫比较多,摩尔分数之和达517%。该C7沥青质表面加氢难度较大的N 6、N 5和噻吩硫的摩尔分数低于石油沥青质,这可能是煤焦油加氢工艺中N、S脱除效率较高的原因之一。     

Asphaltene Deposition During Steam-Assisted Gravity Drainage: Effect of Non-Condensable Gases

Asphaltene deposition was investigated during laboratory-scale steam-assisted gravity drainage (SAGD) experiments to probe in situ upgrading of a heavy oil. Tests were conducted with and without the addition of non-condensable gases (carbon dioxide or n-butane) to the steam. The apparatus was a three-dimensional scaled physical model packed with crushed limestone saturated with 12.4° API heavy-crude oil. Temperature, pressure, and production data, as well as the asphaltene content of the produced oil, were monitored continuously during the experiments. For small well separations, as the fraction of non-condensable gas in the steam increased, the steam condensation temperature and the steam-oil ratio decreased. As a result of lower temperature, the heavy oil was less mobile in the steam chamber relative to pure steam injection. Thus, the heating period was prolonged and the recovery, as well as the rate of oil recovery, decreased. Asphaltene content of the oil produced as a result of pure steam injection decreased initially showing deposition of asphaltene within the porous matrix of the model. As the steam injection continued, the asphaltene content of the produced oil increased but remained below the initial value. Thus, the produced oil indicated some in situ upgrading. As the carbon dioxide concentration in the steam increased, greater asphaltene deposition occurred; however, no significant change in asphaltene content was found when n-butane was added to the steam. Post-experimental analyses of the porous media for asphaltene content confirmed retention for the pure steam and steam with added CO₂ experiments. Numerical simulation of the asphaltene deposition process using a pure solid deposition model corroborated experimental findings and showed that deposition occurred mainly at the steam-chamber boundary.     

胶质沥青质相互作用浅析

为认识胶质沥青质之间的相互作用,以委内瑞拉、辽河减压渣油为研究对象,测定了向沥青质-甲苯溶液中加入不同量的胶质得到的溶液的黏度、电导率以及各自的分子量。结果表明,辽河和委内瑞拉减压渣油的沥青质浓度较低时各浓度的胶质对沥青质的作用主要以分散作用为主;而沥青质浓度较高时低浓度的胶质对沥青质主要以分散作用为主,但随着胶质浓度的增大,吸附作用大于分散作用。由此推断,胶质与沥青质间存在着吸附与解缔的平衡,当平衡打破后,两者的作用会发生变化。     

Thermal stability and sorption properties of asphaltene sulfocathionites

Abstract

Using simultaneous thermogravimetry and differential scanning calorimetry, thermal stability and possible phase transitions of asphaltene sulfocationites and native asphaltenes have been evaluated; the kinetic characteristics of heating have been determined, namely, onset temperature of decomposition, stages of decomposition, and temperature ranges of stability. It has been determined that asphaltene sulfocationites retain structural-group features (IR spectroscopy method) and sorption characteristics while heating up to 350?°C.     

Methodology for Predicting the Phase Envelope of a Heavy Crude Oil and Its Asphaltene Deposition Onset

Abstract

We have presented general ideas to develop a new theoretical methodology, based on molecular simulation and equations of state, for obtaining the phase envelope and to predict pressure, volume, temperature (PVT) conditions of asphaltene precipitation by only taking into account the composition of the heavy crude oil and an asphaltene average molecular structure. Those results show that asphaltene precipitation is a reversible thermodynamic process. The precipitated phase is a liquid phase which consists of mainly asphaltene and some heavy fractions from the crude. This methodology can be applied to find complete phase diagrams of different crude oils based on an asphaltene average molecular structure and the composition of crude oil.     

电站锅炉红外热像技术的应用

应用红外热像非接触特性 ,监测锅炉初步改造后的炉膛运行状况 ,评价运行的安全性和稳定性 ,为进一步的改造提供测试数据     

The Distribution of Ni and V in Resin and Asphaltene Subfractions and Its Variation During Thermal Processes

Ni and V deactivate catalysts and promote coking during heavy oil upgrading. Distribution of metals and metalloporphyrins, and its variation in thermal process, would benefit the more efficient upgrading. Majority of metals concentrate in resins and asphaltenes. To thoroughly study the metals distribution in these fractions, both were subdivided. It is indicated that the interactions between metalloporphyrins and asphaltenes play a significant role in metals distribution. Variation of metals distribution showed that the trend metals concentrated into heavier subfractions and was enhanced by thermal treatment and inhibited by hydrogen sources. Synergism was observed between hydrogen and hydrogen donor for the inhibition.