Correlation Between Properties of Asphaltenes and Precipitation Conditions

Asphaltenes from three crude oils were precipitated by using a pressurized system. Different conditions during the precipitation of asphaltenes were studied: pressure was varied between 15 and 45 kg/cm² and temperature between 40°C and 100°C. The effect of contact time and solvent-to-oil ratio was also studied in the range of 0.5-6 hr and 2:1 to 5:1 mL/g, respectively. Asphaltenes properties were analyzed as a function of pressure and temperature. It was found that in a deeper way temperature influences the asphaltenes properties than pressure in the range studied in this work. Asphaltenes properties were highly dependent on the nature of crude oil. Various correlations were developed and experimental and calculated asphaltenes contents and properties were in good agreement with absolute error less than 0.2%.     

Correlation Between Properties of Asphaltenes and Precipitation Conditions

Abstract

Asphaltenes from three crude oils were precipitated by using a pressurized system. Different conditions during the precipitation of asphaltenes were studied: pressure was varied between 15 and 45 kg/cm² and temperature between 40°C and 100°C. The effect of contact time and solvent-to-oil ratio was also studied in the range of 0.5–6 hr and 2:1 to 5:1 mL/g, respectively. Asphaltenes properties were analyzed as a function of pressure and temperature. It was found that in a deeper way temperature influences the asphaltenes properties than pressure in the range studied in this work. Asphaltenes properties were highly dependent on the nature of crude oil. Various correlations were developed and experimental and calculated asphaltenes contents and properties were in good agreement with absolute error less than 0.2%.     

封隔器压缩式胶筒剪切流变特性探讨

根据流变力学理论,建立了井壁约束条件下封隔器胶筒的剪切应力松弛和蠕变预测方程,通过外推法反演得到呈指数分布的材料参数方程,指出积分导数-指数在时间上具有等效性;提出了基于最小二乘法原理的封隔器胶筒应力松弛试验数据的拟合作法;计算了封隔器胶筒应力松弛模拟试验预加的初始剪应力及剪应变。分析结果表明:封隔器胶筒的应力松弛现象和蠕变效应直接影响封隔器胶筒元件的尺寸稳定性及密封性能;封隔器胶筒的剪应力随时间的增加而衰减,直至达到稳态水平而不再衰减;封隔器胶筒的剪应变随时间的增加而增大,出现快速上升和缓慢平稳2个阶段。较好地描述了井壁约束条件下封隔器胶筒的流变特性。     

Influence of Chemical Composition on the Physical Characteristics of Paving Asphalts

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.     

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.     

Modification of the Properties of Paving Asphalts by Treatment of Vacuum Resid with Sulfur

Interest in utilization of elemental sulfur has increased sharply due to development of the large Astrakhan' gas—condensate field, stiffening of environmental requirements for sulfur content in petroleum products, and simultaneously the drop in demand for elemental sulfur on the world market. Research on modification of the properties of asphalts with elemental sulfur has been conducted in Russia for more than 30 years. However, the results of these studies are often contradictory.     

Investigation of the Molecular Structure of Turkish Asphaltenes

Abstract

Molecular structure of asphaltenes prepared from four Turkish crude oils with different origin were characterized by elemental analysis, proton nuclear magnetic resonance (¹H NMR), gel permeation chromatography (GPC) by X-ray diffraction (XRD) and by Fourier transform infrared spectroscopy (FTIR). The X-ray diffraction method was used to investigate the crystallite and aromaticity parameters of the asphaltenes. Average distance between the aromatic sheets, average distance between the aliphatic chains, average diameter of the cluster, and average number of aromatic sheets per stack parameters were calculated for the asphaltenes. The combined NMR, FTIR, molecular weight, elemental content, and XRD results have been used to calculate hypothetical structure of the Turkish asphaltenes.     

A Study on Antiaging Performances of Two Paving Asphalts

Abstract

In this article, the processes of Anshan oxidizing paving asphalts have been studied and the kinetic models for two paving asphalts were put forward. Based on the change of service performances, viscidity, and Gastel index (Ic), the aging resistance of the two asphalts have been compared. Meanwhile, the aging mechanism also has been investigated. The results show that the presented dynamics models can be used to describe the aging velocity for the two asphalts perfectly. According to dx/dt(AH-90) > dx/dt(AH-70), it can prove that the aging resistance of AH-70 is better than that of AH-90. After aging, the change of both penetration and softening point of AH-70 are lower than that of the corresponding parameters of AH-90, and the aging index of AH-70 is also lower than that of AH-90, which proves that the aging resistance of AH-70 is better than that of AH-90. During aging, every composition tends to be transformed into the heavier one. As a result, the asphltene content increases, the original colloidal structure of asphalt is destroyed to deteriorate paving performances of the asphalt.     

Monitoring the Key Components and Elimination of Asphaltenes Precipitation in Crude by a New Alternative Route

The crude composition was determined by distillation on a true boiling point apparatus individually. Then crude naphthas were introduced to a gas chromatograph and asphaltenes were determined by extraction. Quantities of key components were calculated by prescribed mathematical equations. On the basis of relative quantities of key components, 21 blends of 12 crudes were prepared caused asphaltenes precipitation in desalter. Seven blends remained successful, causing no further asphaltenes precipitation, and one of the successful blends was chosen to prepare a batch of 55,000 barrels and was passed through desalter. No further asphaltenes precipitation was found during the whole operation.     

On the Nature of UV/Vis Absorption Spectra of Asphaltenes

New experimental data show that previously reported UV/vis spectra of asphaltenes/crude oils may have been strongly distorted by artifacts, affecting not only quantitative parameters (spectra's slopes), but also qualitative features (a presence of strong UV peaks). In a popular revised “amorphous semiconductor” (AS) model, the properties of UV/vis spectra are defined by population distribution of higher aromatics. This interpretation is obviously incompatible with the newly observed concentration effects in toluene solutions. Possibly, some specific features of UV/vis absorbance in asphaltenes/crude oils may be better described by the traditional AS model, taking into account the distribution of defects in chromophore carriers, e.g., nanosized carbonaceous species of the graphene family.     

Determination by PIXE of the Metallic Content in Vacuum Residue,Asphaltenes and Maltenes

Abstract

Asphaltenes from Mexican Maya crude oil were precipitated during one agitation hour using n-C₅, n-C₆, n-C₇, and n-C₈ at room temperature. Later the asphaltenes were washed with a soxhlet extraction system during 24 hr to remove the maltenes. The characterization of the vacuum residue, asphaltenes, and maltenes was realized using proton induced x-ray emission (PIXE) for the direct determination of the distributions and abundances of metals in the vacuum residue and their respective fractions. The analysis revealed that vacuum residue contains Fe, Al, V, and Ni, while the asphaltenes and maltenes mainly contain V and Ni.     

An Active Carbon Catalyst Prevents Coke Formation from Asphaltenes during the Hydrocracking of Vacuum Residue

Active carbons were prepared by the steam activation of a brown coal char. The active carbon with mesopores showed greater adsorption selectivity for asphaltenes. The active carbon was effective at suppressing coke formation, even with the high hydrocracking conversion of vacuum residue. The analysis of the change in the composition of saturates, aromatics, resins, and asphaltenes in the cracked residue with conversion demonstrated the ability of active carbon to restrict the transformation of asphaltenes to coke. The active carbon that was richer in mesopores was presumably more effective at providing adsorption sites for the hydrocarbon free-radicals generated initially during thermal cracking to prevent them from coupling and polycondensing.     

An Active Carbon Catalyst Prevents Coke Formation from Asphaltenes during the Hydrocracking of Vacuum Residue

Abstract

Active carbons were prepared by the steam activation of a brown coal char. The active carbon with mesopores showed greater adsorption selectivity for asphaltenes. The active carbon was effective at suppressing coke formation, even with the high hydrocracking conversion of vacuum residue. The analysis of the change in the composition of saturates, aromatics, resins, and asphaltenes in the cracked residue with conversion demonstrated the ability of active carbon to restrict the transformation of asphaltenes to coke. The active carbon that was richer in mesopores was presumably more effective at providing adsorption sites for the hydrocarbon free-radicals generated initially during thermal cracking to prevent them from coupling and polycondensing.     

Determination by PIXE of the Metallic Content in Vacuum Residue, Asphaltenes and Maltenes

Asphaltenes from Mexican Maya crude oil were precipitated during one agitation hour using n-C₅, n-C₆, n-C₇, and n-C₈ at room temperature. Later the asphaltenes were washed with a soxhlet extraction system during 24 hr to remove the maltenes. The characterization of the vacuum residue, asphaltenes, and maltenes was realized using proton induced x-ray emission (PIXE) for the direct determination of the distributions and abundances of metals in the vacuum residue and their respective fractions. The analysis revealed that vacuum residue contains Fe, Al, V, and Ni, while the asphaltenes and maltenes mainly contain V and Ni.     

The Preparation of a Polyether Demulsifier Modified by Nano-SiO2 and the Effect on Asphaltenes and Resins

Abstract

In order to enlarge the range of applications of nanomaterials and improve the performance of macromolecular polymer demulsifier, nano-SiO₂ was integrated with polyether demulsifier TA1031 to form nanomodified demulsifier using an in situ synthesis method. Analysis of the polyether demulsifier modified by nano-SiO₂ was performed using transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. The result showed that applying nanomaterials to crude oil demulsifier greatly improves the performance of the original demulsifier. When the ratio of nano-SiO₂ and TA1031 is 1:10, the performance of the nanomodified demulsifier was best, and the ratio of demulsification was improved by about 20%. The time of demulification and dewatering was also greatly shortened by about 30 min. The influence of nanomodified demulsifier on the asphaltenes and resins was studied by FTIR.     

Studies on Nigerian Crudes. II. Physical Characteristics and Rheological Properties of Residual Asphalts

The characteristics of some residual asphalts samples obtained from Nigerian medium and heavy crudes were studied using ASTM/IP standard tests. The residual asphalts were compared with industrial solid grade asphalts and cut back samples. Penetration and softening point tests performed on the treated samples showed that some of these samples fall within the range of road paving asphalts while sample having a low temperature susceptibility was found to be of better than the solid grade asphalt. The rheological behavior of an asphalt sample was investigated using a rotational viscometer. The sample showed a complex non-Newtonian character with structural breakdown as temperature is raised above its softening point. The study further confirmed the suitability of Nigerian medium crudes for the production of road paving asphalts.     

胜利原油各组分对界面膜扩张流变性的影响

 采取经典的四组分分离方法(SARA)将胜利原油分离得到饱和分、芳香分、胶质和沥青质,利用醇碱萃取法得到酸性组分。通过滴外形分析方法系统研究了上述5类原油组分及稀释原油的界面扩张流变性质,考察了振荡频率和各组分质量分数的影响。结果表明,各类活性组分及稀释原油表现出与表面活性剂类似的界面扩张行为,扩张模量均随振荡频率增大而增大,随质量分数的增加先增大后减小;相角随振荡频率增大而降低,随质量分数增大而增加。各组分模拟油及稀释原油形成的界面膜均表现出较强的弹性行为,且按其界面行为可以分为3组：稀释原油和饱和分、酸性组分和胶质、芳香分和沥青质。模量最大值对应的质量分数高低顺序为稀释原油和饱和分、酸性组分和胶质、芳香分和沥青质。沥青质扩张模量的最大值在 25 mN/m 左右,略高于稀释原油和其它活性组分。     

稠油沥青质水热裂解供氢催化及地质协同作用研究

探讨了辽河稠油中沥青质在注蒸汽热采条件下供氢催化水热裂解反应行为,以及油藏矿物对沥青质水热裂解的强化作用,结果表明,油藏矿物与硫酸镍、甲酸供氢剂可协同催化沥青质水热裂解反应,最终可使沥青质降解率达到49.2%;供氢催化反应前后稠油中沥青质红外谱图说明稠油中沥青质在供氢催化改质降粘反应时所发生的化学结构的变化,反映了沥青质在反应过程中经历了侧链断裂、环烷脱氢芳构化以及芳香结构进一步缩合等反应;对沥青质水热裂解反应产物中轻组分进行气相色谱全烃分析,证实了在注蒸汽热采条件下沥青质可以实现部分催化降解。     

利用石蜡基原油减压渣油生产高等级道路石油沥青的研究

鉴于利用玉门炼油厂原料(一种石蜡基混合原油)的减压渣油和减压渣油的溶剂脱油沥青不能直接生产出合格的道路沥青,根据优质道路石油沥青性能对组成分子的基本要求,利用多元调合法间接试制道路石油沥青,研制出了能生产出包括中石化集团公司2号高等级道路沥青(Q/SHR004-1998)在内的多种牌号道路沥青配方。初步探讨了在减压渣油中调入适量催化裂化油浆,并经溶剂脱沥青工艺直接生产道路沥青的可行性。试验结果表明,在脱沥青油收率增加的同时,脱油沥青的道路石油沥青性质明显改善,因此可优化炼油厂的工艺组合。研究方法对于加工石蜡基或非石蜡基原油的炼油厂具有指导意义。