PHYSICAL AND CHEMICAL CHARACTERIZATIONS OF ASPHALTENES FROM DIFFERENT SOURCES

ABSTRACT

Asphaltenes and resins are two of the several, but important, heavy organics present in petroleum fluids. Asphaltenes are operationally defined as the non-colatile and polar fraction of petroleum that is insoluble in n-alkanes (i.e., n-pentane). Conversely resins are defined as the non-colatile and polar fraction of petroleum that is soluble in n-alkanes (i.e., n-pentane), and aromatic solvents (i.e., toluene), and insoluble in ethyl acetate. A commonly accepted view in the petroleum chemistry is that crude oil asphaltenes form micelles which are stabilized by adsorbed resins kept in solution by aromatics. Two key parameters that control the stability of asphaltene micelles in a crude oil are the ratio of aromatics to saturates and that of resins to asphaltenes. When these ratios decrease, asphaltene micelles will coalesce and form larger aggregates. The precipitation of asphaltene aggregates can cause problems such as reservoir plugging and wettability reversal.     

THE EFFECT OF LOW TEMPERATURE OXIDATION ON THE CHEMICAL AND PHYSICAL PROPERTIES OF MALTENES AND ASPHALTENES DERIVED FROM HEAVY OIL

The chemical changes that occur when the maltene and asphaltene fractions (separated from heavy oil) are subjected to low temperature oxidation (LTO) in the presence and absence of water have been investigated by a combination of classical separation techniques and analytical pyrolysis. In general, it is observed that water has a mitigating effect on the destructive nature of LTO. A detailed analysis of the pyrolytic products suggests that the presence of water reduces the ease with which oxygen reacts with sulfides to give sulfones and thereby supresses the formation of coke. An analysis of the data indicates that most of the coke produced results from LTO of the asphaltenes; only a small portion originates in the maltenes.     

THE EFFECT OF LOW TEMPERATURE OXIDATION ON THE CHEMICAL AND PHYSICAL PROPERTIES OF MALTENES AND ASPHALTENES DERIVED FROM HEAVY OIL

Abstract

The chemical changes that occur when the maltene and asphaltene fractions (separated from heavy oil) are subjected to low temperature oxidation (LTO) in the presence and absence of water have been investigated by a combination of classical separation techniques and analytical pyrolysis. In general, it is observed that water has a mitigating effect on the destructive nature of LTO. A detailed analysis of the pyrolytic products suggests that the presence of water reduces the ease with which oxygen reacts with sulfides to give sulfones and thereby supresses the formation of coke. An analysis of the data indicates that most of the coke produced results from LTO of the asphaltenes; only a small portion originates in the maltenes.     

CHARACTERIZATION OF ASPHALTENES AND RESINS FROM PROBLEMATIC MEXICAN CRUDE OILS

Asphaltenes and resins have been separated from four mexican oils suffering from the deposition of asphaltenic material during recovery operations. A SARA separation of the oils was performed and the resins and asphaltenes further analyzed. Characterization methods employed were FTIR, elemental composition both of CHNSO, and trace metals and molecular weight determination using size exclusion chromatography. NMR techniques were applied to two asphaltene samples. The overall scope of the work was to get a better understanding of the nature of the asphaltene stability at a molecular level in these problematic oils. Separation of resin in two fractions indicates that there is no long alkyl chains in these as given by FTIR, which may be the cause of the lack of stability along with the large difference in bubble point and reservoir pressure.     

减压渣油中胶状沥青状物质的化学结构研究

利用对芳香碳有高选择性转化能力的钌离子催化氧化法研究了减压渣油中轻、中、重胶质和戊烷沥青质的化学结构,定量了与芳香环相连的正构烷基侧链和桥链的分布,并了芳香环系的缩合型式,结果表明,这些石油重质组分中均存在碳数为Ｃ１￣Ｃ３０的与芳香 相连的正构烷基侧链,其摩尔浓度随链长的增加而下降,也存在由正构烷基桥连接的至少具有两个芳香环系的芳香性分子,在芳香结构中存在着渺位缩合,迫位缩合以联苯型结构,其中联苯     

CHARACTERIZATION OF ASPHALTENES AND RESINS FROM PROBLEMATIC MEXICAN CRUDE OILS

Asphaltenes and resins have been separated from four mexican oils suffering from the deposition of asphaltenic material during recovery operations. A SARA separation of the oils was performed and the resins and asphaltenes further analyzed. Characterization methods employed were FTIR, elemental composition both of CHNSO, and trace metals and molecular weight determination using size exclusion chromatography. NMR techniques were applied to two asphaltene samples. The overall scope of the work was to get a better understanding of the nature of the asphaltene stability at a molecular level in these problematic oils. Separation of resin in two fractions indicates that there is no long alkyl chains in these as given by FTIR, which may be the cause of the lack of stability along with the large difference in bubble point and reservoir pressure.

     

PHYSICAL AND CHEMICAL PROPERTIES OF CORNCOB FOR THERMAL CONVERSIONS

Abstract

In order to increase thermal efficiency and reduce pollution, it is necessary to understand the physical and chemical properties of corncob for the service of its gasification and liquefaction. Physical properties of melting point, cohesiveness, heating value, specific gravity, thermal conductivity and specific heat, and chemical properties of chemical composition (cellulose, lignin, semi-cellulose, extractives and ash), element composition (C, H, O. S. N), industrial analysis (content of water, ash, volatile and fixed carbon), reactivity and volatility of corncob have all been tested or collected.     

PHYSICAL AND CHEMICAL PROPERTIES OF CORNCOB FOR THERMAL CONVERSIONS

In order to increase thermal efficiency and reduce pollution, it is necessary to understand the physical and chemical properties of corncob for the service of its gasification and liquefaction. Physical properties of melting point, cohesiveness, heating value, specific gravity, thermal conductivity and specific heat, and chemical properties of chemical composition (cellulose, lignin, semi-cellulose, extractives and ash), element composition (C, H, O. S. N), industrial analysis (content of water, ash, volatile and fixed carbon), reactivity and volatility of corncob have all been tested or collected.     

辽河原油沥青质及胶质油水界面化学性质初探

对由辽河原油中分别提取的沥青质组分,胶质组分配成的模型油与水的界面性质进行了研究,还考察了油相芳香度对涸青质,胶质模型油油水界面粘度的影响及当模型油中沥青质与胶质共存时的油水界面性质。结果表明,含沥青质的模型油的油水界面粘度较高,界面老化现象严重;而仅含胶质的模型油的油水界粘度较小。     

ELEMENTAL COMPOSITION OF ASPHALTENES FROM COAL LIQUEFACTION

The elemental composition (C, H, N, S, O) of asphaltenes isolated from coal liquefaction experiments carried out at different temperatures and tetralin/coal ratios has been determined. The liquefaction experiments were conducted in a 250 ml autoclave, with 10 g of a Spanish subbituminous A coal, for 1 hour, and at 17 ± 1 MPa operating pressure and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The % S and % O are lower in asphaltenes than in coal, while the % C and % N are higher and % H depends on the temperature and tetralin/coal ratio used. On the other hand asphaltenes % C decreases, and % H and % O increase as the tetralin/coal ratio is raised at every temperature except 475 °C, while % S and % N do not have a clear variation.     

MOLECULAR SIZE AND STRUCTURE OF ASPHALTENES

Fluorescence depolarization measurements are used to determine the size of asphaltene molecules and of model compounds for comparison. Mean molecular weights of 750 amu have been found for petroleum asphaltenes. A strong correlation is established between the size of fused rings in asphaltene molecules and the overall size of these molecules, showing that asphaltenes have one or perhaps two fused ring systems per molecule. Coal asphaltene molecules are found to be much smaller than petroleum asphaltenes.     

MOLECULAR SIZE AND STRUCTURE OF ASPHALTENES

Fluorescence depolarization measurements are used to determine the size of asphaltene molecules and of model compounds for comparison. Mean molecular weights of 750 amu have been found for petroleum asphaltenes. A strong correlation is established between the size of fused rings in asphaltene molecules and the overall size of these molecules, showing that asphaltenes have one or perhaps two fused ring systems per molecule. Coal asphaltene molecules are found to be much smaller than petroleum asphaltenes.     

用气相色谱单体烃数据计算汽油的多项物性参数

通过线性回归建立了一种根据气相色谱法测定的汽油单体烃组成及各纯组分的物性常数,计算样品的密度、折光率、热值、饱和蒸气压、平均相对分子质量、碳氢元素含量等物性数据的方法。汽油单体烃数据采用高分辨弹性石英毛细管柱分析获得。计算结果与标准方法测定结果的绝对偏差为:密度小于0.005 g/cm3、折光率小于0.005,碳氢含量计算结果与碳氢元素分析仪测定结果绝对偏差小于0.5%,饱和蒸气压的计算结果与标准方法测定结果的绝对偏差小于标准方法规定的再现性数值。该计算方法有较好的精密度,适合于样品量很少情况下汽油物性数据测算。     

不同来源的TDAE对高结苯充油丁苯橡胶性能的影响

采用国产TDAE与进口TDAE填充高结苯充油丁苯橡胶,研究了两种TDAE对生胶、混炼胶和胎面胶的物理性能和动态力学性能的影响.结果 表明:两种高结苯充油丁苯橡胶的生胶自粘性、软化指数和热稳定性基本一致;应用于轮胎胎面胶时,填充国产TDAE的胎面胶的安全性、耐磨耐老化性和抗湿滑性均优于填充进口TDAE的胎面胶,且抗屈挠龟...     

CHARACTERIZATIONS OF REACTIVITY OF COALS AND CHARS

In this paper an attempt has been made to correlate the reactivity of various coals by using multivariable correlations. It was found chat the ratio of volatile matter to fixed carbon (VH/FC)the ratio of oxygen to carbon, Initial CO₂, surface area, and combinations of these three variables can correlate experimental data well.     

SEPARATIONS AND CHARACTERIZATIONS OF FRACTIONS FROM MAYAN, HEAVY ARABIAN, AND HONDO CRUDE OILS

Mayan, Heavy Arabian, and Hondo crude oil resids have been separated with a modified, extended ASTM D2007 procedure. The fractions obtained have been characterized with various analytical techniques. Chemical properties, hydrodesulfurization, and hydrodemetallation activities of the resids have been correlated with the chemical properties of the separated fractions. Many correlations were indicative of the overall bulk properties of the resids and the broad chemical classes obtained from the separation schemes. Other correlations reflected the unique chemical nature of each crude oil resid. Some potentially important correlations were found between hydrodesulfurization activity and sulfur concentration in polars and asphaltenes, and between hydrodemetallation activity and nitrogen concentration in the acid and bases fractions.     

SEPARATIONS AND CHARACTERIZATIONS OF FRACTIONS FROM MAYAN,HEAVY ARABIAN,AND HONDO CRUDE OILS

ABSTRACT

Mayan, Heavy Arabian, and Hondo crude oil resids have been separated with a modified, extended ASTM D2007 procedure. The fractions obtained have been characterized with various analytical techniques. Chemical properties, hydrodesulfurization, and hydrodemetallation activities of the resids have been correlated with the chemical properties of the separated fractions. Many correlations were indicative of the overall bulk properties of the resids and the broad chemical classes obtained from the separation schemes. Other correlations reflected the unique chemical nature of each crude oil resid. Some potentially important correlations were found between hydrodesulfurization activity and sulfur concentration in polars and asphaltenes, and between hydrodemetallation activity and nitrogen concentration in the acid and bases fractions.     

CHARACTERIZATIONS OF REACTIVITY OF COALS AND CHARS

ABSTRACT

In this paper an attempt has been made to correlate the reactivity of various coals by using multivariable correlations. It was found chat the ratio of volatile matter to fixed carbon (VH/FC)the ratio of oxygen to carbon, Initial CO₂, surface area, and combinations of these three variables can correlate experimental data well.     

VARIATION IN THE CHEMICAL NATURE OF ASPHALTENES WITH THE PROCESS,THE COAL AND THE REACTION CONDITIONS

ABSTRACT

Average structure data for twelve asphaltenes are reported, based on ¹³C- and H- n.m.r. spectroscopy combined with elemental, molecular weight and functional group analyses. The asphaltenes were from supercritical gas extraction, flash pyrolysis and hydrogenation of a brown and a bituminous coal. The effect of the reaction temperature and, for hydrogenation, the catalyst and solvent on the nature of the asphaltene produced was studied. The asphaltene obtained from supercritical gas extraction of the brown coal at 350°C was the least aromatic (f_a = 0.44) with the highest H/C atomic ratio (1.16) and probably consists mainly of single ring aromatlcs with about half of the aromatic sites substituted. A significant proportion of the carbon in this asphaltene is in long alkyl chains and the hydroxyl content is high. Whereas, the asphaltenes produced by hydrogenatlon of the bituminous coal at 450°C were far more aromatic with more highly condensed but less substituted aromatic ring systems and few, if any, long alkyl chains, together with a lower hydroxyl content. The asphaltenes obtained from the brown coal are less aromatic with less condensed aromatic ring systems but a higher degree of aromatic substitution than those produced from the bituminous coal under the same conditions. The asphaltenes formed at 450°C had lower H/C atomic ratios, molecular weights and degree of aromatic substitution, but higher aromaticities Ohan those produced at 35O°C or 400°C under like processing conditions. The asphaltene produced in the presence of both stannous chloride catalyst and tetralin was less aromatic than when either of these species was absent.     

PYROLYSIS AND LIQUEFACTION OF BRAZILIAN COAL AND COAL-DERIVED ASPHALTENES

ABSTRACT

The present work describes a study of the liquefaction and pyrolysis of a Southern Brazilian mineral coal and its derived asphaltenes, using conversion systems developed in our laboratory.

The results show that significant quantities of the intermediate polarity fraction named resins is obtained through the pyrolysis of coal, while after the liquefaction process higher quantities of the higher fractions was found. A model is proposed to explain the liquefaction and pyrolysis processes of both coal and coal-derived asphaltenes.