Structural Description of Polyaromatic Nucleus in Residue

The proton nuclear magnetic resonance spectroscopy （1H-NMR）, the synchronous fluorescence spectrometry （SFS） and the ruthenium ions catalyzed oxidation （RICO） method were used to determine the chemical structure of polyaromatic nucleus in Oman residue fractions. The results of 1H-NMR analyses showed that the average numbers of aromatic rings in the aromatics, resins and asphaltenes units were 3.2, 5.6 and 8.2, respectively. SFS was used to investigate the distribution of aromatic rings in residue fractions, the main distribution range of aromatic rings in aromatics, resins and asphaltenes were 3 4 rings, 3--5 rings and more than 5 rings, respectively. The aromatic network in residue fractions was oxidized to produce numerous carboxylic acids. The types and content of benzenepolycarboxylic acids, such as phthalic acid, benzenetricarboxylic acids, benzenetetracarboxylic acids, benzenepentacarboxylic acid and benzenehexacarboxylic acid disclosed the condensed types of aromatic nuclei in the core. The biphenyl fraction （BIPH）, the cata-condensed fraction （CATA）, the peri-condensed fraction （PERI） and the condensed index （BCI） were calculated based on the benzenepolycarboxylic acids formed. The results implied that there was less biphenyl type structures in all residue fractions. The aromatics fraction was almost composed of the cata-condensed type system, and the asphaltenes fraction was wholly composed of the peri-condensed type system, while in the resins fraction co-existed the two types, herein the peri-con- densed type was predominant over the cata-condensed type. Based on the analytical results obtained in the study, the components --aromatics, resins and asphaltenes -- were given the likely structural models.     

Molecular Characterization of Hydrotreated Atmospheric Residue Derived from Arabian Heavy Crude by GC FI/FD TOF MS and APPI FT-ICR MS

High resolution mass spectrometry in combination with distillation and SARA fractionation provides us an opportunity for in-depth understanding about the hydrotreating process at the molecular level. In this study, the atmospheric residue derived from Arabian heavy crude and its hydrotreated products were initially subjected to distillation and SARA fractionation. The saturates were characterized by GC FI/FD TOF MS. The aromatics and resins were characterized by APPI FT-ICR MS. Compositional changes of different compounds (paraffins, naphthenes, aromatic hydrocarbons, and heteroatomic compounds) contained in different distillates (vacuum gas oil, vacuum residue) were obtained. More detailed knowledge about the hydrotreating process was achieved.     

Boiling Point Distribution of Hydrocarbon Types in Diesel Using Solid-Phase Extraction Followed by GC/FID-EIMS

In this paper, a method was established to determine the boiling point distribution of hydrocarbon types in diesel. The diesel sample was separated into the saturate and aromatic fractions by means of solid-phase extraction （SPE）, and each fraction was analyzed by GC/FID-EIMS. According to the relationship between boiling point and retention time of n-paraffins in the chromatogram, the percentages of saturates and aromatics at each temperature interval were calculated. According to the average mass spectra of the saturate and aromatic fractions at each temperature interval, the hydrocarbon types of the sample were identified through summation of characteristic mass fragments. Using this method, the changes in composition of diesel during hydrotreating process were studied. The results showed that hydrogenation of aromatics is the main reaction during the hydrotreating process. The more rings the aromatics have, the easier the hydrogenation reactions would take place. The aromatics were converted into cycloparaffins via the hydrogenation and saturation process, leading to an increase in low boiling point fractions in the hydrotreated oil.     

基于1H NMR和XRD表征重油组分平均分子结构

The chemical structure of heavy oil fractions obtained by liquid-solid adsorption chromatography was character-ized by 1 H nuclear magnetic resonance and X-ray diffraction.The molecular weight and molecular formula of asphaltene molecules were estimated by combining 1 H nuclear magnetic resonance and X-ray diffraction analyses,and were also ob-tained from vapor pressure osmometry and elemental analysis.Heteroatoms,such as S,N,and O atoms,were considered in the construction of average molecular structure of heavy oils.Two important structural parameters were proposed,including the number of alkyl chain substituents to aromatic rings and the number of total rings with heteroatoms.Ultimately,the av-erage molecular structures of polycyclic aromatics,heavy resins and asphaltene molecules were constructed.The number of α-,β-,γ-,and aromatic hydrogen atoms of the constructed average molecular structures fits well with the number of hydro-gen atoms derived from the experimental spectral data.     

Distribution of calcium, nickel, iron, and manganese in super-heavy oil from Liaohe Oilfield, China

Liaohe super-heavy crude oil was separated into its components, namely saturates, aromatics, resins, and asphaltenes （SARA）, by the group separation method. Several solvents were used to extract different forms of metallic elements from crude oil. The metallic elements, such as calcium, nickel, iron and manganese, in crude oil, SARA and extract samples were analyzed by inductively coupled plasma atomic emission spectroscopy （ICP-AES）. The results demonstrate that the contents of calcium, nickel, iron, and manganese gradually increase in saturates, aromatics, resins, and asphaltenes, suggesting that the abundance of the four metallic elements in asphaltenes is much higher than that in the other groups. For example, the content of calcium in asphaltenes reaches a maximum of 7,920 pg/g. Among the SARA components of Liaohe super-heavy crude oil, resins account for more than 50 wt%, suggesting that the total amount of the four metallic elements are higher in the resin component than in other components. The four metallic elements mainly exist in the form of organic metallic compounds in crude oil. Further analysis shows that calcium and manganese elements exist mainly as metal salts of petroleum acids, and the majority of the iron and all the nickel exist mainly as metalloporphyrin and non-metalloporphyrin compounds.     

Hydrocarbon Composition of Different VGO Feedstocks and Its Correlation with FCC Product Distribution

Three different types of VGO were selected and cut into various distillates by true boiling-point distillation (TBD), and the distillates were further separated into different components (saturates, aromatics and resins) via solid phase extraction (SPE). The hydrocarbon components in saturates and aromatics were characterized on the quasi-molecular level by GC/MS and GC/TOF MS. Cracking reactions of VGO, their distillates, and hydrocarbon components (saturates and aromatics) were performed on an ACE (model AP) unit. Nine correlation parameters (mainly based on the previous assumption of basic structure units, BSU) which could better reflect the structures and compositions of hydrocarbons were put forward based on the quasi-molecular level analysis data, and correlated with FCC product distribution by multi-regression method. A series of correlation formulas were obtained. The formulas were further verified by comparing experimental and calculated FCC yields emanated from two other VGO feedstocks.     

不同氢饱和度稠环芳烃开环裂化的分子模拟研究

In order to investigate the influence of hydrogenation degree and structural variety on reaction trend of polyaro- matic hydrocarbons (PAHs) in resins and asphaltenes portion of heavy oil, a series of PAHs with different hydrogenation degree were selected as model compounds to simulate their different hydrogenation stage, and the PAHs thermal cracking reaction was simulated based on free radical mechanism by the density functional theory (DFT) to search for reactions’transition state. By comparing the dynamic data obtained from reaction simulation, it is showed that processing difficulty could rise with increasing condensed aromatic ring number, and hydrogenation could promote ring cleavage reaction, but excessive hydrogenation would decrease the oil conversion rate to reduce light-end products. In conclusion, proper hydrogenation was quite critical in promoting light-end products conversion efficiency and saving the processing cost as well. Operational instructions were given based on both PAHs hydrogenation performance and conclusions were drawn up from reaction simulation results.     

Effect of Different Aromatic Fractions on Colloidal Property of Tahe Atmospheric Residue

Different amounts of FCC slurry oil and HVGO were added to Tahe atmospheric residue respectively.The colloidal stability and asphaltene agglomeration of atmospheric residue and mixed oils were characterized by means of the mass fraction normalized conductivity and the small-angle X-ray scattering technology(SAXS).The results indicated that the stability of Tahe atmospheric residue decreased with an increasing amount of these oil fractions.It was found that the decline of the colloidal stability was attributed to the component polarity difference between oil fractions and the atmospheric residue.Though the aromaticity of FCC slurry oil was higher than that of HVGO,the polarity of aromatics and resins of FCC slurry oil was lower than those of HVGO.So the degree of the colloidal stability was more seriously destroyed by FCC slurry oil.The dispersion of asphaltenes in Tahe atmospheric residue was changed by adding FCC slurry oil and HVGO.The particle size of asphaltenes increased along with the decline of the colloidal stability.     

Compatibility Evaluation between Direct Coal Liquefaction Residue and Bitumen

The compatibility between direct coal liquefaction residue(DCLR) and five kinds of pure bitumen(Shell-90,SK-90, ZSY-70, DM-70 and KLMY-50) was evaluated in this study. The rheological characteristics, glass transition temperatures(T_g), solubility parameters(SP) and SARA(saturates, aromatics, resins, and asphaltenes) fractions of DCLR,five kinds of pure bitumen and their blends(named as DCLR modified bitumen) were measured using the dynamic shear rheometer(DSR), differential scanning calorimetry(DSC), viscosity, and SARA tests, respectively. And the compatibility between DCLR and pure bitumen was characterized with three approaches, viz. the Cole-Cole plot,T_g, and the solubility parameter difference(SPD) method. Since each method has its own working mechanism, the compatibility ranking for the DCLR and five kinds of pure bitumen is slightly different according to the three approaches. However, the difference is pretty close and sometimes can be ignored. The general compatibility ranking decreases in the following order: Shell-90≈SK-90DM-70≈ZSY-70KLMY-50, which is affected by the asphaltenes content and the colloid index(I_c) value in the pure bitumen. Pure bitumen with lower asphaltenes content and colloid index(I_c) value has better compatibility with DCLR.     

The Effects of Ultrasonic Treatment on the Molecular Structure of Residual Oil

To upgrade residual oil, the residual oil was subjected to ultrasonic treatment with an output of 800 W, at a temperature of 70 ℃ and at intervals ranging from 0 to 11 minutes. The experiment illustrated that 7 minutes of ultrasonic treatment reduced viscosity and carbon residue by 14.1% and 7.4%, respectively. This also produced an increase in saturates content and a decrease in the content of aromatics, resins and asphaltenes. Furthermore, the parameters of the average molecular structure were characterized by FT-IR, and ~1 H-NMR, while an increasingly greater change in the parameters were produced by an ultrasonic treatment interval of up to 7 minutes. The mechanical stirring and cavitation from ultrasonic treatment caused a series of changes in the molecules of residual oil. Microscopic changes affected the parameters of the average molecular structure, as usually shown in SARA fractions. The changes in the thermal reaction properties of residual oil after ultrasonic treatment were analyzed by thermogravimetry. As the ultrasonic treatment time increased, the apparent activation energy needed for pyrolysis decreased gradually, as did the temperature.     

Linkage of Aromatic Ring Structures in Saturates,Aromatics, Resins and Asphaltenes Fractions of Vacuum Residues Determined by Collision-Induced Dissociation Technology

The linkage of aromatic ring structures in vacuum residues was important for the refining process. The Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS) combined with collision-induced dissociation(CID) is a powerful method to characterize the molecular structure of petroleum fractions. In this work, model compounds with different aromatic ring structures were measured by CID FT-ICR MS. The cracking of the parent ions and the generated fragment ions were able to distinguish different linkage of the model compounds. Then, vacuum residues were separated into saturates, aromatics, resins and asphaltenes fractions(SARA), and each fraction was characterized by CID technology. According to the experimental results, the aromatic rings in saturates and aromatics fractions were mainly of the island-type structures, while the aromatic rings in resins and asphaltenes fractions had a significant amount of archipelago-type structures.     

减压渣油及其四组分在接触剂上的裂化反应规律

以减压渣油为原料,采用热解色谱和热重-质谱,考察了减压渣油及其四组分(饱和分、芳香分、胶质和沥青质)在惰性接触剂LHBK和酸性接触剂C上的裂化反应。结果表明：四组分在有孔无酸剂LHBK上裂化程度由强到弱的顺序为胶质、沥青质、芳香分、饱和分,在有孔有酸剂C上裂化程度由强到弱的顺序为饱和分、芳香分、胶质≈沥青质。四组分在2种接触剂上缩合反应生成的积炭均比减压渣油在接触剂上缩合反应生成的积炭具有更低的H/C摩尔比;接触剂的酸性明显促进了四组分的裂化,C_20-馏分产率明显增加;且增加了减压渣油裂化反应的生焦率,增加部分主要来自芳香分和胶质的催化裂化生焦。说明接触剂的酸性能促进饱和分C—C键、芳香分侧链C—C键断裂以及胶质和沥青质中键能较低的键断裂。     

减压渣油微观相结构特性的分子模拟

选用4种模型化合物代表减压渣油四组分(SARA),采用分子动力学模拟了减压渣油微观相结构,发现不同结构分子间相互作用的差异是减压渣油微观非均匀分布的本质原因,并通过电子分布特性分析了不同结构分子间相互作用差异的本质原因。沥青质分子间强相互作用使得沥青质分子自缔合形成聚集体;而多个胶质分子与沥青质分子的强相互作用封闭了沥青质分子自身进一步发生相互作用的活性位;同时,与胶质分子、饱和烃分子具有强相互作用的芳香烃分子将沥青质 胶质分子形成的聚集体分散在由芳香烃 饱和烃分子构成的连续相内,其中芳香烃分子更靠近胶质分子。因此,增加沥青质、饱和烃分子的含量会促进沥青质聚集,降低减压渣油稳定性;增加胶质、芳香烃分子的含量会阻碍沥青质聚集,提高减压渣油稳定性。     

STRUCTURAL CHARACTERIZATION OF ARABIAN HEAVY CRUDE OIL RESIDUE

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.     

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.     

溶剂萃取法分离沙特中质原油VGO及其硫分布规律

以不同水含量的糠醛和N-甲基吡咯烷酮作萃取溶剂,沙中原油减压馏分油经3段萃取被分离为重芳烃相、中芳烃相、轻芳烃相和饱和烃相4个亚组分,采用气相色谱-质谱联用、傅里叶变换离子回旋共振质谱等方法分析了亚组分中烃类组成和硫化物的分布,考察了萃取分离过程各烃类的分离效率和芳烃萃取选择性。结果表明,3段萃取分离出的重芳烃相、中芳烃相和轻芳烃相中芳烃质量分数分别在89.6%~95.6%、80.8%~91.0%和63.9%~77.7%,表明糠醛和NMP是适于分离减压馏分油中芳烃的溶剂;芳烃环数增加,分子极性提高,溶剂对其溶解能力增强,极性较强的三环及以上芳烃主要存在于重芳烃相和中芳烃相;不同水含量的糠醛和NMP对芳烃,尤其是对三环及以上芳烃的分离效率高于饱和烃;水含量增加,溶剂的萃取分离效率降低,但对芳烃的萃取选择性β值提高;NMP对芳烃的萃取选择性高于糠醛。三环及以上噻吩类硫化物主要存在于重芳烃相和中芳烃相中,单、双环噻吩类硫化物基本均匀分布于各亚组分中。     

胜利减压渣油胶质热反应生焦特性的研究

以胜利减压渣油中的饱和分、芳香分和胶质为原料，通过其热反应行为的考察，表明在本反应条件下，饱和分不转化成沥青质和甲苯不溶物；仅有少量芳香分转化成沥青质和甲苯不溶物；在热反应中沥青质和甲苯不溶物的生成主要来自胶质的缩合反应。还比较了饱和分、芳香分和胶质的裂解与缩合性能。研究表明，纯胶质的热反庆体系，其胶溶沥青质的能力很强；原生胶质经热反应后所生成的次生胶质和次生沥青质与减压渣油中的原生胶质和原生沥青     

Removing of resins from crude oils

Crude oil contains four chemical group classes, namely saturates, aromatics, resins, and asphaltenes (SARA fractions). Resins fraction of crude oil comprises polar molecules often containing heteroatoms such as nitrogen, oxygen, or sulfur. Resin is a heavier fraction than aromatics and saturates. Resins are composed of fused aromatic rings with branched paraffin and polar compounds. The resin fraction is soluble in light alkanes such as pentane and heptane, but insoluble in liquid propane. The resins are adsorbed on a solid such as alumina, clay, or silica, and subsequently recovered by use of a more polar solvent and the oils (aromatics and saturates) remain in solution. The resins often coprecipitate with the asphaltenes in controlled propane deasphalting procedures. The composition of the resins can vary considerably and is dependent on the kind of precipitating liquid and on the temperature of the liquid system. The resins are adsorbed on a solid such as alumina, clay, or silica, and subsequently recovered by use of a more polar solvent and the oils (aromatics and saturates) remain in solution.     

Characterization of Asphalt Fractions by NMR Spectroscopy

Abstract

Petroleum asphalt was separated into saturates, naphthalene aromatics, polar aromatics, and asphaltenes using the Corbett method. These asphalt fractions were characterized by H-1 and C-13 nuclear magnetic resonance spectroscopy (NMR). The spectra of saturates illustrate only traceable quantities of aromatic hydrogen and aromatic carbon. Naphthalene aromatics, polar aromatics, and asphaltenes all have broad bands in the aromatic regions of both H-1 and C-13 NMR spectra. These broad bands demonstrate the presence of polycondensed aromatic rings present in the structure of naphthalene aromatics, polar aromatics, and asphaltenes. Based on available literature, numerous NMR resonance bands are identified. The quantitative estimations for various kinds of protons and carbons in the asphalt fractions are compared.