大港减压渣油的多层次分离与组成结构研究

采用超临界戊烷萃取分馏技术,分离了大港减压渣油,得到16个窄馏分和1个萃余残渣,对其组成和结构进行了表征;对超临界萃取分离窄馏分进行了四组分分离,研究了饱和分、芳香分、胶质和沥青质等亚组分的元素组成、相对分子质量分布和平均分子结构。结果表明,由窄馏分得到的四组分（SARA）性质结构差别很大,饱和分的平均分子结构最简单,芳香分的平均相对分子质量最小,胶质中的硫、氮含量最多,从萃余残渣中得到的沥青质相对分子质量分布范围最宽（200~40000）。     

Probing the molecular weight distributions of non-boiling petroleum fractions by Ag+ electrospray ionization mass spectrometry

This work explores the possibility of Ag+ electrospray ionization mass spectrometry (ESI-MS) to determine the molecular weight distributions of non-boiling petroleum fractions. Information about the molecular weight distributions is needed for fundamental studies on the nature of heavy crude oils and bitumens and for the development of novel recovery and processing methods. The method does not depend on thermal processes for the introduction of the fractions into the gas phase of the mass spectrometer, which is a considerable advantage over most other ionization methods. The Ag+ electrospray mass spectra of the fractions analyzed by using a toluene/methanol/cyclohexane (60:28:12%) solvent system display bimodal distributions in the ranges m/z approximately 300 to approximately 3000 and m/z 3000 to approximately 20,000. The abundances of the high molecular weight peak distributions can be reduced by in-source collisional activation experiments. Comparisons with the results obtained for model heteroatom-containing compounds (molecular weight < 600 Da) and high molecular weight polystyrene standards (up to one million Da) indicate that the majority of the structures in the saturate, naphthenoaromatic and polar aromatic fractions, and a significant portion of the asphaltenes, are small molecules. However, a considerable portion of the asphaltenes and some portion of the other fractions contain high molecular weight structures bound by covalent or strong non-covalent bonds. The results obtained by the Ag+ ESI method in this study for the saturate, aromatic, and polar fractions in a bitumen are in qualitative agreement with published molecular weight average results obtained for Cold Lake bitumen fractions analyzed by conventional gel permeation chromatography and field desorption mass spectrometry. Further work is needed to study the nature of the bonds and the interactions of the molecules in the asphaltene fractions by Ag+ ESI-MS.     

石油沥青质的NMR测定及其模型分子推测

从6种不同原油中分离提取了正己烷不溶的沥青质，测定了沥青质的1H NMR(Nuclear Magnetic Resonance)和13C NMR谱，从不同类型氢和碳原子的质量分数计算得到了一系列平均结构参数，结合相对分子质量测定和元素分析，给出了沥青质基本结构单元的平均分子式，推测了模型分子的结构。结果表明，沥青质的基本结构单元可以用稠环芳烃连接环烷烃和烷基侧链并含氧、氮和硫等杂原子的单元表示，结构单元之间形成缔合体，缔合数为4～6。     

克拉玛依减渣热转化前后的溶解度参数研究

对克拉玛依减渣进行适度热转化,确定了其裂解深度最大且不结焦的条件。利用超临界萃取分馏技术,将克拉玛依减渣及其热转化残渣油分离成一系列窄馏分和萃余残渣,对窄馏分及萃余残渣的性质（相对分子质量、密度、残炭、C、H、N、S元素和金属元素等）进行了表征。用改进的方法测定了萃余残渣的溶解度参数,并根据性质计算了各个窄馏分的溶解度参数,克拉玛依减渣及其热转化残渣油萃余残渣的溶解度参数分别为18.27 MPa1/2和19.79 MPa1/2;从溶解度参数的角度解释了渣油加工过程中的分相、结焦等问题。     

油藏矿物和化学剂强化稠油水热裂解降黏研究

采用大庆、辽河两种稠油,研究了油藏矿物、硫酸镍催化剂以及四氢萘供氢剂对其水热裂解反应的影响。结果表明,与单纯水热裂解相比,油藏矿物的加入能使两种稠油的平均相对分子质量减小,饱和烃和芳香烃组分含量增加,胶质和沥青质组分含量减少,稠油的降黏率分别从7.41%和12.95%增加到16.05%和25.29%,油藏矿物对稠油水热裂解反应具有催化作用;将硫酸镍和四氢萘加入反应体系后,稠油平均相对分子质量进一步降低,族组分中饱和烃和芳香烃进一步增加,胶质和沥青质组分进一步减少,稠油黏度明显降低,降黏率可高达84.39%。     

反应温度对加氢残渣油四组分含量和结构的影响

以沙轻减渣为原料,在高压釜内研究了不同反应温度下加氢反应前后渣油的四组分含量及其结构组成变化。结果表明,加氢残渣油中的饱和分含量明显增加,而芳香分和胶质的含量均降低,四组分含量随反应温度的升高均呈现规律性变化。加氢后四组分的H/C摩尔比和平均相对分子质量均降低,芳碳分率增加。随反应温度升高,四组分的H/C摩尔比和平均相对分子质量降低,烷基碳分率降低;芳香分、胶质和沥青质的芳碳分率增加;胶质和沥青质的总环数和芳环数均降低。渣油加氢过程中四组分都发生了明显的氢解和脱烷基反应。加氢反应中,胶质和沥青质结构单元间的各种桥键可发生明显地断裂,导致其结构单元数减少,且结构单元数随反应温度的升高而减少。     

煤焦油重组分沥青质性质分析及对加氢裂化生焦影响的推测

从中/低温煤焦油中切取重组分,提取了重组分C7-沥青质,并以此重组分为原料进行了高压釜加氢实验,通过1H-NMR、XRD、FT-IR、SEM、元素分析和相对分子量测定等手段对重组分沥青质结构参数、官能团、表观形态等方面进行了分析,并将其与加氢过程中生焦情况进行了关联。结果表明,C7-沥青质基本结构单元以稠环芳烃为中心,周围分布少而短的侧链,侧链以小于3个碳的短直链正构烷基为主,相对分子量小,芳香片层没有堆积结构。O是该沥青质中氢键主要来源,大多分布在环氧烷烃和醚类结构中,外围的O数量低,分子间氢键更难形成,结构单元之间缔合性弱,沉积聚合慢而均匀。沥青质中短侧链不易断裂,在反应过程中产生的稠环芳烃自由基少,缩合能力小,使该馏分油生焦能力低,具有较高的加氢潜质。     

Determination of the Onset of Asphaltene Precipitation by Visible Ultraviolet Spectrometry and Spectrofluorimetry

Abstract

Asphaltene deposition is a problem for the petroleum industry, affecting the production, transport, and storage of crude oil. The aim of this work is to develop and compare different methods to determine asphaltene precipitation. Two asphaltene fractions, one extracted from a Brazilian crude oil sample and the other from petroleum distillation residue, were evaluated by using model systems constituted of toluene/n-heptane in different compositions, using visible ultraviolet spectrometry and spectrofluorimetry. The results of the precipitation tests carried out by these two methods agreed, indicating they are effective to analyze asphaltene deposition and the performance of chemicals as asphaltene stabilizers.     

Study of a supramolecular structure of continental type petroleum asphaltenes

Supramolecular, electronic, and chemical structures of petroleum asphaltene molecules are studied. The investigations are carried out by quantum chemistry and molecular mechanics methods. The quantum chemical calculation of the structure-chemical parameters of dimers and trimers of petroleum asphaltenes is made using DFT/B3LYP. The refined values of the ionization potential and electron affinity of petroleum asphaltene molecules, their dimers and trimers agree well with the electron spectroscopy data. The results of the study of geometric structures of petroleum asphaltene dimers and trimers confirm the non-planar structure of asphaltenes.     

Observation of vanadyl porphyrins and sulfur-containing vanadyl porphyrins in a petroleum asphaltene by atmospheric pressure photonionization Fourier transform ion cyclotron resonance mass spectrometry

Vanadyl (VO) porphyrins and sulfur-containing vanadyl (VOS) porphyrins of a wide carbon number range (C(26) to C(52)) and Z-number range (-28 to -54) were detected and identified in a petroleum asphaltene by atmospheric pressure photonionization (APPI) and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). APPI provides soft ionization of asphaltene molecules (including VO and VOS porphyrins), generating primarily molecular ions (M(+.)). The ultra-high mass resolving power (m/Delta m(FWHM) approximately 500 K) of FTICR-MS enabled resolution and positive identification of elemental formulae for the entire family of VO and VOS porphyrins in a complicated asphaltene matrix. Deocophylerythro-etioporphyrin (DPEP) is found to be the most prevalent structure, followed by etioporphyrins (etio)- and rhodo (benzo)-DPEP. The characteristic Z-distribution of VO porphyrins suggests benzene and naphthene increment in the growth of porphyrin ring structures. Bimodal carbon number distributions of VO porphyrins suggest possible different origins of low and high molecular weight species. To our knowledge, the observation of VOS porphyrins in a petroleum product has not previously been reported. The work is also the first direct identification of the entire vanadyl porphyrin family by ultra-high resolution mass spectrometry without chromatographic separation or demetallation.     

Model molecules mimicking asphaltenes

Asphalthenes are typically defined as the fraction of petroleum insoluble in n-alkanes (typically heptane, but also hexane or pentane) but soluble in toluene. This fraction causes problems of emulsion formation and deposition/precipitation during crude oil production, processing and transport. From the definition it follows that asphaltenes are not a homogeneous fraction but is composed of molecules polydisperse in molecular weight, structure and functionalities. Their complexity makes the understanding of their properties difficult. Proper model molecules with well-defined structures which can resemble the properties of real asphaltenes can help to improve this understanding. Over the last ten years different research groups have proposed different asphaltene model molecules and studied them to determine how well they can mimic the properties of asphaltenes and determine the mechanisms behind the properties of asphaltenes.     

Studies of Athabasca asphaltene Langmuir films at air-water interface

Asphaltenes are present in heavy oils and bitumen. They are a mixture of hydrocarbons having complex structures of polyaromatic rings and short side chains. In general, the high-molecular-weight asphaltene is the most aromatic fraction with the highest number of side chains and the low-molecular-weight asphaltene contains the lowest number of side chains, while the number of side chains of the whole asphaltene fraction lies in between. In this study, asphaltenes were extracted and/or fractionated from Athabasca oil sand bitumen. Subfractions of high and low molecular weight and the whole asphaltenes were characterized using a Langmuir trough and complementary techniques such as VPO, FTIR, AFM, and contact angle measurements. At an air-water interface, amphiphilic asphaltene molecules can form a monolayer. Various fractions (high, low, and whole) of the asphaltene molecules behave similarly at the air-water interface, characterized by close resemblance of their surface pressure-area, hysteresis, and relaxation isotherms. The high-molecular-weight asphaltene is the most expanded fraction, while the low-molecular-weight asphaltene fraction is the most condensed, with the whole asphaltene lying in between. At the air-water interface a monolayer of the low-molecular-weight asphaltene relaxes at a faster rate than one of the high-molecular-weight asphaltene.     

大港常压渣油临氮与临氢热反应过程中胶体稳定性变化研究

对比了大港常压渣油临氮和临氢热反应过程中的胶体稳定性变化。结果表明,随着反应时间的延长,在热反应生焦诱导期内,渣油样品的胶体稳定性迅速下降;开始生焦后,胶体稳定性缓慢下降。从组分组成和组分性质角度,对大港常压渣油样品在热反应过程中胶体稳定性变化原因进行了分析。结果表明,随着反应时间的延长,沥青质含量先上升、后下降,在生焦诱导期结束时达到最大值,与体系胶体稳定性的变化特征相一致。随着热反应的进行,饱和分和轻芳烃组分的含量在上升,重芳烃、轻胶质、中胶质、重胶质含量下降,临氮热反应过程中轻胶质、中胶质、重胶质含量的下降更为显著。对渣油样品各组分的数均相对分子质量和平均偶极矩进行了研究。结果表明,随着热反应的进行,轻、中、重胶质组分的数均相对分子质量和平均偶极矩呈下降趋势,而沥青质的数均相对分子质量和偶极矩先增大后减小,从而使沥青质和胶质的分子性质差别先增加后减小,与体系胶体稳定性的变化趋势一致;同时沥青质的偶极矩变化表明,强极性的沥青质优先聚集生焦、临氢热反应过程中,氢与催化剂的作用有助于抑制沥青质分子量增大和极性增强,从而有助于抑制生焦。     

Laser desorption/ionization techniques in the characterization of high molecular weight oil fractions. Part 1: asphaltenes

The molecular weight distribution of the asphaltene fractions of two types of crude oils from two different Italian fields (samples 1 and 2) was investigated. The analytical tools used to perform these analyses were matrix assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) mass spectrometry. After observing that the use of the matrix (as well as the addition of Ag+) did not improve the quality of the data compared to that obtained in LDI conditions, all further measurements were performed with the latter technique. Operating under usual conditions of laser power and delay time, a very low resolution was observed, showing only macroscopic differences between the two samples in the molecular weight distribution of the different components. An accurate study on the possible reasons of this undesirable behavior indicates that it can originate from space charge phenomena occurring either in the ion source region or during the flight. A valid parameterization of the delay time and the laser power allowed higher quality spectra to be obtained. Surface-enhanced laser desorption ionization (SELDI) measurements were also performed using normal phase (silica) as the sample holder surface. Under these conditions, better results are obtained, proving that the sample-surface interaction is important to achieve, by means of laser irradiation, a homogeneous set of product ions. Both asphaltene samples were fractionated in five subfractions by gel-permeation chromatography (GPC) to obtain a better separation of the molecular weight distributions; the related spectra confirmed these findings. By using different approaches, relevant and reproducible differences between the asphaltene fractions of the two oil samples were observed.     

电喷雾质谱法分析三次采油用石油磺酸盐

采用电喷雾质谱法测定了胜利油田三次采油用石油磺酸盐样品的分子量分布范围在200～600,数均分子量为488,重均分子量为534.鉴别出烷基苯磺酸盐、烷基萘磺酸盐、烷基茚满磺酸盐等为胜利油田磺酸盐的主要组分.同时对来自胜利、大庆、克拉玛依和玉门4个不同油田的石油磺酸盐进行区别分析.     

特稠油乳化降黏机理研究

研究了胜利油田罗家高硫特稠油的黏度及其极性四组分、有机杂原子、金属元素的关联。结果表明,该稠油的高黏度主要与三个因素有关：（1） 含有高分子量的胶质和沥青质组分;（2） 硫的质量分数很高;（3） 金属元素V、Fe、Ni形成配位络合物增加了沥青质的内聚力。同时考察了所筛选的降黏剂的效果,降黏剂明显降低了油水界面张力,使得稠油的黏度降低。比较了添加降黏剂前后沥青质的电子探针照片的变化,推测降黏剂分子借助强的形成氢键的能力和渗透、分散作用进入沥青质片状分子之间,破坏了沥青质分子平面重叠的聚集体,使聚集结构变得疏松,表明聚集有序性降低是稠油降黏的主要机理。     

Water-in-Hydrocarbon Emulsions Stabilized by Asphaltenes at Low Concentrations

The role of Athabasca asphaltene particles and molecules in stabilizing emulsions was examined by measuring the surface area of water-in-toluene/hexane emulsions stabilized by various asphaltene fractions, each with a different proportion of soluble and insoluble asphaltenes. The stabilized interfacial area was found to depend only on the amount of soluble asphaltenes. Furthermore, the amount of asphaltenes on the interface was consistent with molecular monolayer coverage. Hence, at low concentrations, asphaltenes appear to both act as a molecular surfactant and stabilize emulsions. The effect of the hexane : toluene ratio on emulsion stability was examined as well. At lower hexane : toluene ratios, more asphaltenes were soluble but the surface activity of a given asphaltene molecule was reduced. The two effects oppose each other but, in general, a smaller fraction of asphaltenes appeared to stabilize emulsions at lower hexane : toluene ratios. The results imply that the emulsifying capacity of asphaltenes is reduced but not eliminated in better solvents. Copyright 2000 Academic Press.     

超声波处理对渣油加氢过程的影响

对四种减压渣油的超声波处理前后渣油加氢反应产物分布研究表明,超声波处理后渣油加氢反应的焦炭和>500℃残渣油收率降低,气体、汽油、柴油和VGO收率提高,轻油产率提高6~10个百分点,渣油转化率增大,轻质化性能明显增强;不同渣油经超声波处理后的加氢反应性能改变不同;利用超声波处理后渣油加氢的虹吸作用模型,从宏观层次解释了超声波改善渣油加氢效果的原因;超声波处理后杂原子的脱除效果均有不同程度的提高,尤其是对金属钒的脱除影响最为明显。超声波处理后加氢残渣油的饱和分和沥青质含量增加,芳香分和胶质的含量减少。     

Thermodynamic characterization of asphaltene-resin interaction by microcalorimetry

This paper collects the work performed by isothermal titration calorimetry (ITC) to characterize the interaction between petroleum asphaltenes and resins. The interaction between these two fractions is of great interest in order to understand the mechanism of stabilization ofasphaltenes in crude oil. To simplify the approach, this preliminary study focuses on toluene solutions of both fractions. This paper reports the experimental determination of the average number of sites in asphaltene molecules and the enthalpy of interaction between asphaltenes and resins. Two models have been used to fit the experimental data. The enthalpies calculated by ITC are in the order of -2 to -4 kJ/mol. These values are in the limit of hydrogen bonding and permanent dipole energies. Similar values have been obtained by using the enthalpy as a fitting parameter in the SAFT equation.     

低温煤焦油常渣C5沥青质的分离与表征

从低温煤焦油中蒸馏提取出大于350℃的常渣,以正戊烷、正戊烷+5%乙醇、正戊烷+5%异丙醇三种溶剂沉淀沥青质。通过1H-NMR、13C-NMR、傅里叶变换离子回旋共振质谱仪(FT-ICR MS)、元素分析和相对分子量测定等手段对重组分沥青质的结构参数、杂原子化合物的分布等方面进行了分析,构建含杂原子的平均分子结构模型。结果表明,乙醇和异丙醇的加入可以显著降低C5-沥青质的收率,所得沥青质的芳香性增强,平均分子量增大,为更高缩合度的具有较短侧链的结构;极性溶剂的加入没有改变沥青质中杂原子化合物的类型,但是O1和O2中一部分低缩合度的化合物转移到可溶质中,O3-O6化合物的相对丰度增大,表明混合溶剂有利于萃取低缩合度的化合物。