13C-N.M.R. STUDIES OF A FLASH PYROLYSIS TAR AND A SUPERCRITICAL GAS EXTRACT USING MODERN PULSE SEQUENCES

The oil and the asphaltene obtained from a flash pyrolysis tar of an Australian sub-bituminous coal and the oil and asphaltene from a supercritical gas extract of an Australian bituminous coal were studied by ¹³;c-n.m.r. apectroscopy using modern pulse sequences which distinguish between primary (CH₃), secondary (CH₂), tertiary )CH( and quaternary (C) carbons. The oil from the flash pyrolysis tar was further separated into three fractions by elution chromatography and these were also studied. All the samples studied contained considerable amounts of long unsubstituted aliphatic chains. In the flash pyrolysis tar, a sizeable proportion of the long chains had a CH = CH₂ end group pertaining to both 1-alkenea and those chains attached to aromatic rings (w-aryl-1-alkenes), but this was much less in the supercritical gas extract. From the quaternary and tertiary carbon subspectra, it appears that the division of the aromatic carbon signal at 129-130 ppm between aromatic CH and C carbons is not valid for polar fractions of coal liquids. Though these pulse sequences are very useful for obtaining information on well resolved signals, broad featureless signals often found in coal liquids pose considerable problems.     

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.     

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

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.     

Structural Changes of Sub-fractions in Residue Hydrotreating Products by Ruthenium Catalyzed Oxidation

Abstract

Structure of aromatics, resins, and asphaltenes in petroleum residue was undertaken by using ruthenium ion catalyzed oxidation. The distribution of alkyl side chains and bridges connected to aromatic rings was quantified, and the condensed type of aromatic rings was deduced. The structural changes of fractions in residue during hydrotreating were discussed. The results showed that fractions have abundant alkyl side chains (C₁–C₂₇), mainly n-alkyl side chains, attached to aromatic carbons, and polymethylene bridges connected to at least two aromatic ring systems are also present. The molar concentrations of these alkyl groups are declined as the increase of chain length. Cata-condensed, peri-condensed, and biphenyl-type aromatic unit structures coexist in fractions, while the proportion of biphenyl type structure is relatively small. The aromatic structure of aromatics is mostly cata-condensed, while for resins the proportion of cata-condensed and peri-condensed type aromatic structures is comparable, and structure of asphaltene is mostly peri-condensed. The chemical structure of fractions in residue changed due to the increase of hydrotreating degree. The enrichment of large aromatic units made asphaltene have more aromatic structures and higher condensed degree.     

STRUCTURAL CHARACTERIZATION OF GUDAO ASPHALTENE BY RUTHENIUM ION CATALYZED OXIDATION

ABSTRACT

Structural characterization of Gudao asphaltene was undertaken by using ruthenium ion catalyzed oxidation (RICO ) which is capable of converting aromatic carbons selectivety to carbon dioxide and/or carboxyUc groups while leaving aliphatic and alicyclic structures essentially unaffected. The oxidation products were dominated by a homologous series of straight chain monocarboxyfic acids ( C₂ -C₃₅) indicating that normal alkyl chains are important constituents of the asphaltene. A series of α,ω; -dicarboxylic acids (C₄ - C₂₆) were also detected and determined, confirming the presence of poh/methylenc mokties linking two aromatic units. Relative high yields of benzenepenta- and hexacarboxyhc acids fonned in the RICO of Gudao asphaltene clearly indicate that substantia] aromatic structures of this asphaltene are peri-condensed.     

PARTICLE SIZE,SOLVENT, OXYGEN,TEMPERATURE AND PRESSURE EFFECTS ON THE CONTENTS OF INSOLUBLE FRACTIONS FROM SOLID VACUUM RESIDUA

ABSTRACT

n-Heptane insoluble contents were determined for an extraheavy-oil vacuum residue, one petroleum and one coal pitch as a function of particle size. This variable was found to affect the yields of insoluble material, aspect which was also observed during extractions carried out with aromatic and halogenated solvents. The precision of results was observed to be independent on the operators. A study was carried out to determine the effect of sample drying time on fraction yields. It was found that maltene fractions were strongly dependent on this variable, whereas asphaltene fractions were totally independent

Predissolution in aromatic solvents proved worthless from the repeatability point of view. However, predissolution of the oil residue in CH₂Cl₂ followed by filtration and asphaltene precipitation with simultaneous solvent removal, was deemed to be a suitable technique to remove mineral matter and isolate asphaltenes in a single step

Sample oxidation during asphaltene precipitation and isolation was detected by gravimetric and spectroscopic techniques. This fact is very important since common precipitation techniques do not address this issue

Preliminary accelerated extraction experiments carried out with pitch samples at high temperature and pressure, revealed that this approach can be a very interesting research tool to investigate solubility properties.     

POLAROGRAPHIC CHARACTERIZATION OF AROMATIC STRUCTURES IN COAL LIQUID PRODUCTS

ABSTRACT

Reducible aromatic species in coal liquid products from five major processes (Synthoil, FMC COED, HRI H-Coal, PAMCO SRC, and Catalytic Inc. SRC) together with solvent elution chromatography fractions of a selected asphaltene has been evaluated. The half-wave potentials measurments are found to be consistant with other methods. The total polarographic reduction of measurement per average molecule for Synthoil solvent fractions, as measured by diffusion constant (i_d /C), increases in the following manner: gas oil → resin → asphaltene → carbene → carboid. The same trend was observed when color indices (I) and refractive indices (n ₂₅) were individually studied.     

沥青质中官能团结构和氢键的红外光谱表征

利用傅里叶红外光谱表征渣油沥青质和煤焦油沥青质分子的官能团结构,并通过软件Origin 2018对沥青质红外光谱的氢键区、脂肪族碳氢伸缩振动区和C—O区的吸收峰进行分峰拟合。结果表明：两种沥青质均主要以碳、氢元素为主,二者杂原子的含量存在明显差异,但杂原子官能团的类型基本相同;渣油沥青质中的氢键主要是由苯环O—H与芳香醚键中的O原子、O—H自缔合形成的氢键,而煤焦油沥青质中的氢键主要是苯环O―H与芳香醚键中的O原子形成的氢键;与渣油沥青质相比,煤焦油沥青质的烷基侧链更短。     

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。     

神木低温煤焦油中含氧化合物的分析与鉴定

采用酸碱分离和萃取色谱分离方法将陕西神木地区低温煤焦油分离为酸性组分、碱性组分和5个中性组分。采用气相色谱-质谱(GC-MS)和负离子电喷雾傅里叶变换离子回旋共振质谱(ESI FT-ICR MS)鉴定了神木低温煤焦油酸性组分、中性组分4和中性组分5中含氧化合物的组成与分布。结果表明,神木低温煤焦油酸性组分中含氧化合物主要包括苯酚、茚满酚、萘酚、联苯酚、芴酚、菲酚类化合物;中性组分4和中性组分5中含氧化合物主要包括C₁₀-C₂₉脂肪酮和少量芳香酮。神木低温煤焦油中含氧化合物主要有O₁、O₂、O₃、O₄、O₅、O₆类化合物,其中O₂类化合物相对丰度最高。     

Physicochemical Properties and Performance Characteristics of Naphthenoaromatic Jet and Diesel Fuels Obtained by Hydrotreating of Highly Aromatic Fractions

The composition and physicochemical and chemmotological properties of jet and diesel fuels obtained by hydrogen treatment of highly aromatic fractions—light cycle oil, pyrolysis tar, and coal tar—are considered in comparison with fuels obtained by hydrotreating of straight-run petroleum fractions. The influence of the hydrocarbon composition on the density, calorific value, viscosity, pour point, smoke point, cetane number, compatibility with elastomers, sooting tendency, combustion stability, and CO and NO _x emissions of fuels are also considered. The interrelation of the composition of hydrocarbons and heteroatomic compounds of naphthenic jet fuels with thermo-oxidative and thermal stability has been analyzed in detail, and differences between the fuels in stability depending on the feedstock and hydrogenation depth have been shown. The usefulness of naphthenoaromatic distillates as additives that enhance both the thermal and thermo-oxidative stability of petroleum jet fuels is pointed out. Promising fields of research have been defined, including selective hydrogenation to produce certain stereoisomers; a targeted approach to feedstock compounding; and optimization of fuel composition to obtain desired characteristics using modern analytical techniques, such as GC × GC, HPLC, GC–MS, GC/TOF-MS, and ESI-MS.     

Investigation of Asphaltene Precipitation Process for Kuwaiti Reservoir

Abstract

As part of an Enhanced Oil Recovery (EOR) research program, Asphalting precipitation processes were investigated for a Kuwaiti dead oil sample using different hydrocarbons and carbon dioxide as precipitants at the ambient and high pressure of 3000 psig conditions. The hydrocarbons used as precipitants were ethane (C2), propane (C3), butane (C4), normal pentane (n-C5), normal hexane (n-C6), and normal heptane (n-C7). The equipment used for this investigation was a mercury-free, variable volume, fully visual JEFRI-DBR PVT system with laser light scattering. The minimum critical value of precipitants concentration for the oil sample has been identified at the ambient and high-pressure conditions for each precipitant. Our investigation has revealed that for this oil sample the most powerful asphaltene precipitant were CO₂ followed by C2, C3, C4, n-C5, n-C6, and n-C7. Moreover, the effect of pressure and temperature on the asphaltene precipitation has been investigated experimentally for CO₂, n-C5, n-C6, and n-C7. The precipitation and redissolution of asphaltene upon the addition and removal of CO₂ and light alkanes (C2–C4), at 3000 psig and ambient temperatures, have shown evidence of reversibility of asphaltene precipitation. A comprehensive fluid characterization analysis for the oil sample has been performed including, physical properties of crude oil, compositional, molecular weight (Mw), and SARA analyses. Advanced analytical techniques such as 1H and 13C NMR and IR spectrometers have been utilized to investigate the molecular structure of the asphaltene for this sample. It was concluded that the asphaltene molecules for this oil contain 120 total aromatic carbons with 42 aromatic rings, 114 naphthenic rings, and 5–7 sets of condensed aromatic rings.     

TWO-DIMENSIONAL SOLUBILITY PARAMETER MAPPING OF HEAVY OILS

ABSTRACT

The solubility and insolubility of heavy oils and their fractions in dilute mixtures with various solvents were used to characterize heavy oil interactions. A two-dimensional solubility parameter, developed for the selection of solvents for organic polymers, was found to group all the solvents for each heavy oil fraction in polygon areas when the complexing solubility parameter component was plotted against the field force solubility parameter component. All fractions of Cold Lake vacuum residua, except for the saturate fraction, form concentric solubility areas. Therefore, in going in the direction of decreasing aromaticity from coke to asphaltenes to resins to aromatics, all solvents for the previous fraction in the series are also solvents for all subsequent fractions in the series. As a result, asphaltenes can be precipitated, but not extracted, from heavy oils. This is attributed to the interaction among polynuclear aromatics being the dominate interaction in petroleum that causes insolubility in hydrocarbon liquids. However, the paraffinic chains on the same petroleum molecules limit their solubility in highly complexing liquids. In contrast, even vacuum gas oils from the Exxon Donor Solvent coal liquefaction process are insoluble in aromatic liquids but soluble in moderately complexing liquids because of hydrogen bonding, resulting from oxygen functionality. Hydrotreating of these coal derived vacuum. gas oils reduces their oxygen functionality and increases their solubility areas so that they become compatible with petroleum liquids.     

STRUCTURAL GROUP ANALYSIS OF RESIDUES FROM ATHABASCA BITUMEN

ABSTRACT

Although the processability of bitumen from tar sand is dependent on its chemical composition, the details of this relationship are poorly understood. In this study, residue fractions from Athabasca bitumen (topped at different temperatures) and hydrocracker and coker residues were analyzed in detail. Separated class fractions were subjected to elemental analysis. NMR and IR spectroscopy, and potentiometrlc titration. These data were combined mathematically to obtain a structural profile of each oil. This analysis defines the structural changes in asphaltene precipitates due to distillation and processing, as well as the quantitative changes in the overall structural composition of the oil. Hydrocarbon structures such as paraffinic chains and naphthenes show definite trends with distillation and processing.     

Composition of products of analytical pyrolysis of resin and asphaltene fractions of Usa oil

Resin and asphaltene fractions of crude oil from the Usa field (Timan-Pechora oil-and-gas province, Russia) obtained by fractional precipitation of asphaltenes and chromatographic separation of resins have been analyzed using Rock-Eval pyrolysis and flash pyrolysis (650°C, 20 s) with on-line chromatographic/mass spectral detection of volatile products. It has been shown that the samples under study contain organic compounds with a relatively low molecular mass in an amount of 2.3 to 15.3 wt % as either impurities or moieties bound in resin and asphaltene molecules by labile chemical bonds. The products of flash pyrolysis of the samples under study differ in the relative amount of the “unresolvable complex mixture” of unidentified compounds; the chemical group and molecular composition; and the relative amount of identified types of compounds, such as normal and isoprenoid alkanes, α-olefins, cyclohexanes, cheilanthanes and hopanes, hopenes, pregnanes and steranes, alkylbenzenes, naphthalenes, phenanthrenes and anthracenes, and benzo- and dibenzothiophenes.     

The Structural Characterization of Saturate,Aromatic, Resin,and Asphaltene Fractions of Batiraman Crude Oil

Abstract

The structural characterization of fractions of Batiraman crude oil, which is the heavy crude oil from a field in the southeastern part of Turkey, was investigated. Batiraman crude oil and its saturate, aromatic, resin, and asphaltene (SARA) fractions were seperated. Treatment of crude oil with n-heptane provided the separation of asphaltene. Maltene was collected by evaporating the n-heptane from the filtrate. Then, maltene was separeted into saturates, aromatics, and resins by SARA technique. Maltene was separated into saturate, aromatic, and resin fractions using column chromatography. SARA fractions were quantified on a weight percent basis. Fractions of Batiraman crude oil were characterized by elemental analysis, proton nuclear magnetic resonance (¹H NMR) analysis, electrospray ionization mass spectrometry (ESI-MS), and Fourier transform infrared (FTIR) spectroscopy techniques.     

固态13C-NMR法表征渣油沥青质的结构组成

以长庆常压渣油、胜利减压渣油和加拿大减压渣油为原料,研究了正庚烷沥青质的结构及组成,根据固态13C NMR分析结果,计算了沥青质分子的平均结构单元参数,并模拟出了沥青质的结构单元模型。结果表明,沥青质分子由4个左右的结构单元组成,每个结构单元包括5～7个缩合芳香环。沥青质中的饱和碳以环烷碳为主,并包含少量的短烷基侧链,沥青质的n(HS)/n(CS)在16左右。对于平均相对分子质量较大、具有较短烷基侧链和较少取代基的沥青质分子,由核磁共振氢谱计算其结构参数时,采用重油计算过程的假设--芳香环烷基侧链上α位及β位和β位以远的氢/碳比为2(x=y=2)是不合理的,可能会导致计算结果与沥青质的真实结构存在较大的误差。     

CONTINUOUS HYDROGENATION OF FLASH PYROLYSIS COAL TAR

ABSTRACT

High melting tars from the flash pyrolysis of Millmerran coal have been upgraded to mobile liquid products by continuous hydrogenation over a fluidized nickel molybdate catalyst. The hydrogenation unit developed specifically for this purpose la described and changes In properties of the tar during hydrogenation are discussed.     

基于预加氢的煤焦油重质馏分油供氢性能研究

对煤焦油重质馏分油进行预加氢处理,利用红外光谱、核磁共振和元素分析等方法,从分子结构角度深入探讨煤焦油重质馏分油的理化性质和供氢性能的变化规律。结果表明,通过预加氢处理,煤焦油重质馏分油的芳碳率（fa）由加氢前的0.89下降到加氢后的0.80,芳环取代度（σ）由加氢前的0.12提高到0.20,供氢指数（PDQI）由3.21 mg/g提高到4.02 mg/g;预处理后的煤焦油重质馏分油在煤油共炼中的氢耗由4.03%下降到3.74%,转化率和油产率均得到提高,产物油中的沥青质含量明显下降,油品质量有明显改善。     

CHEMICAL CHARACTERISTICS OF SUPERCRITICAL TOLUENE EXTRACTS FROM TWO TURKISH LIGNITES

ABSTRACT

Samples from two major deposits of Turkish lignites were subjected to supercritical toluene extraction at 325°C and 14.1 MPa in an autoclave. The resultant extracts were separated into pre-asphaltene, asphaltene, saturates, aromatics and resin fractions by column chromatography. The fractions were characterized by ¹H-NMR, ¹³C-NMR, IR. and elemental analysis in order to compare the chemical composition of extracis from the two coal samples. The results show that the extracts from the Tungbiiek (T-coal) deposits contain aliphatic constituent which is composed of mostly long chain unbranched alkyl compounds while the extracts from the Soma Mcrkeg (S-coal) deposits contain a significant amount of branched paraffinic compounds. The resin fractions from both samples were found to contain a significant amount of single ring aromatic compounds.