高效液相色谱-光电二极管阵列检测法测定柴油中芳烃的类型

在采用美国试验与材料学会(ASTM) D6591标准方法测定柴油芳烃含量的过程中,通过光电二极管阵列检测器(PDAD)检测得到的色谱保留时间值及光谱特征吸收曲线,观察柴油中各类芳烃在极性氨基柱上的分离情况;用PDAD检测器考察了根据ASTM D6591确定的反冲洗时间点B对分析结果的影响,结果发现其允许的变化范围为B±0.2 min。在单环芳烃和双环芳烃分界不明显时,用PDAD检测器可以确定其切割点。     

Production of High-Density Jet and Diesel Fuels by Hydrogenation of Highly Aromatic Fractions

Physicochemical characteristics and hydrocarbon composition of highly aromatic wastes (light gas oil from catalytic cracking, pyrolysis tar, coal tar, coal gasification tar) as a feedstock for producing high-density jet fuels are considered. The hydrogenation reactions of polycyclic aromatic hydrocarbons, including mixtures of hydrocarbons with different numbers of rings, are described. Catalysts for hydrogenation of highly aromatic waste to obtain fuel fractions are considered. Particular attention is paid to catalyst deactivation in the course of processing of this feedstock. A separate section deals with the choice and implementation of procedures for processing highly aromatic feedstock to obtain jet and diesel fuels.     

掺混含氧燃料的柴油替代物部分预混火焰中多环芳香烃的荧光光谱和碳烟浓度

为研究不同含氧燃料与柴油掺混后碳烟降低机理, 本文在自行设计的燃烧器上构建部分预混层流火焰, 采用甲苯和正庚烷混合物(T20, 20%(体积分数)甲苯、80%正庚烷)作为柴油替代物,并分别添加甲醇、乙醇、正丁醇、丁酸甲酯和2,5-二甲基呋喃(DMF), 且保证混合燃料的含氧量均为4%. 进而应用激光诱导荧光法和激光诱导炽光法分别测量不同混合燃料的火焰中多环芳香烃(PAHs)的荧光光谱和碳烟浓度. 结果表明: 通过PAHs的荧光光谱可测量不同燃料火焰中PAHs的生成和增长历程. 四环芳香烃(A4)的生成氧化规律和碳烟基本一致, 说明通过分析A4变化可以预测碳烟变化. 添加含氧燃料后, T20燃料中甲苯含量降低是导致PAHs的荧光光谱强度降低和碳烟生成量减少的主要原因; 同时不同含氧燃料本身对多环芳香烃的生成贡献能力也是影响PAHs的荧光强度和碳烟生成的重要原因. 含氧量相当时, 掺混正丁醇后PAHs的荧光光谱强度和碳烟浓度比添加甲醇、乙醇、丁酸甲酯和DMF这四种含氧燃料的更低. 因此从含氧燃料结构来讲, 正丁醇掺混入T20燃料中降低PAHs和碳烟作用最显著.     

Structure-type separation of diesel fuels by solid phase extraction and identification of the two- and three-ring aromatics by capillary GC-mass spectrometry

A simple and effective solid phase extraction (SPE) method using silica gel micro glass columns has been developed for the separation of diesel fuel into groups of aliphatic, and mono-, di- and polyaromatic hydrocarbons. It is based on a stepwise gradient of dichloromethane in n-pentane. The resulting fractions were analyzed by capillary gas chromatography with a flame ionization detector and coupled gas chromatography-mass spectrometry. Commercially available standards, and retention indices and mass spectra were used for identification of individual aromatic compounds. The principal polycyclic aromatic hydrocarbons (PAHs) in diesel fuel are naphthalene, biphenyl, fluorene, phen-anthrene and their alkylated derivatives. Sulfur-containing PAHs are mainly represented by methyl-substituted dibenzo-thiophenes.     

Determination of total biodiesel fatty acid methyl, ethyl esters, and hydrocarbon types in diesel fuels by supercritical fluid chromatography-flame ionization detection

A method for determining total biodiesel methyl and ethyl ester content in diesel fuels by supercritical fluid chromatography-flame ionization detection (SFC-FID) is developed. A silica column typically used for determining aromatics in conventional diesel fuels by ASTM D5186 is back-flushed after separation of the hydrocarbons to allow elution of the various esters as a single "total biodiesel" distinct peak. The modification concurrently allows the determination of total aromatic hydrocarbons and their distribution as mono- and polynuclear compounds, as described in the current version of D5186. The instrument response is linear from 1.0% to 50% biodiesel esters with a signal-to-noise ratio of 25 at the 0.1% level. The short-term relative standard is 0.8%. Normalized percent quantitation using a hydrocarbon response factor of 1.00 and an ester response factor of 1.19 provide an average percentage error of 1.8% when measuring actual biodiesel/hydrocarbon fuel blends. The ester response factor is the average of the response factors of 10 pure ester compounds. These responses are calculated from respective solutions of each ester and the four compounds, hexadecane, toluene, tetralin, and naphthalene, as used for the D5186 response factor mixture.     

Determination of polycyclic aromatic sulfur heterocycles in diesel particulate matter and diesel fuel by gas chromatography with atomic emission detection

The sulfur content of diesel fuel is of environmental concern because sulfur can facilitate the formation of diesel particulate matter (DPM) and sulfur dioxide (SO2) in the exhaust can poison catalytic converters. The US Environmental Protection Agency (EPA) has established more stringent regulations to reduce the sulfur content of diesel fuels in the near future. In this study, various types of organosulfur compounds in DPM extracts and the corresponding fuels have been determined by gas chromatography with atomic emission detection. The diesel fuels used have sulfur contents of 2284 and 433 ppm, respectively, and are labeled as high-sulfur and low-sulfur diesel fuels. The compounds identified are mainly polycyclic aromatic sulfur heterocycles (PASHs). In the fuels tested, trimethylbenzothiophenes (TMBTs), dibenzothiophenes (DBTs), and 4-methyldibenzothiophene (4-MDBT) were the most abundant sulfur compounds, while larger PASH compounds were more abundant in DPM extracts. The high-sulfur diesel fuel contained a larger proportion of PASHs with one or two rings (lighter PASHs). In DPM, the concentrations of total organic sulfur and individual PASHs are higher for the high-sulfur diesel fuel, and the relative percentage of one or two-ring PASHs is higher as well. The influence of engine load on the DPM composition was also examined. With increasing load, the PASH concentration in DPM decreased for lighter PASHs, increased for heavier PASHs, and had a bell-shaped distribution for PASHs in between.     

汽油替代燃料燃烧过程中多环芳烃生成的化学动力学模型

提出了一个包含103组分和395个基元反应, 能够较好描述多组分汽油替代燃料多环芳烃(PAHs)生成的化学动力学机理模型. 计算结果与实验数据的对比表明, 该机理能够准确地计算乙烯、甲苯、正庚烷预混火焰和正庚烷部分预混对冲火焰中PAHs及其前驱物组分分布. 虽然本文机理目前还无法直接应用于汽油燃烧过程的PAHs多维数值模拟, 但与现有的汽油替代燃料PAHs机理相比, 本文提出的机理规模更小, 距离实际应用的目标更近.     

基于不同燃料PAH特性改进的适用于多组分燃料的碳烟模型

将多环芳烃(PAH)骨架模型与甲苯参比燃料(TRF)氧化模型耦合,构建了一个新的TRF-PAH骨架模型.以新的TRF-PAH骨架模型作为燃料燃烧的气相化学反应模型,基于不同分子结构的燃料氧化过程中生成PAHs和碳烟的路径也不同的研究结论,本文进一步优化了以PAHs为碳烟前驱生成物的碳烟半经验模型.通过甲苯在流动反应器、搅拌反应器和激波管中的氧化/裂解实验验证发现,新的TRF-PAH骨架模型可以相对准确地预测小分子PAHs和重要中间组分的浓度.通过对比烷烃和芳香烃氧化过程中生成苯的计算值可以发现,燃料的分子结构对PAHs的生成路径影响很大.另外,改进后的碳烟模型利用甲苯、正庚烷/甲苯及异辛烷/甲苯混合物为燃料的激波管中裂解和氧化实验验证,结果表明在较宽的工况内碳烟模拟值与实验值吻合较好.最后,将新的碳烟模型应用于KIVA程序,模拟以TRF20为燃料的柴油机碳烟排放,结果表明TRF-PAH骨架模型和碳烟模型能重现缸内燃烧和排放的特性.     

Local round robin test for determination of aromatics in diesel fuels by HPLC

Determination of aromatics in diesel fuels by HPLC is covered by European Standard EN 12916 (April 2000). The Standard is based on former standards IP 391/90 and IP 391/95. The method used for measurements is NP HPLC and separation is performed on silica or modified silica columns with RI detection. The precision of the method was checked by determining the repeatability and reproducibility. The content of aromatics was measured in a number of commercial samples. The measurements have been performed in three different laboratories and under different working and instrumental conditions. Satisfactory agreement was established for repeatability and was slightly poorer for reproducibility. The content of polyaromatics is within the tolerance range (IP 590/99) and the content of tricyclic and higher aromatics (tri+) is close to the limit of quantitition in some samples. Clear differences in the content of polycyclic aromatics in domestic diesel and eurodiesel fuels were observed. The results have confirmed the ruggedness and robustness of the measuring method.     

Identification of naphtho [8.1.2 abc] coronene in the extract of diesel particulate matter by non-aqueous reversed-phase liquid chromatography coupled with UV multichannel detector

Summary Non-aqueous reversed-phase liquid chromatography coupled with a UV multichannel detector has been used for the identification of large polycyclic aromatic hydrocarbons in the extract from diesel engine particulate matter. The existence of naphtho[8,1,2,abc]coronene is first confirmed by this technique.     

Production of Environmentally Friendly Diesel Fuel and Petroleum Aromatic Solvents by Extraction Combined with Azeotropic Distillation

A method is proposed for production of environmentally friendly diesel fuel, including five-step countercurrent extraction of aromatic hydrocarbons from the hydrofined diesel fraction with dimethylformamide or dimethylacetamide containing 3-5 wt % H₂O and pentane followed by regeneration of the extractants from the extract phase by azeotropic distillation. The process allows production of diesel fuel with the content of aromatic hydrocarbons below 10 wt %. Another product is a petroleum aromatic solvent like Nefras AR-150/330.     

Characterization of fuel samples by on-line LC-GC with automatic group-type separation of hydrocarbons

Characterization of fuels by LC-GC is possible by use of automatic successive transfer (multiple transfer) of HPLC fractions to a GC via an on-column interface. This paper describes the instrumentation and the methodology for the HPLC separation of the hydrocarbons (aliphatic and aromatic) into separate groups and the on-line transfer of these groups to a capillary GC column. Two HPLC methods were used with the same valve configuration: single column (silica) with column back-flush to detector; and double column (silica and amino-bonded silica) with multiple fraction transfer and back-flush. The first method was used for the analysis of total saturated compounds and total aromatic compounds; the second was used for the separation of the one-, two-, three-, and four-ring aromatic compounds present in diesel fuels. Examples are shown of the characterization of diesel fuels, and the repeatability of the data.     

Characterization and Identification of Polycyclic Aromatic Hydrocarbons in Diesel Particulate Matter

Emission of toxic exhaust from diesel engines is one of the major problems associated with the use of petroleum fuels. Particulate matter emission is perceived as a major pollutant, detrimental to the human health and environment, and has led to considerable study. Vehicular emissions comprise toxic pollutants that include unburnt hydrocarbons, polycyclic aromatic hydrocarbons, dioxins, and others. In this study, experiments have been carried out with the objective of determining overall particulate matter chemical composition and size. Electron microscopic images of the emitted soot were studied for average particle size distribution. More than 50 percent of the particles were in the range of 25 to 35 nanometers. Approximately 7, 9, 16, and 5 percent of the measured particles were from 35 to 40, 40 to 45, 45 to 50, and 50 to 55 nanometers, respectively. Determined elements were Al, Ba, Ca, K, Mg, Ti, Zn, and Zr at concentrations of 727, 53, 1100, 701, 1145, 638, 177, and 800 micrograms per milliliter respectively. Fifteen polycyclic aromatic hydrocarbons were detected in the extracts of filters and their concentrations were estimated. This investigation allows the comparison of particulate matter from different fuels and their blends.     

A silica-based monolithic column in capillary HPLC and CEC coupled with ESI-MS or electrospray-atmospheric-pressure laser ionization-MS

We describe the successful coupling of CEC and capillary HPLC with the recently developed atmospheric-pressure laser ionization (APLI) method. APLI is suitable for selectively and sensitively ionizing nonpolar aromatic compounds at ambient pressure for subsequent mass-selective detection. The polycyclic aromatic hydrocarbons used as analytes are first separated either by CEC on a silica-based monolithic column or by capillary HPLC. The eluent, along with a sheath flow, is volatilized by microelectrospray and then selectively ionized by excimer laser (KrF*) radiation via two-photon excitation. A QTOF-MS is used as mass-selective detector. This interface combination makes soft ionization of thermally labile nonpolar aromatic analytes possible.     

油品族组成的详细分析和燃油中芳烃的分析

用毛细管液相色谱-毛细管气相色谱联用方法详细分析了航空煤油、各种柴油、润滑油、抽出油和塔底油的族组成。在毛细管液相色谱上分离得到的单环、双环、三环、四环和稠环芳烃族,经过多位存储接口后,顺序进入毛细管气相色谱,通过毛细管气相色谱对每个族组分作详细分析及定量。用单检测器的二维毛细管气相色谱切割-反吹方法定性定量分析汽油、航空煤油中的各种芳烃,从第一维柱流出的组分和第二维柱流出的组分都先后进入同一氢火焰离子化检测器中,因此能用质量校正响应因子归一化方法准确定量分析而不需要标准样。用上述技术分析实际样品,证明了     

HPLC analysis of the large polycyclic aromatic hydrocarbons in a diesel particulate

Summary High performace liquid chromatography (HPLC) was used to separate the large polycyclic aromatic hydrocarbons in a diesel particulate extract. Identification of individual peaks was made using a photodiode array UV/visible detector to collect their absorbance spectra. Comparisons between standard compounds and the peaks were made using both retention times and spectra. Compounds of up to 10 rings were identified.     

Determination of total and polycyclic aromatic hydrocarbons in aviation jet fuel

The aviation jet fuel widely used in turbine engine aircraft is manufactured from straight-run kerosene. The combustion quality of jet fuel is largely related to the hydrocarbon composition of the fuel itself; paraffins have better burning properties than aromatic compounds, especially naphthalenes and light polycyclic aromatic hydrocarbons (PAHs), which are characterised as soot and smoke producers. For this reason the burning quality of fuel is generally measured as smoke fermation. This evaluation is carried out with UV spectrophotometric determination of total naphthalene hydrocarbons and a chromatographic analysis to determine the total aromatic compounds. These methods can be considered insufficient to evaluate the human health impact of these compounds due to their inability to measure trace (ppm) amounts of each aromatic hyrcarbon and each PAH in accordance with limitations imposed because of their toxicological properties. In this paper two analytical methods are presented. Both are based on a gas chromatographic technique with a mass detector operating in be selected ion monitoring mode. The first method was able to determine more than 60 aromatic hydrocarbons in a fuel sample in a 35-min chromatographic run, while the second was able to carry out the analysis of more than 30 PAHs in a 40-min chromatographic run. The linearity and sensitivity of the methods in measuring these analytes at trace levels are described.     

喷气燃料裂解产物中芳烃的全二维气相色谱-质谱分析

采用全二维气相色谱-质谱联用仪(GC×GC-MS),通过优化程序升温和调制周期,建立了喷气燃料裂解产物中芳烃的定性定量分析方法。该方法对多环芳烃(PAH)同分异构体具有良好的分离能力。利用MS检测器谱库检索结果、芳烃标准品及相关的文献报道,对喷气燃料裂解产物中常见的单环芳烃、二环芳烃、三环芳烃及四环芳烃等共27种芳烃进行了准确定性,并利用外标GC×GC-FID法对其进行定量。定量结果表明,芳烃含量均随着裂解产气率的增加而增大,当裂解产气率达到22%时,二环芳烃开始产生,且其含量随着裂解产气率的增加呈指数形式增加。该方法与传统的气相色谱-质谱相比,具有更好的分离及定性能力,可应用于复杂样品的分离及其定性定量分析。     

Determination of polycyclic aromatic sulfur heterocycles (PASH) in diesel fuel by high performance liquid chromatography and photodiode-array detection

An oxidation method (sulfone method) for the determination of polycyclic aromatic sulfur heterocycles (PASH) in diesel fuel is presented. The aromatic fraction of a diesel fuel, isolated by solid phase extraction, is oxidized under controlled conditions with hydrogen peroxide. The oxidation products, mainly methylated dibenzosulfone, are determined and quantified directly, without further clean-up, by HPLC with photodiode-array detection.     

Chromatographic determination of polycyclic aromatic hydrocarbons in oil sludge

It has been demonstrated that the Oasis HLB polymer adsorbent can be used for the purification of hexane extracts of oil sludge for the determination of polycyclic aromatic hydrocarbons by high-performance liquid chromatography with a fluorometric detector in these samples. The determination of polycyclic aromatic hydrocarbons has been carried out in samples of different wastes.