Synthesis and some aspects of the formation mechanism of carbon structures under hydrothermal conditions

The formation of carbon structures upon the reactions of organic compounds with strong mineral acids under hydrothermal conditions was studied. The reactions were found to give amorphous carbon, microcrystalline graphite, nanodiamonds, diamond-like carbon, diamonds, C₆₀ and C₇₀ fullerenes, and carbolite. Hydrocarbons of various compositions including aromatics and naphthenes were detected among the reaction products. A possible mechanism of the formation of carbon structures with sp ² bond hybridization under hydrothermal conditions was proposed.     

Measurement and prediction of phase equilibria in the extraction of aromatics from naphtha reformate by tetraethylene glycol

The extraction of aromatics from naphtha reformate was carried out by the solvent tetraethylene glycol at six temperatures and three solvent to feed ratios. The concentrations of paraffins, naphthenes and aromatics in the extract and raffinate phase were measured and compared to values predicted by the UNIFAC group contribution model. It was shown that the UNIFAC model is capable of predicting the concentrations in this multicomponent system with an overall RMSD of 1.27 mol.%.     

Change in consistency and composition of trichloroethylene- and trichloroethane-treated asphalts

Solvent extraction of asphalt from pavement mixtures is a technique used to study the change in asphalt during service. Rheological measurements indicate that asphalts recovered from trichloroethylene or trichloroethane are markedly hardened. Compositional studies on asphaltic fractions reveal a notable decrease in saturates, naphthenes, H, N, Ni and V, and increase in polar aromatics and asphaltenes along with incorporation of Cl in all fractions. These structural changes are responsible for the hardening of the asphalt and are interpreted in terms of cyclization of saturates, aromatization of naphthenes, coupling of free radicals with neutral species to give a high content of asphaltenes, and in terms of loss of the relatively volatile Ni and V porphyrins during the extraction—recovery process.     

Towards comprehensive hydrocarbons analysis of middle distillates by LC-GCxGC

The detailed characterization of middle distillates is essential for a better understanding of reactions involved in refining processes. Owing to a higher resolution power and an enhanced sensitivity, but especially to a group-type ordering in the chromatographic plane, comprehensive two-dimensional gas chromatography (GCxGC) offers unsurpassed characterization possibilities for petroleum samples. However, GCxGC fails to totally discriminate naphthenes from unsaturates occurring in hydrotreated diesel samples. This article aims at promoting the implementation of LC-GCxGC for the quantitative determination of hydrocarbon distribution in middle distillates, including naphthenes. In this configuration, liquid chromatography (LC) enables the separation of hydrocarbons into two fractions (viz., saturated and unsaturated) before the subsequent analysis of each fraction by GCxGC. In this paper, the choice of GCxGC conditions in order to achieve the separation and identification of hydrocarbons by chemical class is discussed; under these conditions, naphthenes are separated according to the number of saturated rings. For the first time, the presence of di-, tri-, and tetra-naphthenes resulting from the hydroconversion of aromatics can clearly be evidenced. A quantitative procedure for the determination of the distribution of hydrocarbons, including the distribution of naphthenes according to the number of saturated rings, is also proposed and discussed in detail. LC-GCxGC is found to provide an unequalled degree of information that will widely contribute to a better understanding of hydroconversion processes.     

Coupling of Methanol and Carbon Monoxide over H‐ZSM‐5 to Form Aromatics

The conversion of methanol into aromatics over unmodified H‐ZSM‐5 zeolite is generally not high because the hydrogen transfer reaction results in alkane formation. Now circa 80 % aromatics selectivity for the coupling reaction of methanol and carbon monoxide over H‐ZSM‐5 is reported. Carbonyl compounds and methyl‐2‐cyclopenten‐1‐ones (MCPOs), which were detected in the products and catalysts, respectively, are considered as intermediates. The latter species can be synthesized from the former species and olefins. ¹³C isotope tracing and ¹³C liquid‐state NMR results confirmed that the carbon atoms of CO molecules were incorporated into MCPOs and aromatic rings. A new aromatization mechanism that involves the formation of the above intermediates and co‐occurs with a dramatically decreased hydrogen transfer reaction is proposed. A portion of the carbons in CO molecules are incorporated into aromatic, which is of great significance for industrial applications.     

Investigating comprehensive two-dimensional gas chromatography conditions to optimize the separation of oxygenated compounds in a direct coal liquefaction middle distillate

Considering the global energetic context, diversifying fuels is of growing importance and many new alternatives are promising. Coal liquefaction products definitely appear among the new generation substitutes. These product's characteristics are very far from fuel specifications as they are mainly composed of naphthenes, aromatics, polycondensed naphthenic and aromatic structures and heteroatomic compounds (nitrogen and oxygen), with a very low paraffin content. Identification and quantification of oxygen-containing species in coal-derived liquids are of considerable importance to understand their behaviors in further processing. However, these species have not been characterized as fully as the predominant hydrocarbon components. Literature shows that these compounds consist mainly in alkylated phenolic and furanic structures. Therefore, comprehensive two-dimensional gas chromatography has been investigated to provide enhanced molecular characterization of these complex samples. Several different configurations involving innovative column configurations were tested. Each of them was optimized by testing different column lengths, modulation periods, and oven conditions. A comparison of the contribution of each column configuration was carried out regarding four main criteria: individual separation of oxygenates, group type separation, resolution, and space occupation. One of them enabled an outstanding separation of paraffins, naphthenes, monoaromatics, diaromatics and targeted O-compounds in a direct coal liquefaction product. It was therefore subjected to further experimentations using a time-of-flight mass spectrometer to validate the identification and unravel more than fifty oxygenated molecular structures. A group-type quantification was also established for four column arrangements and gives the distribution of paraffins, naphthenes and aromatics. It can be concluded from this study that a non-orthogonal arrangement involving a highly polar column in the first dimension was the most adapted one.     

Investigation of catalytic degradation of high-density polyethylene by hydrocarbon group type analysis

Catalytic degradation of waste high-density polyethylene (HDPE) to hydrocarbons by ZSM-5, zeolite-Y, mordenite and amorphous silica–alumina were carried out in a batch reactor to investigate the cracking efficiency of catalysts by analyzing the oily products including paraffins, olefins, naphthenes and aromatics with gas chromatography/mass spectrometry (GC/MS). Catalytic degradation of HDPE with zeolite-Y, mordenite and amorphous silica–alumina yielded 71–82 wt.% oil fraction, which mostly consisted of C₆–C₁₂ hydrocarbons, whereas ZSM-5 yielded much lower 35% oil fraction, which mostly consisted of C₆–C₁₂ hydrocarbons. Both all zeolites and silica–alumina increased olefin content in oil products, and ZSM-5 and zeolite-Y particularly enhanced the formation of aromatics and branched hydrocarbons. ZSM-5 among zeolites showed the greatest catalytic activity on cracking waste HDPE to light hydrocarbons, whereas mordenite produced the greatest amount of coke. Amorphous silica–alumina also showed a great activity on cracking HDPE to lighter olefins in high yield, but no activity on aromatic formation.     

Heat Capacity of a Synthetic Distillation Cut+n-Hexane System under Pressure

Isobaric heat capacities of synthetic mixtures were determined up to 40 MPa with a modified C-80 Setaram calorimeter equipped with cells designed for high pressures. The system investigated was a pseudo-binary hexane+synthetic cut, the latter consisting of compounds of the three chemical families that occur most frequently in natural effluents (paraffins, naphthenes and aromatics). The additional knowledge of density vs. pressure and temperature affords the specific heat γ ratio.     

An automatic PNA analyser for the under 200°C fraction contained in a higher boiling product

Summary We present a modified circuit for the PNA-analyser, which allows analysis for paraffins, naphthenes and aromatics in the under 200°C fraction of a sample having a final boiling point above 200°C. The modified separation scheme gives, in addition, improved type separation. By the introduction of adapted instrumentation the analyser has been suited to fully automated serial analysis. The new concept will eventually be commercialized.A glossary of abbreviations has been included at the end of this paper.     

Multidimensional gas chromatography for the detailed PIONA analysis of heavy naphtha: hyphenation of an olefin trap to comprehensive two-dimensional gas chromatography

A multidimensional method providing the composition of a heavy naphtha in paraffins, isoparaffins, olefins, naphthenes, and aromatics (PIONA) in the C8-C14 range is presented. The analytical set-up consists in a silver modified silica olefin trap on-line coupled to comprehensive two-dimensional gas chromatography (GC x GC). In this configuration, hydrocarbons are separated, in gaseous state, in two fractions, saturate and unsaturate, each fraction being subsequently analysed by GC or by GC x GC. The resolution between saturates and olefins was found to be improved compared to a single GC x GC run. The characterisation of the olefin trap highlights the benefits and the limits related to the use of that stationary phase as a double bond selective fractionation medium.     

Study of the inhibiting effect of a quaternary ammonium surfactants mixture synthesized from petroleum fraction (reformate) against the carbon steel corrosion in HCl 1 M

Quaternary ammonium cationic surfactants were synthesized from reformate, a liquid mixture of hydrocarbons (aromatics, naphthenes and paraffins), via chloromethylation/quaternization sequences. The petroleum surfactants thus obtained were evaluated as corrosion inhibitors for carbon steel in 1 M HCl, by gravimetry, potentiodynamic polarization and electrochemical impedance spectroscopy. The corrosion inhibiting efficiency was assessed as functions of surfactant concentration. The results showed that the inhibiting efficiency increased with surfactant concentration; its optimal value of 70 % was for a surfactant concentration of 320 mg/L at 25 °C. Potentiodynamic polarization measurements showed that the mixture acts as a mixed type inhibitor. The corrosion inhibiting mechanism is thought to proceed via an adsorption of the surfactant molecules on the steel surface, generating a film and hindering the active sites. Our experimental adsorption data were found to obey the Langmuir adsorption isotherm. SEM images of the treated specimens, revealing the likely formation of a protective film, demonstrated the inhibiting capacity of the petroleum quaternary ammonium surfactants against the carbon steel corrosion.     

Hydrocarbon type analysis by gas chromatograph using a single capillary column and a multi-column valve system

Summary Two different gas chromatographic methods are used for the determination of hydrocarbon type distribution in naphtha and gasoline samples with final boiling points up to 275 °C. The methods are based either on a single capillary column or on a valve-switched packed column system. Both methods give extensive information on paraffins, olefins, naphthenes and aromatics in total as well as by carbon-number. In each case the analysis is fully automated with a computer controlling the entire analysis from injection to results presentation. The advantages and limitations of both methods are discussed.Presented at the 14th International Symposium on Chromatography London, September, 1982     

吸热型碳氢燃料的核磁共振和色谱/质谱分析及热力学性质

测定两种吸热型碳氢燃料的^1H和^13C NMR谱,从NMR等实验数据计算得到平均分子结构参数。以基团贡献法为桥梁,总结定量结构—性能关系,从NMR结构信息预测了燃料的蒸发焓和燃烧焓,与热力学实验结果吻合良好。用GC/MS分析燃料的化学组成,检出主要由脂肪烃、芳烃和环烷烃3类构成的60余种烃类化合物,为吸热型碳氢燃料的结构和特性表征以及燃料的开发提供重要信息。     

New Insight into the Hydrocarbon‐Pool Chemistry of the Methanol‐to‐Olefins Conversion over Zeolite H‐ZSM‐5 from GC‐MS,Solid‐State NMR Spectroscopy,and DFT Calculations

Over zeolite H‐ZSM‐5, the aromatics‐based hydrocarbon‐pool mechanism of methanol‐to‐olefins (MTO) reaction was studied by GC‐MS, solid‐state NMR spectroscopy, and theoretical calculations. Isotopic‐labeling experimental results demonstrated that polymethylbenzenes (MBs) are intimately correlated with the formation of olefin products in the initial stage. More importantly, three types of cyclopentenyl cations (1,3‐dimethylcyclopentenyl, 1,2,3‐trimethylcyclopentenyl, and 1,3,4‐trimethylcyclopentenyl cations) and a pentamethylbenzenium ion were for the first time identified by solid‐state NMR spectroscopy and DFT calculations under both co‐feeding ([¹³C₆]benzene and methanol) conditions and typical MTO working (feeding [¹³C]methanol alone) conditions. The comparable reactivity of the MBs (from xylene to tetramethylbenzene) and the carbocations (trimethylcyclopentenyl and pentamethylbenzium ions) in the MTO reaction was revealed by ¹³C‐labeling experiments, evidencing that they work together through a paring mechanism to produce propene. The paring route in a full aromatics‐based catalytic cycle was also supported by theoretical DFT calculations.     

全二维气相色谱用于轻质石油馏分中芳烃含量的测定

建立了采用全二维气相色谱(GC×GC)技术一次进样完成轻质石油馏分中非芳烃、一环芳烃和二环芳烃的分离、定性 和定量。通过对柱系统的选择和色谱条件的优化,实现了一次全二维气相色谱分析即完成轻质石油馏分的族组成分离以及 目标化合物的分离。方法的加标回收率为89.5%～106.1%;样品中各组分含量重复测定的相对标准偏差均不大于5.8%,能 够满足样品测定的精密度和准确性要求,且完成1次分析最多只需要30 min。     

重整生成汽油样品中烃的类别分析

用气相色谱以程序升温方式分析了重整生成汽油,并将各组分升温保留时间转换为恒温保留指数。以各组分在ＯＶ－１和ＳＥ－５４固定相上,同一柱温下的保留指数差及在各柱上的温度系数为三因素进行斜交因子分析和本征矢量旋转,给出了重整生成汽油样品中烷烃、烯烃、环烷烃、芳烃值,经气相色谱－质谱分析验证了结果的正确性,为重整成成汽油样品中烃的类别分析提供了一种新方法。     

Study of the role of Zn in aromatization of light alkanes with probe molecules

The role of Zn²⁺ in ZnZSM-5 catalyst in the process of aromatization of alkanes has been studied with the probe molecules - n-hexane, cyclohexane and 1-hexene. IR measurements showed that the parent HZSM-5 zeolite contains predominantly Br?nsted acid sites, while Zn cations in ZnZSM-5 catalyst represent Lewis sites. From the results it follows, that Zn cations in ZnZSM-5 catalyst as Lewis acid sites have strong hydro-dehydrogenation activity and they catalyze the dehydrogenation of n-hexane as well as of cyclic intermediates into the corresponding aromatics. From the results of catalytic tests we conclude that the hydro-dehydrogenation activity of the catalyst plays an essential role in aromatization of light alkanes. The results indicate that for improving the yields of aromatics in aromatization of light alkanes on bifunctional catalysts it is inevitable to increase the participation of the dehydrogenation reactions in the activation of alkane as well as in the formation of the corresponding aromatics from cyclic intermediates. This revised version was published online in August 2006 with corrections to the Cover Date.     

判别分析用于烃类化合物分类及汽油样品的族组成分析

研究了判别分析用于烃类化合物分类的可行性，以198个烃类化合物在BD－1和BD－5固定相上同一柱温下的保留指数差及其在各柱上的温度系数为判别变量，成功地建立了烷烃、环烷烃、芳烃和烯烃的判别函数，以此对裂化汽油，重整生成汽油、石脑油和蒸馏常顶汽油进行了族组成分析，经气相色谱－质谱分析验证了结果的正确性，为汽油产品的族组成分析提供了一种新的方法。     

Starshaped block copolymers. I. Synthesis of new A(B)2 starshaped block copolymers based on vinyl or diene hydrocarbons (A) and oxirane (B)

Naphthalene-terminated polyvinyl aromatics and polyisoprene were obtained successfully. These functional polymers were metalated by potassium in THF at 25°C. The formation of a stable dinegative ion is observed unless the naphthalene is directly attached to the end of the polyvinyl aromatics, in which case a few isoprene units can be advantageously inserted between the naphthalene end group and the polyvinyl aromatics. The polymeric and stable dinegative ion polymerizes oxirane by both anionic sites and forms three-branched starshaped block copolymers.     

Improved separation and quantitative determination of hydrocarbon types in gas oil by normal phase high‐performance TLC with UV and fluorescence scanning densitometry

Improved methods for separation and quantitative determination of hydrocarbon types from gas oil have been developed, which were based on high‐performance thin‐layer chromatography with ultraviolet and fluorescence scanning densitometry using horizontal elution. One of the methods allows the separation, detection, and determination of alkanes and naphthenes to be carried out, using berberine‐impregnated silica gel HPTLC plates, elution with n‐hexane, and berberine‐induced fluorescence detection at 365 nm. Another developed method allows total aromatics to be determined using silica gel HPTLC plates by elution with n‐hexane and acetone, and UV detection. In turn, PACs over three aromatic rings can be determined on either silica gel or caffeine‐impregnated silica gel HPTLC plates, elution with n‐hexane, and selective detection using native fluorescence at 365 nm. Concentrations lower than 5 wt% can be determined using this technique. In addition, a technique for an efficient, baseline‐resolved separation of a gas oil according to the number of aromatics rings (mono + di‐, tri‐, and polyaromatic compounds with more than three rings) is presented here. This technique involves a multistep elution on a mixed (silica gel and caffeine‐impregnated silica gel HPTLC plate) using a counter‐elution device, and UV detection.