裂解色谱法研究渣油中硫化物的结构及组成特征

采用裂解气相色谱(PY-GC)方法研究重油中的大分子硫化物。实验考察了裂解时间和裂解温度对裂解反应的影响,在此基础上确定了裂解色谱条件,并分析了渣油裂解产物的组成。通过对大港、俄罗斯、前郭、孤岛及俄罗斯-大庆混合减压渣油等5种渣油的裂解实验,发现不同来源的渣油裂解产物中硫化物的组成和含量存在较大差异。实验中所得到的裂解产物中硫化物的组成为渣油中硫化物的组成提供了重要信息。     

Study of sulphur in oxidised coals by atmospheric pressure-temperature programmed reduction

The influence of oxidation of coal, performed with different oxidising agents, on the sulphur species was studied. Conversions of the sulphur species were investigated by the Atmospheric Pressure-Temperature Programmed Reduction method (AP-TPR). The removal of pyrite proved to be advantageous for AP-TPR analysis. It was found that non-thiophene sulphur species undergo easier oxidation by different agent then thiophenic structures.This revised version was published online in November 2005 with corrections to the Cover Date.     

Studies of the soluble part of oxidised coals

Soluble products obtained from the oxidation of four types of coal, each characterised by different degree of coalification and different degree of sulphur content, are studied. The coals are oxidised with peracetic acid (PAA) and nitric acid. Analyses are performed by Atmospheric Pressure-Temperature Programmed Reduction (AP-TPR) and Fourier Transform Infrared Spectroscopy (FTIR). The soluble products contain much more sulphur than the insoluble products of oxidation. The products obtained from the reaction with HNO₃ contain higher amounts of inorganic sulphur compounds, while those obtained from the reaction with PAA are characterised by an increased content of organic sulphur species.     

Composition of extraction products from alkylated high-sulphur coals

Products of reductive and non-reductive methylation of two high-sulphur coals (Mequinenza and Illinois No. 6) have been extracted by dichloromethane. It has been established that the efficiency of the transformation of coal to the products soluble in CH₂Cl₂ is higher for coals subjected to non-reductive methylation by the Liotta method than for those after reduction in the potassium/liquid ammonia system. The extracts and the extraction residues were subjected to elemental analysis, IR spectroscopy, and AP-TPR (Atmospheric Pressure-Temperature Programmed Reduction) measurements. It has been shown that the main species undergoing extraction by CH₂Cl₂ are aliphatic compounds or aromatic structures of low degree of condensation. The effect of the extraction on the sulphur groups in coal has been discussed.     

Determination of mercury in industrial materials by atomic absorption spectrometry after thermal volatilisation

The pyrolysis of samples containing copper, lead, iron, sulphur compounds and organic carbon is applied to separate mercury prior to its determination by a.a.s. Amalgamation on gold collectors followed by thermal desorption, or trapping in an absorption solution followed by reduction/aeration were used depending on the mercury content in the materials. Appropriate additives to the samples and filters are used to ensure complete release of mercury and removal of interfering pyrolysis products.     

Investigation of sulphur compounds in coal tar using monodimensional and comprehensive two-dimensional gas chromatography

Coal is a non renewable fossil fuel, used mainly as a source of electrical energy and in the production of coke. It is subjected to thermal treatment, pyrolysis, which produces coke as a main product, in addition to a condensed liquid by-product, called tar. Tar is a complex mixture of organic compounds which contains different chemical classes, presenting aromatic and sulphur heterocyclic compounds. In general, identification of these compounds requires steps of isolation and fractionation, mainly due to co-elution of these compounds with polyaromatic hydrocarbons (PAH). The objective of this work is to characterize the sulphur compounds present in the coal tar obtained via pyrolysis, using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry detector (GC×GC/TOFMS). Coal samples from the State of Paraná, Brazil were subjected to laboratorial scale pyrolysis. Several experimental conditions were tested, such as sample weight (5, 10 and 15g), heating ramp (10, 25 and 100°C/min) and final temperature (500, 700 and 900°C). Samples were analyzed by one dimensional gas chromatography (1D-GC) coupled to a quadrupole mass spectrometry detector (GC/qMS) and two-dimensional gas chromatography with time-of-flight mass spectrometry detector (GC×GC/TOFMS). The higher amount of sulphur compounds was obtained at a final temperature of 700°C and a heating ramp of 100°C/min. The main classes observed in the color plot were thiophenes, benzothiophenes and alkylated dibenzothiophenes. GC×GC/TOFMS allowed the identification of the greater number of compounds and the separation of several sulphur compounds from one another. Moreover, separation of sulphur compounds from polyaromatic hydrocarbons and phenols was achieved, which was not possible by 1D-GC. Comparing GC×GC/TOFMS and 1D-GC (SIM mode) also showed that 1D-GC, one of the most employed quantification tools for sulphur compounds, can be misleading for detection, identification and quantification, as the number of isomers of sulphur compounds found was greater than theoretically possible.     

In Process Citation

The method for the determination of sulphur in organic compounds (E. Debal and R. Levy, Bull. Soc. Chim. France, 1968, 426; 1971, 3374) by combustion in oxygen at 1310-1320 degrees C and coulometric titration of the sulphur dioxide formed is improved. Silver and 8-hydroxy-quinoline are successfully used to remove halogens (fluorine included) from combustion products. A new glass cell for the acidimetric titration of sulphur dioxide with an automatic coulometer is devised, with a water-jacket for its cathodic and reference compartments. The constant-temperature water-flow makes this determination easy to carry out with no drawbacks, even in varying ambient temperature.     

Sulphur distribution in the products of waste tire pyrolysis

The aim of the presented work was to investigate the distribution of sulphur in tire pyrolysis products as well as the influence of process parameters (temperature and residence time) on sulphur distribution due to environmental concerns. Among modern methods used for waste tire recycling, pyrolysis is one of the most reasonable alternatives meeting current environmental standards. However, waste tire sulphur content can be a potential drawback for pyrolysis products utilisation as fuels. Sulphur is present in tires in different concentrations, depending on the type and age of the tires. Typical sulphur content in tires is about 1.6 mass %. In this paper, the distribution of sulphur in tire pyrolysis products was investigated. Tire pyrolysis yields three different products: liquid, gaseous, and solid residue composed mostly of carbon black (chars). Temperature and residence time are the two most important parameters affecting the yield and composition of the volatile fraction and they are therefore expected to affect the sulphur content in residues. Pyrolysis experiments were carried out in a laboratory pyrolysis reaction unit in the temperature range of 650°C to 750°C at different residence times: 88.6 s, 80.2 s, and 73.9 s. Liquid and solid products were analysed by elemental analysis and the distribution of total sulphur in tire pyrolysis products was calculated.     

Pyrolysis—gas chromatography—mass spectrometry of model compounds from coal hydrogenates: Part III. Sulphur compounds

A pyrolysis—gas chromatography—mass spectrometry study of some model sulphur compounds encountered in coal hydrogenates was performed in order to determine the fate of the sulphur during thermal cracking in an inert atmosphere. Heterocyclic sulphur compounds such as thiophene, 3-methylthiophene and benzothiophene were thermally more stable than thiophenol and 4-methylthiophenol. For all these compounds, the first pyrolysis step was a dimerization reaction. Desulphurization was always unimportant and therefore the amounts of desulphurized light aromatic hydrocarbons obtained were always very low. Several cracking mechanisms are proposed.     

Analysis of low-volatility organic sulphur compounds in wines by solid-phase microextraction and gas chromatography

A method for analysing low-volatility sulphur compounds using solid-phase microextraction has been developed. The analytes were extracted directly from the liquid sample using fibres coated with different stationary phases. The best extraction efficiency was obtained with Carboxen-polydimethylsiloxane coating. Ionic strength, sample volume, time and temperature of the extraction were optimised and the matrix effect studied. The method enables 15 sulphur compounds in wine to be determined at trace levels with recoveries close to 100% and limits of detection between 0.05 and 5 microg/L. The overall method was successfully applied to the determination of the sulphur compounds studied in several red, white and rosé wines.     

Application of the iodine-azide reaction to the catalytic determination of divalent sulphur compounds in alcoholic medium: Determination of ethylenethiourea in some biological materials

A new catalytic method for the determination of divalent sulphur compounds, which are soluble or insoluble in water, based on the iodine–azide reaction in various alcoholic solutions is described. As model divalent sulphur catalysts the sodium sulphide and thiourea were chosen. Determination of ethylenethiourea in alcoholic extracts from apples and bananas was an example of practical application of the proposed method. To that purpose five previous elaborated techniques were adopted: titration, volumetric, gas chromatographic, enthalpimetric and potentiometric. The effect of other organic solvents, salts, acids and pH on the determination of divalent sulphur catalysts was also evaluated.     

Determination and fractionation of sulphur in a contaminated dredged sediment

Conversion of sulphur compounds in reduced, contaminated sediments that are brought in upland conditions may largely affect the potential mobility of heavy metal contaminants. We applied selected methods for the determination of total sulphur and sulphur fractions in a contaminated sediment in the reduced state and after gradual drying and oxidation during 1 month. Dry ashing, followed by ion chromatographic detection, was reliable for the determination of total sulphur. Good recoveries were obtained in both reference samples and spiked samples. Total sulphur was 14.5±0.6 g kg⁻¹ relative to dry sediment. Wet chemical methods that involve the determination of acid-volatile, Zn–HCl-reducible, chromium-reducible, acetone-soluble and HI-reducible sulphur were used to estimate specific sulphur forms. Results for acetone-soluble sulphur were to high and not consistent with results for other fractions. Major part of sulphur in the sediment (90%) was inorganic. Sulphides were converted partially to sulphate and to intermediary oxidised sulphur compounds upon oxidation of the sediment. The results suggested that the intermediary oxidised sulphur pool in the reduced sediment (2.5 g kg⁻¹) mainly consisted of pyrite, that was not converted during drying and oxidation. No significant changes in organic sulphur were detected.     

低阶煤程序升温热解过程中钠、硅和硫间的相互作用

对一种澳大利亚低阶煤中,钠、硅和硫在热解过程中的相互作用进行了研究,以便深入了解钠的固硫作用和硫对流化床燃烧和气化中颗粒团聚的影响。制备了水洗、酸洗煤样和酸洗、乙酸钠离子交换煤样,样品在马弗炉中以17．7℃／min升至1000℃进行程序升温热解。对700℃-100℃热解半焦样品的依次水洗、酸洗、SEM—EDX和X射线元素扫描分析表明,部分有机结合的钠形成水溶性Na2O和NaOH化合物,水溶性的硅酸钠,以及与半焦中的硫形成酸不溶组分。最后一点解释了为何以往研究中发现,热解过程中有机结合的钠具有固硫作用,以及固硫历程中为何未发现Na2S的生成。在硅酸钠区域边缘存在的高硫区域,在流化床燃烧和气化过程中将形成含硫黏性相,导致床料的黏结。当用于酸洗、钠离子交换煤样的乙酸钠从0．25mol／L增加到1．0mol／L,固硫率将增加10％。相应的酸不溶钠组分的增加表明,酸不溶钠／硫组分随乙酸钠浓度的增加而增加,从而导致固硫率上升。     

Determination and fractionation of sulphur in a contaminated dredged sediment

Conversion of sulphur compounds in reduced, contaminated sediments that are brought in upland conditions may largely affect the potential mobility of heavy metal contaminants. We applied selected methods for the determination of total sulphur and sulphur fractions in a contaminated sediment in the reduced state and after gradual drying and oxidation during 1 month. Dry ashing, followed by ion chromatographic detection, was reliable for the determination of total sulphur. Good recoveries were obtained in both reference samples and spiked samples. Total sulphur was 14.5±0.6 g kg⁻¹ relative to dry sediment. Wet chemical methods that involve the determination of acid-volatile, Zn–HCl-reducible, chromium-reducible, acetone-soluble and HI-reducible sulphur were used to estimate specific sulphur forms. Results for acetone-soluble sulphur were to high and not consistent with results for other fractions. Major part of sulphur in the sediment (90%) was inorganic. Sulphides were converted partially to sulphate and to intermediary oxidised sulphur compounds upon oxidation of the sediment. The results suggested that the intermediary oxidised sulphur pool in the reduced sediment (2.5 g kg⁻¹) mainly consisted of pyrite, that was not converted during drying and oxidation. No significant changes in organic sulphur were detected.     

The pyrolytic identification of organic molecules: II. A quantitative evaluation

Results are presented of an investigation made to set up a system for the study of pyrolysis of organic compounds, and to determine some of the important conditions in this system. Acetone, methanol, ethanol, and n-propanol were used as model compounds. Degradation of the compounds was studied quantitatively over a temperature range of 300–1200 °C using flash vaporization into a heated reaction chamber. The volatile products were analyzed by gas chromatographic techniques. A mechanism of the thermal decomposition of acetone by its high-temperature pyrolysis is proposed.     

Determination of organic sulphur compounds in sediments of the river Elbe using gas chromatography with flame photometric detection

Sediment samples from different reference sites representing typical situations on the river Elbe were analyzed for organo-sulphur compounds (OSC). Gas chromatography with sulphur specific flame-photometric detection was used for the identification and quantification of individual OSC. Chromatographic retention data for 42 standard heterocycles were determined and compared with the composition of sediment extracts. An extraction scheme used for the OSC determination is described. Dibenzothiophene (DBT), its alkylated homologues, phenanthro[4,5-bcd]thiophene, benzo[b]naphtho[2,1-d]thiophene and in some cases still unidentified compounds were the predominant OSC. Depending on sampling site and date the qualitative composition of sulphur heterocycles detected by the described method varied, and the total concentrations of all OSC ranged from 0.3 to 21 mg/kg.     

型煤中硫的还原热解MS和GC/MS分析(英文)

以煤和生物质为主要原料的商用型煤为研究对象，采用还原热解（AP-TPR）在线质谱（MS）联用，以及离线色谱/质谱（GC/MS）分析法，定性和定量研究了家用型煤释放的含硫化合物。不同组成的型煤表现出各自不同的硫释放特性。对于生物型煤来说，仅检测到少量二烷基硫醚和脂肪硫醇的存在。褐煤型煤检测到种类最多的有机硫化物。在高阶煤制成的型煤中没有检测到氧化态的硫化物，其典型特征是存在一些噻吩类硫化物。     

An alternative method for the measurement of mineral sulphide in wastewater

A simple and rapid procedure for sulphide measurement in crude oil refinery wastewater has been developed. This method is based on the knowledge of the UV response of sulphur compounds and the mathematical deconvolution of the sample spectrum using reference spectra (specific compounds or aggregate spectra). The detection limit of the method is 0.5 mg l(-1) for a quartz cell pathlength of 10 mm. The range is up to 15 mg l(-1). The method has been validated for crude oil refinery wastewater. Compared to conventional methods, the UV determination is quicker and easier to run.     

A new approach for the determination of sulphur in airborne particles by HR-CS ETAAS

In this work, water and nitric acid extractable sulphur concentrations in PM2.5 fraction of urban aerosols were determined by high-resolution continuum source electrothermal molecular absorption spectrometry using most suitable CS molecular absorption band at 258.056 nm. For this purpose, the PM2.5 airborne particulates were collected on quartz filters using a high-volume sampler (500 L/min) in Istanbul (Turkey) during six months (January–June) of two consecutive years. The instrumental and experimental parameters (pyrolysis temperature, molecule formation temperature and leaching reagents) were optimised. The validity of the method for the sulphur was tested using standard reference material and the results were found to be in the uncertainty limits of the certified value.