Joint conversion of butane and hexane in the presence of supported platinum catalysts

It has been found that the joint conversion of butane and hexane over alumina-platinum catalysts opens up a new route of butane conversion yielding C₄₊ hydrocarbons with an increased yield of the C₆₊ products on a converted hexane basis. It has been shown that a necessary condition for the occurrence of this reaction is the presence of finely divided platinum in the ionic form (Pt^σ) in the catalysts. The results of catalytic testing of the samples modified with Cl⁻and F⁻ anions allowed a possible mechanism and the nature of active sites of the reaction of the joint conversion of butane and hexane to be proposed.     

Joint aromatization of butane and hexane on alumina-platinum catalysts

It has been found that the joint aromatization of C₄ and C₆ alkanes proceeds during the conversion of a butane and hexane mixture on alumina-platinum catalysts. It has been shown that a necessary condition for realization of the joint aromatization is the presence of highly dispersed platinum as ionic species (Pt^σ) and “hard” Lewis acid sites (L_z) of a catalyst. It has been determined that an optimum L_z/Pt^σ ratio for joint conversion reaction of light alkanes is from 1 to 2.     

Effect of oxygen and hydrogen sulfide on carbon dioxide corrosion of welded structures of oil and gas installations

Conclusions  

Solubility of β-cyclodextrin in different mixed solvents

The solubility of β-cyclodextrin (β-CD) in ionic liquid/N, N-dimethyl-acetamide (IL/DMAC) mixed solvent and in LiCl/DMAC mixed solvent was investigated at 323.15 K and 353.15 K. The results showed that the solubility of β-CD in IL/DMAC system increased with increasing temperature, but decreased in LiCl/DMAC system. β-CD had the highest solubility in IL/DMAC system with [Cl]⁻ or [Br]⁻ anions. The solubility of β-CD in LiCl/DMAC system was lower than that in IL/DMAC system with [Cl]⁻ or [Br]⁻ anions but higher than that in IL/DMAC system with weak-coordinated anions (e.g [BF₄]⁻ or [PF₆]⁻). The effects of substituent groups (benzyl and butyl) of cation and the structure of cations on β-cyclodextrin solubility were also investigated.     

Catalytic reforming of <Emphasis Type="Italic">n</Emphasis>-heptane on platinum-tungsten supported on gamma-alumina

The mono-metallic and bi-metallic catalysts have been prepared by impregnating with solutions containing a compound of H₂PtCl₆, WO₃ and 1 ml HCl (0.1 mol). It should be noted that the catalysts’ activity and selectivity have been determined under these conditions: 450–500°C, and 15–25 atm by H₂. For converting n-heptane, the molar ratio H₂/C₇H₁₆ is 5, and LHSV is 1.5 ml/h. It has been proved that, under these experimental conditions, the conversion of n-heptane into branched aliphatic isomers is catalyzed by a bifunctional mechanism. The results indicate that in the presence of W, the catalysts have much higher selectivity and stability for isomerization reaction. At a given conversion, the bi-metallic catalysts produce much lower concentrations of cracked products. According to the tests, W modifies the support acidity resulting to the higher selectivity for isomerization and the lower one for cracking, and it also modifies the Pt properties.     

离子液体催化癸烯-苯烷基化合成高性能润滑油基础油

 采用Et₃NHCl-AlCl₃离子液体催化剂对苯与癸烯-1的烷基化反应和癸烯-1齐聚反应进行了研究。探讨了反应温度(25~75℃)和反应时间(1~4 h)对烷基化反应和齐聚反应的影响。采用气相色谱、质谱和红外光谱表征了产物的组成和结构,按照石油和石油产品试验方法国家标准测定了产物的黏度、倾点和相对分子质量。结果表明,在实验条件下,烷基化产物和齐聚产物均为理想的高黏度指数、低倾点的润滑油基础油组分,其中烷基化产物为癸烯四聚、五聚物以及二烷基苯的混合物,该产物的黏度指数(114~158)高、倾点(-48~-56℃)低、相对分子质量(425~515)适中;齐聚产物(PAO)的100℃黏度范围19.4~29.6 mm²/s、黏度指数范围138~164、倾点范围-48~-60℃、相对分子质量范围460~620。     

Study of the products of benzene transformation in the presence of argon,hydrogen, and propane-butane mixture in barrier discharge

The conversion of benzene in a medium of Ar, H₂, and propane-butane mixture in a dielectric-barrier discharge reactor, accompanied by polymerization yielding liquid and solid compounds, has been investigated. The amount of polymerization products reaches 79.7 wt %. Addition of H₂ to benzene reduces the amount of benzene-soluble polymer-like compounds in the products to ∼61 wt % and precludes the formation of solid polymerization products. The transformation of benzene with a propane-butane mixture yields alkylbenzenes (up to 38.5 wt %) and liquid alkanes (to 20.5 wt %, mainly with a branched structure). It has been found that an increase in benzene flow rate from 0.08 to 0.4 cm³/min in the case of benzene conversion with the propane-butane mixture can significantly reduce the amount of polymerization products from 56.7 to 9.1 wt %.     

Heteroaromatic compounds of bitumenoids from the Cambrian oil shale formation

The molecular composition of NSO heterocyclic aromatic compounds in the lube stock fractions of chloroform-extractable bitumenoids isolated from Cambrian shale formation rocks of Kuonam oil shale, which differ in their organic carbon content, was studied. Of the sulfur compounds, C₃–C₄ alkylbenzothiophenes; dibenzothiophene, its C₁–C₅ alkyl and naphtheno derivatives; naphthobenzothiophene; and methylnaphthobenzothiophenes were identified. Among the oxygen compounds, unsubstituted dibenzofuran, unsubstituted naphthobenzofuran, and their C₁–C₄ and C₁–C₂ homologues, respectively, were detected. The nitrogen compounds present in the test fractions were supposed to be 7H-benzo[c]- and 7H-benzo[b]acridin-12-ones and methylbenzoacridin-12-ones.     

Use of the structure parameter for predicting the properties of high-molecular-mass organic compounds

The structure parameter “degree of unsaturation,” which is defined for a structural unit composed of hundred carbon atoms, is proposed for the assessment of characteristics of high-molecular-mass organic compounds. The introduction of the structure parameter has been substantiated. For the natural bitumen and fractions of its hydrogenation products used as an example, it has been shown that the density is linearly related to the number of bonds and the average molecular mass correlates with the parameter of unsaturation in the structural unit. The proposed structure parameter can be used for tentative classification of high-molecular-mass hydrocarbons and their processing products.     

Hygroscopicity of poly-α-olefin based oils

The hygroscopicity of poly-α-olefin based oils is studied. Moisture saturation of all oils used in this study is reached by 60 h into the tests. The dependence of the hygroscopocity of the oils on the molecular mass of the oligomer is determined. The presence of functional additives in the oils does not greatly affect their hygroscopicity, while polar compounds (products of aging) sharply (almost twofold) increase the hygroscopicity.     

Sulfur compounds in crude oils of the Jurassic-Paleozoic play in Western Siberia

The composition and structure of sulfur compounds in low-, medium-, and high-sulfur crude oils from the Jurassic-Paleozoic play of Western Siberia have been studied. It has been shown that the distribution of organic sulfur compounds in the oils is determined by the depositional environment of source organic matter. Highly alkylated dibenzothiophenes (up to 15 carbon atoms in the aliphatic chain), naphthobenzothiophene isomers and their C₁ and C₂ homologues, and the α-n-alkylthiolane and α-n-alkylthiane homologous series have been identified for the first time among sulfur compounds of Western Siberia crude oils.     

Conversions of mixtures of propane and benzene on Pt,Re/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> + H-zeolite systems

The conversion of C₆H₆: C₃H₈C mixtures on mixed catalysts composed of the metal catalysts Pt,ReOx/Al₂O₃ and zeolites Y, M, and ZSM-5 in the H form was studied. The products of benzene dehydroalkylation by propane and propane dehydrogenation products are formed at 180–350°C. It has been shown that propane is activated on the metal catalysts and C₆H₆ interacts with the zeolites yielding the C₆H₇ ⁺ intermediate, which acts as an agent of proton transfer from a zeolite to a metal catalyst, and another intermediate C₉H₁₃⁺ (I). Cumene, alkylbenzenes, and propene are formed as a result of the conversion of I. A comparison of the results of the conversion of these mixtures on the composite catalysts with different zeolites shows that the formation of cumene and propene is thermally controlled and the formation of the other products is kinetically controlled. It has been concluded that the coupling of the redox properties of the metal catalysts with the acid-base properties of the zeolite catalysts facilitates the low-temperature transformations of the mixtures.     

Photochemical oxidation of thiophene by O<Subscript>2</Subscript> in an organic two-phase liquid-liquid extraction system

Photochemical oxidation products and the kinetics of thiophene in an n-octane/acetonitrile extraction system using O₂ as an oxidant was studied. The results could be used as a reference for the oxidative desulfurization of gasoline because thiophene is one of the main components containing sulfur in a fluid catalytic cracking (FCC) gasoline. Thiophene dissolved in n-octane was photodecomposed and removed into the water phase at an ambient temperature and atmospheric pressure. A 500-W high-pressure mercury lamp (main wavelength 365 nm, 0.22 kW m⁻²) was used as the light source for irradiation and air was introduced by a gas pump to supply O₂. Thiophene could be photooxidized to SO₄ ²⁻ and CO₂. The desulfurization yield of thiophene in n-octane is 65.2% for a 5-h photoirradiation under the conditions of air flow at 150 m min⁻¹ and V(n-octane): V(acetonitrile) = 1:1. It can be improved to 96.5% by adding 1.5 g L⁻¹ artificial zeolite, which is an absorbent for O₂. Under such conditions, the photooxidation kinetics of thiophene with O₂ is of the first order with an apparent rate constant of 0.6297 h⁻¹ and a half time of 1.10 h. The sulfur content can be depressed from 800 to 28 ppm. The text was submitted by the authors in English.     

Optimization of Oxidative Desulfurization of Dibenzothiophene Using a Coordinated Ionic Liquid as Catalytic Solvent

Abstract

Oxidative desulfurization (ODS) of dibenzothiophene (DBT) in n-octane with hydrogen peroxide/acetic acid using a quaternary ammonium coordinated ionic liquid (IL) (C₄H₉)₄NBr · 2C₆H₁₁NO as catalytic solvent has been studied. The ODS mechanism by coordinated ionic liquid [(C₄H₉)₄NBr · 2C₆H₁₁NO] was also carried out. The sulfur-containing compounds in model oil were extracted into ionic liquid phase and oxidized to their corresponding sulfones by H₂O₂. The effect factors for desulfurization of model oil were investigated in detail by means of monofactorial and orthogonal experiments (L₁₆(4)⁴). The results showed that the desulfurization efficiency of model oil could reach 98.6% under the optimal conditions of oxidation time, oxidation temperature, molar ratio of H₂O₂/sulfur (O/S), and volume ratio of model oil to coordinated ionic liquid were 30 min, 50°C, 16, and 1, respectively. The influences to the desulfurization efficiency of DBT decreased in the following order: volume ratio of model oil to coordinated ionic liquid (C₄H₉)₄NBr · 2C₆H₁₁NO (V_{model oil}/V_IL) > molar ratio of O/S > oxidation temperature > oxidation time, according to extreme analysis of the orthogonal test. The coordinated ionic liquid (C₄H₉)₄NBr · 2C₆H₁₁NO can be recycled 5 times without a significant decrease in desulfurization.     

Generation of C<Subscript>11</Subscript>–C<Subscript>17</Subscript> monoalkyladamantanes via catalysis of some oxygen-containing precursors of petroleum hydrocarbons

Oxygen-containing compounds that are known to be precursors of petroleum hydrocarbons have been subjected to catalysis on an aluminosilicate catalyst. It has been found for the first time that along with C₁₁–C₁₂ monoalkylated adamantanes, which are typically present in crude oils, the homologous series of 1- and 2-n-alkyladamantanes up to and including n-heptyladamantanes are generated via the catalysis (monoalkyl-substituted adamantanes with a substituent heavier than the ethyl radical have never been found in any crude oil). It has been shown that, with the increasing degree of conversion, C₁₃–C₁₇ adamantanes disappear and only 1- and 2-methyl- and ethyladamantanes remain in the catalyzates. The absence of high-molecular alkyladamantanes (C₁₃ and higher) in crude oils is supposedly attributed to relatively high maturity of crude oil.     

Thermophysical properties of transformer and turbine oils

Transformer and turbine oils must have good physicochemical, antioxidant, anticorrosive, and heat transfer properties. The latter are primarily determined by the thermal conductivityλ and isobaric heat capacity c′_p. The thermophysical properties of turbine and transformer oils have been relatively completely investigated at low temperatures and atmospheric pressure. However, the experimental values of parametersλ and c′_p occasionally differ significantly for the same oils, probably due to their origin and manufacturing technology. Translated fromKhimiya i Tekhnologiya Topliv i Masel, No. 6, pp. 26 – 28, November – December, 1999.     

Variation of levels of aflatoxin M1 in raw milk from different localities in the central areas of Punjab, Pakistan

The occurrence of aflatoxin M₁ (AFM₁) in samples of raw milk of buffaloes and cows from different localities in the central areas of Punjab, the province of Pakistan, was determined by using high-performance liquid chromatography (HPLC) with prior clean-up step applying immunoaffinity columns. The present study has been designed to find out the variation of levels of aflatoxin M₁ in raw milk of different localities. Feed has major role for prevalence of aflatoxin M₁ in milk and different feed regimen is being used in different areas. Total 480 milk samples were analyzed, among these 360 were of buffalo milk and 120 were of cow milk. The percentage of AFM₁ contamination in buffalo milk and cow milk was 42.5% and 52.5%, respectively. The mean value of AFM₁ was 0.027 μg L⁻¹ in buffaloes’ milk and was 0.044 μg L⁻¹ in cows’ milk. In both types of milk, level of AFM₁ concentration was higher in milk samples obtained from urban and semi-urban areas and it was minimal in milk from rural areas.     

The Removal of Thiophene from n-Heptane/Thiophene Mixtures by Polyethylene Glycol-Block-Polyacrylonitrile Membranes

Abstract

Polyethylene glycol-block-polyacrylonitrile (PEG-b-PAN) copolymers were synthesized and membranes were prepared for sulfur removal from thiophene/heptane mixtures by pervaporation. The desulfurization performance of n-heptane/thiophene mixtures with 1,000 μg·g^?1 sulfur content was considerably influenced by the PEG molecular weight (M _PEG ) and weight content (W _PEG ) in the block copolymer. The maximum separation factor and moderate permeate flux displayed for the block copolymer membrane with M _PEG = 20,000 and W _PEG = 26 wt%. The effect of feed temperature on pervaporation was also analyzed. It was found that the total flux increased with temperature, the sulfur enrichment factor increased before 352 K and decreased then. The pervaporation performance was mainly in terms of PEG microphase separation behavior in the PEG-b-PAN block copolymer and PEG solubility properties in n-heptane/thiophene mixtures with temperature.     

The catalytic properties of tungstated zirconia in <Emphasis Type="Italic">n</Emphasis>-heptane isomerization

The catalytic properties of zirconia modified with different amounts of tungstate anions in the hydroisomerization of n-heptane and its mixtures with benzene or toluene have been studied. It has been found that at a low temperature of 170°C, the yield of isoheptanes reaches 62.8% with a fairly high selectivity of 87.6% on the Pt/WO₄²⁻/ZrO₂ catalyst prepared by impregnation to contain 17.6 mol % tungstate anions. Under the same conditions, the yield of isoheptanes on a sulfated Pt/SO₄²⁻/ZrO₂ catalyst is as low as 14.0% with a selectivity of 20.3%. The hydroisomerization process effectively occurs on the tungstated catalyst in the presence of benzene or toluene.     

A study of structural transformations of asphaltene molecules during hydroconversion of vacuum residue at various temperatures in the presence of nanosized molybdenum disulfide particles

Elemental analysis, molecular mass, and ¹H NMR data are presented for vacuum residue asphaltenes and the products of vacuum residue hydroconversion in the presence of nanosized MoS₂ catalyst particles obtained “in situ” in the hydrocarbon medium. Structural group analysis of average asphaltene molecules has been performed and their structural units have been described. The main trends of change in the structural parameters of the molecules under the hydroconversion conditions and the effect of temperature on the character of these changes have been revealed.