Petroleum Chemistry (v.53, #5)
Identification of tetramantanes in crude oils by M. V. Giruts; N. B. Derbetova; O. G. Erdnieva; O. A. Stokolos; V. N. Koshelev; G. N. Gordadze (285-287).
Determination of tetramantanes in crude oils is complicated by low concentrations, the lack of information on retention times, and the fact that their characteristic m/z 292 and 291 mass chromatograms typically contain a variety of foreign peaks having the same ions. Since tetramantanes could not be isolated in pure form using separation by thermal diffusion, the catalytic isomerization of the thermal diffusion concentrate of polycyclic hydrocarbons (most likely, prototetramantanes) over aluminosilicate has been carried out; as a result, all the three tetramantane isomers (iso-, anti-, and skew-) and methyltetramantane have been obtained in pure form. Mass chromatograms at m/z 291 and 292 before and after the separation by thermal diffusion and after the isomerization of the concentrate of saturated polycyclic hydrocarbons on aluminosilicate are presented. The retention indices of tetramantanes on HP-5 are as follows: iso-tetramantane (2293), anti-tetramantane (2365), and skew-tetramantane (2431). It is interesting that methyltetramantane, a homologue with a higher molecular weight, elutes before iso-tetramantane, the tetramantane isomer with the lowest boiling point. Its retention index on HP-5 is 2287.
Modeling of catagenetic transformation of saturated and alkylaromatic petroleum hydrocarbons by G. S. Pevneva; V. V. Savel’ev; A. K. Golovko (288-297).
Thermolysis of crude oil at a temperature of 350°C for 1 h with and without aluminosilicates has been conducted in the isothermal regime mode. The composition of liquid and gaseous thermolysis products has been analyzed. The amount of resins and asphaltenes in the liquid products of thermal or thermocatalytic treatment decreases and that of oils increases as compared with the crude oil. The individual composition of saturated hydrocarbons (alkanes, steranes, terpanes) and alkylaromatic compounds (benzenes, naphthalenes, and phenanthrenes homologoues) has been studied. It has been shown that thermolysis increases the amount of thermodynamically more stable m- and p-isomers of alkyltoluenes, and the β-isomers of alkyl-naphthalenes and alkylphenanthrenes. Geochemical parameters for the composition of alkyl substituted benzenes, naphthalenes, and phenanthrenes have been calculated.
Keywords: thermolysis; crude oil; alkylarenes; organic substance; catagenetic transformation; degradation
Synthesis and use of polyfunctional catalyst nanoparticles for hydroconversion of natural bitumen by Kh. M. Kadiev; S. N. Khadzhiev; M. Kh. Kadieva (298-308).
The results of the hydroconversion of high-molecular-mass bitumen components in a mixture with light gasoil after catalytic cracking in the presence of in situ synthesized novel polyfunctional nanocatalysts are presented. The influence of the composition and different modes of introduction of catalyst precursors on the conversion of the high-molecular-mass components and the yield of polycondensation products has been studied. The size, structure, and morphology of in situ forming nanoheterogeneous catalyst particles have been investigated. It has been found that binary nanocatalysts based on Fe1 − x S and MoS2 are the most active in the conversion of asphaltenes and the highest degree of desulfurization is achieved with the use of (Ni3S2 + MoS2)/Al2O3 and (Co9S8 + MoS2)/Al2O3 nanocatalysts.
Keywords: hydroconversion; nanocatalyst; polyfunctional catalysts; natural bitumen; high-molecular-mass bitumen component
A study of structural transformations of asphaltene molecules during hydroconversion of vacuum residue at various temperatures in the presence of nanosized molybdenum disulfide particles by O. V. Zaytseva; E. E. Magomadov; Kh. M. Kadiev; E. A. Chernysheva; V. M. Kapustin; S. N. Khadzhiev (309-315).
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.
Keywords: hydroconversion; catalyst nanoparticles; asphaltenes; vacuum residue; hydroconversion product; elemental analysis; average molecular mass; 1H NMR spectroscopy; structural group analysis
An in situ study of dimethyl ether conversion over HZSM-5/Al2O3 zeolite catalysts by high-temperature diffuse reflectance infrared fourier transform spectroscopy by A. S. Rodionov; G. N. Shirobokova; G. N. Bondarenko; Yu. V. Pavlyuk; N. V. Kolesnichenko; T. I. Batova; E. N. Khivrich; S. N. Khadzhiev (316-321).
Isolated and associated OH groups have been in situ identified by high-temperature diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy of the surface of zeolites calcined until complete removal of water. It has been shown that the Brønsted acid sites (BASs) involved in dimethyl ether (DME) conversion on the zeolite surface exhibit two characteristic bands in the DRIFT spectra. It has been found that the composition of DME conversion products on HZSM-5 zeolite catalysts modified with Mg or Rh is temperature-dependent. Ethanol and a small amount of methanol were detected on an Rh-HZSM-5/Al2O3 zeolite catalyst at T = 270°C and were not observed on Mg-HZSM-5/Al2O3 under the same conditions. Spectral features of ketene were detected in the DRIFT spectra of the surface of Mg-HZSM-5/Al2O3 in a stream of DME. The spectrum of Rh-HZSM-5/Al2O3 calcined at 200°C exhibited spectral features of ethyl alcohol and bands characterizing a strong Lewis acid site (LAS) capable of hydrogenating ketene to ethyl alcohol. The spectra of the surface of all the zeolite catalysts tested in a DME stream at 320°C contain bands characterizing olefins and alkanes and do not exhibit the spectral features of alcohols and ketene.
Keywords: dimethyl ether; zeolite catalyst; Brønsted and Lewis acid sites; FTIR spectroscopy
Effect of promoters on the structure and catalytic properties of tungstated zirconia in n-heptane isomerization by L. I. Kuznetsova; A. V. Kazbanova; P. N. Kuznetsov (322-325).
The effect of manganese and aluminum cations on the formation of the crystalline structure and catalytic properties of tungstated zirconia has been studied. It has been shown that the modification of ZrO2 with both cationic and anionic additives leads to the stabilization of its tetragonal form and the formation of substitutional solid solutions on its basis. It has been found that manganese and aluminum additives have different effects on catalytic properties in heptane isomerization.
Keywords: tungstated zirconia; oxide catalysts; cationic modification; catalytic isomerization; alkanes
The role of labile products of styrene epoxide conversion in its oxidation in polar acid medium by L. V. Petrov; V. M. Solyanikov (326-330).
Phenylacetaldehyde (PAA) and benzyl alcohol (BAl) are formed in oxygen atmosphere from styrene epoxide in the presence of p- toluenesulfonic acid (TSA) in a solution of 90 vol % tert-butanol with 10 vol % chlorobenzene (BUC). The ratio of the propagation (k 2 ) to the termination (k 6) rate constants has been measured to be k 2/√k 6 = 8.6 × × 10−3 (L/(mol s))1/2 at 343 K by the method of initiated oxidation of PAA in a BUC solution. One of the products of the radical chain PAA oxidation is BA. This reaction leads to BAl accumulation during the conjugated oxidation of PAA with the epoxide in an acid alcohol medium. The contribution of BAl formed to the oxidation is almost unnoticeable.
Keywords: styrene epoxide; p-toluenesulfonic acid; phenylacetaldehyde; benzaldehyde; benzyl alcohol; oxidation by molecular oxygen
Bacterial synthesis of n-Alkanes with an odd number of carbon atoms in the molecule by A. R. Stroeva; M. V. Giruts; V. N. Koshelev; G. N. Gordadze (331-334).
n-Alkanes with an odd number of carbon atoms in the molecule and respective unsaturated even-chain fatty n-acids have been found in native biomass of Arthrobacter sp. RV and Pseudomonas aeruginosa RM hemoorganoheterotrophic bacteria. In addition, C8 and C10 n-alkanes with an even number of carbon atoms in a much lower concentration compared with odd-numbered alkanes have been found within native biomass of the bacteria under investigation. Both strains have synthesized an unsaturated irregular isoprenane, squalene (2,6,10,15,19,23-hexamethyltetracosa-2,6,10,14,18,22-hexaene). It has been supposed that the prevalence of odd-over even-carbon-number alkanes in low-maturity oils is due to not only high-temperature decarboxylation of the relevant acids with an even number of carbon atoms, but also bacterial synthesis.
On the concerted one-step mechanism of rearrangement of 1,1′-bicyclobutyl radical cations in Freon-113 at 77 K by Nay Win Tun; I. Yu. Shchapin; A. I. Nekhaev (335-340).
Conformationally selective rearrangement of 1,1′-bicyclobutyl radical cations to radical cations of bicyclo[3.3.0]octane and bicyclo[3.2.1]octane that occurs at 77 K via the concerted one-step mechanism in a 1% 1,1′-bicyclobutyl solution in Freon-113 irradiated with X-rays at 77 K has been detected by means of the EPR technique. The assignment of the EPR spectra has been confirmed by MNDO-UHF calculations.
Keywords: 1,1′-bicyclobutyl; bicyclo[3.3.0]octane; bicyclo[3.2.1]octane; radical cation; rearrangement; EPR; Freon-113
Effect of ethylene-vinyl acetate copolymer-based depressants on the low-temperature properties of components of light- and heavy-grade marine fuels by N. K. Kondrasheva (341-348).
The possibility of using ethylene copolymers with vinyl acetate as additives for light and heavy distillate marine fuels for improving their low-temperature properties has been examined. The maximum depressing effect of these additives is achieved at an optimal concentration for each distillate and a definite copolymer molecular mass and composition.
Keywords: pour-point depressants; diesel fuel; copolymer additives; ethylene-vinyl acetate copolymer; performance characteristics; marine fuel
Determination of oxygenates and benzene in gasoline by various chromatographic techniques by A. Yu. Kanateva; A. V. Paleev; A. A. Kurganov; A. V. Gorshkov; M. G. Gribanovkaya (349-355).
A comparative analysis of gasoline samples has been performed using several chromatographic methods: one-dimensional detailed hydrocarbon analysis (DHA), which allows for determination of the individual component composition of a liquid petroleum product with identification by retention times; two-dimensional gas chromatography 2D-GC with identification by retention times; two-dimensional gas chromatography 2D-GC-MS with identification by retention times and mass spectra of compounds; and determination of the group composition of gasoline by multidimensional gas chromatography using traps and a reactor with a flame-ionization detector. The advantages and disadvantages of each procedure have been shown and application areas for each method have been specified.
Keywords: two-dimensional gas chromatography; oxygenates; chromatography-mass spectrometry