Petroleum Chemistry (v.51, #3)
Mesoporous aluminosilicates as components of gas oil cracking and higher-alkane hydroisomerization catalysts by S. V. Lysenko; I. O. Kryukov; O. A. Sarkisov; A. B. Abikenova; S. V. Baranova; V. A. Ostroumova; S. V. Kardashev; A. B. Kulikov; E. A. Karakhanov (151-156).
Mesoporous aluminosilicates with a Si/Al ratio of 5 to 20, a pore diameter of 30 to 84 Å, and a specific surface area up to 1030 cm3/g have been prepared using hexadecylamine and Pluronic P123 as templates. These materials exhibit high activity in the cracking of hydrotreated vacuum gas oil. Bifunctional catalysts derived on their basis have high selectivity in the hydroisomerization of hexadecane.
Selective dimerization of styrene to 1,3-diphenylbutene-1 in the presence of [(acac)Pd(PAr3)2]BF4/BF3OEt2 catalytic systems by D. S. Suslov; V. S. Tkach; M. V. Bykov; M. V. Belova (157-163).
Selective dimerization of styrene to 1,3-diphenylbutene-1 in the presence of [(acac)Pd(PAr3)2]BF4 + BF3OEt2 catalytic systems, where R = C6H5, o-CH3C6H4, p-CH3C6H4, or o-CH3OC6H4, has been studied. Under the optimal conditions (B/Pd = 8, T = 75°C, R = C6H5), the conversion of styrene to the products exceeds the conversion for the known analogs and reaches 1.5 tons of styrene/g-atom of palladium with amounts of dimers and trimers of 91 and 9%, respectively. The dimers consist of up to 100% 1,3-diphenylbutene-1 with a trans/cis isomer ratio of 95/5.
Effects of cracking and coke formation on the selectivity of iron oxide catalysts in the dehydrogenation of methylbutenes to isoprene by Kh. Kh. Gil’manov; A. A. Lamberov; R. R. Gil’mullin; E. A. Pavlova (164-168).
The contributions of cracking and coke formation reactions to a decrease in the selectivity of domestic and imported catalysts for the dehydrogenation of methylbutenes (isopentanes and isoamylenes) into isoprene have been determined. It has been found that hydrothermal treatment in industrial reactors favorably affected an increase in the catalytic characteristics of a domestic iron oxide catalyst for dehydrogenation. The conditions for catalyst activation have been optimized with respect to the temperature and duration of hydrothermal treatment.
Study of magnesium-containing zeolite catalysts for the synthesis of lower olefins from dimethyl ether by T. I. Goryainova; E. N. Biryukova; N. V. Kolesnichenko; S. N. Khadzhiev (169-173).
The catalytic properties of magnesium-containing zeolite catalysts in the synthesis of olefins from dimethyl ether (DME) were studied. The optimal concentrations of magnesium in the zeolite catalyst were found, and a procedure for its introduction was developed. The effect of the operation conditions of DME conversion into lower olefins on the catalyst activity and selectivity was studied. The stability of the catalytic properties of the synthesized catalyst after oxidative regeneration was examined.
Methane conversion to valuable chemicals over nanostructured Mo/ZSM-5 catalysts by Z. R. Ismagilov; E. V. Matus; M. A. Kerzhentsev; L. T. Tsikoza; I. Z. Ismagilov; K. D. Dosumov; A. G. Mustafin (174-186).
Results of the ongoing study of nonoxidative methane dehydroaromatization (DHA) over Mo/ZSM-5 catalysts have been analyzed. The effects of the composition, preparation procedure, pretreatment, and the CH4 DHA reaction conditions on the physicochemical and catalytic properties of Mo/ZSM-5 catalysts have been discussed. The data on Mo-containing active sites, the methane DHA reaction mechanism, and the nature of carbonaceous deposits have been considered. The principal causes of the deactivation of Mo/ZSM-5 catalysts and means of their regeneration have been revealed. Approaches to the improvement of the methane DHA process and trends of its further development have been detailed.
High-molecular-mass asphaltene fraction and its effect on the structure and stability of oxidized bitumens by E. S. Okhotnikova; Yu. M. Ganeeva; T. N. Yusupova; V. I. Morozov; I. N. Frolov; G. V. Romanov (187-191).
Asphaltenes derived from oxidized asphalts are separated into five fractions that differ in solubility. The amount of the low-molecular-mass fraction in the asphaltenes does not exceed 20%, and that of the high-molecular-mass fraction is above 50 wt %. The high and low-molecular-mass fractions of the asphaltenes are studied by EPR spectroscopy, thermal analysis, and calorimetry. It is found that the high molecularmass fraction of the asphaltenes is characterized by a high amount of condensed aromatic structures; it has a tendency to form mesophases with different thermal stability and is responsible for the formation of ordered structures in asphalt. It is revealed that an increase in the amount of the high molecular-mass fraction in asphaltenes of oxidized petroleum asphalts leads to a decrease in their stability, which has an adverse effect on the stability of physicochemical characteristics and quality of the commercial products. It should be noted that this dependence is more pronounced for structured asphalts.
Fractionation of resins and asphaltenes and investigation of their composition and structure using heavy oil from the Usa field as an example by A. A. Grin’ko; A. K. Golovko (192-202).
Asphaltenes and resins of crude oil from the Usa oil field have been subjected to fractionation. The asphaltenes have been separated into fractions by fractional precipitation with chloroform/hexane solvent blends in the ratios of 30/70, 30/75, and 30/120. The resins have been fractionated by liquid adsorption chromatography on silica gel with hexane/benzene and hexane/ethanol mixed solvents taken in the ratios of 3/1, 1/1, and 10/1, 3/1, respectively. The obtained fractions have been analyzed by 1H and 13C nuclear magnetic resonance spectroscopy and infrared spectroscopy, their molecular masses have been measured, and the elemental composition has been investigated. On the basis of structuralgroup analysis data, the structures of the resin and asphaltene molecules have been hypothesized.
A study of heavy oil fractions by Fourier-transform near-infrared Raman spectroscopy by A. Kh. Kuptsov; T. V. Arbuzova (203-211).
Oil fractions with a boiling-point step size of 20°C (300 to 560°C) for six different crude oils of Western Siberia have been studied by Fourier-transform Raman and Fourier-transform IR spectroscopy. Weak bands have been more clearly revealed, previously noninterpreted bands have been attributed, and corrections to the published assignment of their characteristic Raman bands have been made. The capabilities and the informative value of the method have been shown, as applied to the determination of nitrogen heterocycles and the ratios between mono-, bi-, tri-, and polycyclic aromatic hydrocarbons or between CH2 and CH3 groups. The true band envelopes of polycyclic aromatic hydrocarbons have been found with the use of corrected difference Fourier-transform Raman spectroscopy at different temperature increments, and the tendency toward their approach to the Raman band envelopes of disordered carbon (in particular, for the case of sedimentary rocks) has been shown. A complementary application of Fourier-transform Raman and Fourier-transform near-infrared absorption spectroscopy to the monitoring of industrial streams and processes in the near-infrared region through integrated fiber-optic networks has been suggested.
Kinetics and mechanism of the catalytic reaction of ozone with toluene in the liquid phase by S. G. Galstyan; N. F. Tyupalo; A. G. Galstyan (212-215).
The kinetics and product composition of the liquid-phase catalytic oxidation of toluene with an ozone-air mixture were studied. It was shown that at low temperatures in an acetic anhydride medium in the presence of manganese acetate and an inorganic acid, oxidation develops mainly at the methyl group, yielding benzyl acetate, benzaldehyde, and benzylidene diacetate. The scheme of redox catalysis to explain the experimental data is discussed.
Hydrogen peroxide oxidative desulfurization of model diesel fuel mixtures in the presence of crown ethers and transition metal peroxo complexes by E. V. Rakhmanov; Dan Jinyuan; O. A. Fedorova; A. V. Tarakanova; A. V. Anisimov (216-221).
The catalytic ability of crown ethers and their complexes with transition metal cations in the desulfurization reaction of mixtures that simulate diesel fuel has been investigated. It has been found that the use of monoaza-15-crown-5-ethers with an admixture of NbCl5 resulted in a fourfold decrease of the total sulfur content, thereby indicating partial oxidation of benzothiophenes and dibenzothiophenes. The complexation of azacrown ethers with NbCl5 has been studied by 1H NMR spectroscopy. A moderate efficiency of adsorption purification procedure using silica and alumina for both initial and oxidized model mixtures has been revealed.
Synthesis of ethylene glycol esters of petroleum acids and their use as diesel additives by T. A. Mamedova; A. G. Talybov; Kh. R. Veliev; N. R. Abdullaeva; E. N. Askerova; V. M. Abbasov (222-225).
Optimum conditions for the synthesis of ethylene glycol esters of various fractions of petroleum acids are described; the possibility of using synthesized esters as diesel additives for improving the quality of fuels and increasing their service life is shown.
Simulation of cumene oxidation in the presence of a binary mixture of initiators by I. A. Opeida; N. M. Zalevskaya; Yu. I. Skichko; R. A. Voloshkin (226-229).
The oxidation of cumene in the presence of a mixture of two initiators, azobisisobutyronitrile and benzoyl peroxide, revealed the antagonistic effect of their action. This phenomenon was explained using mathematical simulation of the process by means of analyzing kinetic schemes. It was shown that the antagonistic effect is a result of formation of alkoxyl radicals at the stage of combination of cumene peroxyl radicals and their further participation in cross-termination reactions with initiator radicals. The temperature dependence of the initiators’ effect has been analyzed.