Degradation of phenylethyl hydroperoxide in the presence of styrene epoxide and <Emphasis Type="Italic">p</Emphasis>-toluenesulfonic acid in an acetonitrile solution

It was shown that phenylethyl (ethylbenzene) hydroperoxide (EBHP) decomposes in an acetonitrile solution in an argon atmosphere in the presence of a styrene epoxide (SE)-p-toluenesulfonic acid (TSA) binary system yielding acetophenone and methylphenylcarbinol in a molar ratio of 1: 1. The expression for the EBHP degradation rate v = k _p[TSA]¹[SE]⁰[EBHP]⁰ is equivalent to the relationships obtained earlier for the rates of oxygen uptake by the binary system and the buildup of the oxidation product. The temperature dependence of the specific rate of degradation is given by k _p = 1 × 10¹⁴exp (?111.8 kJ mol^?1/RT) s^?1 (333–348 K).     

Influence of hexamethylphosphoric triamide and dimethylformamide admixtures on the mechanism of tris(acetylacetonato)iron(III)-catalyzed ethylbenzene oxidation with molecular oxygen

The influence of electron-donating monodentate ligands L², such as hexamethylphosphoric triamide (HMPA) and dimethylformamide (DMF), on the mechanism of tris(acetylacetonato)iron(III)-catalyzed oxidation of ethylbenzene with molecular oxygen was kinetically studied. It was found that the admixtures of L² cause a nonadditive (synergistic) increase in the rate of ethylbenzene oxidation catalyzed by Fe(III)(acac)₃, as well as a growth in the α-phenylethyl hydroperoxide selectivity (S _PEH) and/or ethylbenzene conversion (C) relative to the Fe(III)(acac)₃ catalysis in the absence of L², changes that are due to the formation of more active complexes, mFe(III)(acac)₃ · nL² and Fe(II)(acac)₂ · L² (L² is HMPA or DMF) and products of Fe(II)(acac)₂ · L² (L² is DMF) transformation. The most significant effects of ligands L² on S _PEH and C was revealed in the case of catalysis by the {Fe(III)(acac)₃-HMPA} system at 80°C. In the presence of the {Fe(III)(acac)₃-DMF} catalyst system, methyl phenyl carbinol (MPC) was produced at a selectivity of S _MPC ? 58%, a value that exceeds S _PEH = 25–30% at the initial steps of ethylbenzene oxidation. The formation mechanism for the principal products—ethylbenzene hyroperoxide, acetophenone, and methyl phenyl carbinol—of ethylbenzene oxidation catalyzed by Fe(III)(acac)₃ in the presence of HMPA and DMF was established. The activity of the Fe(II)(acac)₂ · L² complexes formed during ethylbenzene oxidation catalyzed by {Fe(III)(acac)₃-L²} (L² is HMPA or DMF) at the microsteps of chain initiation (O₂ activation) and propagation in the presence of the catalyst (Ct) (Ct + RO ₂ ^· →) was evaluated, and the role of these steps in the mechanism of the iron-catalyzed oxidation of ethylbenzene to α-phenylethyl hydroperoxide was discussed.     

Dimerization of vinylarenes on zeolite catalysts

The main features of dimerization of vinylarenes, such as styrene, α-methylstyrene, β-methylstyrene, p-methylstyrene, p-methoxystyrene, p-methoxy-β-methylstyrene, m-chlorostyrene, and m-nitrostyrene used as an example, over zeolite catalysts were studied, and the high activity and selectivity of these catalysts in the reaction was shown. For styrene and α-methylstyrene, the vinylarenes having the largest production volume, catalysts that hold promise for industrial application were developed. Conditions for the selective linear dimerization (85–93%) and cyclodimerization (85–98%) of styrene and α-methylstyrene at a high conversion (100%) were determined.     

Investigation of deep catalytic cracking of various model compounds of different classes of light hydrocarbons on a mesoporous catalyst based on ZSM-5 zeolite

The catalytic cracking performance of light hydrocarbon model compounds (1-hexene, n-octane, i-octane, ethylcyclohexane and ethylbenzene) over a mesoporous catalyst based on ZSM-5 zeolite was analyzed and compared using a microscale apparatus with a fixed-bed reactor. The effects of reaction temperature and weight hourly space velocity (WHSV) on feed conversion and the yields of ethene and propene were investigated. The results showed that with increased reaction temperature, the conversion of model compounds increased monotonically, and that of 1-hexene was close to 100% above 660°C; the yield of ethene plus propene of n-octane, i-octane and ethylcyclohexane increased continuously, while that of 1-hexene and ethylbenzene passed through maximum. With increased WHSV, the yield of ethene plus propene of ethylbenzene increased continuously, and that of the other model compounds decreased continuously. Through comprehensive analysis of the data, it is indicated that 1-hexene exhibited the highest cracking performance, followed by n-octane and ethylcyclohexane, whereas i-octane and ethylbenzene exhibited the lowest.     

Kinetic parameters of the reaction of isobornylphenols with peroxy radicals

The stoichiometric factors of inhibition and the rate constants (k ₇) were measured for the reaction of isobornylphenols with peroxy radicals of ethylbenzene. The values of k ₇ of the compounds under study increase with an increase in the amount of alkyl substituents and OH groups on the aromatic ring. The introduction of the oxygen atom between the o-isobornyl substituent and the aromatic ring decreases k ₇ by a factor of 6.5. The inhibiting action of binary mixtures of sterically hindered phenols with 2-isobornyl-4-methylphenol and 2,6-diisobornyl-4-methylphenol in the initiated oxidation of ethylbenzene is close to additive.     

The influence of organic additives on the regioselectivity of oxygenation of alkanes with hydrogen peroxide in the presence of TS-1titanium silicalite

Hydrogen peroxide oxidizes n-hexane, n-heptane, and n-octane at 50°C in the presence titanium silicalite TS-1 as a catalyst, forming isomeric mixtures of ketones and alcohols. Admixtures of organic acids, alcohols, benzene, and ethylbenzene sharply change the ratio of position isomers. For example, the normalized ratio is C(4): C(3): C(2) = 0.44: 1.0: 0.47 for n-heptane oxidation in the absence of additives, but it becomes 0.52: 1.0: 1.00 in the presence of benzyl alcohol and the addition of ethylbenzene changes it to 0.16: 1.0: 0.94.     

Synthesis and gas transport properties of polypentafluorostyrene

Polypentafluorostyrene (PPFS) (M _w = 1.7 × 10⁵ Da, M _w /M _n = 1.6, and Т _g = 110°С) has been synthesized by radical polymerization of pentafluorostyrene. The chemical structure of the polymer has been confirmed by ¹H and ¹⁹F NMR data. The permeability and diffusion coefficients of gases (He, H₂, O₂, N₂, CO₂, and CH₄) have been measured on a barometric setup. The permeability, diffusion, and solubility coefficients of gases have been shown to increase with the increases in the fluorine content in the repeat unit of the polymer in the polystyrene–poly(p-fluorostyrene)–PPFS series. Such behavior of transport parameters in the polymer series is associated with the growth in the fractional free volume and decrease in the cohesive energy density. The investigated polymers on the basis of styrene and its derivatives including PPFS are located in the middle of clouds of Robeson diagrams for N₂/CH₄, CO₂/CH₄, and O₂/N₂ and are not of interest for their separation.     

Assessment of the competitiveness of the radical and nonradical mechanisms in the acid-catalyzed oxidation of styrene epoxide

The oxidizability value of styrene epoxide as the ratio k ₂/√k ₆, where k ₂ and k ₆ are the propagation and termination rate constants of the epoxide oxidation chain, respectively, was calculated from experimental data on the oxidation of neat styrene epoxide with oxygen in the presence of the initiator dicumyl peroxide in a quartz reactor of a manometric unit. Alternative calculations of the oxidizability value with the use of two procedures and two experimental setups yielded close values of k ₂/√k ₆ = 0.333exp(?22.5 kJ mol^?1/RT) and k ₂/√k ₆ = 0.18exp(?22.1 kJ mol^?1/RT)(l/(mol s))^1/2 (393–413 K), which characterize a quite high stability of styrene epoxide toward oxidation by peroxide radicals. With allowance for the new data, it was concluded that the radical mechanism is unfeasible under the conditions of the earlier-studied mild acid-catalyzed oxidation of styrene epoxide (333–348 K).     

Hybrid connectionist model determines CO2–oil swelling factor

In-depth understanding of interactions between crude oil and CO₂ provides insight into the CO₂-based enhanced oil recovery (EOR) process design and simulation. When CO₂ contacts crude oil, the dissolution process takes place. This phenomenon results in the oil swelling, which depends on the temperature, pressure, and composition of the oil. The residual oil saturation in a CO₂-based EOR process is inversely proportional to the oil swelling factor. Hence, it is important to estimate this influential parameter with high precision. The current study suggests the predictive model based on the least-squares support vector machine (LS-SVM) to calculate the CO₂–oil swelling factor. A genetic algorithm is used to optimize hyperparameters (γ and σr2) of the LS-SVM model. This model showed a high coefficient of determination (R² = 0.9953) and a low value for the mean-squared error (MSE = 0.0003) based on the available experimental data while estimating the CO₂–oil swelling factor. It was found that LS-SVM is a straightforward and accurate method to determine the CO₂–oil swelling factor with negligible uncertainty. This method can be incorporated in commercial reservoir simulators to include the effect of the CO₂–oil swelling factor when adequate experimental data are not available.     

Kinetics and mechanisms of the catalytic thermal cracking of asphaltenes adsorbed on supported nanoparticles

The production of heavy and extra-heavy oil is challenging because of the rheological properties that crude oil presents due to its high asphaltene content. The upgrading and recovery processes of these unconventional oils are typically water and energy intensive, which makes such processes costly and environmentally unfriendly. Nanoparticle catalysts could be used to enhance the upgrading and recovery of heavy oil under both in situ and ex situ conditions. In this study, the effect of the Ni-Pd nanocatalysts supported on fumed silica nanoparticles on post-adsorption catalytic thermal cracking of n-C7 asphaltenes was investigated using a thermogravimetric analyzer coupled with FTIR. The performance of catalytic thermal cracking of n-C7 asphaltenes in the presence of NiO and PdO supported on fumed silica nanoparticles was better than on the fumed silica support alone. For a fixed amount of adsorbed n-C7 asphaltenes (0.2 mg/m2), bimetallic nanoparticles showed better catalytic behavior than monometallic nanoparticles, confirming their synergistic effects. The corrected Ozawa– Flynn–Wall equation (OFW) was used to estimate the effective activation energies of the catalytic process. The mechanism function, kinetic parameters, and transition state thermodynamic functions for the thermal cracking process of n-C7 asphaltenes in the presence and absence of nanoparticles are investigated.     

Partial oxidation of methane to synthesis gas: Novel catalysts based on neodymium–calcium cobaltate–nickelate complex oxides

Novel catalysts based on neodymium–calcium cobaltate–nickelate complex oxides for the partial oxidation of methane to synthesis gas have been synthesized and studied using catalyst precursors with the general formula NdCaCo_1–xNi _x O _n (x = 0, 0.2, 0.4, 0.6, 0.8, 1) prepared by the solid state synthesis method. It has been shown that the synthesized samples form a series of solid solutions with a K₂NiF₄ structure at x ≤ 0.8 or a rhombically distorted K₂NiF₄ structure at x = 1. The products of conversion of the resulting precursors in a methane–oxygen mixture at high temperatures have shown high methane conversions and synthesis gas yields. The highest values of these parameters have been achieved in the presence of catalysts synthesized by the reduction of NdCaCo_0.4Ni_0.6O _n and NdCaNiO _n precursors. The complete replacement of cobalt with nickel has led to an increase in the synthesis gas yield; however, it has been found that the resulting catalyst is prone to carbonization. It has been determined that an optimum nickel to cobalt ratio in the catalyst composition provides the formation of a carbonization-resistant catalyst.     

Hydroalkylation of benzene and ethylbenzene over metal-containing zeolite catalysts

The hydroalkylation reaction of benzene and ethylbenzene over BEA zeolites with a Si/Al ratio of 9–190, MOR with Si/Al = 48, and MFI with Si/Al = 25 containing ruthenium, rhodium, platinum, or palladium was studied, as well as over the Ru/BEA zeolites with Si/Al = 42 doped with a second metal: nickel, cobalt, or rhodium. The catalytic experiments were conducted under flow conditions in the temperature range 130–190°C, a pressure of 1 MPa, a feed weight hourly space velocity of 2–64 h^?1, and a stoichiometric reactant ratio. It was shown that the main reaction routes are the complete hydrogenation of benzene and ethylbenzene yielding cyclohexane and ethylcyclohexane, respectively; hydroalkylation yielding cyclohexylbenzene, para- and meta-ethylcyclohexylbenzenes, and diethylcyclohexylbenzenes; and alkylation resulting in dicyclohexylbenzenes and ethyldicyclohexylbenzenes. The ruthenium-promoted (1 wt %) zeolite BEA with Si/Al = 42 displayed the highest activity and selectivity in the benzene and ethylbenzene hydroalkylation reactions. Doping of the catalyst with cobalt and rhodium did not improve its catalytic properties, presumably, owing to the fact that the dopant metals largely occur in the cationic form according to the IR data for adsorbed CO. An admixture of nickel (0.5 wt %) to the catalyst increases the catalyst operation stability without reducing the yield of ethylcy-clohexy lbenzenes.     

Correlation of basic <Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR-measurable structural group parameters of crude oils of the Volga–Urals oil and gas basin

Among 120 pairwise relations between 16 main ¹H and ¹³C NMR-measurable characteristics of the structural group composition of Volga–Urals crude oils, 10 most consistent relations (correlation coefficients |r_s| ≥ 0.9), 13 relations with |r_s| in the range of 0.8–0.9, and 33 pairs with loosely related or mutually independent members (|r_s| ≤ 0.3) have been revealed. Several relationships are parametric. The main parameter is C_ar. The overall picture of the relationships is complex; correlation coefficients with the absolute value above 0.7 are observed not only between the parameters characterizing the structure in the same group of entities (aromatic, n-alkyl): it has been found that C_ar correlates with the total content of n-alkyl structures (r_s =–0.76). Having definitely common features, oils from the Volga–Urals and Western Siberia oil and gas basins noticeably differ from one another. To explain the differences, it is necessary to launch an integrated study that is methodologically beyond the scope of contemporary petroleum geochemistry. The paper demonstrates the capabilities of correlation analysis for solving problems to which this method has not been yet applied in petroleum geochemistry: partial correlation coefficients as a means of identifying parametric relationships and Spearman correlation coefficients for nonnumeric values in determining differences in the composition between oils of different structures and from different territories or stratigraphic plays.     

Application of Ultrasonic Cavitation in the Etherification Reaction of a Coker Naphtha Narrow-Cut Fraction with Ethanol

The effect of ultrasonic cavitation on the process of etherification of a coker-naphtha light fraction (IBP–85°C) with ethanol using an HCl-treated zeolite catalyst has been studied. Optimal process conditions have been determined to be T = 80°C, P = 0.2 MPa, and V_space = 0.5 h^-1, under which the olefin conversion and the yield of alkyl ethyl ethers increase by 12.1 and 5.6%, respectively, and the motor octane number of the etherification product is enhanced by 6 points, with catalyst coking being reduced by 50–55%.     

Synthesis of cresotic acids by carboxylation of cresols with sodium ethyl carbonate

Carboxylation of o-cresol, m-cresol, and p-cresol with sodium ethyl carbonate (SEC) proceeds regioselectively with the formation of cresotic acids: 2-hydroxy-3-methylbenzoic acid, 2-hydroxy-4-methylbenzoic acid, and 2-hydroxy-5-methylbenzoic acid, respectively. Optimal conditions for conducting the process have been found to be as follows: the reactants ratio of [cresol]: [sodium ethyl carbonate] = (1.5–2): 1, T = 180–185°C, \({P_{C{O_2}}}\) = 10 atm, and t = 6–7 h. Simple and convenient methods for the synthesis of cresotic acids, which can be used for their industrial manufacturing, have been developed.     

Can Mesoporous TiO<Subscript>2</Subscript>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-Supported NiMoS OR CoMoS Effectively Perform in Ultra-Deep Desulfurization of Gas Oil?

Waste aluminum foil was used for preparation of mesoporous TiO₂-Al₂O₃ using starch as a textural modifier. The catalytic species, Mo and Ni or Co were loaded onto the mesoporous support, following incipient wetness sequential impregnation. To gain an insight into the pore dimensions effect, Ni and Mo species with the same mass ratio were loaded onto the TiO₂-Al₂O₃, prepared from analytical grade chemicals without templating. TPR spectra, TEM images and BET analysis showed how the promoter (Ni or Co), TiO₂ and the template (starch) affect the ease of reduction of Mo species, the morphology of the active MoS₂ phase and the pore dimensions of the catalysts. The catalysts were employed in hydro-desulfurization process of gas oil using a fixed bed down flow microreactor at varying operating conditions, viz., temperature (320–400°C), Liquid hourly space velocity (0.5–4 h^–1), H₂/oil ratio of 450 v/v, and 6 MPa operating pressure. The results showed that the promotion effect prevails over the textural effect, where Ni promoted catalyst (with lower surface parameters) exhibits higher activity than Co promoted one. The dual layer catalytic bed system achieved the sulfur level less than 10 ppm.     

Radiolysis products of the cyclohexane–bicyclic diene binary system

Solutions of 5-vinyl-2-norbornene (VNB, 5-vinylbicyclo[2.2.1]hept-2-ene) and the related compounds 5-ethylidene-2-norbornene (ENB, 5-ethylidenbicyclo[2.2.1]hept-2-ene) and 2-vinyl-2-norbornane (VNN, 2-vinylbicyclo[2.2.1]heptane) in cyclohexane have been irradiated with γ-rays at 40°C. The initial radiation-chemical yields G ₀ for the consumption of the solutes and the formation of final products of γ-radiolysis of the solvent cyclohexane have been determined. It has been shown that solute consumption and molecular hydrogen formation yields G ₀(?RH) and G ₀(H₂), respectively, are linearly related to the first vertical ionization potential of the solute. The G ₀ values of molecular hydrogen, cyclopentadiene (CPD), butadiene, and methylallene, minor products of γ-radiolysis (40°C) of liquid VNB, ENB, and dicyclopentadiene (tricyclo[5.2.1.0^2.6]decadiene-3.8), have been determined. It has been shown that the G ₀ values of CPD formation linearly depend on the first vertical ionization potentials of γ-irradiated bicyclic dienes. It is concluded that the γ-irradiation of cyclohexane generates two kinds of radical cations, which differ in mobility and reactivity.     

Determination of critical temperatures for mixtures of alkylbenzenes

The liquid-vapor critical temperatures of benzene mixtures with 1,3-di-tert-butylbenzene, 1,4-di-tert-butylbenzene, and 1,3,5-tri-tert-butylbenzene; a mixture of di-tert-butylbenzene isomers; and a toluene mixture with 3,5-di-tert-butyltoluene were determined over the entire range of composition by means of the amouule method. It was found that the excess critical temperature of the mixtures is related to the critical volumes of the substances. The capabilities of several calculation methods for predicting the critical temperature of mixtures were analyzed on the basis of published data and the obtained results. The Lee-Kesler rules of mixtures were refined by introducing binary interaction parameters.     

Comments to the article “Kinetics and Thermodynamics of Formation and Degradation of α-Hydrohyperoxyl Radicals” by E. T. Denisov and T. G. Denisova

In these comments, a substantiated conclusion was made that the additive calculation scheme proposed by E.T. Denisov and T.G. Denisova for the enthalpies of formation, ΔH _f ⁰ (g), of α-hydroxyhydroperoxides (15 compounds) is erroneous, since the well-known interaction in the systems when two O atoms are located on the same carbon atom was ignored. As a consequence, the cited authors overestimated the values of ΔH _f ⁰ for molecules by ～30 kJ mol^?1 and more. Using some examples, we present another empirical scheme of calculation of ΔH _f ⁰ for such systems, which gives more accurate results. Since the formation enthalpies for the starting molecules calculated by the authors of the article in question were used further in the calculation of the kinetic and thermodynamic parameters of α-hydroxyperoxyl radicals, the values of these parameters and ΔH _f ⁰ for these free radicals are incorrect.