Vol 58, No 3 (2017)

Experimental kinetic data on reactions of the chlorine atom with halogenated derivatives of methane and ethane (37 reactions) have been analyzed by the intersecting-parabolas method. The following five factors have an effect on the activation energy of these reactions: the enthalpy of reaction, triplet repulsion, the electronegativities of the reaction center atoms, the dipole–dipole and multidipole interactions between the reaction center and polar groups, and the effect of π electrons in the vicinity of the reaction center. The increments characterizing the contribution from each factor to the activation energy of the reaction have been calculated. The contribution from the polar interaction, ΔE_μ, to the activation energy depends on the dipole moment of the polar group and obeys the following empirical equation: ln(Δ_Eμ/Σμ) = −0.74 + 0.87(ΔE_μ/Σμ) − 0.084(ΔE_μ/Σμ)².

This review deals with the UV laser photodissociation of metal carbonyls, ferrocene, carbon suboxide, and other precursors. The formation of supersaturated atomic vapors followed by the formation of carbon, metal, and metal–carbon nanoparticles is discussed. Application of UV laser synthesis to preparation of catalytic nanomaterials is considered.

Catalysts prepared by the modification of FIBAN K-4 and FIBAN X-1 fibrous ion exchangers with the hydroxides of iron and manganese were developed and tested in a water deoxygenation process. It was established that the samples obtained by the supporting of Fe(III) hydroxide onto the FIBAN X-1 ampholyte were most effective. The conclusion that the high activity of the catalytic system is caused by the formation of a mixed phase of Fe(II) and Fe(III) hydroxides of the spinel type containing mobile (weakly bound) lattice oxygen was made. A reaction scheme was proposed to explain the reaction mechanism.

The main routes of catalytic gasoline reforming are considered. A kinetic model is chosen, substantiated, and modified to adequately describe the most important chemical reactions occurring in the process. The kinetic model is used to construct a mathematical model taking into account the nonisothermal character of the process. To reconcile calculated data with the corresponding industrial data, kinetic parameters (activation energies of reactions and preexponential factors of the Arrhenius equation) have been corrected for basic reactions of the process and have been redetermined for some ones. Process stages and concentration profiles of groups of reactants have been analyzed. Foundations have been laid for modeling of the entire chemical technological system of the catalytic reforming process.

CO adsorption on (0.5–15)%CoO/ZrО₂ catalysts has been investigated by temperature-programmed desorption and IR spectroscopy. At 20°С, carbon monoxide forms carbonyl and monodentate carbonate complexes on Co_m²⁺O_n^2- clusters located on the surface of crystallites of tetragonal ZrO₂. With an increasing CoO content of the clusters, the amount of these complexes increases and the temperature of carbonate decomposition, accompanied by CO₂ desorption, decreases from 400 to 304°С. On the 5%CoO/ZrО₂ sample, the carbonyls formed on the Со²⁺ and Со⁺ cations and Со⁰ atoms decompose at 20, 90, and 200–220°С, respectively, releasing CO. At 20°С, they are oxidized by oxygen to monodentate carbonates, which decompose at 180°С. Adsorbed oxygen decreases the temperature of their decomposition on oxidation sites by ~40°C, and the sample remains in an oxidized state ensuring the possibility of subsequent CO adsorption and oxidation. The rate of the oxidation of 5%CoO/ZrО₂ containing adsorbed CO by oxygen is higher than the rate of the oxidation of the same sample reduced by carbon monoxide, because the latter reaction is an activated one. In view of the properties of the complexes, it can be concluded that the carbonates decomposing at 180°С are involved in CO oxidation by oxygen from the gas phase in the presence of hydrogen, a process occurring at 50–200°С. The rate-limiting step of this process the decomposition of the carbonates, which is characterized by an activation energy of 77–94 kJ/mol.

The hypercrosslinked porous ionic polymer has been synthesized via one-pot polymerization and quaternization of vinyl pyridine and chloromethyl styrene under solvothermal condition. The effects of solvents and synthetic process on the polymer structure were investigated. Polymer from n-butanol showed the highest BET surface area of 555.6 m²/g. The catalytic activities were investigated though the aza-Michael addition and the results showed that the polymer owned even higher activity than homogenous ionic liquid. The high BET surface area, high catalytic activity and high stability made the polymer hold great potential for green chemical processes.

A zero-dimensional model (perfectly-stirred reactor) in conjunction with CHEMKIN II and a scheme resulting from the merging of validated kinetic schemes for the oxidation of benzene were used to investigate the effect of hydrogen addition on the formation-depletion of C₂H₂, which is known as a soot precursor. The current modeling study treats the dependence of acetylene amounts on hydrogen percentage in the fuel mixture, and defines the key reaction mechanisms responsible for the observed reduction in C₂H₂ and consequently in polycyclic aromatic hydrocarbons and soot amounts induced by the hydrogen additive. The main objective of this work was to obtain fundamental understanding of the mechanisms, through which the hydrogen affects the acetylene yields. It was found that, at high temperatures hydrogen/benzene fuel mixtures displayed lower acetylene concentrations compared to the pure benzene fuel, whereas opposite trends were observed at low reaction temperatures.