Vol 59, No 1 (2019)

Methods for the selective catalytic oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones are surveyed. This part of the review is devoted to the catalysts on the basis of salts and oxides of transition metals. The greatest attention is paid to the reactions of oxidation with air or molecular oxygen. The influence of various factors (the nature of the alcohol, oxidizing agent, catalyst, and solvent) on the rate of the oxidation reaction and its direction is discussed.

The effect of the natural minerals pyrite and hematite as a catalyst on the efficiency in destruction of the organic matter of Domanik rock, rich in organic matter, at a temperature of 300°C in a steam–carbon dioxide gas environment has been studied. Compared with the original rock and a control experiment, the presence of the natural catalysts in the reaction system leads to an increase in both the amount of mobile hydrocarbons in the rock and the yield of extracts, in which the concentration of saturated hydrocarbons is increased by factors of 12 and 16 in the experiments with pyrite and hematite, respectively, and the asphaltene content is halved. The degradation processes of high-molecular-weight resinous–asphaltenic components and insoluble kerogen lead to the formation of lower n-alkanes and the structuring of asphaltenes to increase the degree of their carbonization, followed by the formation of insoluble substances of the carbene–carboid type appearing as a new dispersed solid phase in the products. The distinctive features of the structural composition of asphaltenes and carbenes–carboids have been revealed. The close composition of the products of hydrothermal–catalytic experiments suggests that pyrite and hematite exhibit similar catalytic properties under hydrothermal conditions.

It has been shown that the hydrothermal–catalytic conversion of solid natural asphaltite of the Spiridonovskoe oilfield (Republic of Tatarstan) at 250°C in the presence of hematite yields liquid products with a reduced amount of resins and asphaltenes. At the same time, a dispersed phase of insoluble carburized substances of the carbene and carboid types appears in the conversion products. The structural-group and molecular compositions of oils in the liquid products of conversion, which are enriched in aromatic, polycycloaromatic, and carbonyl-containing structural units and sulfoxides according to ¹H NMR and IR data, have been determined. It has been established that the molecular composition of oils from the initial asphaltite and its conversion products is almost the same, but there are changes in the relative amount of various types of compounds. A low concentration of alkanes and an increased concentration of triterpanes characterize the initial Spiridonovskoe asphaltite as a biodegraded object. In the conversion products, the relative amount of alkanes has sharply increased and the concentrations of tri- and tetracyclic aromatic hydrocarbons (HC) and dibenzothiophenes have become greater. The proportion of phenanthrenes and tetracyclic aromatic hydrocarbons has increased by factors of 9.3 and 2.6, respectively, and alkylcyclohexanes have been identified, which are absent in the original asphaltite. But the relative amount of polycyclic naphthenes (pregnanes, steranes, cheilanthanes, and hopanes) significantly decreased. The revealed differences are apparently determined by the scale of generation of these compounds by the degradation of resins and asphaltenes, in which the compounds occur as structural units of molecules or in an adsorbed and/or occluded form.

Quantum-chemical calculations on the mechanism of catalytic alkylation of adamantane with isooctane cracking products using the density functional theory DFT B3LYP/6-31G* have been carried out. It has been shown that the initial stage of transformations is the interaction of AlCl₃ · HCl (as a model of an acid catalyst) with isooctane. At the first cracking stage, proton transfer from the catalyst to isooctane occurs (activation energy is calculated to be 24.64 kcal/mol) to give intermediate 1, which consists of three interacting subsystems: the cation (СН₃)₃С⁺; the anion \({\text{AlCl}}_{4}^{ - }\); and СН₃–СН(СН₃)₂, i.e., isobutane. The second stage is proton transfer from the carbocation (СН₃)₃С⁺ to form the olefin CH₂=C(CH₃)₂. The activation energy of this stage was calculated to be 7.85 kcal/mol. This is the final stage of isooctane cracking, yielding an olefin and an alkane smaller than the parent one. The mechanism of formation of the adamantyl cation has been considered, in which the cation adds the olefin without activation energy and the resulting complex can form either 1-isobutylenyladamantane (unsaturated byproduct of adamantane alkylation) via deprotonation by the catalyst anion or the final product 1-isobutyladmantane via interaction with another adamantane molecule. The latter can also be formed by the joint action of isobutane and the catalyst anion on the adamantyl cation, with the activation energy being 26.79 kcal/mol.

Results of a study of 1,2-epoxycyclopentane carboxylation to cyclopentene carbonate (CPC) in the presence of various catalyst systems have been described. It has been found that the reaction occurs most efficiently in the presence of cobalt (nickel) chloride (bromide) hydrate and a quaternary ammonium salt (TEAB, TBAB). It has been recommended that CPC should be synthesized under a CO₂ pressure of no less than 3.5 MPa at a temperature of 140–150°С without any solvent or in the medium of a solvent, such as target CPC, DMF, or N-MP, at a 1,2-epoxycyclopentane weight fraction in the feed mixture of no less than 25%. These conditions provide the formation of CPC with a selectivity of 97–99% and almost complete epoxide conversion within 2–4 h. It has been shown that the developed catalyst system can be recycled.

The nonoxidative conversion of methane to aromatic hydrocarbons in the presence of a high-silica ZSM-5 zeolite modified with molybdenum and rhenium nanopowders has been studied. Data on the acid characteristics of the catalysts have been derived by temperature-programmed desorption of ammonia. The microstructure and composition of the Re/ZSM-5 and Re–Mo/ZSM-5 catalyst systems have been studied by transmission electron microscopy. It has been shown that modification of a Mo-containing zeolite with rhenium leads to an increase in the activity and stability of the catalyst in the methane dehydroaromatization reaction.

The possibilities of reducing the viscosity of heavy fuel oil with an increased proportion of residual fractions through the use of nanomaterials, such as carbon nanotubes (CNTs) and dehydrated carbonate sludge, have been investigated. The results of studying of rheological characteristics of fuel oil and composite fuel containing carbon nanotubes dispersed in an oil-soluble nonionic surfactant (M100 fuel oil + 0.0125 wt % CNT + 0.5 wt % Diproxamine) or dehydrated carbonate sludge (M100 fuel oil + 0.1 wt % carbonate sludge) are presented, as well as their heating value. The existence of a synergistic effect of the combined use of CNTs and carbonate sludge has been established. The possible mechanisms of change in the viscosity of the fuel are considered. It has been shown that carbon nanotubes together with dehydrated carbonate sludge can be most promising for use as heating oil additives, since they reduce fuel viscosity, improve combustion efficiency, and reduce the emission of hazardous gases.

The thermal stability of 4-tert-butylphenol has been studied in the temperature range of 673–738 K, the components of the thermolysis reaction mixture have been identified, a kinetic model of the process has been proposed, and the rate constants and parameters of the Arrhenius equation have been calculated for all of the reactions considered. The predominant role of 4-tert-butylphenol isomerization transformations has been established. Information on the 4-tert-butylphenol thermal stability facilitates to a more substantiated approach to its use as an additive that increases the oxidative stability of fuels and lubricants, as well as an antioxidant for polymer compositions.