Vol 59, No 9 (2019)

The products of thermolysis of asphaltenes of Lower Visean natural bitumens mined from different parts of the Voya field in the Timan–Pechora province have been studied. It has been found that the thermolysis of asphaltenes results in generation of alkanes, isoprenanes, alkenes, steranes, and hopanes. Genetic indices determined from the composition of biomarkers identified in the thermolysis products of asphaltenes do not contradict the possible genetic relations of the bitumens under study and Domanik crude oils of the Timan–Pechora province.

Concentrated suspensions of molybdenum, nickel, iron, and tungsten sulfide nanoparticles have been synthesized from inverse emulsions of aqueous solutions of molybdenum, nickel, iron, and tungsten salts in the presence of a sulfiding agent and hydrogen in a vacuum residue of oil distillation and have been tested in hydrocracking reactions of a mixture of paraffin wax and heavy cycle oil (HCO). The hydroconversion has been carried out in an autoclave at 445°C and a hydrogen pressure of 7 MPa. The results of the study have shown that the catalytic activity of the synthesized catalysts in cracking reactions increases in the order: MoS₂, (MoS₂ + Ni₇S₆), Ni₇S₆, Fe_{1 − x}S, (NH₄)_0.25 ⋅ WO₃.

In the synthesis of 1,3-butadiene from dimethyl ether (DME) on a Zn-Al₂O₃ catalyst, it has been found that the yield of the target product is 20% lower relative to the conversion of ethanol. However, the results of thermodynamic calculations showed an equal probability of the conversion of ethanol and DME and the same temperature dependence of the equilibrium composition of the reaction products. Using calculation by the quantum-chemical method of density functional theory DFT B3LYP/6-31(d), it has been established that dehydration and dehydrogenation of DME proceeds with a lower activation energy. The interaction of ethanol and DME molecules with the Zn₄O₄ cluster has been considered. It has been shown that interacting with zinc oxide, the ethanol molecule is to a greater extent subject to degradation due to the polarity of the OH bond in the molecule. It has been found that the catalytic system based on zinc oxide is not sufficiently active to ensure the effective reaction of DME conversion to 1,3-butadiene, unlike the case of ethanol.

Results of a study of the catalytic properties of platinum-containing tungstated zirconia in the hydroisomerization of an n-heptane–benzene mixture as a function of the reduction temperature of the catalyst in a hydrogen medium have been described. The main products of n-heptane conversion are di- and monomethyl-branched heptane isomers, and benzene is hydrogenated to cyclohexane, which undergoes isomerization to methylcyclopentane. It has been shown that an increase in temperature above 300°C leads to a significant decrease in the catalyst activity, while the parameters of the crystalline and pore structure of the catalyst remain stable. Using X-ray photoelectron spectroscopy, it has been found that an increase in the reduction temperature leads to an increase in the concentration of tungsten and platinum reduced to the metallic state on the catalyst surface.

The feature of hydroformylation of model gas mixtures with different ethylene, hydrogen, and methane concentrations in the presence of rhodium catalysts have been studied. The effect of the initial pressure in the reactor and the reaction temperature on the reaction rate and selectivity has been determined. It has been shown that ethylene hydroformylation occurs with a high propanal selectivity (up to 99%), with the turnover frequency of the reaction reaching 9500 h^–1. It has been proposed that various phosphine ligands should be used to implement alternative methods of separating the catalyst system from the reaction products.

Biodiesel is an environmental-friendly and renewable energy, many countries have begun to research and use biodiesel instead of diesel. However, the low temperature fluidity and oxidation stability of biodiesel are poor, which limits its development. In recent years, great progress has been made in the study of pour point depressants. This review discusses the types, preparation methods and future prospects of novel pour point depressants in recent years.

The poly(diphenylamine) derivative (PDPA) as amine antioxidant was synthesized via diphenylamine, styrene, and formaldehyde. The steps of the synthesis were discussed in detail, and the structure of PDPA was fully characterized with multiple analysis techniques. Furthermore, the anti-oxidative properties of PDPA were evaluated through oxidation–corrosion tests and differential scanning calorimetry. It was found that PDPA significantly improved the oxidation stability of base oils, especially pentaerythritol ester when it was added at concentrations of only 0.5 wt % to 0.8 wt %. Thermogravimetric analysis shows that anti-oxidation behavior of PDPA is better than traditional additive p, p-dioctylphenylamine. The synthesized PDPA antioxidant is a potential alternate additive in high-temperature conditions.

It has been shown that borate-containing alumina can be used as a support for sunflower oil hydrodeoxygenation catalysts at 380°C, 4.0 MPa, and a feed space velocity of 1 h^–1 with a liquid product yield of 81–85 wt %. It has been found that, with an increase in the boron oxide content in the catalyst, owing to an increase in the catalyst acidity, the fraction of isoalkanes in the products increases to 77–78% and the contribution of decarboxylation/decarbonylation reactions to the formation of the products increases.