Том 56, № 9 (2016)

Main methods for the polymerization of higher α-olefins (1-hexene, 1-octene, and 1-decene) with the formation of high molecular weight products, key properties of poly-α-olefins from the viewpoint of their use as drag reducing agents in the transportation of petroleum and petroleum products, as well as the challenges and prospects of the production of these important functional materials of the petroleum industry have been considered.

Polydimethylsildimethylene-dimethylsiloxane (PSDMS) and polydimethylsiltrimethylenedimethylsiloxane (PSTMS) have been first studied as pervaporation membrane materials for the recovery of butanol from aqueous media. New synthesis procedures that make it possible to obtain the monomers 2,2,5,5-tetramethyl-1-oxa-2,5-disilacyclopentane (1) and 2,2,6,6-tetramethyl-1-oxa-2,6-disilacyclohexane (2) in high yields and with high purity required for subsequent polymerization have been developed. The optimum concentration of the crosslinking agent (tetraethoxysilane (TEOS)) of 5% has been found, which provides the maximum degree of crosslinking without sacrificing high values of separation factor and permeate flux. It has been shown that the permselectivity of PSDMS or PSTMS for butanol–water is higher by a factor of 1.5 or- almost 2, respectively, than the selectivity of the industrial membrane polymer, PDMS, at comparable values of the butanol permeability coefficient.

Comparative data obtained by studying the synthesis of С₅₊ hydrocarbons from dimethyl ether (DME) on catalysts using MFI zeolites available from different manufacturers are presented. It has been shown that MFI zeolite samples substantially differ in their acidic properties and structural, morphological, and textural characteristics. The catalysts based on different MFI zeolites also noticeable differ in the yield and chemical composition of С₅₊ hydrocarbons. By switching from the stand-alone operation of a DME conversion reactor to the joint operation of two reactors for synthesis of oxygenates (DME and/or methanol) from synthesis gas and synthesis of hydrocarbons from oxygenates connected by a single circuit, high selectivity for hydrocarbons of the gasoline fraction is achieved with the catalyst based on the MFI zeolite, for which the bands characteristic of Н₃О⁺ acid sites are observed in diffuse reflectance IR spectra.

Based on a commercial zeolite of the MFI type, nanoparticles have been produced using mechanical methods (grinding in a ball or planetary mill, classification by “stirring-up”) and ultrasonic treatment (UST) of zeolite in water. It has been found by spectral methods (XRD, DRIRS, ²⁷Al and ²⁹Si solid-state NMR) and adsorption analysis that the grinding of the zeolite leads to partial degradation of its structure and appearance of defects in the crystalline framework, whereas the zeolite crystal lattice remains completely intact after sonication in the aqueous medium. The sonication destroys MFI agglomerates to form nanoparticles down to 40–50 nm in size. The dispersion of the zeolite nanoparticles in silicone or hydrocarbon oil–(Syltherm 800 or Dowtherm RP, respectively) as a high-boiling-point liquid leads to the formation of ultrafine suspensions, the stability of which depends on the type of the dispersion medium. The nanosized zeolite suspensions are more stable in Dowtherm RP than in Syltherm 800: without agitation, they are persistent for at least 3 weeks (settling at room temperature).

The hydroconversion of rapeseed oil fatty acid triglycerides (TGs) over a mesoporous platinum–palladium aluminosilicate catalyst has been studied. It has been shown that, in a temperature range of 250–375°C at a hydrogen pressure of 60 atm, the TGs undergo complete deoxygenation and the resulting products undergo isomerization. Under optimum process conditions, the diesel fraction yield is 94%. The resulting fraction can be used as an environmentally safe fuel component.

Oxide systems prepared by thermal decomposition of mixtures of ammonium heptamolybdate with varying amounts of aluminum, gallium, and yttrium nitrates have been studied by thermal analysis, X-ray powder diffraction, and scanning electron microscopy. The formation processes, the nature of interaction between the components, and the states of these systems have been determined. It was shown that the nature of oxides in the molybdenum systems have a significant effect on their physicochemical properties.

The development of single-stage synthesis of dimethyl ether (DME) from synthesis gas makes it possible to obtain hydrocarbons directly from DME. The effect of the nature and concentration of components of the vapor–gas mixture that arrives at the stage of DME conversion to liquid hydrocarbons on activity and selectivity of a zinc–palladium zeolite catalyst has been examined. It has been found that and increase in DME concentration to more than 20 vol % in the reaction stream leads to lowering both DME conversion and gasoline selectivity and increasing the yield of byproducts. The presence of components such as H₂, CO, H₂O in the vapor–gas mixture ensures high stability of the catalytic system. Switching from the flow-through to the recycle operation mode increases the catalyst selectivity for gasoline, decreases the formation of durene, and reduces catalyst coking.

A method has been proposed for decomposition of heavy hydrocarbons into light fractions in arc plasma with rotating electrodes immersed in the hydrocarbon feedstock. Chromatographic analysis of the product gases has been performed, and the carbonaceous deposits formed on the electrodes during the experiment have been studied using electron microscopy and infrared spectroscopy.

The structural-group composition and properties of the base oil samples obtained by solvent extraction technology and with the use of hydrofinishing of the solvent refined product have been studied. Sample 1 has been obtained via solvent refining and subsequent dewaxing, and samples 2 and 3 have been obtained according to a scheme comprising solvent refining and raffinate hydrofinishing over a NiMoW/ZnO-Al₂O₃ catalyst followed by dewaxing. The hydrotreating of the raffinate in the presence of the modified NiMoW/ZnO-Al₂O₃ catalyst can be conducted under mild conditions at 5.0 MPa.

The process of co-hydrofining of pyrolysis products and Fischer–Tropsch synthetic crude with petroleum diesel distillate at a pressure of 5–8 MPa and 330–370°C in the presence of a conventional CoMo–Al₂O₃ hydrotreating catalyst has been studied, and the trends in the behavior of the physicochemical characteristics of the resulting products have been revealed. The feasibility of manufacturing class K5 diesel fuel containing the alternative components in amounts of 20 and 30 vol % by involving the pyrolysis products and synthetic crude, respectively, in the process has been demonstrated.