New challenges are emerging for improving desulfurization technologies due to the introduction of heavy oil feedstock into fuel energy. In this work, catalysts based on Fe, Co, Mn and Bi molybdates are tested in the process of aerobic oxidation of sulfur-containing compounds of the thiophene series in an alkane medium. The catalysts are characterized by a set of physicochemical methods: XRD, FTIR, TGA, low-temperature nitrogen adsorption-desorption, SEM, TEM, NH3-TPD, H2-TPR, XPS. A comparative assessment of the catalytic activity of the obtained molybdates in the oxidation reaction of a model mixture of dibenzothiophene (DBT) in dodecane with air is carried out. It is shown that iron molybdate has the highest activity, in which an important role is played by excess molybdenum in the form of trioxide MoO3. In the presence of a biphasic catalyst, 100 % conversion of DBT is achieved in 15 min at 170 degrees C. The specific activity is 172 mmol*g-1*h-1 (170 degrees C, 10 min). A possible reaction mechanism based on the activation of O2 and the generation of active species in the presence of the Fe3+/Fe2+ redox couple, and the oxidation of the sulfur substrate at molybdenum sites has been proposed. The high efficiency of the catalyst is confirmed by the results of aerobic oxidative desulfurization of non-hydrotreated vacuum gas oil with a high sulfur content (18 000 ppm), achieving more than 85 % desulfurization degree.
This work investigates the factors affecting the electrical conductivity (EC) of aviation kerosene during transportation, both with and without the addition of antistatic additives, namely: changes in temperature and fuel viscosity, fuel filtration, contact with water of varying pH and aqueous salt solutions, presence of dissolved water, contamination by other petroleum products, fuel oxidation, as well as contact with corroded surfaces. The isolated factor of fuel viscosity influences its electrical conductivity. A linear dependence of the fuel's electrical conductivity on the reciprocal of its viscosity has been demonstrated. Filtration does not affect fuel without additives; however, it causes a decrease in EC of fuels containing additives due to adsorption of active additive components on the filter elements. Contact with acidic water leads to a multiple decrease in EC in fuel with additives and a multiple increase in fuel without additives. The presence of metal salts in dissolved water contributes to an increase in EC when additives are present. Contamination with heavy petroleum products promotes an increase in EC due to a higher content of polar compounds. It has been established that rust intensively adsorbs additive components, reducing the fuel's electrical conductivity; however, their desorption is observed upon heating. Fuel oxidation results in a temporary increase in EC followed by stabilization.
A series of dinuclear alkali metal 2,6-dibenzhydryl-4-methylphenolates [Ar*OM(THF)] 2 (Ar* = 2,6-(Ph 2 CH) 2 -4-MeC 6 H 2 -; M1, M = Li, Na, K) were isolated from the reaction of metal bis(trimethylsilyl)amides with Ar*OH phenol in the THF medium.
A composite polymer electrolyte system based on a polyvinylidene fluoride/polysulfone (PVDF/PSF) mixture with perchlorate lithium salt (LiClO4) and dispersed titanium dioxide nanoparticles in different concentrations was studied. Structural studies were performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Electrochemical analysis of the composite films showed that the ionic conductivity increased with the content of titanium dioxide particles, reached a peak at about 10-15 wt. %. After this point, conductivity began to decrease. The effect of increased ion conductivity on temperature was also investigated. A maximum ionic conductivity of 1.5 x 10-5 Sm/cm was achieved at a 10 wt. % concentration of nanoparticles in the composite polymer electrolyte at room temperature. However, preheating the film up to 80°C increased the value of ionic conductivity by three times (when comparing systems with and without nanoparticles) at the same temperature. The LFP//PVDF/PSF/TiO2//Li cells exhibited excellent rate capability – 149 mAh/g at C/5 rate.
This paper is devoted to a systematic study of composite materials based on industrial and recycled polypropylene (PP) with controlled operational, technological, and environmental characteristics. The results of experimental studies aimed at forming functional structures of various natures in the PP matrix are summarized: cellulose fibers, microcrystalline cellulose, nanodispersed silica, intumescent flame retardants, and antioxidant stabilizers. Approaches have been implemented to reduce PP crystallinity and shrinkage through in situ sol-gel synthesis of SiO2 in the melt, increase mechanical rigidity and biodegradability through cellulose reinforcement, impart fire resistance through the use of expandable graphite and IFR systems, and stabilize regenerated PP with vitamin E. It has been shown that a combination of these methods enables the production of composites tailored to the needs of additive manufacturing (FDM printing), injection molding, structural and thermal insulation products for construction applications, and the recycling of polymer waste.
