The hydrogen-donor abilities of polymers and the activity of catalysts in the process of thermal destruction of the organic mass of primary coal tar (PCT) are studied by non-isothermal kinetics methods. PCT,magnetic microspheres, nickel-deposited chrysotilechrysotile and Fe3O4nanocatalysts were used as initial raw materials. Рolymers such as polyethylene (PE), polystyrene(PS) and polyethylene glycol (PEG) were selected as a hy-drogen donor. The phases Mg3[OH]4{Si2O5} and NiO were determined by X-ray phase analysis (XRD) in the obtained catalyst (nickel-deposited chrysotile), and the presence of highly dispersed nickel oxide particles on the surface and inside the nanotubes was shown by the transmission electron microscope (TEM). Nickel oxide particles of 8–11 nmand 30–37 nmwere evenly distributed on the surface and inside the chrysotile nanotubes. The kinetic parameters of the thermal destruction of a mixture of PCT, catalyst and polymer material were determined on the basis of thermogravimetric analysis using the integral method and the method for determin-ing the thermokinetic parameters by the inflection point on the thermogravimetric curve(TG). The change in the activation energy, rate constant and pre-exponential factor with an increase in the degree of destruction of the organic mass of the PCT is established. It was shown that the nature of polymers and catalysts significantly affects the value of the rate constant and the activation energy. The calculated activation energies of the thermal destruction of a mixture of coal tar with PS and PE in the presence of a catalyst (nickel-deposited chrysotile) by the first method are 47.6 kJ/mol and 40.4 kJ/mol, and by the second method are 47.3 kJ/mol and 86.5kJ/mol respectively.
The catalytic activity of the binary composite catalysts of Fe2O3-CoO/CaA and Fe2O3-CoO/ZSM-5 was studied. They were obtained by impregnation of CaA and ZSM-5 zeolites with aqueous solutions of sulfates of iron (FeSO4·7H2O) and cobalt (CoSO4·7H2O). The total metal content was no more than 5%. Then, oxidizing burning at 720 °C for 60 min was performed to produce the metal oxides. It was found that the obtained Fe-Co/CaA catalyst contains iron and cobalt as CoFe2O4 compound, and the Fe-Co/ZSM-5 catalyst includes CoFe2O4 and CoFe. The phase composition of the obtained catalysts was detected by the X-ray diffraction analysis. The surface morphology was investigated by the electron microscopy. The elemental composition of the obtained catalysts was determined by energy dispersive spectroscopy with mapping and inductively coupled plasma atomic emission spectroscopy. The atomic absorption analysis by the IR-spectroscopy showed the shifts of absorption bands in the infrared spectra of the pure zeolites and with added Fe and Co. The catalytic hydrogenation of anthracene was performed to determine the catalytic properties of the obtained catalysts. It is one of the most common model compounds applied to investigate the efficiency of catalytic systems. The result of hydrogenation found that conversion of anthracene at 400 °C, initial pressure of 6 MPa and duration of 60 min using the Fe-Co/CaA catalytic system equaled to ~87%. However, hydrogenation products equaled to ~84%. Anthracene conversion using the Fe-Co/ZSM-5 catalytic system and the same conditions was ~91%; among them, hydrogenated derivatives were ~71%. The proposed method is characterized by its simple execution. The obtained catalysts are be slightly inferior to platinum and rhodium catalysts in the catalytic activity.
Regularities of influence of nickel nanpowder on the thermal degradation of coal tar distillate were determined using model-free Kissinger, Flynn-Wall-Ozawa and model-fitting Coats-Redfern methods. Coal tar distillate with a boiling point <350 °C was obtained by simple distillation of primary coal tar from the Shubarkol deposit. Nickel nanopowder was used as a catalyst and was added to coal tar distillate in a quantity of 1 % of the mass of the distillate and then the process of thermal degradation of coal tar distillate was conducted at heating rates 5, 10 and 20 °C/min in an inert gas medium. Nickel powder was obtained by high-voltage discharge impact on the dc electrolysis. X-ray diffraction (XRD) analysis showed that the obtained nickel powder has face-centered cubic structure and the average crystallite size calculated by Scherrer equation was ~ 34 nm. Calculations of activation energy were performed via processing of thermogravimetric data. The Kissinger method showed that the activation energy value decreases from 145.19 kJ/mol to 43.65 kJ/mol, by the Flynn-Wall-Ozawa (FWO) method the value decreases from 152.82 kJ/mol to 51.65 kJ/mol, and by the Coats-Redfern method the value decreases from 143.38 kJ/mol to 52.64 kJ/mol. Applicability of these methods are ensured by the high values of correlation coefficients.
Impact of the nanosized iron powder on the process of thermal degradation of coal tar distillate was determined by the thermogravimetric analysis. Coal tar distillate was obtained by simple distillation up to 350°C of primary coal tar from the Shubarkol deposit. Iron powder was obtained by electrochemical reduction of iron from sulfate electrolytes at simultaneous impact of high-voltage electric discharge on cathodic zone. Scanning electron microscopy showed that iron powder consists of nanosized particles (30-124 nm) forming aggregates. X-ray diffraction analysis revealed the presence of α-Fe and FeO(OH) phases. The average crystallite size determination was made using Scherrer equation and amounted to 31.7 nm. Obtained iron powder was added to the coal tar distillate in amount of 1% of distillate weight and this mixture was subjected to thermal degradation at heating rate 5°C/min in an inert atmosphere. Processing of the data obtained was carried out using the model-fitting Coats-Redfern method. The values of activation energy were calculated from the linear approximation constructed as a result of processing thermoanalytical data. It was found that the addition of iron powder in amount of 1% to the coal tar distillate reduces the activation energy from 153.98 kJ/mol to 84.48 kJ/mol.
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