Albert Zh. Kaltaev

High-entropy diborides (TiZrHfTaMo)B2, (TiZrHfMoW)B2 and (TiZrHfTaW)B2 were synthesised for the first time using a three-electrode DC arc reactor in open air. Replacing Mo with W increases crystallite size of the high-entropy phase from 30 to 48 nm, reduces microstrains, but promotes a secondary W2B5 phase. Specific surface area rises from 0.116 to 0.96 m2/g, forming a mesoporous structure. In betulin oxidation, (TiZrHfTaMo)B2 shows conversions of 5.34 % (dark) and 6.45 % under UV(420 nm) with up to 19.6 % selectivity to betulinic acid, while W-containing samples are less active and exhibit no photocatalysis. For the hydrogen evolution reaction, (TiZrHfMoW)B2 delivers the best performance: overpotentials η10 of 642 mV (0.5 M H2SO4) and 510 mV (1 M KOH), and Tafel slopes of 208 and 226 mV/dec. These findings demonstrate that replacing Mo with W tunes the microstructure and properties of high-entropy borides, making (TiZrHfMoW)B2 a promising non-precious electrocatalyst for hydrogen production.

High-moisture coal tar is a challenging fuel for energy utilization due to difficulties in ensuring its stable combustion and its low calorific value. One promising solution is its co-combustion with energy-rich pyrolysis oil derived from waste tires. To the best of our knowledge, the synergistic effect and chemical interactions during the co-combustion of high-moisture coal tar and waste tire pyrolysis oil have not been investigated previously. It has been experimentally established that the addition of high-moisture coal tar to waste tire pyrolysis oil enhances its reactivity, which is reflected in a reduction of ignition delay time. Using comparative experiments with acetic acid and ethanol, it was confirmed that chemical interactions between oxygenated components of the tar and hydrocarbons of the tire-derived pyrolysis oil play a decisive role in enhancing fuel reactivity. It was also found that increasing the mass fraction of tar in the fuel blend reduces CO and NOx emissions.

The possibility of using petroleum coke and the pyrolytic carbon residue from scrap tires as a mixed fuel is considered. The influence of the coke/residue

The influence of metal-rolling production waste and iron nitrate on the characteristics of the process of layer combustion of coal is investigated. As a solid fuel, coal of the T grade was used. Metal scale and iron nitrate were introduced into the fuel by mechanical mixing. According to XRD data, phases of iron oxides Fe3O4 and manganese Mn3O4 were identified in the metal scale. The characteristics of the combustion process of the studied samples were studied using high-speed video with the use of a combustion chamber at a heating medium temperature of 700°C. Combustion Also, the process of activated layer combustion coal was scaled using a solid fuel boiler unit. It has been experimentally established that the use of metal scale and iron nitrate leads to an increase in the reactivity of the fuel, as evidenced by a decrease in the ignition delay time. Due to the intensification of the combustion process, the fuel underburning and the concentration of CO formed in the composition of gas-phase combustion products were reduced.

The influence of metal-rolling production waste and iron nitrate on the characteristics of the process of layer combustion of coal was investigated. Coal o

The pyrolysis processing of waste tires is a promising technology for obtaining products with high marginality. One of the possible methods of solid pyrolysis product utilization is its combustion for energy production, but this is complicated by poor reactivity and sulfur emissions. The combustion of char together with more reactive fuels could solve this problem. The current study is devoted to the combustion characteristics of waste tires pyrolysis carbon residue mixed with biomass: pine sawdust and peat. The oxidation characteristics in thermal analyzer conditions were found to change insignificantly. In contrast, 15 wt% of peat and sawdust additives was found to decrease ignition delay times in realistic conditions of combustion at 800 °C by 42 and 78%, respectively, while the SO₂ emissions also dropped by 73 and 52%, respectively. The extra sulfur was found to be contained in ash residue in the form of CaS and CaSO₄. While increasing peat concentration from 5 to 15 wt% was found to have almost no effect, the same increase for sawdust resulted into an almost proportional decrease in ignition delay times. The results obtained could be used for the integration of waste tires pyrolysis char mixtures with peat or sawdust into the energy sector.