V. A. Bolotov

Initiation of underground fire sources

Porous structure parameters of different rank Kuzbass coal and gas- and mass-exchange processes under coal heating are analyzed. The main part of volatile matter is dissolved in the volume of coal beds. For all coal specimens, it is typical that mass fraction of methane and ethane decreases with temperature while mass fraction of hydrogen, carbonic oxide and ethane increases. The latter gases can be the sources of violent burning of coal beds. UHF pyrolysis of bituminous coal reveals physical balance and composition of gaseous products. The results permit coal rating based on carbonization, enable recommending the use of inert gases in underground fire fighting and allow estimating temperature level in fire source zones in coal beds based on chemical composition of emitted gases.

New approach to the novel synthesis of boehmite (γ-AlOOH) by microwave irradiation of gibbsite: Kinetics of solid-phase reactions and dielectric properties of the reactants

Microwave irradiation of gibbsite is suggested as a method of obtaining crystalline boehmite. The kinetics of solid-state transformations of gibbsite under microwave radiation has been investigated, and the dielectric properties of the initial and microwave-activated gibbsite samples have been determined. Extending the gibbsite irradiation time leads to an increase in tanδ. This indicates that microwave-activated gibbsite has a stronger capacity for dissipating microwave energy owing to the formation of an amorphous component containing a variable amount of weakly bound molecular water. The general chemical formula of the amorphous component can be represented as Al2O3 · xH2O (0.5 < x < 3.0). The results of this study can provide a basis for developing new, low-waste, resource- and energy-saving methods for the synthesis of crystalline boehmite and for converting it into γ-Al2O3 with acid-base and textural properties that are atypical of the known low-temperature modifications of Al3+ oxides.

Ceramic matrix composites prepared from CoAl powders

Multiscale structure of two CoxAlyOz cermets was examined by a combination of XRD, SEM coupled with EDX, NMR (59Co; 27Al), and textural measurements. A strong CoAlO/CoAl cermet monolith prepared by mechanical alloying of Co and Al powders followed by hydrothermal treatment and calcination in air comprised two parts: the metal core consisting of Co and a Co–Al alloy, and the outer oxide matrix including a mixture of CoxAl3–xO4 spinel and cobalt oxides. The two parts were separated by the alumina interface protecting the metal core against the oxidation. Al2O3/CoAlO/CoAl cermet prepared by mixing the Co–Al mechanically alloyed product and pure aluminum hydroxide with subsequent hydrothermal treatment and calcination in air consisted of three main parts: (i) large cobalt-free porous alumina (ii) surrounded by CoxAl3–xO4 spinel oxides, and (iii) the inner core containing pure Co metal particles covered with the Co–Al alloy. A random distribution of metal particles in the oxide matrix provided an enhanced microwave absorption. A developed porosity ensured a high activity of the catalyst prepared from the porous cermet in the hexane dehydrogenation under microwave heating.

Characteristics of a chemical reactor that is a loaded microwave resonator

Relationships for calculation of the following parameters of reactors with microwave heating of chemical reagents are presented: the coefficient of absorbed microwave energy distribution in the reactor (in the cavity between the resonator walls and reagents) and the efficiency of transformation of microwave energy into heat of the reagents. The range of variation of microwave properties of the reactor during variation of reagent properties is estimated, and the coupling parameters of the resonator with the external line that provide for a high efficiency are determined.

SHF stand for performing high-temperature chemical processes

SHF stand for performing high-temperature chemical processes is designed. SHF stand includes high-Q cavity excited on H102 mode and the magnetron SHF generator of the level of SHF power of 1 kW, the operating frequency of 2470±100 MHz. The power of energy release up to 100 W/cm3, the rate of heating is more than 1000°C/sec. The study of selective catalytic pyrolysis of high-molecular hydrocarbons is performed. The formation of carbon nanostructure from alkanes has studied.

Heating efficiency of chemical reagents in the microwave cavity

Relationships for technical calculation of the parameters of reactors with microwave heating of chemical reagents are presented. The range of variation of microwave properties of the reactor during variation of reagent properties is estimated, and the coupling parameters of the resonator with the external line providing high efficiency are determined. The experimental data of the absorption degree of microwave energy by different chemical objects in the high-Q resonator are obtained.