Yu. S. Naiborodenko

Methane conversion with carbon dioxide on nickel aluminides

The catalytic activity of several samples based on nickel aluminides in methane conversion with carbon dioxide was studied. Nickel aluminides were prepared by the method of self-propagating high-temperature synthesis. The Ni3Al system containing the nickel metal phase exhibited high activity at temperatures above 1073 K. The systems based on Ni2Al3 and NiAl only containing intermetallic compound phases were inactive.

Fe-Containing Intermetallic Compounds As Catalysts of Methane Conversion with Carbon Dioxide

Systems based on iron and aluminum were studied in methane conversion with carbon dioxide. The systems were prepared by the method of self-propagating high-temperature synthesis. Massive iron did not exhibit noticeable catalytic activity in methane conversion with carbon dioxide. The deactivation of iron-containing intermetallic compounds was shown to occur because of the formation of the FeC and FeO phases, which screened the active centers of the catalyst surface. The suggestion was made that the active center of the dissociative adsorption of methane was the γ-Fe phase, which existed at the working temperature of methane conversion with carbon dioxide.

Combustion of low-gas systems with redox stages

Low-gas thermal compositions based on thermites are widely used for practical purposes [i, 2]. In estimating the suitability of their use, it is necessary to know the basic characteristics: combustion temperatures, the thermal conditions, and the composition of the products formed. It is difficult to determine these parameters experimentally because of the high temperatures and short times of the processes and the aggressive character of the combustion products. At the same time, the presence of high temperatures ensures the possibility of achieving equilibrium conditions, which creates the preconditions for applying equilibrium thermodynamics in the analysis of such systems. The possibility of calculating adiabatic temperatures and the equilibrium composition of the combustion products emerges there.

Formation of compaction products in methane dry reforming on a Ni-containing catalyst

The formation of compaction products and their morphological features in the process of methane dry reforming on a Ni3Al catalyst were studied. It was shown that the initial porous structure of a sample was retained in the course of reaction, and the formation of carbon deposits did not decrease the catalytic activity of Ni3Al over a long period of time.

Combustion of Composite Metal Systems

Characteristic features of combustion of Ni–Al, Co–Al, and Pd–Al composite metal systems forming intermetallic compounds are studied. The effect of the inert‐gas pressure, initial temperature, diameter, and initial porosity of compacts on the rates, maximum temperatures, and phase composition of the combustion products are studied. It is inferred that self‐propagating high‐temperature synthesis of composite powders is more adaptable to manufacture and effective than that of elementary powder mixtures.

Features of self-propagating high-temperature synthesis of spinel pigments

The method of self-propagating high-temperature synthesis (SHS) was used to synthesize spinel ceramic pigments. Producing aluminum-nickel and aluminum-cobalt pigments in a finely dispersed state is a complex stepwise (combined) process involving a reduction stage and simultaneous natural air filtration. In the case of small-diameter samples, a flat combustion front is observed and in large samples, the front is formed of many hot spots. The dependence of combustion rate on porosity is presented. The maximum combustion rate of these systems are recorded for porosity of 50–60%. Powdered SHS pigments were obtained for the first time.

Laser ignition of a heterogeneous nickel-aluminum system

The ignition of a heterogeneous nickel—aluminum system by laser radiation is investigated experimentally. The ignition characteristics are investigated as a function of the incident flux and the diameter, height, and porosity of the samples. It is established that the ignition of nickel—aluminum composites consisting of highly disperse powder is determined by the solid-phase interaction of the initial reagents.

Maximum temperatures achievable in interactions of metals with gases

A complete thermodynamic calculation of adiabatic combustion temperatures of certain metals (Mg, Ba, B, Al, Ti, and Zr) in oxygen was performed on a BESM-6 computer using the technique previously described. Conservation of enthalpy and matter with dissociation equations were used. The thermodynamic characteristics of the materials and equilibrium constants of the reactions at various temperatures were found. Estimates of the maximum interaction temperatures of the metals studied with oxygen using the approximate method show that the highest temperature is achieved in the interaction of zirconium with oxygen. The calculations of maximum temperatures for metal interactions with oxygen performed in this study show that the values are lower than the combustion temperatures of gas-phase reactions and are limited by product dissociation.