N. I. Il'chenko

Kinetic and mechanistic features of carbon monoxide hydrogenation over supported transition metals

Data on the kinetics and mechanism of carbon monoxide hydrogenation to form alkanes, alkenes, and alcohols over supported transition metals are summarized and correlated. The observed kinetics of the overall carbon monoxide conversion can be interpreted on the basis of a mechanism that includes equilibrium adsorption of CO in the molecular form and equilibrium dissociative adsorption of hydrogen. Detailed mechanistic schemes and the corresponding kinetic models are presented for the reactions of formation of alkanes, alkanes, and alcohols. Catalytic activity and selectivity are examined in relation to the adsorptive and physicochemical properties of the catalysts.

Methane oxidative coupling over SrCoO3-based perovskites in periodic regime

The SrCoO3 and AxSr1−xCoO3 (A = Li, Na, K) perovskites are active and stable catalysts for methane coupling reaction performed in a periodic regime where methane and oxygen alternatively react with a catalyst. The temperature-programmed reduction of the catalysts has been made, and a correlation found between catalytic activity and catalyst oxygen reactivity. Experimental and simulation study of reaction kinetics has been performed, and the probable heterogeneous–homogeneous reaction mechanism has been discussed.

Influence of the composition of Co-containing perovskites on their catalytic properties in the conversion of methane into higher hydrocarbons in non-stationary conditions

The oxidative coupling of methane in a periodic regime was studied using Co-containing perovskites as solid oxidants. Partial substitution of strontium with alkali metals in the perovskite SrCoO3 increased the activity and selectivity of the catalyst with respect to higher hydrocarbons. The substituted catalysts continued to work after many oxidation-reduction cycles.

Methane coupling over SrCoO3-based perovskites in the absence of gas-phase oxygen

Methane coupling reaction over SrCoO 3 -based perovskites has been studied in a periodic regime where a catalyst was alternatively supplied with methane and oxygen. The correlation between catalytic activity and catalyst oxygen reactivity measured with temperature-programmed reduction method has been found. Experimental and simulation study of reaction kinetics has been performed, and the probable heterogeneous-homogeneous reaction mechanism has been discussed *

Catalytic properties of the carbides of transition metals in oxidation reactions

It was shown that the carbides of transition metals are effective catalysts of oxidation reactions on account of their metal-like nature, combined with their high chemical and thermal stability. The results from systematic investigations into the catalytic characteristics of the carbides in the oxidation of hydrogen, carbon monoxide, and ammonia and in the oxidative coupling of methane (OCM) are examined. The first two reactions are total oxidation processes, and the oxidation of ammonia is a selective oxidation process. The oxidative coupling of methane is a heterogeneous-homogeneous process and represents a prospective method for the direct transformation of methane into higher hydrocarbons.

Effect of Alkali Metals on the Strength of Oxygen–Catalyst Bond in Co-Containing Perovskites

Modification of the perovskite SrCoO3 with alkali metal atoms has a considerable influence on the strength of the oxygen–catalyst bond and causes an increase in the weakly bonded oxygen in the modified samples. An approximate correlation has been established between the reactivity of the oxygen in the perovskite and its catalytic activity in the non-stationary condensation of methane to higher hydrocarbons.

Kinetics of nonstationary condensation of methane on a perovskite catalyst

The interaction of methane with the oxidized surface of the KNaSrCoO3−x is first order in methane with respect to formation of higher hydrocarbons and zero order with respect to formation of CO2. At the initial stage the rate of formation of the reaction products is independent of the amount of oxygen from the catalyst consumed (up to 5–7 monolayers of oxygen), after which the rate of the reaction falls linearly. The overall amount of oxygen consumed in the reaction reaches 30 monolayers.

Modeling of the kinetics of the heterogeneous-homogeneous conversion of methane into ethane and ethylene in the absence of oxygen in the gas phase

Computer calculations were carried out on the kinetics of the gas phase chain process for the conversion of methyl radicals into higher hydrocarbons in an oxygen-free atmosphere based on a scheme of reactions consisting of 23 homogeneous elementary steps and the heterogeneous stage of methyl radical formation. The results of the calculations are in good agreement with experimental kinetic results obtained for the interaction of methane with the oxidized surface of the perovskite catalyst KNaSrCoO3.

Kinetic peculiarities of the heterogeneous-homogeneous conversion of ethylene to butadiene

The influence of the surface of the quartz packing and degree of crystallinity of aluminosilicate crystals on the total conversion of C2H4 and selectivity in the conversion of ethylene to butadiene have been established. It was shown that the data agree with the hypotheses of a heterogeneous-homogeneous mechanism of the process.

Conversion of ethylene to butadiene and higher hydrocarbons in the absence of a catalyst

The conversion of ethylene to butadiene and higher hydrocarbons in the absence of a catalyst in the temperature range 973–1023 K, an ethylene partial pressure of 2–15 kPa and a flow rate of 30–150 cm3/min. The effect of the reactor free space on the overall conversion of ethylene and its selectivity has been studied. The probable steps in the formation of the principal products is discussed.