The mechanism of selective NOx reduction by hydrocarbons in excess oxygen on oxide catalysts: VII. The nature of synergism on a mechanical mixture of catalystsстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Based on a mechanistic study of the selective reduction of NOx by propane on NTK-10-1 and Ni-Cr oxide (NCO) catalysts, the reason for synergism in this process on a mechanical mixture of the catalysts was determined. On the NCO catalyst at temperatures higher than 250 degrees C without NOx activation, C3H8 was oxidized with the formation of a considerable amount of hydrogen. This hydrogen migrated to the surface of NTK-10-1 through a gas phase and reduced this surface. On the reduced surface, H-2 reacted with NOx by a mechanism characteristic of supported platinum group metals. In accordance with this mechanism, nitrogen atoms, which were formed by the dissociation of NO on metal atoms reduced by hydrogen, recombined to form nitrogen molecules in a gas phase, whereas oxygen atoms reacted with the hydrocarbon to form CO2 and H2O molecules in a gas phase. The positive effect of H-2, which was formed on the NCO surface, on the reduction of NOx on NTK-10-1 is the main reason for synergism. An analysis of the experimental data demonstrated that an effectively working mechanical mixture of catalysts can be obtained if one of the mixture components is responsible for the effective activation of nitrogen oxides and the other is responsible for the activation of hydrocarbons.