J. R. Kittrell

Inactivation of immobilized glucose oxidase by hydrogen peroxide

Abstract In the presence of hydrogen peroxide, the stability of immobilized glucose oxidase was found to be inferior in continuous operation to that in storage tests. Analysis confirmed that the reduced form of the enzyme, which is a product of the glucose-oxidation reaction, is much more readily inactivated by hydrogen peroxide than is the oxidized form. It was found that if the hydrogen peroxide could be removed in the microenvironment of the enzyme, this inactivation could be reduced. Descriptions of the hydrogen peroxide concentration in the microenvironment are presented as an aid to understanding and overcoming the problem. The problem has important implications when the continuous use of immobilized glucose oxidase is being considered, particularly in the analytical field.

Nitric Oxide Reduction By Ammonia on Copper Exchanged Hydrogen Mordenite

Abstract The catalytic activity of copper ion-exchanged hydrogen mordenite with various copper loadings for the SCR of NO by NH 3 has been examined in a packed bed flow reactor with actual flue gas. Two orders of magnitude increase in the reaction rate were achieved by the copper ion-exchange in the catalyst. The first order, irreversible kinetic model with respect to NO adequately fits all experimental data over the reaction temperature range covered (250 – 450° C), independent of the copper level and particle size of the catalysts. The optimum content of copper in the CuHM is about 2.3 wt%, which corresponds to exchanging about 30% of the initial hydrogen ions with copper ions.

CONSISTENCY OF KINETIC AND DEACTIVATION MODELS

Abstract Data on the solid-catalyzed conversion of benzyl alcohol to benzaldehyde and hydrogen are analyzed to show that consistent models of the primary reaction and the deactivation reaction provide an adequate description of data from both fresh and deactivating catalyst. Problems often encountered in The use of inconsistent models are discussed and illustrated. The mechanistic consistency of primary and deactivation reactions in parallel deactivation is also discussed regarding the rationale of the definition of activity at the start of deactivation.