Aspects of in Situ Controlled Promotion

Having surveyed the dual electrocatalytic/catalytic aspects of electrochemical promotion and established that NEMC A is due to the controlled 

The rate enhancement ratio p is defined as the ratio of the promoted, r, to the unpromoted, Tq, catalytic rate  

Pt/)ff -Al203. They showed that Na coverages of less than 0.1 suffice to completely poison the rate of hydrogenation.  

From a catalytic viewpoint, the promotion index P/ is the most important phenomenological parameter for quantifying the promoting or poisoning effect of a given coadsorbed species i (e.g., O , F, Na , on the rate of a catalytic reaction. It is defined by 

The measurement of P/ and / , is quite straightforward when the promoting species (e.g., Na ) does not react appreciably with any of the reactants or products. In this case, the coverage 0Na of sodium on the metal surface can be easily measured coulometrically via  

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Purely Catalytic Aspects of In Situ Controlled Promotion... 

After surveying the dual electrocatalytic-catalytic aspects of EP in Section 3 and establishing that NEMCA is due to electrochemically controlled introduction of promoters on catalyst surfaces, we concentrate now on the purely catalytic aspects of in situ controlled promotion. 

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