Hydrocarbon Reactions on Alloys

Classification of the Reactions on Metals and General Description of Alloying Effects 

One of the most studied alloys is undoubtedly the Ni-Cu system. When the studies started, many problems remained open with regard to the phase and surface composition of these alloys and their electronic structure. Today, it seems that these problems have basically been solved admittedly not in all details, but to a sufficient extent to allow discussion of the results. 

At temperatures 450-S00 K, Ni-Cu alloys form only one phase. Since 

With this in mind, we must conclude that when changes in activity and selectivity occur with alloying, they should be primarily ascribed to the changes in surface concentration of Ni. This statement holds true most probably for other Group VIII-IB metal alloys as well. 

Presently, data on about 40 reactions are known for Ni-Cu alloys. If the activity (defined as the relative rate with regard to Ni, measured at standard reaction conditions for both metals and all alloys) is plotted as a function of the Cu bulk concentration, all available data for various reactions are split into two groups, characterized as follows (245) (see Fig. 13)  

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