Support and Structural Promoter Effects

A structural promoter can also affect the surface structure by introducing bulk defects that anchor surface defects such as steps that have a high activity. This is, for instance, the case in the industrial methanol synthesis catalyst The catalyst is based on Cu nanoparticles, and the steps are found to be the most active for synthesis (Fig. 9.10). 

The support determines the particle size by controlling the degree to which the individual particles aggregate to form larger particles. In that way, the support indirectly affects the activity as discussed earlier. 

The support can also be a direct participant in the reaction. This can happen in three ways  

The support may have a catalytic activity of its own, such that it will transform one or more of the products at the other active phase into a new product. 

FIGURE 9.8 Geometries for a supported nanoparticle for different values of the ratio of y, the interface free energy minus the surface free energy of the support, and y, the surface 

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