General Potential Energy Surfaces for Catalytic Processes

Here we argue that one may describe, in general terms, how catalysts modify reaction mechanisms by entering and leaving a conversion sequence, using potential energy surfaces that are conceptually correct. Thermochemical and kinetic constraints providing bounds that limit catalytic processes are formulated. 3-D diagrams are proposed. These clearly illustrate the basic principle that catalysts initially associate with the substrates and thus directly participate in modified conversion pathways, but are regenerated in the final step, thereby providing for a turnover number greater than unity.