Experimental laws in heterogeneous catalysis

The kinetic experimental laws of heterogeneous catalysis express the reaction rate as a function of three main parameters the concentrations or partial pressure of reactants and products temperature and surface area of the catalyst. 

There are several types of laws ranging, from simple laws such as rate per unit area that admit a single order with respect to reactants, to negative orders compared to the reaction prodncts, such as the following (for a reaction with two gas reactants, A and B, for example)  

The amounts shown in the denominator may involve all the gases involved in the reaction (reactants, products and inert gases may be present) or only some of them 

The reaction rate often seems to obey Arrhenins law, althongh this property is sometimes controversial. Sometimes the rate is not influenced by temperature. 

In general, the absolute rates are proportional to the area of the catalyst. This is obviously trae of the area including the pore walls and not the outer area of the solid. 

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