In heterogeneous catalysis, the reaction occurs at the interface between the catalyst and the reactants, which are typically in different phases e.g., solid catalyst and gaseous or liquid reactants . The surface area of the catalyst plays a crucial role in determining the rate of the reaction. An increase in the surface area of the catalyst leads to an increase in the number of active sites available for the reactants to interact with. This results in a higher probability of reactant molecules coming into contact with the catalyst's active sites, leading to more frequent formation of intermediate species and, ultimately, products. Consequently, the rate of the reaction increases.There are several ways to increase the surface area of a catalyst, such as:1. Using a porous catalyst material: Porous materials have a higher surface area due to the presence of pores or channels within the material, which provide additional active sites for the reactants to interact with.2. Reducing the particle size of the catalyst: Smaller particles have a higher surface area to volume ratio, which means more active sites are exposed to the reactants, leading to an increased reaction rate.3. Using a catalyst support: A catalyst can be dispersed onto a support material with a high surface area, such as alumina, silica, or activated carbon. This not only increases the surface area of the catalyst but can also enhance its stability and prevent sintering agglomeration of catalyst particles .In summary, the surface area of the catalyst is a critical factor in heterogeneous catalysis, as it directly affects the number of active sites available for the reactants to interact with. A higher surface area generally leads to an increased reaction rate, as more reactant molecules can interact with the catalyst's active sites simultaneously.