The active site of a heterogeneous catalyst plays a crucial role in determining the reaction rate and selectivity in the process of olefin hydroformylation. Olefin hydroformylation, also known as the oxo process, involves the conversion of an olefin alkene to an aldehyde by reacting with carbon monoxide CO and hydrogen H2 in the presence of a catalyst, typically a transition metal complex.The active site of a heterogeneous catalyst is the specific location on the catalyst surface where the reactant molecules adsorb and interact to form the desired product. The structure, composition, and electronic properties of the active site directly influence the reaction rate and selectivity of the hydroformylation process.1. Reaction rate: The reaction rate depends on the ability of the active site to adsorb the reactants olefin, CO, and H2 and facilitate their interaction. The active site should have a suitable size and geometry to accommodate the reactants and promote their bonding. Additionally, the electronic properties of the active site should facilitate the transfer of electrons between the reactants, leading to the formation of the desired product. A well-designed active site can significantly enhance the reaction rate by lowering the activation energy required for the reaction to proceed.2. Selectivity: The selectivity of the hydroformylation process refers to the preference for forming a specific isomer or product over others. In the case of olefin hydroformylation, the selectivity is often determined by the preference for linear aldehydes over branched aldehydes. The active site's size, shape, and electronic properties can influence the orientation of the olefin and the subsequent insertion of the CO and H2 molecules, thus affecting the selectivity. A highly selective active site will preferentially stabilize the desired transition state and product, leading to a higher yield of the desired isomer.In summary, the active site of a heterogeneous catalyst plays a critical role in determining the reaction rate and selectivity in the olefin hydroformylation process. By tailoring the active site's structure, composition, and electronic properties, chemists can develop more efficient and selective catalysts for this important industrial process.