The mechanism of heterogeneous Catalysis

Heterogeneous catalysts began to be important technically about 1900. By 1962, as A. G. Oblad has shown, the wholesale value of products which depended upon heterogeneous catalytic processes was about 15% of the S130 billion total of all manufactured goods. Such products include that resulting from the hydrogenation of a few kilograms of an expensive drug intermediate, as well as products made in large quantities, such as ammonia (8.6 million tons in the U.S. in 1965), sulfuric acid (24.8 million tons), hydrogenated edible oils (1.5 million tons), and the products of the catalytic cracking of millions of barrels of crude oil per day. Catalysis resembles the steam engine in that its technology preceded understanding. Reasonably detailed and coherent theories of the mechanism by which solid catalysts augment the rates of reaction in liquid or gaseous phases are of recent origin. This article discusses just one aspect, the chemical mechanism of heterogeneous catalysis as exemplified primarily ...