A catalytic surface, whether it be a clean surface of a finely divided metal or metal oxide, or the active site of an enzyme molecule, must be structured in such a way that it can bind substrate molecules from the reaction that it catalyzes, enable them to react, and release the products afterward.

In the words of Emil Fischer, a turn-of-the-century enzyme chemist, a catalyst and its substrate molecules must fit one another like a lock and key.

Catalysis And The Environment

One aspect of the current pollution problem is that substances that should be degraded spontaneously by the atmosphere or by microorganisms are not, so they remain in the environment to cause trouble. Much of this trouble is our own fault. In the presynthetic era, most raw materials were natural substances taken from the environment. They blended back into the environment when we were through with them. They decayed, decomposed, and rotted, oxidized by the atmosphere and eaten by bacteria that had evolved with these substances as their natural foods.

The problem is not quite so simple. A general oxidation catalyst would be a disaster. In a simpler era of chemistry, an intellectual nonproblem in the tradition of the Philosopher's Stone and the Perpetual Motion Machine was the Universal Solvent. (What would you keep it in?)