Catalysis in Perspective: Historic Review

Catalysis as a scientific discipline originated in the early part of the last century. Earlier, the unique feature of a catalytic substance, namely that when added in small quantities to a reaction it affects its rate and selectivity but is not consumed, had become widely recognized, and many applications had been developed. Only after chemical thermodynamics had been defined did a rational approach to discover new catalytic processes become possible. Thermodynamics would define the proper conditions at which a material should be tested as a catalyst and catalytic turnover would be expected. Ostwald, one of the founding fathers of chemical thermodynamics, introduced thermodynamics into the physical chemical definition of a catalyst, specifying that it is a material that will leave the equilibrium of a reaction unchanged. The past century can be viewed as the age of the molecularization of the sciences. It took nearly a century before the molecular basis of catalytic processes, now widely applied at very large scale, became understood. The Haber–Bosch process of ammonia synthesis was discovered early in the twentieth century once the thermodynamics of this process had become properly understood. The Nobel Prize to Ertl in 2007 recognized his discovery of the molecular principles of this reaction. The three scientific disciplines that are essential to catalysis: chemical engineering, inorganic chemistry, and organic chemistry, which developed in the past fairly independently, now have a common basis (see Figure 1.1). The chemical tradition of the nineteenth century had culminated 100 years earlier in the Nobel Prize for Sabatier for catalytic hydrogenation, useful because coal hadmade the production of hydrogen cheap. Sabatier formulated the principle that the reaction intermediates formed at the surface of a catalytic material should have an intermediate stability. When too stable they would not decompose, when too unstable they would not be formed. This molecular view of the catalytic