A case of negative catalysis in a homogeneous system

Abstract

The purpose of a series of studies (2) made recently has been to elucidate the mechanism of the so-called promoter action on reactions taking place in homogeneous systems. The reactions chosen for this purpose were the catalytic decompositions of hydrogen peroxide as effected by various salts. Hydrogen peroxide was selected because its decomposition products, oxygen and water, have no effect upon the reaction, and because the mechanism of some of its catalytic decompositions are well enough known to admit of the study of the anomalous effects observed when two or more catalysts are present at once. Sometimes the effect of mixed catalysts is the sum of their separate effects, as when hydrogen peroxide is decomposed by sols of platinum and gold.(3) However, in many cases, the total effect is much greater than the sum of the individual effects; one of the catalysts being then said to exert a promoter action. In other cases, the resultant effect is less than the sum of the individual effects, and one of the substances is then said to produce negative catalysis.