Microcalorimetric studies of the structure of supported bimetallic catalyst particles

Microcalorimetric studies of oxygen and hydrogen chemisorption during the last decade improved the understanding of the structure and structural dynamics of supported bimetallic catalyst particles. For example, it was found that on graphitic supports two different reduced surface compositions/structures can be created for base metal/noble metal particles. Appropriate treatments switch the surface from almost pure reduced base metal to true alloy. Calorimetric studies also indicate support interactions play a major role in controlling bimetallic particle surface structure. In contrast to behaviour found on graphitic supports, iron/noble metal particles supported on refractory oxides apparently do not form alloy surfaces. The reduced surface is dominated by the noble metal. Several studies indicate the value of the models of surface composition/structure developed using microcalorimetry for predicting the activity/selectivity of bimetallic particles.