Preparation and characterization of silica- and magnesia-supported poly(3-aminopropylsiloxane)-platinum complexes and their catalytic activity in the oxidation of cyclohexanol and cyclopentanol with molecular oxygen

Abstract

We have prepared silica- and magnesia-supported poly(3-aminopropylsiloxane)-platinum complexes (abbreviated as SiO 2 -PAPSPt and MgO-PAPSPt, respectively) in which mixed valent platinum is coordinated by amino groups and aggregated to a certain extent. MgO-PAPSPt contains low-valent, very small and almost homogeneously dispersed platinum aggregates (diameter ca. 20 A) and is highly active, stable and recyclable in the oxidation of cyclohexanol and cyclopentanol under atmospheric pressure of oxygen. In contrast, large platinum aggregates (ca. 30-100 A, 60 A on an average) are found in SiO 2 -PAPSPt, and almost no zero-valent platinum is present. We assume this is the reason for its very low activity in oxidations under the same conditions