Pt catalysts supported on ion exchange resins for selective glycerol oxidation. Effect of Au incorporation

Abstract

In this paper, bimetallic Pt-Au catalysts were studied for the selective liquid phase oxidation of glycerol. The support used was a macroporous weak anion exchange resin. Two different preparation methods were employed: simultaneous exchange of both metals, and a sequential exchange using the controlled surface reaction technique. PtAu catalysts with a total metal content of 0.4 wt% were prepared, with different Pt:Au molar ratios: 1:1; 2:1 and 1:2. The monometallic Au catalyst resulted inactive for the reaction. Nevertheless, it was found that the addition of Au improved the monometallic Pt catalyst activity. XPS results suggest the formation of a Pt-Au alloy, which could be related with conversion improvement. Not only the presence of Pt-Au alloyed particles, but also the Pt/Au ratio on the catalyst surface influences the activity. When the Au particles reduced on top of Pt (controlled surface reaction method), the Pt amount exposed at the catalyst surface was considerably reduced. For this reason, this Pt-Au sample did not show a significant improvement of conversion with respect to the monometallic platinum.