Structure and properties of Pt-Re/TiO_2 catalyst for low-temperature water gas shift reaction

摘要

Recently, we found that the Pt-Re catalysts, especially the Pt-Re/TiO_2 (rut.) catalyst, have superior catalytic activities for water gas shift reaction at low temperature. In this study, the support effects of ZrO_2, TiO_2 (rut.), and TiO_2 (ann.) and the additive effects of Re to Pt/ZrO_2 and Pt/TiO_2 (rut.) catalysts were mainly studied by DRIFT and TPD measurements, which adsorbates are CO, HCOOH, and CO_2. As the results, the following facts became clear. First, TiO_2 (rut.) has the function that weakens the Pt-CO bonding by the interaction between metal and support, and accelerates of oxidation of formate species (reaction intermediate) and desorption of CO_2 (reaction product). Further, the addition of Re to Pt/ZrO_2 catalyst brings about the weakening of Pt-CO bonding by the electric effect of Re to Pt, neither Re has the role of active site for CO species directly. Finally, the Re addition to Pt/TiO_2 (rut.) enhances the Pt dispersion in addition to the weakening of Pt-CO bonding.