Comparison of TiO2 Degussa P25 with anatase and rutile crystalline phases for methane combustion

In this work, the application and comparison of TiO2 supports with different crystalline structures in a Pt/TiO2 catalyst for trace methane combustion are presented. Special attention is given to check the strong-metal-support-interaction (SMSI) in Pt/TiO2 and the synergetic effect between anatase (A-TiO2) and rutile (R-TiO2) in a Pt/P25 catalyst, and their effects on the performance of catalysts. Anatase-rutile mixtures with different compositions using commercial A-TiO2 and R-TiO2 or isolated rutile particles from P25 (sR-TiO2) are used in the Pt/TiO2 catalysts. It is found that (1) SMSI in Pt/A-TiO2 is stronger than that in Pt/(s)R-TiO2, and SMSI in the mixed phases TiO2 supported Pt catalysts is much stronger than its component (or single phase TiO2) supported Pt catalysts; (2) the activity of Pt/sR-TiO2 can be much enhanced when A-TiO2 and sR-TiO2 mixture particles are used as the support, especially at a high reaction temperature (>375 degrees C); and (3) SMSI influences the electronic and catalytic properties of the surface Pt and the density of the chemisorbed oxygen. Finally, the performance of the catalyst and its SMSI is related, and a synergetic model is proposed for the mixed phases TiO2 supported catalysts. The good activity of Pt/P25 can also be explained with this proposed reaction mechanism. (C) 2014 Elsevier B.V. All rights reserved.