Stable and Efficient Pt-Re/TiO2 catalysts for Water-Gas-Shift: On the Effect of Rhenium

The catalytic performance of PtRe/TiO2 catalysts, that is, activity and stability, in single-stage water gas shift reactions was investigated by studying the influence of preparation strategies, Pt/Re molar ratios, and metals contents. Results show that sequential impregnation of Re precursor prior to Pt precursor without intermediate pretreatment is the optimum preparation strategy. The Pt/Re ratio of unity with 0.5wt.% Pt content resulted in the most significant effect on activity and stability. Insitu characterizing of both monometallic and the optimal bimetallic PtRe catalysts by means of CO chemisorption, H2 temperature programmed reduction, and FTIR spectroscopy under the reaction conditions provided evidence that Re increases the activity by enhancing the activation of water. No evidence was found for any direct influence of Re on the properties of Pt in the catalyst under the reaction conditions.