Sonochemical synthesis of Pt, Ru doped TiO2 for methane reforming

Platinum group materials (Pt, Ru, Rh) are highly active materials for reforming. In the present study, bimetallic Pt and Ru substituted TiO2 catalysts were synthesized by sonochemical method. The bimetallic 2% Pt 2% Ru/TiO2 showed high surface area of 66 m(2)/g compared with the other catalysts. The prepared catalysts were characterized by XRD, XPS, TEM, TPR and BET. Dry reforming, partial oxidation and combined reforming (CR) with CO2 were studied on these materials. Synthesized catalysts were found to be highly active for dry reforming reaction. 26% and 95% of methane conversions were obtained with Ru substituted TiO2 (4% Ru/TiO2) at 400 degrees C and at 700 degrees C. The H-2/CO ratio was close to unity with both Pt and Ru substituted catalysts after 650 degrees C. The apparent activation energies found to be 51 and 56 kJ mol(-1) with respect to methane for 4% Ru/TiO2 and 4% Pt/TiO2, respectively. High oxygen storage capacity of 4% Pt/TiO2 further showed the good activity for dry reforming. The bimetallic catalyst 2% Pt 2% Ru/TiO2 sintered under time on stream condition and also resulted in the formation of amorphous carbon on to the surface of catalysts, which made them an inactive catalyst for reforming process. The surface intermediates during these reactions were found by in situ FTIR at different temperatures for reforming processes. The peaks corresponding to CO2 adsorption were not observed in case of 4% Ru/TiO2 and 2% Pt 2% Ru/TiO2 for dry reforming and this indicates the Eley-Rideal mechanism on both catalysts. A kinetic model was developed by considering CH4 dissociation as rate determining step (RDS) and the model was validated to the obtained experimental data. (C) 2015 Elsevier B.V. All rights reserved.