Effect of TiO 2 on Pd/La 2 O 3 -CeO 2 -Al 2 O 3 Systems during Catalytic Oxidation of Methane in the Presence of H 2 O and SO 2 .

New results on the effect of TiO 2 on Pd/La 2 O 3 -CeO 2 -Al 2 O 3 systems for catalytic oxidation of methane in the presence of H 2 O and SO 2 have been received. Low-temperature N 2 -adsorption, XRD, SEM, HRTEM, XPS, EPR and FTIR techniques were used to characterize the catalyst. The presence of Ce 3+ on the catalytic surface and in the volume near the lantana was revealed by EPR and XPS. After aging, the following changes are observed: (i) agglomeration of the Pd-clusters (from 8 nm to 12 nm); (ii) transformation of part of the TiO 2 from anatase to larger particles of rutile; and (iii)-the increase in PdO/Pd-ratio above its optimum. The modification by Ti of the La 2 O 3 -CeO 2 -Al 2 O 3 system leads to higher resistance towards the presence of SO 2 most likely due to the prevailing formation of unstable surface sulfites instead of thermally stable sulfates. Based on kinetic model calculations, the reaction pathway over the Pd/La 2 O 3 -CeO 2 -TiO 2 -Al 2 O 3 catalyst follows the Mars-van Krevelen mechanism. For evaluation of the possible practical application of the obtained material, a sample of Pd/La 2 O 3 -CeO 2 -TiO 2 -Al 2 O 3 , supported on rolled aluminum-containing stainless steel (Aluchrom VDM ® ), was prepared and tested. Methane oxidation in an industrial-scale monolithic reactor was simulated using a two-dimensional heterogeneous reactor model.