XANES investigation of the enhanced chemical stability of Pd in supported Pd–Mo catalysts

The XANES (X-ray absorption near edge structure) technique was used to study Pd and Mo catalysts deposited on supported Al2O3/SiO2 and Al2O3/Si-MCM-41 in the form of monometallic and bimetallic systems. The results indicate that Pd has stronger chemical stability when in the presence of Mo and is always in the metallic form, which is surprising, because the samples were not subjected to reducing conditions prior to the measurements. The increased stability was attributed to the formation of a core-shell structure with a Pd rich core and a Mo rich surface.

Research highlights
► Enhanced chemical stability of Pd in Pd-Mo supported catalysts.
► High activity of PdMo catalysts for the NOx and NOx + CO decomposition reactions.
► Formation of a core-shell structure with a Pd rich core and a Mo rich shell.