Synthesis and Catalytic Properties of Pure and Pd-Modified SrMoO4 Catalysts for VOC Oxidation

SrMoO4 nanoparticles were effectively prepared through direct mechanochemical activation carried out under ambient conditions. In order to improve their catalytic properties, the obtained SrMoO4 was modified with palladium and comprehensively characterized by X-ray diffraction analysis (XRD), N2-physisorption, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Catalytic tests for VOCs were carried out. The XRD patterns showed that the as-synthesized SrMoO4 and Pd/SrMoO4 samples are crystallized in a scheelite-type structure. It was found that the use of SrMoO4 as a catalytic support enables the preparation of a catalytic system with highly dispersed Pd species and strong metal–support interactions. The presence of reduced Mo species on the Pd-modified SrMoO4 catalyst, together with oxygen-deficient surface regions, suggests that the Mo species actively participate in the catalytic process through their redox cycle. The possible coexistence of both Pd2+ and Pd0 species and partially reduced Mo environments further indicates the active involvement of the Pd/SrMoO4 surface in oxygen activation and VOC oxidation, supporting the Mars–van Krevelen mechanism as the most probable reaction route. In addition, the high stability of the material demonstrates the reliability of the Pd-modified SrMoO4 catalyst. Therefore, this material can be considered a promising catalyst in environmental catalysis.