Synthesis and characterization of Pd over novel TiO2 mixtures: Insights on metal-support interactions

BELTRÁN, ANA M.; MORALES MARIA ROXANA; FERNANDEZ, MARIA ASUNCION; RINAUDO MATIAS; CADUS LUIS E.

Berna

Congreso; 1st International Electronic Conference on Catalysis Sciences Section:Catalyst Synthesis and Characterization; 2020

MDPI

Palladium nanoparticles were supported on unusual mixtures of anatase, TiO2 (II) andrutile titania phases by wet impregnation, obtaining catalysts with metal contents of ca. 0.25 wt %labeled Pd/Ti5, Pd/Ti45, and Pd/Ti120. Crystalline structures were confirmed by X-ray diffraction.Pd particle sizes in the range of 4?20 nm were observed by scanning-transmission electronMicroscopy. External surface areas (SBET) in the range 10?17 m2 g−1 were higher enough to achieve agood distribution of palladium over titanium oxide outer surface, as evidenced by energydispersiveX-ray spectroscopy elemental profiles. Pd0/Pdδ+ atomic ratio measured by X-rayphotoelectron spectroscopy showed a decrease from Pd/Ti5 to Pd/Ti120, in line with the decrease inanatase phase present in the catalysts. This behavior suggested that palladium tended to form moreTiPdxO structures in Pd/Ti5 whilst PdOx structures were more likely to be present on supports withgreater amounts of TiO2 (II) and rutile, due to the distinct metal?support interactions. An increasein reducibility and oxygen mobility from Pd/Ti5 to Pd/Ti120 was observed by temperatureprogrammed measurements and associated to the different high-energy ball milled supports.Catalysts with improved properties reported herein could exhibit an excellent performance inoxidation reactions, e.g., glycerol selective oxidation.