Influence of the support surface chemistry on the catalytic performances of PdO/BN catalysts
Résumé
Two high surface areas BN powders have been prepared to be used as supports for palladium catalysts in propylene oxidation. Two different precursors originating from borazines were used for BN preparation. The BN prepared from trichloroborazine (TCB) had a surface area of 184 m(2) g(-1) and micrometric spherical (ball-shaped) texture. When polytrimethylaminoborazine was used as a precursor, the support obtained (BN1-xOx) presented an oxi-nitride structure with a surface area of 115 m(2) g(-1) and a glassy aspect. Palladium oxide catalysts were prepared by impregnation of these two supports. Characterization techniques, such as BET, XRD, TEM, XPS, TG, and electrical properties measurements, have been used to study the influence of the surface chemistry of the support on the catalytic performances of the prepared catalysts. The acidic and redox properties of the resulting samples were characterized by TPR and adsorption microcalorimetry. The presence of oxygen in the structure of BN1-xOx support induced different behaviors when compared with pure BN and played an important role in the catalytic activity of PdO/BN1-xOx sample.