Structure and reactivity of titania-supported oxides: V. Influence of phosphorus and potassium impurities on the properties of molybdenum oxide supported on titania

✍ Scribed by Geoffrey C. Bond; Saad F. Tahir

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 483 KB
• Volume: 105
• Category: Article
• ISSN: 0926-860X
• DOI: 10.1016/0926-860x(93)80253-m

✦ Synopsis

MoOa has been deposited to TiOl (anatase) from which P and K impurities have been largely removed by washing. The Moo9 was introduced by impregnation using aqueous oxalic acid solutions of (NH1)aMo70U-4H10. The results are compared with those previously obtained using ths same support without washing. Temperature-programmed reduction (TPR) profiles at low MoOa contents suggest that the impurities inhibit the formation of reducible tetrahedral Moe+ species in the monolayer phase, perhaps by creating species such as KsMoO, and a mixed PO,-MOO, phase. These may bs responsible for peaks seen in the Raman spectra at 972 and982 cm-' only when the impurities are present. Variation of the Mo/Ti signal intensity ratio in X-ray photoelectron spe&mscopy (XPS) as a function of Moos content is consistent with a structure in which, above the monolayer point, lo-2096 of the surface is covered by MoOa "towers".