Influence of the co-precipitation pH on the physico-chemical and activity properties of vanadium aluminum oxide catalyst

N. BLANGENOIS; M. FLOREA; R. PRADA SILVY; P. GRANGE; S. P. CHENAKIN; J. M. BASTIN; N. KRUSE; B. P. BARBERO; L. E. CAD¨²S

APPLIED CATALYSIS A-GENERAL

Elsevier

Año: 2004 vol. 263 p. 163 - 170

0926-860X

Vanadium-aluminum oxide catalysts for propane oxidative dehydrogenation (ODH) are investigated with respect to their physico-chemical properties and catalytic activity as a function of the co-precipitation pH. Modifications of the specific surface area, the particle size distribution, and the chemical nature of the active phase are found. At co-precipitation pH 5.5, an amorphous V-Al-Ox mixed phase was formed by condensation of tetrahedral polymeric [VOx]n(n-) and amorphous aluminum hydroxide species. At pH between 7.5 and 8.5, the catalyst consists of [VOx]n(n-) species supported on amorphous aluminum hydroxide. At pH = 10, V2O7(4-) ions are presumably adsorbed on boehmite surface. The propane conversion and the rate of propylene formation per gram-atom of vanadium are higher for the samples prepared at pH =8.5. A correlation exists between the reduction temperature of the vanadium species and the catalytic activity for the propane oxidative dehydrogenation reaction.