Action of Salt Formation on the Bifunctional Nature of 12- Molybdophosphoric Acid and Their Relationship to the Catalytic Activity

Acidic properties and the catalytic activity of 12-molybdophosphates (M"nn+H3-,PM012040; M = Cu2+, BP+, Cr3+ and X = 1-3) have been studied. The results are discussed as the effect of these catalyst components on the partial charge on oxygen atom which is in a relation with the acidity. It is shown that the oxygen-hydrogen bond is weakened as the value of partial charge on oxygen (-bo) becomes more negative, while the vapor-phase dehydration activity of 2 propanol is explained on the basis of the reacting zone wideness taking into account the pseudo liquid phase nature of the heteropoly compounds. Correlation, the percentage conversion of 2-propanol with the fractional charge on molybdenum atom was successful to interpret the effect of the redox properties of these catalysts on their catalytic activity

Physical Adsorption Studies on Mixed Vanadium Oxide Catalysts

Physisorption of N 2 gas at 77 K has been used to measure the surface area (S BET ) and porosity of V 2 O 5 pure and mixtures with Fe, Co or Ni ions in atomic ratios extending from 1 to 50 at %. Calcination of samples was carried out between 473 and 873 K in flowing air. Adsorption isotherms are of type IV in the Braunauer classification with hysteresis loops of mixed A and B types, which reveal a very small external surface. Calculation of the pore volume distribution was carried out in addition to V a -t plots in order to study the surface porosity nature which was found to be mesoporous. Finally, the effect of foreign ions on S BET was discussed