Partial oxidation of propylene on V 2O 5P 2O 5-based catalysts

Abstract

The vapor-phase oxidation of propylene was studied over V 2O 5, V 2O 5P 2O 5, and V 2O 5P 2O 5TeO 2 catalysts in the presence of water vapor. On pure V 2O 5, the oxidation products were acetic acid and carbon oxides, plus a small amount of acetone. As the content of phosphorus added to V 2O 5 increases, the oxidation activity markedly decreases; on the other hand, the selectivity to acrylic acid increases and passes through a maximum at P V atomic ratio = 1.15 to 1.6, while that to acetic acid gradually decreases. With the V 2O 5P 2O 5 ( P V = 1.15 ) catalyst, the yield of acrylic acid attains 25 mol%, that of acetic acid is less than 10 mol%, and that of acrolein is less than 0.7 mol%. The effects of the third components added to V 2O 5P 2O 5 ( P V = 1.15 ) were also studied. It was found that TeO 2 is the sole additive which can improve the catalyst performance. As the amount of TeO 2 increases, the specific oxidation activity increases, as do the formation of acrolein and the sum of the yields of acrylic acid and acrolein, while the formation of acetic acid passes through a maximum at Te V = 0.02 to 0.04 . With the V 2O 5P 2O 5TeO 2 (Te/P/V = 0.15/1.15/1) catalyst, the yield of acrylic acid attains 38 mol% when air is used as the oxidant and 42 mol% when oxygen is so used. The effects of reaction variables, such as the oxygen concentration, the propylene concentration, the water vapor, and the temperature, on the activity and selectivity were also studied.