| abstract |
ABSTRACT OF THE DISCLOSURE The gaseous oxidation of methacrolein to methacrylic acid is not at present used on an industrial scale as the known catalysts have a low activity and a short life. The present invention seeks to overcome this drawback by providing a catalyst having a heteropoly-acid structure and the general formula: MoaVbPcAldYeOf, wherein Mo, V, P, Al and O represent respectively molybdenum, vanadium, phosphorus, aluminum and oxygen, Y represents one or more elements selected from the group consisting of copper, tin, cobalt, iron, zirconium, thorium, lead and cerium and a, b, c, d, e and f represent the atomic ratio of the elements where, a is 10 b is a number of 3 or less than 3 excluding 0, c is a number between 0.5 to 10 d is a number of 3 or less than 3 excluding 0, 4 is a number of from 0 to 3 and f is a number determined depending on the valency and atomic ratio of other elements. |