Method of preparing methacrolein and/or methacrylic acid

A method of preparing methacrolein and/or methacrylic acid by catalyst gas phase oxidation of isobutane which comprises contacting the isobutane with a catalyst containing divanadyl pyrophosphate and represented by the general formula (2)

• P.sub.a V.sub.b X.sub.c O.sub.x ( 21)
• wherein P, V, and O represent phosphorus, vanadium and oxygen, respectively;
• X represents at least one element selected from the group consisting of cobalt and nickel;
• a, b, c and x represent atomic ratios, respectively, provided that when a is 1, b is 0.2 to 2, c is 0.01 to 5, and x represents number of oxygen atoms necessary for satisfying atomic valences of respective component elements.

A method of preparing methacrolein and/or methacrylic acid by catalyst gas phase oxidation of isobutane which comprises contacting the isobutane with a catalyst containing divanadyl pyrophosphate and represented by the general formula (1)

• P.sub.a V.sub.b X.sub.c Y.sub.d Z.sub.e O.sub.x ( 1)
• wherein P, V, and O represent phosphorus, vanadium and oxygen, respectively;
• X represents at least one element selected from the group consisting of cobalt and nickel;
• Y represents at least one element selected from the group consisting of niobium, tantalum, manganese, iron, copper, zinc, lanthanum, neodymium, samarium, cerium, zirconium, chromium, magnesium, tungsten, tin, hafnium, uranium, indium, cadmium, molybdenum, antimony, bismuth, rhodium, silver and sulfur;
• Z represents at least one element selected from the group consisting of potassium, rubidium, cesium and thallium;
• a, b, c, d, e, and x represent atomic ratios, respectively, provided that when a is 1, b is 0.2 to 2, c is 0.01 to 5, d is 0.01 to 5, and e is 0 to 2, and x represents number of oxygen atoms necessary for satisfying atomic valences of respective component elements.