Patent ID: 7662742

Claim:
A method for producing a catalyst having a composition represented by the following formula (1) for use in producing methacrylic acid through gas-phase catalytic oxidation of methacrolein with molecular oxygen, comprising: (i) preparing a solution or slurry comprising at least molybdenum, phosphorus, and vanadium (liquid I); (ii) preparing a solution or slurry containing ammonium radical (liquid II); (iii) preparing a mixture of the liquid I and the liquid II by: introducing one of the liquid I and the liquid II (liquid PR) into a tank (tank A), subsequently pouring the other of the liquid I and the liquid II (liquid LA) into the tank already containing the liquid PR, the liquid LA is poured into the tank A so that when the liquid LA contacts the liquid PR the contact occurs at a continuous region on a surface of the liquid PR, and the continuous region comprises 0.01 to 10% of an entire surface area of the liquid PR in the tank A; and (iv) drying and calcining the resultant solution or slurry containing a catalyst precursor comprising all the catalyst constituents, P a Mo b V c Cu d X e Y f Z g O h (1) wherein: P, Mo, V, Cu and O represent phosphorous, molybdenum, vanadium, copper and oxygen, respectively; X represents at least one element selected from the group consisting of antimony, bismuth, arsenic, germanium, zirconium, tellurium, silver, selenium, silicon, tungsten and boron; Y represents at least one element selected from the group consisting of iron, zinc, chromium, magnesium, tantalum, cobalt, manganese, barium, gallium, cerium and lanthanum; Z represents at least one element selected from the group consisting of potassium, rubidium and cesium; subscripts a, b, c, d, e, f, g and h represent an atomic ratio of each element, respectively; and when b is 12, a is in the range of from 0.5 to 3, c is in the range of from 0.01 to 3, d is in the range of from 0.01 to 2, e is in the range of from 0 to 3, f is in the range of from 0 to 3, g is in the range of from 0.01 to 3 and h represents the atomic ratio of oxygen necessary for fulfilling the requirement of the valence of each element above.