Patent ID: 7304179
Filing Date: 2007-12-04
Classification: C07C

Abstract:
1. A method for producing methacrylic acid through gas-phase catalytic oxidation of methacrolein or a methacrolein-containing gas with molecular oxygen or a gas containing molecular oxygen by the use of a fixed-bed multitubular reactor comprising a plurality of reaction tubes each having a catalyst layer therein, wherein the above catalyst layer is divided in the direction of the tube axis of a reaction tube into two or more layers, to thereby provide a plurality of reaction zones, and the catalyst is caused to be present in the catalyst layer in such a way that a reaction load ratio CRc(i) per unit mass of the catalyst in each reaction zone defined by the following equations (1) to (3) becomes 0.8 to 1.0, wherein Rc(i) is the reaction load of an i th layer (° C.·m/kg), Li(j) is a distance (m) from a j th measuring point in a i th catalyst layer to the j+1 th measuring point in the direction of the tube axis, Wc(i) is a packing amount (kg) of the catalyst in the i th layer, Ti(j) is a catalyst-layer temperature (° C.) of the j th measuring point in the i th catalyst layer, TB is a heat transfer medium temperature (° C.), RcMAX is a maximum value of Rc(i), n is the number of the reaction zones, and m is the number of the temperature measuring points in the i th catalyst layer; i is 1 to n; i and j are counted in turn from the inlet side of the reaction gas.