Patent ID: 6657080
Filing Date: 2003-12-02
Classification: C07C

Abstract:
A process for producing acrylic acid comprising vapor-phase catalytic oxidation of acrolein-containing gas using a shell-and-tube fixed bed reactor, said process being characterized by dividing each of the reaction tubes into three reaction zones in its axial direction, filling the first reaction zone closest to the gas inlet with a catalyst having a higher activity expressed in acrolein conversion as a mol % than that of the catalyst filling the adjacent, second reaction zone and filling the subsequent reaction zones with catalysts of different activity levels such that the catalyst activity successively rises from the second reaction zone toward the gas outlet sidewherein said catalysts are formed of oxides or complex oxides expressed by the following general formula (1) MoaVbWcCudAeBfCgDhOiâ€ƒâ€ƒ(1) wherein Mo is molybdenum; V is vanadium; W is tungsten; Cu is copper; A is selected from the group consisting of zirconium, titanium and cerium; B is selected from the group consisting of magnesium, calcium, strontium and barium; C is selected from the group consisting of niobium, antimony, tin, tellurium, phosphorus, cobalt, nickel, chromium, manganese, zinc and bismuth; D is selected from alkali metals; and O is oxygen; and where a is 12, b, c, d, e, f, g and h are respectively, 1&lE;b&lE;14, 0