Patent ID: 6563000
Filing Date: 2003-05-13
Classification: C07C

Abstract:
A process for producing acrylic acid by vapor-phase catalytic oxidation of acrolein or an acrolein-containing gas with molecular oxygen or a molecular oxygen-containing gas using a catalyst-filled fixed bed shell-and-tube reactor, which process is characterized by providing plural reaction zones in each of the reaction tubes in said fixed bed shell-and-tube reactor, by dividing inside of each tube in the axial direction thereof and filling the plural reaction zones with plural catalysts of different activity levels in such a manner that the activity level rises from the gas-inlet side of each reaction tube toward the gas-outlet side thereof, wherein the catalysts are oxides or complex oxides having the metallic elementary composition represented by the following general formula (I):â€ƒMoaVbWcCudAeQfRgDhOiâ€ƒâ€ƒ(I)wherein Mo is molybdenum; V is vanadium; W is tungsten; Cu is copper; A is an element selected from the group consisting of zirconium, titanium and cerium; Q is an element selected from the group consisting of magnesium, calcium, strontium and barium; R is an element selected from the group consisting of niobium, antimony, tin, tellurium, phosphorous, cobalt, nickel, chromium, manganese, zinc and bismuth; D is an element selected from alkali metals; and O is oxygen; and a, b, c, d, e, f, g, h and i represent atomic ratios of Mo, V, W, Cu, A, Q, R, D and O, respectively, in which where a is 12, 1&lE;b&lE;14, 0