Patent ID: 6998504
Filing Date: 2006-02-14
Classification: B01J,C07C

Abstract:
1. A process for the catalytic gas-phase oxidation of propene to acrylic acid, comprising: passing a reaction gas starting mixture 1 which comprises molecular oxygen and propene in a molar O thereby obtaining a product gas mixture 1; wherein said passing of said reaction gas starting mixture 1 proceeds in such a way that a propene conversion in a single pass is ≧90 mol %, an associated selectivity of an acrolein formation and of an acrylic acid byproduct formation together is ≧90 mol %, passing said product gas mixture 1, as reaction gas starting mixture 2 which comprises molecular oxygen and acrolein in a molar O thereby obtaining a product gas mixture 2, wherein said passing of said reaction gas starting mixture 2 proceeds in such away that an acrolein conversion in a single pass is ≧90 mol %, wherein a) a loading of said first fixed-bed catalyst with the propene contained in reaction gas starting mixture 1 is ≧160 l(S.T.P.) of propene/l of catalyst bed·h, b) said first fixed-bed catalyst comprises a catalyst bed arranged in two spatially successive reaction zones A, B, wherein a temperature of reaction zone A is from 300 to 390° C. and a temperature of reaction zone B is from 305 to 420° C. and at the same time at least 5° C. above the temperature of reaction zone A, c) the reaction gas starting mixture 1 flows first through reaction zone A and then through reaction zone B, d) the reaction zone A extends to a propene conversion of from 40 to 80 mol %, e) a loading of said second fixed-bed catalyst with the acrolein contained in reaction gas starting mixture 2 is ≧140 l(S.T.P.) of acrolein/l of catalyst bed ·h, f) said second fixed-bed catalyst comprises a catalyst bed arranged in two spatially successive reaction zones C,D, wherein a temperature of reaction zone C is from 230 to 270° C. and a temperature of reaction zone D is from 250 to 300° C. and at the same time at least 5° C. above the temperature of reaction zone C, g) the reaction gas starting mixture 2 flows first through reaction zone C and then through reaction zone D, and h) the reaction zone C extends to an acrolein conversion of from 55 to 85 mol %.