Catalytic gas-phase oxidation of acrolein to acrylic acid

摘要

A process for the catalytic gas-phase oxidation of acrolein to acrylic acid in a fixed-bed reactor with contacting tubes, at elevated temperature on catalytically active oxides with a conversion of acrolein for a single pass of >/=95%, wherein the reaction temperature in the flow direction along the contacting tubes in a first reaction zone before the starting reaction gases containing the reactants enter the contacting tubes is from 260 DEG to 300 DEG C. until an acrolein conversion of from 20 to 40% is reached, and the reaction temperature is subsequently reduced by a total of from 5 DEG to 40 DEG C., abruptly or successively in steps or continuously along the contacting tubes until a methacrolein conversion of >/=95% has been reached, with the proviso that the reaction temperature in this secondary reaction zone is not lower than 240 DEG C.