| 摘要 |
Partial oxidation of acrolein to acrylic acid comprises conducting a starting reaction gas mixture comprising acrolein, molecular oxygen, and an inert gas(es), containing molecular oxygen and the acrolein in a molar ratio of >=0.5 in one reaction stage over a fixed catalyst bed whose active composition is a multimetal oxide(s) comprising the elements molybdenum and vanadium. Partial oxidation of acrolein to acrylic acid in the gas phase under heterogeneous catalysis comprises conducting a starting reaction gas mixture which comprises acrolein, molecular oxygen and an inert gas(es) containing >=20 vol.% of molecular nitrogen and contains molecular oxygen and the acrolein in a molar ratio of >=0.5 in one reaction stage over a fixed catalyst bed which is arranged in two spatially successive reaction zones A,B, the temperature of reaction zone A being 230-320[deg]C, and the temperature of reaction zone B likewise being 230-320[deg]C, whose active composition is at least one multimetal oxide comprising the elements molybdenum and vanadium, such that reaction zone A extends to an acrolein conversion of 45-85 mol % and, on single pass of the starting reaction gas mixture through the overall fixed catalyst bed, the acrolein conversion is >=90 mol % and the selectivity of acrylic acid formation, based on acrolein converted, is >=90 mol %, the chronological sequence in which the starting reaction gas mixture flows through the reaction zones corresponding to the alphabetic sequence of the reaction zones, where the hourly space velocity of the acrolein contained in the starting reaction gas mixture on over the fixed catalyst bed is =145 L (STP) acrolein/L of fixed catalyst bed-hour and >=70 L (STP) acrolein/L fixed catalyst bed-h, the volume-specific activity of the fixed catalyst bed is either constant or increases at least once in the flow direction of the reaction gas mixture over the fixed catalyst bed, and the difference T(maxA)-T(maxB), determined from the highest temperature T(maxA) which the reaction gas mixture has within the reaction zone A and the highest temperature T(maxB) which the reaction gas mixture has within reaction zone B, is 0[deg]C. |
