| 摘要 |
Heterogeneously catalyzed partial gas phase oxidation of propylene to acrylic acid comprises introducing a reaction gas initial mixture (1) into a first reaction zone; reducing the temperature of the product gas mixture (1) by direct and/or indirect cooling, and adding a secondary gas to the product gas mixture (1); and subsequently introducing the product gas mixture (1), into a second reaction stage; and subsequently transferring the product gas mixture (2) containing acrylic acid in a first separation zone into the condensed phase and subsequently in a second separation zone. Heterogeneously catalyzed partial gas phase oxidation of propylene to acrylic acid comprises introducing a reaction gas initial mixture (1) containing propylene and molecular oxygen in a molar ratio of >=, 1 and at least an inert dilution gas in a first reaction stage, into a first reaction zone through at least a first catalyst bed at increased temperature, where the catalyst exhibit at least a multi-metal oxide (A) containing molybdenum, iron and bismuth as active mass, such that the propylene conversion during a single passage through the catalyst bed is >= 90 mol.% and the resulting selectivity of the acrolein- and acrylic acid by-product- formation is >= 80 mol.%; reducing the temperature of the product gas mixture (1) from the first reaction stage by direct and/or indirect cooling, and adding a secondary gas in the form of molecular oxygen and/or inert gas to the product gas mixture (1); and subsequently introducing the product gas mixture (1) as a reaction gas initial mixture (2) containing molecular oxygen and acrolein in a molar ratio of >= 0.5 and at least an inert dilution gas, in a second reaction stage at increased temperature by at least a second catalyst bed, whose catalysts exhibits multi-metal oxide (A1) containing at least an molybdenum and vanadium as active mass in such a way that the acrolein conversion during a single passage through the catalyst bed is >= 90 mol % and the selectivity of the acrylic acid formation over both the reaction stages is >= 70 mol %, with respect to converted propylene; subsequently transferring the product gas mixture (2) containing acrylic acid in a first separation zone into the condensed phase and subsequently in a second separation zone, where: the acrylic acid is separated from the condensed phase by application of at least a thermal separation process comprising at least a crystallization separation of the acrylic acid, and the reaction gas initial mixture (1) contains cyclopropane (up to 3 mol.%), with respect to the propylene. |
