Manufacture of acrylic acid by oxidation of propylene with oxygen-containing gases in two separate catalyst stages

US4031135A · kind A · utility

Assignee

• BASF SE

Inventors

• Heinz Engelbach
• Richard Krabetz · Tauberbischofsheim, DE
• Gerd Duembgen · Schifferstadt, DE
• Carl-Heinz Willersinn · Ludwigshafen, DE
• Ulrich Lebert · Hettenleidelheim, DE
• Fritz Thiessen · Ludwigshafen, DE

Key dates

• Filing date: Jul 11, 1975
• Grant date: Jun 21, 1977
• Expiry date: Jul 11, 1995

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C51/252
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

In the oxidation of propylene to acrylic acid in the gas phase in two spatially separate oxidation stages, a part of the off-gas, which has been freed from condensable products, is fed to the oxidation stages in addition to freshly charged propylene and air, under the following conditions: A. The recycled off-gas and air are in part fed to the first oxidation stage and in part to the second oxidation stage, B. The molar ratio of propylene : oxygen : residual gases fed to the first stage is 1 : 1.5-2.3 : 11-19, C. The molar ratio of the total propylene fed in, to the total oxygen fed in, in the form of air or off-gas, before and after the first stage, and to the total residual gases fed in is 1 : 1.9-2.5 : 13-25, with the proviso that D. The air and the recycled off-gas are divided between the two feed points in such a way that from 10 to 50% by volume of the total quantity of air and off-gas fed in are added after the first stage and E. The air and off-gas are admixed to the reaction gas mixture after the first stage, immediately after it leaves the catalyst zone, so that the mixture is rapidly cooled to a temperature of from 150.degree. to 320.degree. C.