Patent ID: 6989454
Filing Date: 2006-01-24
Classification: C07D

Abstract:
1. A process for preparing maleic anhydride by heterogeneously catalyzed gas-phase oxidation of an n-butene-containing hydrocarbon stream by means of oxygen-containing gases in a shell-and-tube reactor, which comprises conducting the gas-phase oxidation of the n-butene-containing hydrocarbon stream in a shell-and-tube reactor which has two successive reaction zones (a) and (b), (a) being the first, feed-side reaction zone and containing at least one catalyst which is suitable for oxydehydrogenating n-butenes to obtain 1,3-butadiene, and (b) being the second, product-side reaction zone and containing at least one catalyst which is suitable for oxidizing 1,3-butadiene to obtain maleic anhydride, and wherein the shell-and-tube reactor has, in the region of each of the reactions zones (a) and (b), at least one heat transfer medium circuit which is separate and independent from the heat transfer medium circuit of the other reaction zone.