Preparation of phthalic anhydride by gas phase oxidation of O-xylene in a main reactor and postreactor

US8106220B2 · kind B2 · utility

Assignee

• BASF SE

Inventors

• Thomas Mackewitz · Mannheim, DE
• Frank Rosowski · Mannheim, DE
• Andreas Tenten · Maikammer, DE

Key dates

• Filing date: May 18, 2007
• Grant date: Jan 31, 2012
• Expiry date: Dec 15, 2027

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C51/265
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process is described for preparing phthalic anhydride by catalytic gas phase oxidation of o-xylene, in which a gaseous mixture of o-xylene and an oxygenous gas is converted in a main reactor to a gaseous intermediate reaction product which comprises unconverted o-xylene, phthalic anhydride underoxidation products and phthalic anhydride, the heat of reaction which arises in the main reactor being removed at least partly by indirect cooling with a heat carrier medium, and the intermediate reaction product being introduced into a postreactor. The concentration of unconverted o-xylene in the intermediate reaction product is at least 1% by weight, and the sum of the concentrations of phthalic anhydride underoxidation products in the intermediate reaction product is at least 0.5% by weight. The process allows an increase in the overall yield of phthalic anhydride without or without significant deterioration in the product quality.