Preparation of phthalic anhydride

US7151184B2 · kind B2 · utility

Assignee

• BASF SE

Inventors

• Sebastian Storck · Mannheim, DE
• Frank Rosowski · Mannheim, DE
• Michael Baier · Frankfurt, DE
• Andreas Tenten · Maikammer, DE
• Hans-Josef Wolf

Key dates

• Filing date: Feb 4, 2003
• Grant date: Dec 19, 2006
• Expiry date: Jul 12, 2023

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C51/313
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Process for preparing phthalic anhydride by gas-phase oxidation of xylene, naphthalene or mixtures thereof in a shell-and-tube reactor thermostatted by means of a heat transfer medium over three or more different fixed-bed catalysts arranged in zones, wherein the process is carried out so that the maximum temperature in the second catalyst zone in the flow direction is up to 50° C. lower than the maximum temperature in the first catalyst zone and the maximum temperature in the third zone from the gas inlet is from 30 to 100° C. lower than that in the first catalyst zone.The process of the present invention makes it possible to prepare phthalic anhydride in high yields under industrially relevant conditions.