Method for producing phthalic anhydride

US7390911B2 · kind B2 · utility

Assignee

• BASF SE

Inventors

• Samuel Neto · Brussels, BE
• Jürgen Zühlke · Speyer, DE
• Sebastian Storck · Mannheim, DE
• Frank Rosowski · Mannheim, DE

Key dates

• Filing date: May 15, 2004
• Grant date: Jun 24, 2008
• Expiry date: Jun 13, 2025

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D307/89
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The invention relates to a process for preparing phthalic anhydride, in which the catalytic gas-phase oxidation of o-xylene and/or naphthalene is carried out over at least three zones of catalysts of increasing activity, with only the last zone of the catalyst system containing phosphorus and the last zone also comprising at least 10% by weight of vanadium (calculated as V2O5) based on the active composition of the catalyst and having a ratio of vanadium (calculated as V2O5) to phosphorus of greater than 35.