Method for producing phthalic anhydride that conforms to specifications

US7619098B2 · kind B2 · utility

Assignee

• BASF SE

Inventors

• Werner Peschel · Lohr am Main, DE
• Matthias Kummer · Schaffhausen, CH
• Marcus Bechtel · Dossenheim, DE

Key dates

• Filing date: Dec 31, 2005
• Grant date: Nov 17, 2009
• Expiry date: Dec 31, 2025

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D307/89
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

Process for the preparation of on-spec phthalic anhydride by the distillative purification of crude phthalic anhydride at reduced pressure, where the crude phthalic anhydride is passed to the distillation column above a side take-off, the low-boiling components are removed at the top of the column or in the vicinity of the top of the column and the on-spec phthalic anhydride is removed from the side take-off of the column, in which a distillation column is used whose number of theoretical plates located above the supply of the crude phthalic anhydride into the distillation column is 10 to 20 and the column is operated at a reflux ratio of from 0.1 to 0.5.