Process for the oxidative purification of waste gases containing nitrogen oxides

US5366711A · kind A · utility

Assignee

• Degussa AG · DE

Inventors

• Wegido von Wedel · Paris, FR
• Ernst-Robert Barenschee · Hanau, DE
• Hubertus Eickhoff · Alzenau, DE

Key dates

• Filing date: Oct 30, 1992
• Grant date: Nov 22, 1994
• Expiry date: Oct 30, 2012

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02C20/10
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

A process is described for the removal of nitrogen oxides from waste gases with the recovery of nitric acid or a nitrate solution. The waste gas is reacted with hydrogen peroxide in an amount appropriate to the desired degree of removal of nitrogen oxides, on a catalyst, at a temperature of less than 800.degree. C., preferably in the range of 20.degree. to 100.degree. C., to give the valuable product, nitric acid or a nitrate solution. This may be done in accordance with the invention by bringing the hydrogen peroxide as a solution, i.e., in the liquid phase, into contact with the catalyst through which the waste gas is flowing. The reaction product is either utilized in a gaseous form or processed to nitric acid or a nitrate solution. Alternatively, the hydrogen peroxide may be introduced in a gaseous form, using a honeycombed catalyst, and wherein the hydrogen peroxide is present in at least one half of the stoichiometrically determined amount. Regardless of whether the hydrogen peroxide is introduced in a liquid or vapor form, the resulting nitric acid solution may be scrubbed, preferably with a nitrate salt solution, to provide the concentrated product.