Selective catalytic reduction processes using doped cerias

US9555371B2 · kind B2 · utility

Assignee

• Johnson Matthey Public Limited Company · GB

Inventors

• Janet Mary Fisher · Calcot, GB
• Raj Rao Rajaram · Slough, GB
• David Thompsett · Reading, GB
• Jillian Elaine Collier · Reading, GB

Key dates

• Filing date: Dec 19, 2014
• Grant date: Jan 31, 2017
• Expiry date: Dec 19, 2034

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02A50/20
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

Niobia- and tantala-doped ceria catalysts, their use in selective catalytic reduction (SCR) processes, and a compact after-treatment system for exhaust gases are disclosed. In some aspects, the catalyst comprises at least 91 wt. % of ceria and 0.1 to 9 wt. % of niobia or tantala doped on the ceria. While conventional SCR catalysts can deactivate at higher temperatures, the doped cerias, particularly ones having as little as 1 or 2 wt. % of Nb2O5 or Ta2O5, are activated toward NOx conversion by calcination. The doped cerias are also valuable for SCRF® catalyzed filter applications, including an after-treatment system that comprises a diesel particulate filter having inlets and outlets, and a dual-function catalyst coated on the inlets, outlets, or both. Compared with conventional SCR catalysts, the niobia or tantala-doped cerias enable a higher level of NO2 to be present.