The influence of gas phase reactions on the design criteria for catalysts for lean NOx reduction with dimethyl ether
Journal article, 2009

In the selective catalytic reduction (SCR) of NO by dimethyl ether (DME), the formation of unexpectedly high amounts of NO2 over 300 degrees C has previously been reported, In this study, we explain this phenomenon by radical reactions initiated by DME and O-2, during which DME is partly oxidized and NO2 is formed in the presence of NO. For the design criteria of a DME-SCR catalyst, these gas phase reactions have mainly three consequences: (i) another type of reducing agent than that fed into the reactor reaches the catalyst. (ii) no activation of the reducing agent such as partial oxidation is required, and (iii) several of the proposed intermediate species for HC-SCP, e.g. NO2, HONO, CH3-NO2, and CH3-NO form already in the gas phase. An efficient DME-SCR catalyst should thus have high selectivity for reduction of NO, predominately by partially oxidized Cl-compounds, and it should not have particularly strong oxidizing properties to avoid non-selective oxidation of these Cl-compounds. These two requirements appear to be reasonable well met by the acidic zeolite H-ZSM-5.

H-ZSM-5

reducing agent

Gas phase reaction

nitric-oxide

Dimethyl ether

selective reduction

kinetics

Radical

zeolite

oxygen

nitrogen-oxides

dme

low-temperature oxidation

NOx-reduction

mechanism

Author

Stefanie Tamm

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

Hanna Härelind Ingelsten

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

Magnus Skoglundh

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

Anders Palmqvist

Competence Centre for Catalysis (KCK)

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Applied Catalysis B: Environmental

0926-3373 (ISSN) 1873-3883 (eISSN)

Vol. 91 1-2 234-241

Driving Forces

Sustainable development

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Transport

Energy

Materials Science

Subject Categories

Physical Sciences

DOI

10.1016/j.apcatb.2009.05.030

More information

Latest update

11/5/2018