Jump to main content
Jump to site search

Issue 3, 2019
Previous Article Next Article

N–H bond activation in ammonia by TM-SSZ-13 (Fe, Co, Ni and Cu) zeolites: a first-principles calculation

Author affiliations

Abstract

N–H activation is crucial for NH3-assisted selective catalytic reduction (SCR) and selective catalytic oxidation (SCO) of NH3 in exhaust emission treatment of the diesel engine. Copper-exchanged CHA-type zeolites show high performance for N–H activation, however, the atomic-level understanding of the activation mechanism is inaccessible. In this work, we use density functional theory (DFT) calculations to investigate the origin of high activity through electronic structures, magnetic properties and the N–H bond of NH3 activation on the naked Cu2+ as the active site in Cu-SSZ-13. Fe, Co and Ni-SSZ-13 were also systematically studied for comparison. The incorporation of transition metal ions leads to high-spin d-states around the Fermi level. The magnetic moment of 3.858, 2.889, 1.920 and 0.946 μB is observed for Fe, Co, Ni, and Cu-SSZ-13, respectively. A distorted square planar crystal field is found. For Cu-SSZ-13, the electronic configuration of Cu2+ ensures the lowest unoccupancy of b1g (dx2y2), enabling to receive electrons from base NH3 and thus activate the N–H bond with a barrier of 1.26 eV significantly lower than that in Fe, Co and Ni-SSZ-13. These findings may provide fundamental insights into the high activity and selectivity of Cu-SSZ-13 catalysts for NOx removal and NH3 oxidation at high temperature.

Graphical abstract: N–H bond activation in ammonia by TM-SSZ-13 (Fe, Co, Ni and Cu) zeolites: a first-principles calculation

Back to tab navigation

Supplementary files

Article information


Submitted
08 Oct 2018
Accepted
04 Dec 2018
First published
05 Dec 2018

Phys. Chem. Chem. Phys., 2019,21, 1506-1513
Article type
Paper

N–H bond activation in ammonia by TM-SSZ-13 (Fe, Co, Ni and Cu) zeolites: a first-principles calculation

L. Wang, H. Chen and W. Wang, Phys. Chem. Chem. Phys., 2019, 21, 1506
DOI: 10.1039/C8CP06263C

Social activity

Search articles by author

Spotlight

Advertisements