Spectroscopic IR, EPR, and operando DRIFT insights into surface reaction pathways of selective reduction of NO by propene over the Co-BEA zeolite

doi:10.1039/C1CP23038G

Spectroscopic IR, EPR, and operando DRIFT insights ...

Bibliographic description

punktacja MNiSW [2012 A]: 40

title:	Spectroscopic IR, EPR, and operando DRIFT insights into surface reaction pathways of selective reduction of NO by propene over the Co-BEA zeolite
author:	Pietrzyk Piotr , Dujardin Christophe, Góra-Marek Kinga , Granger Pascal, Sojka Zbigniew
Journal title:	Physical Chemistry Chemical Physics
volume:	14
issue:	7
date of publication:	2012
pages:	2203-2215
ISSN:	1463-9076
eISSN:	1463-9084
DOI:	10.1039/C1CP23038G
language:	English
Journal language:	English
abstract in english:	Interaction of a Co–BEA catalyst with individual components (NO, C 3 H 6,CO,O 2) and mixtures simulating the real feed of the selective catalytic reduction (SCR) of nitric oxide in static and pulse experiments at variable temperatures was investigated by means of IR, EPR, and operando DRIFT spectroscopy coupled with QMS/GC analysis of the products. Speciation of cobalt active sites into Co( II ), mono- and polynuclear oxo-cobalt species as well as CoO clusters was quantified by IR using CO and NO as probe molecules. The key intermediates, by-products, and final products of the SCR reaction were identified and their spectroscopic signatures ascertained. Based on the spectroscopicoperando results, a concise mechanistic scheme of the selective catalytic reduction of nitric oxide by propene, triggered by a two-electron Co( II )/Co(0) redox couple, was developed. It consists of a complex network of the sequential/parallel selective reduction steps that are interlocked by the rival nonselective oxidation of the intermediates and their thermal decomposition. It has been shown that the SCR process is initiated by the chemoselective capture of NO from the reaction mixture by the cobalt active sites leading to the cobalt(II) dinitrosyls, which in the excess of oxygen are partially oxidized to surface nitrates and nitrites. N 2 Oisproduced by semi-decomposition of the dinitrosyl intermediates on the mononuclear centers, whereas NO 2 via NO oxidation on the polynuclear oxo-cobalt sites. Cyanide and isocyanate species, formed together with propene oxygenates in the course of the CQC bond scission, are the mechanistically pivotal reaction intermediates of C 3 H 6 interaction with the dinitrosyles and NO 3 /NO 2 surface species. Dinitrogen is produced by three main reaction routes involving oxidation of cyanides by NO/NO 2, reduction of dinitrosyls, nitrates, and nitrites by propene oxygenates (medium temperature range) or their reduction by carbon monoxide (high temperature range)
departmental parameterization:	40
affiliation:	Wydział Chemii : Zakład Chemii Nieorganicznej
type:	journal article
subtype:	academic paper