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Role of tetrahedral Co(II) sites of CoSiBEA zeolite in the selective catalytic reduction of NO: XRD, UV–vis, XAS and catalysis study

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Abstract.
The CoSiBEA zeolites are prepared by a two-step postsynthesis method which allows to incorporate
cobalt in BEA zeolite as isolated tetrahedral Co(II) species. The incorporation of Co ions in vacant T-sites
and their reaction with silanol groups are evidenced by XRD and FTIR respectively. It does not generate
acidic Brønsted sites as shown by FTIR of adsorbed pyridine. The state of cobalt species is characterized
by DR UV–vis and XAS. These techniques allow to show that for low Co content (0.8 wt%) the cobalt is
present as lattice tetrahedral Co(II) species. For much higher Co content (11 wt%) mainly extra-lattice
octahedral Co(II) species and/or cobalt oxides are evidenced by DR UV–vis spectroscopy. Zeolite with
isolated tetrahedral Co(II) species is active in SCR of NO by ethanol with selectivity towards N2 exceeding
85% for NO conversion from 30 to 70%. When extra-lattice octahedral Co(II) species and/or cobalt oxides
appear, the full oxidation of ethanol and NO by dioxygen to CO2 and NO2 respectively, are the main
reaction pathways. Possible way of the formation of lattice tetrahedral Co(II) species in the BEA structure
is proposed.

Keywords: SiBEA zeolite, Cobalt, SCR, NO, Ethanol, XRD, FTIR, DR UV–vis, XAS

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Informasi Detail

Judul Seri

Applied Catalysis B: Environmental

No. Panggil

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Penerbit

London : Elsevier B.V.., 2009

Deskripsi Fisik

Applied Catalysis B: Environmental 89 (2009) 196–203

Bahasa

English

ISBN/ISSN

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Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

KIMIA

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

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