Publication detail

Periodic Density Functional and FTIR Spectroscopic Studies on CO Adsorption on the Zeolite Na-FER

Year: 2007

Type of publication: článek v odborném periodiku

Name of source: Microporous and Mesoporous Materials

Publisher name: Elsevier Science BV

Place: Amsterdam

Page from-to: 162-173

Titles:

Language	Name	Abstract	Keywords
cze	Studium adsorpce CO na Na-FER pomocí periodického hustotního funkcionálu a IČ spektroskopie	Adsorpce CO na Na-FER zeolitech byla studována pomocí VTIR spektroskopie a výpočetních metod. jak vibrační dynamika, tak energetika adsorpce byla zkoumána. Byly nalezeny následující typy komplexů. (i) C-down monokarbonyl na izolovaném Na+ kationtu charakterizovaný pásem 2175 cm-1, (ii) o-down izokarbonyl vykazující charakteristický pás na 2113 cm-1, (iii) můstkový Na+...CO...Na+ tvořící duální kationtové centrum charakterizované pásem 2158 cm-1 . Můstkový komplex je o zhruba 4 kJ/mol stabilnější než klasický C-down karbonyl. Nejméně stabilní je O-down izokarbonyl. Mimo detailní charakterizace CO/Na-FER systému, byla prokázána existence nového typu komplexu (můstkových karbonylů) i v tomto systému.	adsorpce CO;duální kationtové centrum;Na-FER;periodická DFT;IČ spektroskopie za variabilní teploty
eng	Periodic Density Functional and FTIR Spectroscopic Studies on CO Adsorption on the Zeolite Na-FER	Carbon monoxide adsorption on Na-FER was studied by a combination of variable-temperature IR spectroscopy and computational methods involving, mainly, periodic density functional theory and omega(CO)/r(CO) correlation. Both, C-O stretching frequency and interaction energy of adsorption complexes were investigated. Interplay between calculated and experimental results led to identification of the following adsorbed species: (i) C-down monocarbonyls formed on single Na+ sites, characterized by an infrared absorption band at 2175 cm(-1); (ii) O-down isocarbonyls showing a characteristic IR absorption band at 2113 cm(-1) and (iii) bridged Na+center dot center dot center dot CO center dot center dot center dot Na+ complexes formed on dual cation sites constituted by a pair of nearby Na+ ions, and characterized by an IR absorption band at 2158 cm(-1) The bridged carbonyl complex was found to be about 4 kJ mol(-1) more stable than the C-down monocarbonyl, despite its smaller C-O stretching frequency. The least stable adsorption complex is the O-down (isocarbonyl) species formed on single Na+ sites. Besides carrying out a detailed characterization of the CO/Na-FER system, investigation of the bridged CO complex on dual cation sites was one of the main aims pursued; such a novel type of CO adsorption complex was described very recently, for the first time, for the case of CO adsorbed on K-FER [J. Phys. Chem. B 110 (2006) 22542].	CO adsorption;dual cation sites;Na-FER;periodic DFT;variable-temperature FTIR

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