Crotonaldehyde Hydrogenation on Rh/TiO2 catalysts: In situ DRIFTS studies

The surface and catalytic properties in the vapor-phase hydrogenation of crotonaldehyde on Rh/TiO2 has been studied. It was found that a partial reduction of the support produces a surface decoration of the metal component. Thus, interfacial sites are created, which are responsible of an increase in...

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Autores principales:	Reyes,P., Aguirre,M del C, Melián-Cabrera,I., López Granados,M., Fierro,J. L. G.
Lenguaje:	English
Publicado:	Sociedad Chilena de Química 2002
Materias:	Rh/TiO2 crotonaldehyde hydrogenation DRIFTS
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442002000400027
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spelling	oai:scielo:S0366-164420020004000272009-12-18Crotonaldehyde Hydrogenation on Rh/TiO2 catalysts: In situ DRIFTS studiesReyes,P.Aguirre,M del CMelián-Cabrera,I.López Granados,M.Fierro,J. L. G. Rh/TiO2 crotonaldehyde hydrogenation DRIFTS The surface and catalytic properties in the vapor-phase hydrogenation of crotonaldehyde on Rh/TiO2 has been studied. It was found that a partial reduction of the support produces a surface decoration of the metal component. Thus, interfacial sites are created, which are responsible of an increase in the selectivity to crotyl alcohol, via enhancement of the polarization of the C=O bond. Photoelectron spectra revelead that rhodium is in different oxidation states, with a contribution of ca. 20 % Rhd + and 80 % Rhº species for LTR catalyst and only a slight increase of Rhd + for HTR catalyst. TEM studies revelead that Rh has metal particle size close 3 nm with small increases in the catalyst reduced at high temperature. DRIFTS essayed carried out under reaction conditions allowed to identify crotonaldehyde species strongly adsorbed through the C=C bond and weakly coordinated through both the C=C and C=O bonds. After reduction at 723 K an increase in the peak at 1660 cm-1 ascribed to an interaction between the carbonyl group and the surface, was observed. This peak seems to be stabilized at interfacial Rh/TiOx sites The deactivation in crotyl alcohol formation can be ascribed to the generation of strongly chemisorbed asymmetric carboxylate species detected by band at 1740 cm-1. This band grows at expense of crotonaldehyde O s - bonded intermediate chemisorbed on coordinatively unsaturated sites (Lewis acid sites) responsible of the crotyl alcohol obtaintion (detected by a band at 1653 cm-1). Additionally, a small band at 2068 cm-1 assigned to CO adsorbed on transition metals, which increases with time on-stream may explain the deactivation of the catalysts in flow systems.info:eu-repo/semantics/openAccessSociedad Chilena de QuímicaBoletín de la Sociedad Chilena de Química v.47 n.4 20022002-12-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442002000400027en10.4067/S0366-16442002000400027
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	Rh/TiO2 crotonaldehyde hydrogenation DRIFTS
spellingShingle	Rh/TiO2 crotonaldehyde hydrogenation DRIFTS Reyes,P. Aguirre,M del C Melián-Cabrera,I. López Granados,M. Fierro,J. L. G. Crotonaldehyde Hydrogenation on Rh/TiO2 catalysts: In situ DRIFTS studies
description	The surface and catalytic properties in the vapor-phase hydrogenation of crotonaldehyde on Rh/TiO2 has been studied. It was found that a partial reduction of the support produces a surface decoration of the metal component. Thus, interfacial sites are created, which are responsible of an increase in the selectivity to crotyl alcohol, via enhancement of the polarization of the C=O bond. Photoelectron spectra revelead that rhodium is in different oxidation states, with a contribution of ca. 20 % Rhd + and 80 % Rhº species for LTR catalyst and only a slight increase of Rhd + for HTR catalyst. TEM studies revelead that Rh has metal particle size close 3 nm with small increases in the catalyst reduced at high temperature. DRIFTS essayed carried out under reaction conditions allowed to identify crotonaldehyde species strongly adsorbed through the C=C bond and weakly coordinated through both the C=C and C=O bonds. After reduction at 723 K an increase in the peak at 1660 cm-1 ascribed to an interaction between the carbonyl group and the surface, was observed. This peak seems to be stabilized at interfacial Rh/TiOx sites The deactivation in crotyl alcohol formation can be ascribed to the generation of strongly chemisorbed asymmetric carboxylate species detected by band at 1740 cm-1. This band grows at expense of crotonaldehyde O s - bonded intermediate chemisorbed on coordinatively unsaturated sites (Lewis acid sites) responsible of the crotyl alcohol obtaintion (detected by a band at 1653 cm-1). Additionally, a small band at 2068 cm-1 assigned to CO adsorbed on transition metals, which increases with time on-stream may explain the deactivation of the catalysts in flow systems.
author	Reyes,P. Aguirre,M del C Melián-Cabrera,I. López Granados,M. Fierro,J. L. G.
author_facet	Reyes,P. Aguirre,M del C Melián-Cabrera,I. López Granados,M. Fierro,J. L. G.
author_sort	Reyes,P.
title	Crotonaldehyde Hydrogenation on Rh/TiO2 catalysts: In situ DRIFTS studies
title_short	Crotonaldehyde Hydrogenation on Rh/TiO2 catalysts: In situ DRIFTS studies
title_full	Crotonaldehyde Hydrogenation on Rh/TiO2 catalysts: In situ DRIFTS studies
title_fullStr	Crotonaldehyde Hydrogenation on Rh/TiO2 catalysts: In situ DRIFTS studies
title_full_unstemmed	Crotonaldehyde Hydrogenation on Rh/TiO2 catalysts: In situ DRIFTS studies
title_sort	crotonaldehyde hydrogenation on rh/tio2 catalysts: in situ drifts studies
publisher	Sociedad Chilena de Química
publishDate	2002
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442002000400027
work_keys_str_mv	AT reyesp crotonaldehydehydrogenationonrhtio2catalystsinsitudriftsstudies AT aguirremdelc crotonaldehydehydrogenationonrhtio2catalystsinsitudriftsstudies AT meliancabrerai crotonaldehydehydrogenationonrhtio2catalystsinsitudriftsstudies AT lopezgranadosm crotonaldehydehydrogenationonrhtio2catalystsinsitudriftsstudies AT fierrojlg crotonaldehydehydrogenationonrhtio2catalystsinsitudriftsstudies
_version_	1718438156042240000

Crotonaldehyde Hydrogenation on Rh/TiO2 catalysts: In situ DRIFTS studies

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