Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts

Autores
Garetto, Teresita Francisca; Apesteguia, Carlos Rodolfo
Año de publicación
2000
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
The reaction kinetics, structure sensitivity, and in situ activation of cyclopentane and methane combustions were studied on Pt/Al2O3 catalysts of different platinum and chlorine loadings. The catalyst activities were evaluated through both conversion vs. temperature (light-off curves) and conversion vs. time catalytic tests. Cyclopentane oxidation turnover rates (TOF) increased dramatically with increasing Pt crystallite size while TOF values for methane oxidation increased only three times by diminishing the Pt dispersion from 65 to 15%. The reaction orders in oxygen were one (cyclopentane) and zero (CH4). For both reactions, the orders and activation energies did not change by changing the Pt dispersion. Results are interpreted in basis of two different reaction mechanisms over the metallic Pt active sites. Cyclopentane oxidation proceeds via a surface redox mechanism, being the dissociative adsorption of oxygen the rate-determining step. The observed turnover rate increase with increasing Pt particle size reflects an increase in the density of reactive Pt–O species resulting from higher Pt oxidation rates. The methane oxidation mechanism is interpreted in terms of Mars–van Kravelen reduction–oxidation pathways which include the abstraction of the first hydrogen on the adsorbed methane molecule as the rate-determining step. Low-conversion catalytic tests performed at constant temperature showed that on well-dispersed Pt/Al2O3 catalysts the cyclopentane conversion increases with time on stream, while the methane activity decreases. Activating induction periods during the oxidation of cyclopentane are related to the sintering of the metallic phase in reaction conditions. Hot-spots on the metallic particles together with the presence of gaseous water cause the formation of larger, more reactive, Pt crystallites, even at mild reaction conditions. The activation phenomenon ab initio of the reaction is not verified for methane oxidation on Pt/Al2O3 catalysts. The different structure sensitivity of the slowest steps in the reaction–oxidation mechanisms explains the existence of induction periods on well-dispersed Pt catalysts only for cyclopentane oxidation.
Fil: Garetto, Teresita Francisca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentina
Fil: Apesteguia, Carlos Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentina
Materia
Hydrocarbon Combustion
Pt/Al2o3 Catalysts
Methane Oxidation Mechanism
Cyclopentane Oxidation Mechanism
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
OAI Identificador
oai:ri.conicet.gov.ar:11336/37066

id CONICETDig_257855aa78456250145a99024408a679
oai_identifier_str oai:ri.conicet.gov.ar:11336/37066
network_acronym_str CONICETDig
repository_id_str 3498
network_name_str CONICET Digital (CONICET)
spelling Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalystsGaretto, Teresita FranciscaApesteguia, Carlos RodolfoHydrocarbon CombustionPt/Al2o3 CatalystsMethane Oxidation MechanismCyclopentane Oxidation Mechanismhttps://purl.org/becyt/ford/2.4https://purl.org/becyt/ford/2The reaction kinetics, structure sensitivity, and in situ activation of cyclopentane and methane combustions were studied on Pt/Al2O3 catalysts of different platinum and chlorine loadings. The catalyst activities were evaluated through both conversion vs. temperature (light-off curves) and conversion vs. time catalytic tests. Cyclopentane oxidation turnover rates (TOF) increased dramatically with increasing Pt crystallite size while TOF values for methane oxidation increased only three times by diminishing the Pt dispersion from 65 to 15%. The reaction orders in oxygen were one (cyclopentane) and zero (CH4). For both reactions, the orders and activation energies did not change by changing the Pt dispersion. Results are interpreted in basis of two different reaction mechanisms over the metallic Pt active sites. Cyclopentane oxidation proceeds via a surface redox mechanism, being the dissociative adsorption of oxygen the rate-determining step. The observed turnover rate increase with increasing Pt particle size reflects an increase in the density of reactive Pt–O species resulting from higher Pt oxidation rates. The methane oxidation mechanism is interpreted in terms of Mars–van Kravelen reduction–oxidation pathways which include the abstraction of the first hydrogen on the adsorbed methane molecule as the rate-determining step. Low-conversion catalytic tests performed at constant temperature showed that on well-dispersed Pt/Al2O3 catalysts the cyclopentane conversion increases with time on stream, while the methane activity decreases. Activating induction periods during the oxidation of cyclopentane are related to the sintering of the metallic phase in reaction conditions. Hot-spots on the metallic particles together with the presence of gaseous water cause the formation of larger, more reactive, Pt crystallites, even at mild reaction conditions. The activation phenomenon ab initio of the reaction is not verified for methane oxidation on Pt/Al2O3 catalysts. The different structure sensitivity of the slowest steps in the reaction–oxidation mechanisms explains the existence of induction periods on well-dispersed Pt catalysts only for cyclopentane oxidation.Fil: Garetto, Teresita Francisca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Apesteguia, Carlos Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaElsevier Science2000-12info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/37066Garetto, Teresita Francisca; Apesteguia, Carlos Rodolfo; Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts; Elsevier Science; Catalysis Today; 62; 2-3; 12-2000; 189-1990920-5861CONICET DigitalCONICETenginfo:eu-repo/semantics/altIdentifier/url/https://www.sciencedirect.com/science/article/pii/S092058610000420Xinfo:eu-repo/semantics/altIdentifier/doi/10.1016/S0920-5861(00)00420-Xinfo:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-29T10:21:12Zoai:ri.conicet.gov.ar:11336/37066instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-09-29 10:21:12.726CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts
title Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts
spellingShingle Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts
Garetto, Teresita Francisca
Hydrocarbon Combustion
Pt/Al2o3 Catalysts
Methane Oxidation Mechanism
Cyclopentane Oxidation Mechanism
title_short Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts
title_full Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts
title_fullStr Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts
title_full_unstemmed Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts
title_sort Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts
dc.creator.none.fl_str_mv Garetto, Teresita Francisca
Apesteguia, Carlos Rodolfo
author Garetto, Teresita Francisca
author_facet Garetto, Teresita Francisca
Apesteguia, Carlos Rodolfo
author_role author
author2 Apesteguia, Carlos Rodolfo
author2_role author
dc.subject.none.fl_str_mv Hydrocarbon Combustion
Pt/Al2o3 Catalysts
Methane Oxidation Mechanism
Cyclopentane Oxidation Mechanism
topic Hydrocarbon Combustion
Pt/Al2o3 Catalysts
Methane Oxidation Mechanism
Cyclopentane Oxidation Mechanism
purl_subject.fl_str_mv https://purl.org/becyt/ford/2.4
https://purl.org/becyt/ford/2
dc.description.none.fl_txt_mv The reaction kinetics, structure sensitivity, and in situ activation of cyclopentane and methane combustions were studied on Pt/Al2O3 catalysts of different platinum and chlorine loadings. The catalyst activities were evaluated through both conversion vs. temperature (light-off curves) and conversion vs. time catalytic tests. Cyclopentane oxidation turnover rates (TOF) increased dramatically with increasing Pt crystallite size while TOF values for methane oxidation increased only three times by diminishing the Pt dispersion from 65 to 15%. The reaction orders in oxygen were one (cyclopentane) and zero (CH4). For both reactions, the orders and activation energies did not change by changing the Pt dispersion. Results are interpreted in basis of two different reaction mechanisms over the metallic Pt active sites. Cyclopentane oxidation proceeds via a surface redox mechanism, being the dissociative adsorption of oxygen the rate-determining step. The observed turnover rate increase with increasing Pt particle size reflects an increase in the density of reactive Pt–O species resulting from higher Pt oxidation rates. The methane oxidation mechanism is interpreted in terms of Mars–van Kravelen reduction–oxidation pathways which include the abstraction of the first hydrogen on the adsorbed methane molecule as the rate-determining step. Low-conversion catalytic tests performed at constant temperature showed that on well-dispersed Pt/Al2O3 catalysts the cyclopentane conversion increases with time on stream, while the methane activity decreases. Activating induction periods during the oxidation of cyclopentane are related to the sintering of the metallic phase in reaction conditions. Hot-spots on the metallic particles together with the presence of gaseous water cause the formation of larger, more reactive, Pt crystallites, even at mild reaction conditions. The activation phenomenon ab initio of the reaction is not verified for methane oxidation on Pt/Al2O3 catalysts. The different structure sensitivity of the slowest steps in the reaction–oxidation mechanisms explains the existence of induction periods on well-dispersed Pt catalysts only for cyclopentane oxidation.
Fil: Garetto, Teresita Francisca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentina
Fil: Apesteguia, Carlos Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentina
description The reaction kinetics, structure sensitivity, and in situ activation of cyclopentane and methane combustions were studied on Pt/Al2O3 catalysts of different platinum and chlorine loadings. The catalyst activities were evaluated through both conversion vs. temperature (light-off curves) and conversion vs. time catalytic tests. Cyclopentane oxidation turnover rates (TOF) increased dramatically with increasing Pt crystallite size while TOF values for methane oxidation increased only three times by diminishing the Pt dispersion from 65 to 15%. The reaction orders in oxygen were one (cyclopentane) and zero (CH4). For both reactions, the orders and activation energies did not change by changing the Pt dispersion. Results are interpreted in basis of two different reaction mechanisms over the metallic Pt active sites. Cyclopentane oxidation proceeds via a surface redox mechanism, being the dissociative adsorption of oxygen the rate-determining step. The observed turnover rate increase with increasing Pt particle size reflects an increase in the density of reactive Pt–O species resulting from higher Pt oxidation rates. The methane oxidation mechanism is interpreted in terms of Mars–van Kravelen reduction–oxidation pathways which include the abstraction of the first hydrogen on the adsorbed methane molecule as the rate-determining step. Low-conversion catalytic tests performed at constant temperature showed that on well-dispersed Pt/Al2O3 catalysts the cyclopentane conversion increases with time on stream, while the methane activity decreases. Activating induction periods during the oxidation of cyclopentane are related to the sintering of the metallic phase in reaction conditions. Hot-spots on the metallic particles together with the presence of gaseous water cause the formation of larger, more reactive, Pt crystallites, even at mild reaction conditions. The activation phenomenon ab initio of the reaction is not verified for methane oxidation on Pt/Al2O3 catalysts. The different structure sensitivity of the slowest steps in the reaction–oxidation mechanisms explains the existence of induction periods on well-dispersed Pt catalysts only for cyclopentane oxidation.
publishDate 2000
dc.date.none.fl_str_mv 2000-12
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/37066
Garetto, Teresita Francisca; Apesteguia, Carlos Rodolfo; Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts; Elsevier Science; Catalysis Today; 62; 2-3; 12-2000; 189-199
0920-5861
CONICET Digital
CONICET
url http://hdl.handle.net/11336/37066
identifier_str_mv Garetto, Teresita Francisca; Apesteguia, Carlos Rodolfo; Oxidative catalytic removal of hydrocarbons over Pt/Al2O3 catalysts; Elsevier Science; Catalysis Today; 62; 2-3; 12-2000; 189-199
0920-5861
CONICET Digital
CONICET
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/url/https://www.sciencedirect.com/science/article/pii/S092058610000420X
info:eu-repo/semantics/altIdentifier/doi/10.1016/S0920-5861(00)00420-X
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv Elsevier Science
publisher.none.fl_str_mv Elsevier Science
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
collection CONICET Digital (CONICET)
instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
_version_ 1844614199577149440
score 13.070432