The nature of active Ni sites and the role of Al species in the oligomerization of ethylene on mesoporous Ni-Al-MCM-41 catalysts

Although nickel dispersed in mesoporous aluminosilicates are efficient catalysts for the oligomerization of ethylene, the nature of the active nickel sites still remains controversial. Here we applied in situ FTIR-CO spectroscopy during reaction with ethylene combined with reaction kinetics with onl...

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Detalles Bibliográficos
Autores: Moussa, Sara, Concepción, Patricia, Arribas, M.A, Martínez, Agustín
Tipo de recurso: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2020
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:dnet:digitalcsic_::5976da95e569eba85c374778ef85f7a3
Acceso en línea:http://hdl.handle.net/10261/224951
Access Level:acceso abierto
Descripción
Sumario:Although nickel dispersed in mesoporous aluminosilicates are efficient catalysts for the oligomerization of ethylene, the nature of the active nickel sites still remains controversial. Here we applied in situ FTIR-CO spectroscopy during reaction with ethylene combined with reaction kinetics with online MS analysis of reaction products to unravel the nature of the active nickel species in working mesoporous Ni-Al-MCM-41 catalysts. The results revealed that isolated ion-exchanged Ni cations are irreversibly blocked during the initial reaction stages leaving unsaturated Ni cations grafted on silanols and at the surface of small (confined) NiO nanoparticles as the active species in the pseudo-steady state. The low activity of these species in pure silica materials suggested a promotional role of aluminum in the Al-MCM-41 matrix on enhancing the activity of Ni sites, probably through a close interaction between Al species and nearby Ni sites, as inferred from quantitative Al MAS NMR and FTIR spectroscopies.

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