resumo
The hetero-functionalized phosphines HPN2. H2PNO and HPN-Pip containing tricarbonyl Re(V) complexes, i.e. [Re(CO)(3)(kappa(3)-PN2)] (I), [Re(CO)(3)Br(kappa(2)-H2PNO)] (II) and [Re(CO)(3)Br(kappa(2)-HPN-Pip)] (III) were covalently bonded to modified and MCM-41 to obtain novel supported hybrid catalysts. Remarkable high catalytic effects were observed with these catalysts in the hydroisomerization of n-alkanes at low temperature. The catalyst II/MCM-41 provided the highest TONs 3.32 x 10(3) with 37% yield for n-hexane and 3.18 x 10(3) with 30% yield for n-heptane. Under optimized condition, good selectivities for n-hexane (85%) and for n-heptane (91%) were obtained. The TGA was used to evaluate the stability of catalysts and reusable for several cycles. A possible carbenium-based mechanism been used to explain product formation. (C) 2012 Elsevier B.V. All rights reserved.
palavras-chave
MODIFIED SILICA-GEL; N-HEXANE; RHENIUM(I) COMPLEXES; ISOMERIZATION; MECHANISM; REFORMATION; PARAFFINS; LIGANDS; ALKANES; HEPTANE
categoria
Chemistry; Environmental Sciences & Ecology
autores
Mishra, GS; Kumar, A
nossos autores
Gopal Shankar Mishra
Bolseiro de pós-DoutoramentoGrupos
agradecimentos
The author expresses his gratitude to Foundation of Science and Technology (FCT), Portugal, for "Ciencia 2007" and partial financial support under Project PTDC/EQU-ERQ/110825/2009. We also thank Prof. P. Santos (UTAD) for valuable discussion, Kelly Machado (UTAD) for some useful help and the Analytical Laboratory, Instituto Superior Tecnico, IST, Lisbon.