resumo
The first catalytic active composites based on CoAl2O4 nanoparticles with different size (5.5 and 2.5 nm) were successfully prepared using a simple methodology of incorporation into MIL-101(Cr) framework, CoAl-x@MIL(Cr). Characterization of CoAl-x@MIL(Cr) composites by elemental analysis, vibrational spectroscopy (FT-IR and FT-Raman), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) confirmed the successful preparation and stability of the support structure after nanoparticle immobilization. A remarkable catalytic performance was found for thioanisole oxidation under sustainable conditions (95% of conversion after 30 min of reaction) and the catalytic application of the most active composite was extended to styrene oxidation. Higher catalytic performance was achieved for the composite prepared with larger CoAl2O4 nanoparticles. The recyclability and the stability of composites after catalytic use were investigated. For the CoAl-x@MIL(Cr) catalytic systems, the loading parameter instead of the nanoparticle size seemed to have a pronounced influence in the heterogeneous catalytic performance. The confinement effect promoted by MIL-101(Cr) cavities associated to the higher number of catalytic active centers (CoAl2O4) is clearly more important than the size of the catalytic nanoparticles used.
palavras-chave
METAL-ORGANIC FRAMEWORKS; HETEROGENEOUS CATALYSTS; SELECTIVE OXIDATION; STYRENE; EPOXIDATION; COMPLEXES; OXIDE; GOLD; TEMPERATURE; FABRICATION
categoria
Chemistry
autores
Granadeiro, CM; Karmaoui, M; Correia, E; Juliao, D; Amaral, VS; Silva, NJO; Cunha-Silva, L; Balula, SS
nossos autores
Diana Julião
Estudante de doutoramento
Mohamed Karmaoui
Bolseiro de pós-Doutoramento
Nuno João Silva
Investigador Principal
Vitor Brás Sequeira Amaral
Professor CatedráticoProjectos
agradecimentos
This work was partly financed by FEDER (Fundo Europeu de Desenvolvimento Regional) through COMPETE (Programa Operacional Factores de Competitividade) and by national funds through the FCT (Fundacao para a Ciencia e a Tecnologia) within the projects FCOMP-01-0124-FEDER-020658 (FCT ref. PTDC/EQU-EQU/121677/2010), FCOMP-01-0124-FEDER-013026 (FCT ref. PTDC/CTM/100357/2008), CICECO - FCOMP-01-0124-FEDER-037271 (FCT ref. PEst-C/CTM/LA0011/2013) and Requimte - FCOMP-01-0124-FEDER-037285 (FCT ref. PEst-C/EQB/La0006/2013), and the fellowships SFRH/BPD/73191/2010 (to CG) and SFRH/BPD/74477/2010 (to MK).