Mo/KIT-6, Fe/KIT-6 and Mo–Fe/KIT-6 as new types of heterogeneous catalysts for the conversion of MCP

Quantum-dots containing Fe/SBA-15 silica as “green” catalysts for the selective photocatalytic oxidation of alcohol (methanol, under visible light)

“…In order to design new efficient Fe-based catalysts, it was demonstrated that isolated Feions and dispersed iron oxide NP with several allotropic varieties can be obtained by using 2D hexagonal SBA-15 silica as support. Fe/SBA-15 catalysts were used for selective oxidation reactions in the gas phase [6,7] as well as in the liquid phase for the transformation of phenol derivatives, such as catechol and hydroquinone [8] and also for water purification treatments (in particular by dyes decomposition [6,9,10]). To the best of our knowledge, interrogations remain about the nature of Fe-species responsible for the catalytic activity of Fe-SBA- 15 catalysts and also about their long-term stability since a silica dissolution associated with a photo-activated corrosion of Fe-species have been observed, at neutral pH and in basic aqueous solutions [11].…”

Síntese de materiais mesoporosos: um estudo comparativo entre o SBA-15 e o KIT-6

“…Para a amostra de KIT-6 pode-se observar que as partículas se encontram bastante organizadas. As partículas apresentam formas e tamanhos irregulares (BOULAOUED et al, 2012), na qual, os tamanhos em escala nanométrica variaram entre 100 e 500 nm. Apesar das formas irregulares pode-se observar claramente a tendência a forma cúbica referente à estrutura característica do KIT-6.…”

“…Segundo designação da IUPAC, esses materiais possuem diâmetro médio de poros entre 2 e 50 nm. Dentre os materiais mesoporosos o SBA-15 e o KIT-6, que possuem estruturas hexagonal e cúbica, respectivamente (KO; SHIN;CHOI, 2011;BOULAOUED et al, 2012) tem sido alvo de vários estudos recentemente, devido a suas características promissoras e suas aplicações variadas na área de catálise e meio ambiente (SONI et al, 2009;QIAN et al, 2012;HUSSAIN et al, 2013).…”

“…Os seus mesoporos, ordenados hexagonalmente e interligados por microporos, possibilitam o alojamento ou a difusão de grandes moléculas, o que confere a ele uma vasta aplicabilidade na área de catálise (DAO et al, 2008) e adsorção (HIYOSHI et al, 2005) O material do tipo KIT-6 é assim denominado por que sua descoberta ocorreu no Instituto Avançado de Ciência e Tecnologia da Corea (Korea Advanced Institute of Science and Technology) (KALBASI; MOSADDEGH, 2012). Esse material apresenta largo diâmetro médio de poro, espessura de parede por volta de 4-6 nm, estrutura simétrica cúbica tridimensional Ia3d (BOULAOUED et al, 2012), grande volume de poro, área superficial elevada, e rede interpenetrante bicontínua de canais (DOU et al, 2011). O KIT-6 possui estrutura semelhante à encontrada no MCM-48, porém apresenta algumas vantagens: microporos complementares com cerca de 1,8 nm que interligam os mesoporos (QIAN et al, 2012), maior estabilidade hidrotérmica (FALAHATI et al, 2011) e maior diâmetro de poro (KUMARESAN et al, 2010), o que confere ao material maior aplicabilidade.…”

Effect of support modification on the characterization and catalytic activity of Mo/Al2O3 catalysts

“…The catalytic performances of supported catalysts depend on the type of support, which has an important influence on the catalyst properties that are revealed by improvement of the dispersion of the active phase and the modification of their reducibility. Various materials are used as supports for preparing new types of molybdenum catalysts, such as MgO [2], MgO-coated polyhedral 3D mesoporous SBA-16 [3], activated carbon [4], zirconia [5], and silica mesoporous KIT-6 [6]. Al 2 O 3 has been regarded as a superior support for Mo catalysts because its surface area and pore-size distribution are easily controlled and because it has good mechanical strength and thermal stability.…”