Mono (V, Nb) or bimetallic (V–Ti, Nb–Ti) ions modified MCM-41 catalysts: synthesis, characterization and catalysis in oxidation of hydrocarbons (aromatics and alcohols)

Predictive design of engineered multifunctional solid catalysts

“…Mesoporous MCM-41 molecular sieves have also been suitably modified with V and Ti metal ions. 91 It was found that the inclusion of the titanium ion, in addition to the vanadium ion, resulted in a catalytic enhancement for styrene epoxidation, whilst the oxidation of toluene was markedly diminished (Figure 12). 91 This clearly demonstrates that the addition of a second metal can have a dramatic influence on the properties of a monometallic catalyst and the strategy can be successfully extended to mesoporous architectures.…”

“…91 It was found that the inclusion of the titanium ion, in addition to the vanadium ion, resulted in a catalytic enhancement for styrene epoxidation, whilst the oxidation of toluene was markedly diminished (Figure 12). 91 This clearly demonstrates that the addition of a second metal can have a dramatic influence on the properties of a monometallic catalyst and the strategy can be successfully extended to mesoporous architectures. A similar observation was found with a series of bimetallic Co-containing MCM-41 catalysts with different combinations of dopants either favouring the styrene epoxidation or the toluene oxidation (see Table 5 for other examples).…”

“…Figure 12: Contrasting the effects of bimetallic substitution in mesoporous solids -substrate versatility. 91 …”

Low-Temperature Active Pt-catalysts Supported on Mesoporous Silica and Metal-Silicates for Cleaning Diesel-NOx Exhausts

“…MPS and the metal-silicates probably possess the Brønsted acid-sites, while γ-alumina contains Lewis acid-sites. The observation of the Brønsted acid-sites of transition-metal inserted MCM-41 was unsuccessful because of really ineffective pyridine adsorption FT-IR assessment (Zhang et al, 1998;Briot et al, 2000;Parvulescu et al, 2003). Although the measurement of acid-sites of MPS and the metal-silicates by the above standard method is very difficult, the support effect is undoubtedly due to the strong Brønsted acid-sites locally distributed on the support surfaces.…”

Processos avançados de oxidação de compostos fenólicos em efluentes industriais

“…As aplicações baseadas em metais nobres (platina, rutênio, paládio, ródio, irídio e prata) e óxidos metálicos (manganês, cobalto, cobre, zinco, vanádio, níquel, ferro, bismuto e titânio), usando diversos suportes (alumina, dióxido de cério, dióxido de titânio, dióxido de zircônio e zeólitas), são bastante amplas e encontram-se descritas de forma detalhada na literatura 8,38 . As recentes investigações científicas têm buscado o desenvolvimento de catalisadores que apresentem alta atividade na oxidação de fenóis e elevada seletividade, na geração de dióxido de carbono e água, tornando o processo reacional limpo 23,29,40 . Esses catalisadores devem apresentar, como principais propriedades, uma elevada capacidade de conversão total, estabilidade física e quími-ca em meio ácido e resistência a venenos presentes nas correntes a serem tratadas 20 .…”