Recent developments in polymer-supported ruthenium nanoparticles/complexes for oxidation reactions

Fotocatálise: uma Ferramenta para Valorizar Resíduos de Combustão e Compostos Derivados de Biomassa

“…Contudo, os metais nobres não são abundantes e são dispendiosos, pelo que a sua utilização como catalisadores na transformação de HMF em DFF tem vindo a ser substituída por metais de transição (e.g., Mn, Co, Mo e Fe). No entanto, para aumentar a atividade catalítica destes catalisadores são usados oxidantes fortes e tóxicos, como hipoclorito de sódio ou clorocromato de piridínio [8,9]. A título de exemplo, realça-se a utilização de um catalisador de cobalto suportado em dióxido de titânio (TiO 2 ) por Ning et al [10] onde foi observada uma conversão de 91% de HMF em DFF com uma seletividade de 40% usando acetonitrilo como solvente a 80 °C, durante 5 h e com hidroperóxido de terc-butilo como oxidante [1,10].…”

Conversion of Plastic Waste into Supports for Nanostructured Heterogeneous Catalysts: Application in Environmental Remediation

“…Additionally, the impact of these nanomaterials on ecosystems and human health is a significant issue that limits the use of nanotechnology in some situations [196,197]. To overcome these drawbacks, catalytically active components, such as metallic nanoparticles or nanostructured metallic oxides (usually in a low concentration), are immobilized in a dispersed state on a support [199,200]. Choosing a suitable, non-toxic, and recoverable support is very important [201].…”

“…It is noteworthy that in determining catalyst performance, the interaction between metal and support plays an essential role [201,202]. The most investigated supports in the literature to immobilize nanoparticles are zeolites [203,204], metal oxides [205,206] silica spheres [207,208] and alumina [209,210]; nanomaterials have also been largely immobilized in polymeric materials, adding value to waste that is normally dumped into the environment, causing problems [199,211,212]. Therefore, encouraging the choice of support based on polymeric materials is a topic of great importance.…”

TEMPO-Ru-BEA Composite Material for the Selective Oxidation of Alcohols to Aldehydes

“…A key part of these processes is an efficient catalyst able to perform the oxidation of alcohols with high activity, selectivity, and stability. There is a broad range of heterogeneous and homogeneous catalysts based on metals such as Pt, Pd, Ru, Au, Ag, Cu, and Fe, which are commonly used for oxidation reactions. − For example, different Ru compounds including RuCl 3 , RuCl 2 (PPh) 3 , [( n -Pr) 4 N] + RuO 4 – , Ru nanoparticles, and Ru/Al 2 O 3 exhibit excellent performances in the catalytic oxidation of activated alcohols such as allylic and benzylic alcohols with molecular oxygen as the oxidant. − However, the oxidation of aliphatic mono- and polyalcohols containing additional N, O, or S functional groups is difficult to perform with the selective generation of carbonyl compounds. The reaction usually proceeds further with the overoxidation of these compounds and the generation of more stable products, such as acids, esters, etc. , …”