Oxidative dehydrogenation of ethylbenzene to styrene over ultra-dispersed diamond and onion-like carbon

Abstract

The catalytic properties of sp 3 -hybridized ultra-dispersed diamond and sp 2 -hybridized onion-like carbon in the oxidative dehydrogenation of ethylbenzene to styrene were investigated, highlighting the structure sensitivity of the reaction. The sp 3 -carbon led initially to C-C cleavage and benzene formation, while a switchover of the main reaction pathway into the styrene formation occurred with time on stream due to the formation of surface sp 2 carbon, required for the selective styrene formation. This was confirmed by the behavior and the high stable styrene selectivity shown by onion-like carbons. High temperature oxygen pre-treatment created catalytically active species at the sp 2 carbon surface, confirming that a high thermal stability carbon-oxygen complex was the active surface site for forming styrene.

Surface Modifications of Nanodiamonds and Current Issues for Their Biomedical Applications

“…4.6). OLC have promising properties for energy storage, catalysis or composites [147][148][149]156].…”

Nanotecnologia: aspectos gerais e potencial de aplicação em catálise

“…44 Os nanotubos e nanofibras de carbono têm sido extensivamente estudados como suportes catalíticos em diversas reações, tais como a hidrogenação do buteno, 118 a hidrogenação do cinamaldeído, 119 a decomposição do óxido de nitrogênio, 120 a hidroformilação do etileno, 121 a desidrogenação do ciclo-hexanol, 122 a reação esqueletal do n-hexano, 123 a oxidação do metanol, 124 a decomposição do metano e na desidrogenação oxidativa do etilbenzeno para produzir estireno. 125,126 Em particular, os nanotubos de paredes múltiplas e as nanofibras, quando utilizados para catalisar reações em fase líquida, apresentam a vantagem de diminuir significativamente as limitações de transferên-cia de massa, em relação aos carvões ativados, devido à sua elevada área superficial específica e mesoporosidade. 107 Entretanto, foram publicados poucos trabalhos abordando catalisadores baseados em nanotubos de paredes múltiplas, devido à sua microporosidade e à dificuldade de obter grandes quantidades do material puro, de modo a permitir estudos de catálise.…”

Mesostructured CeO2 as an Effective Catalyst for Styrene Synthesis by Oxidative Dehydrogenation of Ethylbenzene

“…Due to its highly endothermic nature, this conventional route suffers from several disadvantages such as intensive energy consumption and rapid coking. Alternatively, the oxidative dehydrogenation (ODH) of EB has attracted considerable recent attention since it can be operated at lower temperatures and the EB conversion would not be equilibrium limited [2,[4][5][6]. A range of catalysts have been reported for this process in the recent literature including amorphous AlPO 4 [1], V 2 O 5 /CeO 2 / Al 2 O 3 [2], CaO/SiO 2 [7], MnO 2 /SiO 2 [8], Mg(VO 4 ) 2 -MgO [9].…”