Ruthenium-doped Titania-pillared Clay for The Selective Catalytic Oxidation of Cyclohexene: Influence of Ru Loading

Abstract

A series of ruthenium-based catalysts supported on acid-activated montmorillonite (PILC) and interspersed with titanium (Ru/Ti-PILCs) were prepared with various amounts of ruthenium. Their catalytic performances in the selective oxidation of cyclohexene, using tert-butylhydroperoxide (TBHP) as oxidant were checked. The clay structure modification by acid activation and impregnation of transition metals resulted in an enhanced Lewis and Bronsted acidities. The Ru/Ti-PILCs materials were characterized using X-ray diffraction (XRD), surface area and pore volume measurements, surface acidity followed by Fourier transform infrared (FTIR) spectroscopy, chemical analysis, and Scanning Electron Microscopy (SEM). It was found that all catalysts can selectively oxidize cyclohexene through allylic oxidation leading mainly to 2-cyclohexene-1-one (Enone) as the major product, and 2-cyclohexene-1-ol (Enol) as secondary product. With the 5 %Ru/Ti-PILC, it was possible to reach 59 % cyclohexene total conversion, and 87 % selectivity into 2-cyclohexene-1-one and 13 % selectivity into 2-cyclohexene-1-ol. external surface of the material is active, as large organic molecules cannot dodge in and out layers. Moreover, though non-polar molecules have reduced dimensions, they cannot penetrate into the material due to the hydrophilic character of the layers [3]. In order to obtain thermally stable materials with a greater interlayer distance, cations can be intercalated between the clay layers. These cations act as pillars that help in keeping the silicate layers separated, even in the absence of solvents.

Clay-Supported Metal Oxide Nanoparticles in Catalytic Advanced Oxidation Processes: A Review

“…This scheme takes two steps: pillarization, followed by an impregnation procedure, as described in Figure 10. Combinations such as TiO2-impregnated Fe-pillared clay (TiO2/Fe-PILC), Fe-impregnated Co-pillared clay (Fe/Co-PILC), Ru-impregnated Ti-pillared clay (Zn/Fe-PILC), and Co/Al-PILC exhibited hybrid properties for gaining either homogeneous dispersion or material stability, which are sufficiently accommodating for surface interactions for the catalytic process [147][148][149][150]. The immobilized Co 2+ and Sn 2+ have been proven as successful catalysts for dye oxidation.…”

“…The order of polymer species which determines the intercalating layers changed as the ageing temperatures changed. From varied ageing temperatures between 25 and 100 °C, it was found that different species sizes caused the irregular stacking of clay layers, and the optimum Combinations such as TiO 2 -impregnated Fe-pillared clay (TiO 2 /Fe-PILC), Fe-impregnated Co-pillared clay (Fe/Co-PILC), Ru-impregnated Ti-pillared clay (Zn/Fe-PILC), and Co/Al-PILC exhibited hybrid properties for gaining either homogeneous dispersion or material stability, which are sufficiently accommodating for surface interactions for the catalytic process [147][148][149][150]. The immobilized Co 2+ and Sn 2+ have been proven as successful catalysts for dye oxidation.…”

Preparation of α-MoO3 from H3PMo12O40 precursor: synthesis of 1,2-cyclohexanediol from cyclohexene over α-MoO3-TiO2 catalyst

“…The partial oxidation of saturated and unsaturated hydrocarbons is a very important process in organic synthesis due to the importance of the products obtained as valuable commercial intermediates [1][2][3][4][5]. Among the unsaturated hydrocarbon compounds, cyclohexene has been the subject of great attention leading to many industrial applications [6]. It is a cheap chemical, an easily obtained raw material and can be oxidized into various oxygenated chemicals which are important intermediates for the production of drugs, pesticides, spices, surfactants, chemicals and polymers [7,8].…”