We have developed a new synthesis strategy to prepare ∼5 nm metallic silver nanoparticles (AgNPs) supported on tungsten oxide (WO 3 ) nanorods with diameters between 40 and 60 nm in the presence of a cationic surfactant, cetyltrimethylammonium bromide (CTAB). The catalyst was characterized by XRD, XPS, ICP-AES, FT-IR, Raman spectroscopy, EXAFS, SEM and TEM. The catalyst is very effective in liquid phase oxidation of cyclohexene to adipic acid with hydrogen peroxide as an oxidant. The synergy between the surface AgNPs and WO 3 nanorods plays the most vital role towards this very high catalytic activity. The reusability of the catalyst which is a prerequisite for practical applications was analysed and it was found that the catalyst exhibits no significant changes in its catalytic activity even after five cycles of reuse. A cyclohexene conversion of >99.9% with an adipic acid selectivity of ∼94% was achieved over ∼5 nm AgNPs supported on the WO 3 nanorod catalyst with a very high turnover frequency of ∼12 h −1 . † Electronic supplementary information (ESI) available. See
A facile hydrothermal synthesis method is developed to prepare CuCr 2 O 4 spinel nanoparticle catalysts with sizes between 25-50 nm. A detailed characterization of the material was carried out by XRD, ICP-AES, XPS, EXAFS, SEM, TEM, and TGA. XRD revealed the formation of a CuCr 2 O 4 spinel phase and TEM showed the that particles size was 20-50 nm. The catalyst was highly active for the selective oxidation of benzene to phenol with H 2 O 2 . The influence of reaction parameters such as temperature, solvent, substrate to oxidant molar ratio, reaction time, etc. were investigated in detail. The reusability of the catalyst was tested by conducting the same experiments with the spent catalyst and it was found that the catalyst did not show any significant activity loss, even after 5 reuses. A benzene conversion of 72.5% with 94% phenol selectivity was achieved over this catalyst at 80°C. However, significant H 2 O 2 decomposition occurs on the catalyst, necessitating its usage in five-fold excess.
Here we demonstrate a simple and cost effective synthetic route for selective esterification of aldehydes with high productivity in the presence of molecular oxygen (O 2 ) on a gold supported lanthanum oxide (Au/La 2 O 3 ) nanoparticle catalyst. Au nanoparticles with sizes of 2−7 nm supported on 1D La 2 O 3 nanorods with diameters between 20 and 50 nm were synthesized by a room-temperature surfactantassisted single-step preparation method. The as-synthesized catalyst was thoroughly characterized by powder XRD, SEM, HR-TEM, H 2 -TPR, XPS, TGA/DTA, FTIR, BET, EXAFS, and UV−visible spectroscopy. This prepared nanostructured catalyst was found to be highly effective in the liquid phase synthesis of methyl methacrylate (MMA) via direct oxidative esterification of methacrolein (MA) with a high turnover number of ∼1136. The effect of various reaction controlling parameters like reaction temperature, pressure, and time of reaction was investigated and studied. High methacrolein conversion of 89% with high methyl methacrylate selectivity of 98% was attained without the use of any external additives. The synergistic effect between the surface AuNPs and La 2 O 3 nanorods plays an important role toward the activity of the catalyst.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.