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Size Selected Gold Cluster Supported Alumina as Catalyst in Reduction of 4-Nitrophenol to 4-Aminophenol |
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PP: 57-65 |
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Author(s) |
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Mostafa Farrag,
Samia Ibrahim,
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Abstract |
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| The catalytic activity of one-pot synthesis gold clusters protected by L-glutathione is studied. Different sizes gold clusters Au25(SG)18 and in average 1.5 nm and 3 nm Aun(SG)m are deposited over aluminium dioxide (Al2O3 Puralox SCCa-190HPV). The synthesized clusters on alumina (1% Aun(SG)m/Al2O3) were tested as new catalysts in reduction of 4nitrophenol (4-NP) in presence of aqueous NaBH4. The results showed that the 1% Au25(SG)18/Al2O3 catalyst exhibited the best catalytic performance in the reduction of 4-NP into 4-aminophenol (4-AP) and revealed 100% conversion following 2 min stirring at room temperature. The catalyst weight was used in this reaction 0.3 g/L. The particles sizes and optical properties of synthesized clusters were investigated by transmission electron microscopy and UV–vis spectroscopy, respectively. The catalytic reduction reaction of 4-NP were followed by UV–vis spectroscopy. N2 sorptiometry were used for the characterization of surface morphology, specific surface area SBET, pore volume and average pore diameter for synthesized clusters on alumina. The extreme catalytic activity of the small gold clusters attribute to their electronic properties. The partial positive charges of the surface gold atoms in the Au25(SR)18 clusters should facilitate the electron transfer from the negatively charged BH4− to 4-NP. |
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