| dc.description.abstract | This research, Au/FeOOH, Au/CeO2,Au/TiO2 and Au/Al2O3 catalysts was prepared by using conventional deposition precipitation method with pre-adjusting the pH value of the initial solution, and gold was dispersed on a solid base of Mg2AlO hydrotalcite using a modified deposition precipitation method. To confer gold catalysts in nitrobenzene hydrogenation and in nitrostyrene selective hydrogenation,and the catalysts were characterized by XRD,TEM,XPS and CO2-TPD.
Gold catalysts can hydrogenate nitrobenzene to aniline in CXN solvent effectively. Among them, Au/FeOOH and Au/Al2O3 have found the best activity. Au/Mg2AlO have found the worst, the results were different from selective unsaturated aldehydes hydrogenation.
The activity of nitrobenzene hydrogenation was not depend on the ratio of Au3+/Au0 and particle size, the amount of lewis base sites were the main factor to affect the catalyst activity. Al2O3 support has found the most weak lewis base sites , so the best activity it was. Mg2AlO support has found the least weak lewis base sites, but the most strong base OH group. The weak lewis base site can help hydrogen dissociation to yield (Hδ+ ＆ Hδ-),it was good for hydrogenation, but strong base sites wasn’t.
Gold catalysts can hydrogenate nitrostyrene to vinylaniline effectivitly in CXN solvent. Au/FeOOH and Au/CeO2 have found the best activity, Au/Mg2AlO also the worst, the activity rank, except for Au/Al2O3, was mostly like nitrobenzene hydrogenation. The weak lewis base sites of the support were also the main factor of affecting nitrostyrene selective hydrogenation. The C=C double bond of nitrostyrene has the interfact with Al2O3, and affect the activation and absorption of nitro group.
Nitrobenzene hydrogenation, Au/Mg2AlO,Au/FeOOH,Au/TiO2 and Au/Al2O3 have found the better activity and selectivity in apolar solvent; The side product can be found in polar solvent, and the activity is lower. Au/CeO2 wasn’t like the other gold catalysts, it had the better activity in polar solvent. Nitrostyrene selective hydrogenation, the apolar solvent affected the direction of absorption, so the gold catalyst had the better activity in polar solvent.
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