Highly Selective Amination of o- and p-Alkyl Phenols over Pd/Al2O3-BaO

A series of Pd-based catalysts were prepared and examined for the amination of 2,6-dimethylphenol in a fixed-bed reactor. The best results were obtained for Pd/Al2O3-BaO with a conversion of 99.89% and a selectivity of 91.16%. These catalysts were characterized using BET, XRD, XPS, TEM and NH3-TPD. Doped BaO not only improved the dispersion of the Pd particles but also decreased the acidity of the catalyst, which remarkably enhanced the selectivity and stability of the catalyst. The generality of Pd/Al2O3-BaO for this kind of reaction was demonstrated by catalytic aminations of o- and p-alkyl phenols.