Selective Hydrogenation of Adiponitrile to 6-Aminocapronitrile over Ni/α-Al2O3 Catalysts Doped with K2O and La2O3

Abstract

A series of Ni/Al2O3, Ni/K2O-Al2O3 and Ni/La2O3-K2O-Al2O3 catalysts that possess high activities for partial hydrogenation of adiponitrile to 6-aminocapronitrile has been successfully synthesized by the impregnation method. The catalytic performance was investigated under atmospheric pressure and in the absence of ammonia and a significant enhancement in the activity after the introduction of potassium oxide and lanthana was observed. Aiming to study the influence of K2O and La2O3 promoters on the physicochemical properties, we characterized the catalysts by N2 adsorption/desorption, XRD, H2-TPR, H2-chemisorption, H2-TPD and TEM techniques. A combination of XRD, TEM and H2-chemisorption showed that Ni0 particles with a higher dispersion are obtained after the addition of La2O3. Compared with the Ni/Al2O3 catalyst, the Ni/La2O3-K2O-Al2O3 catalyst with an appropriate amount of promoter enjoys a more catalyst surface alkalescence, enhances the electronic density of nickel and higher dispersion of nickel and exhibits higher activity and 6-aminocapronitrile selectivity than Ni/α-Al2O3 during the hydrogenation of adiponitrile in the absence of ammonia, i.e., K2O and La2O3 improved the performance of the nickel-based catalyst.