Effect of the catalyst preparation method on the performance of Ni-supported catalysts for the synthesis of saturated amines from nitrile hydrogenation

• Published in: Chinese journal of catalysis 2019-11, Vol.40 (11), p.1693-1703
• Main Authors: Segobia, D.J., Trasarti, A.F., Apesteguía, C.R.
• Format: Article
• Language: English
• Subjects: Catalyst preparation; Ni-phyllosilicates; Ni-supported catalysts; Nitrile hydrogenation; Saturated amines
• ISSN: 1872-2067; 1872-2067
• DOI: 10.1016/S1872-2067(18)63179-1

The liquid-phase hydrogenation of butyronitrile to saturated amines was studied on silica-supported Ni catalysts prepared by either incipient-wetness impregnation (Ni/SiO2-I) or ammonia (Ni/SiO2-A) methods. A Ni/SiO2-Al2O3-I sample was also used. Ni/SiO2-I was a non-acidic catalyst containing large Ni0 particles of low interaction with the support, while Ni/SiO2-A was an acidic catalyst due to the presence of Ni2+ species in Ni phyllosilicates of low reducibility. Ni/SiO2-I formed essentially butylamine (80%), and dibutylamine as the only byproduct. In contrast, Ni/SiO2-A yielded a mixture of dibutylamine (49%) and tributylamine (45%), being the formation of butylamine almost completely suppressed. The selective formation of secondary and tertiary amines on Ni/SiO2-A was explained by considering that butylamine is not release to the liquid phase during the reaction because it is strongly adsorbed on surface acid sites contiguous to Ni0 atoms, thereby favoring the butylimine/butylamine condensation to higher amines between adsorbed species. Ni/SiO2 prepared by the ammonia method forms selectively secondary and tertiary amines from butyronitrile hydrogenation. The catalyst contains Ni0 nanoparticles in close contact with Ni+2 species in Ni phyllosilicates that favor the condensation reactions.