Ni/MgAlO and K2CO3 Ni/MgAlO catalysts for the hydrogenation of acetonitrile to primary amine were studied. Microcalorimetric measurements and infrared spectroscopy were used to study the adsorption of CO, H-2, acetonitrile, and ethylamine onto the catalysts. It was found that the addition of K2CO3 led to an increase in the heat of adsorption of CO on Ni, due to increased surface electron density of Ni. The presence of K2CO3 weakened the strength of H-Ni and strengthened the bonding of CH3CN onto Ni by changing adsorptive states of CH3CN, which might be two main reasons for the decreased activity of Ni doped with K2CO3. Furthermore, the addition of K2CO3 decreased adsorptive strength of ethylamine on Ni, resulting in an increase in ethylamine selectivity. Finally, infrared spectra of CH3CN adsorbed onto the Ni surface with preadsorbed hydrogen indicated that the hydrogenation might occur preferentially on carbon atoms in C equivalent to N, leading to the formation of surface species Ni-N=CH-CH3 and Ni=N-CH2-CH3. (C) 2012 Elsevier Inc. All rights reserved.