Microcalorimetric adsorption and infrared spectroscopic studies of Ksingle bondNi/MgAlO catalysts for the hydrogenation of acetonitrile

Ni/MgAlO and K2CO3single bondNi/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, H2, 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 Hsingle bondNi 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 Ctriple bond; length of mdashN, leading to the formation of surface species Nisingle bondNdouble bond; length as m-dashCHsingle bondCH3 and Nidouble bond; length as m-dashNsingle bondCH2single bondCH3.