Résumé
A Ni/Mg(Al)O catalyst was obtained from a composite NiMgAl lamellar double hydroxide precursor. This material was tested in the gas-phase hydrogenation of acetonitrile between 353 and 423
K, after calcination and reduction at various temperatures. The highest selectivity to monoethylamine, 94.6% at 47% reactant conversion, was reached after calcination at 623
K and reduction at 723
K. FTIR spectroscopies of adsorbed CD
3CN and CO were carried out on the reduced sample. The adsorption of CD
3CN provided evidences that the acidity of Ni/Mg(Al)O was the lowest after calcination at 623
K and reduction at 723
K. Depending on the activation treatment, the
ν
CO of (Ni)
x
CO, at low CO coverage, took different values reflecting some modifications of the Ni
d-band. The increased selectivity in monoethylamine in the hydrogenation of acetonitrile on Ni/Mg(Al)O was correlated with the decrease of acidity of the sample, and not with a modification of the electronic properties of Ni. The decrease of the acidity of the support lowered the acid-catalysed transamination reaction leading to secondary and tertiary amines.