Nickel and nickel-magnesia catalysts active in the hydrogenation of 1,4-butanedinitrile

Several NiO-MgO systems were synthesized to be studied as nickel catalysts for the hydrogenation of 1,4-butanedinitrile in the gas phase and compared with a bulk NiO of controlled morphology, All samples were characterized by XRD, BET, TPR, TPD, SEM, and H-2 chemisorption techniques. The Ni-MgO syst ems had higher activities than the Ni bulk catalyst. The most active cataly st at all reaction temperatures was type R4C(B) which had homogeneous parti cles of about 1000 Angstrom, the highest metal surface area, and the highes t coverage with weakly bound hydrogen. The presence of basic magnesia suppr esses the condensation reactions and consequently favors the elimination of amines, and prevents catalyst deactivation. The selectivity toward the dif ferent products not only depends on the catalytic properties but can also b e modified by controlling the hydrogen/dinitrile ratio. The highest selecti vity to 4-aminobutanenitrile was achieved by catalyst R4C(B), with 85% at 1 00% conversion and working at a space velocity of 13,000 h(-1) and 343 K. T his selectivity could be increased by lowering the hydrogen/butanedinitrile ratio. (C) 2001 Academic Press.