Effect of MgO Addition on the Properties of Ni/Al2O3 and Its Catalytic Activity in Hydrogenation of N-(2′,3′-dimethoxy benzyl)-3,4-dioxy-methylene-phenylethylamine

the nickel based alumina-supported catalysts modified or promoted by magnesia were prepared by wet impregnation and successfully used for hydrogenation of N-(2',3'-dimethoxy benzyl)-3,4-dioxy-methylene-phenylethylamine, the 20Ni-6MgO/74Al(2)O(3) samples exhibits the highest BET surface area, the largest pore volume, and the largest pore diameter in all of the samples such as Ni/Al2O3 and 20Ni-xMgO(80-x)Al2O3 excepted the highest BET surface area of Ni/Al2O3. the average pore diameter of the 20Ni-6MgO/74Al(2)O(3) samples were two times as large as Ni/Al2O3, it was indicated that the function of expanding role or the mesoporosity was increased by addition of MgO, and MgO might be regarded as pore-enlarge agent for the bare Al2O3 support and benefit for the transport of large molecules reactants and products The weak formation of MgO-Al2O3 and MgO-NiO solid solution as a result of competing interaction of MgO with Al2O3 support and Ni0 precursors restrained the strong interaction of NiO species with Al2O3 support, which favored the dispersion of active Ni centers and improved the reducible degree of NiO species on the surface of the catalysts. The improvement of basicity or the decrease in the number of acid centers in the catalysts avoid the secondary reactions, and subsequently resulted in high catalytic activity. The utilization of meso-porous 20Ni-6MgO/7Al(2)O(3) for catalytic hydrogenation of N-(2',3'-dimethoxy benzyl)-3,4-dioxy-methylene-phenylethylamine(Shiff's base) with the highest selectivity of 99.70% and yields of 94.36% implied that the instead of Raney Ni was feasible.