PARTIAL HYDROGENATION OF CYCLOPENTADIENE OVER AMORPHOUS NIB ALLOY ON ALPHA-ALUMINA AND TITANIA-MLODIFIED ALPHA-ALUMINA

Amorphous nickel-boron alloys supported on alpha-alumina (NiB/Al2O3) a nd on titania-modified alpha-alumina (NiB/TMA) with titania loadings r anging from 1.25 to 10 wt% were prepared by a reductive impregnation m ethod, which resulted in a highly dispersed NiB amorphous alloy on the support. When used as catalysts for partial hydrogenation of cyclopen tadiene to cyclopentene in a flow fixed-bed reactor at atmospheric pre ssure, the NiB/Al2O3 showed higher activity than Ni/Al2O3 and Pd/Al2O3 but the NiB/TMA with 5 wt% of titania loading (NiB/TMA5) showed the h ighest activity of all for the production of cyclopentene in a tempera ture range of 80-200 degrees C with 10 g gcat(-1) h(-1) of cyclopentad iene feed. The maximum yield of cyclopentene was 97% on NiB/TMA5, 92% on NiB/Al2O3, 60% on Ni/Al2O3 and 23% on Pd/Al2O3, respectively. The c atalytic stability of the amorphous NiB/TMA5 was also excellent with t ime on stream. The catalyst samples were characterized by ICP, XRD, XP S, BET, TEM and O-2 adsorption. The probable modification mechanism is discussed. (C) 1998 SCI.