Study on the deactivation of amorphous NiB/SiO2 catalyst during the selective hydrogenation of cyclopentadiene to cyclopentene

The deactivation of the silica supported NiB amorphous catalyst during the selective hydrogenation of cyclopentadiene (CPD) to cyclopentene (CPE) in a fixed-bed reactor was studied According to the characterizations of the initial and used catalysts by ICP, BET, SEM, XRD and XPS, no significant sintering of the active component or crystallization of the amorphous structure was observed, while severe surface oxidation occurred after the deactivation of the catalyst. Those results demonstrated that such a deactivation should mainly be attributed to the oxidation of the active component. Water promoted the deactivation because the surface oxidation of elemental Ni was accelerated by forming Ni(OH)(2) in the presence of water. The deactivation resulted from salification and carboneous species deposition was not observed in the present conditions, although it really occurred at high sulfur concentration and low CPD conversion. (C) 1998 Elsevier Science B.V.