Characterization of Ni, Mo and Ni-Mo catalysts supported on alumina-pillared α-zirconium phosphate and reactivity for the thiophene HDS reaction

A series of fluorinated alumina pillared a-zirconium phosphate supported with nickel, molybdenum and nickel-molybdenum sulfide catalysts was prepared in order to investigate the use of an alumina-pillared material, i.e., an alumina diluted within another inorganic matrix, as a support of sulfide catalysts. The catalysts were prepared by impregnation, with loadings of 4, 8, 12 wt.% of Ni; 13 wt.% of Mo and 2.1-9, 3-13 wt.% of Ni-Mo followed by calcination at 673 K. Sulfidation was performed at 673 K for 2 h. They were characterised by X-ray diffraction (XRD), temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The set of data indicated that in the Ni-based catalysts a fraction of the loaded Ni2+ interacts with the support and cannot be sulfided at 673 K. However, a total sulfidation of Ni2+ is reached in the NiMo-based catalysts. The Ni 2p(3/2) binding energy (B.E) of Ni-Mo sulfided catalysts shifted to higher values (> 1 eV) with respect to those observed in Ni-based catalysts suggesting the existence of different environments for Ni in these materials. The catalysts can be easily regenerated by treatment with 5% (v/v) O-2/N-2 mixture at 673 K without noticeable loss of activity. The catalysts exhibited a high activity and stability for thiophene HDS particularly the NiMo catalysts due to the promotion of Ni for Mo-based catalysts. (C) 1999 Elsevier Science B.V. All rights reserved.