Characterization of ex Situ Presulfided Ni/Al₂O₃ Catalysts for Pyrolysis Gasoline Hydrogenation

Author： Hoffer B.W. Devred F. Kooyman P.J. van Langeveld A.D. Bonné R.L.C. Griffiths C. Lok C.M. Moulijn J.A.

ISSN： 0021-9517

Source： Journal of Catalysis, Vol.209, Iss.1, 2002-07, pp. : 245-255

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Abstract

Partially sulfided oxidic as well as reduced and passivated Al₂O₃-supported nickel catalysts for pyrolysis gasoline hydrogenation were successfully prepared by ex situ presulfidation with di-tert-butyl polysulfide followed by in situ reduction. The catalysts were characterized by temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The Ni particles in the catalysts are covered with a limited amount of sulfur, which depends on the sulfur loading. Complete saturation of the Ni monolayer has been reached between 1.0 and 2.0 wt% S, corresponding to a S/Ni_surf atomic ratio of 0.2–0.5. From TPD and extraction experiments it was inferred that the excess of sulfide, exceeding monolayer coverage, is weakly bound to the support. The high dispersion of the catalysts was maintained during sulfidation. TPR showed that the presulfided oxidic catalysts can be activated (by reduction) at lower temperatures (ΔT=150 K) than the nonsulfided oxidic catalyst. This eliminates the intermediate reduction and passivation procedure, resulting in more efficient catalyst activation procedures. © 2002 Elsevier Science (USA).