PtNi catalysts prepared via borohydride reduction for hydrogenation of benzene

Pt/Ni supported on silica catalysts were synthesized via co-impregnation (CI) and step-impregnation (SI) techniques using NaBH4 as the metal ions reducing agent. They were characterized by H-2-TPR and H-2-TPD, XRD, TEM, SEM and EDSX analyses as well as tested for the hydrogenation of benzene. The preparation method employed facilitates the formation of totally reduced pure metal or bimetallic metal particles on the surface and catalytic properties are governed by both the Pt/Ni ratio and mode of preparation. Co-impregnated catalysts exhibit a synergistic effect when a moderate amount of Pt is available: Pt55Ni45-Cl catalyst was more active than both the pure monometallic catalysts. XRD and SEM equipped with EDSX lead us to believe that alloying occurs in the catalyst. Furthermore, surface segregation of Pt on the alloys as proven by XPS also contributes to this enhanced reactivity. In contrast to co-impregnated catalyst, all the step-impregnated catalysts show low catalytic reactivity when compared to pure Pt. (C) 2009 Elsevier Inc. All rights reserved.