The Influence of Residual Chlorine on Pt/Zeolite Y/γ-Al2O3 Composite Catalysts: Acidity and Performance

In previous studies H2PtCl6 center dot 6H(2)O or Pt(NH3)(4)(NO3)(2) were used to control the location of Pt nanoparticles in Zeolite/gamma-Al2O3 composites for the synthesis of metal-acid bifunctional catalysts. Use of H2PtCl6 center dot 6H(2)O led to Pt nanoparticles located on the gamma-Al2O3 binder, in a 'nanoscale' intimacy with zeolite acid sites being beneficial for performance in the conversion of hydrocarbons, compared to catalysts with Pt nanoparticles located in zeolite Y ('closest' metal-acid intimacy) obtained by use of Pt(NH3)(4)(NO3)(2). A side effect of using H2PtCl6 center dot 6H(2)O was a higher NH3 uptake in NH3-TPD experiments, that suggested a higher acidity possibly affecting catalysis. In this study the effect of residual chlorine on Pt/Zeolite Yty-Al2O3 catalysts (0.1-0.6 wt.% Cl) was investigated by (pyridine) FTIR, NH3 -TPD and n-alkane hydro-isomerization. The coordination of chlorine to gamma-Al2O3 was observed and led to a higher NH3 uptake, but no effect of chlorine on the catalytic performance of the catalysts was detected.