Effect of residual Cl- derived from metal precursors on catalytic activity in the hydrogenation of naphthalene over supported Pd catalysts

Hydrogenation of naphthalene was performed over supported Pd catalysts prepared from precursors that contained Cl- and from precursors that were free of Cl-. The activity of catalyst prepared from PdCl, was much higher than that prepared from Pd(NH3)(2)(NO2)(2). The species of Pd precursor strongly affected the activity of Pd/Al2O3, whereas no significant influence was observed in the effect of Pd/SiO2, because residual Cl- was easily removed by calcination and/or reduction. Catalytic activity was increased by addition of NH4Cl to Cl--free Pd/Al2O3. Residual Cl- was concluded to enhance the catalytic activity of the supported Pd catalysts. (C) 2002 Elsevier Science B.V. All rights reserved.