Effect of preparation parameters on properties and performance of Pd/Al2O3 catalyst in saturation of olefins

The complete saturation of commercial olefin-containing (3.3 mol%) C-4 stream over Pd/gamma-Al2O3 catalysts was studied. The catalysts were prepared by wet impregnation of the support using acidified PdCl2 solutions. The effect of different preparation parameters such as HCl/PdCl2 ratio in impregnation solution, impregnation time and solution volume on palladium distribution and catalytic performance was investigated. The catalysts were characterized by N-2 adsorption/desorption, ICP measurements, X-ray diffraction, temperature programmed desorption of ammonia (NH3-TPD) and scanning electron microscopy. Catalytic performance tests were carried out in a three-phase co-current trickle-bed reactor at 50 degrees C, 27bar and high olefin conversions in accordance with industrial operating conditions. The catalysts showed different palladium distributions according to preparation procedure. The best performance was observed for egg-shell catalysts prepared by employing short impregnation times (5-10 min) and low competitor levels (HCl/PdCl2 = 2.2 mol mol(-1)) in impregnation solution. The catalyst lifetime was found to correlate with its activity which was explained by a parallel deactivation mechanism.