Characteristics of the Pd-only three-way catalysts prepared by sol-gel method

Abstract

Pd-only three-way catalysts prepared by the sol-gel method were investigated by the three-way catalytic performance test with a simulated exhaust gas in a continuous U-tube quartz reactor at a gas hourly space velocity of 72 000 h(-1). The catalysts were characterized with XRD, XPS, BET surface area and pore volume. The activity and thermal stability of the Pd-Al2O3 catalyst prepared at pH 10 were superior to those at pH 4 during hydrolysis and condensation, which could be explained by the anchoring effect. Zr and V were found to be good promoters for the enhancement of the thermal stability and SO2\ resistance, respectively. Optimally formulated catalyst, Pd(1)-V(2)-Zr(10)-Al2O3, was thermally stable up to 900 degrees C and showed a much more improved low-temperature activity and excellent SO2 resistance. (C) 1999 Elsevier Science B.V. All rights reserved.