CO and C3H8 total oxidation over Pd/La-Al2O3 catalysts： Effect of calcination temperature and hydrothermal treatment

A series of Pd/La-Al2O3（PLA） catalysts with La-Al2O3（LA） support calcined at different temperatures（500, 700, 900 and 1050 oC） were prepared using an incipient wetness impregnation method. The activity of the fresh and hydrothermally aged PLA catalysts were tested for total oxidation of CO and C3H8. The activity of the fresh PLA catalysts for CO and C3H8 oxidation increased with increasing calcination temperature of the support, while the activities of the aged catalysts declined and became essentially the same. CO chemisorption results revealed that the suppressed activities of the aged catalysts were mainly due to the decline of palladium dispersion. The turnover frequency（TOF） of CO oxidation increased with increasing reduction ability of the catalysts, with a fresh catalyst calcined at 1050 oC having the highest value（0.048 s–1）. However, the TOF of C3H8 total oxidation was affected by not only the redox properties of catalysts but also the size of Pd particle, and large Pd particles possessed higher TOF value of C3H8 oxidation, with the highest value（0.125 s–1） being obtained on an aged catalyst calcined at 500 oC.