Ling-Yun Jin

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 °C) 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 °C 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 °C.

Sorption Properties of Ordered Mesoporous Silica for Toluene and Ethyl Acetate

The sorption properties of SBA-15 and MCM-41 for toluene and ethyl acetate were investigated by temperature programmed desorption (TPD) techniques and an analysis of breakthrough curves. The amount of toluene adsorbed onto SBA-15 was distinctly larger than that onto MCM-41, while the desorption temperature of toluene from the former was also higher than that from MCM-41. However, in the case of ethyl acetate, similar adsorption and desorption behaviours were observed on these two samples. The interaction between organic molecules and adsorbents was evaluated in terms of the affinity index. It was found that both SBA-15 and MCM-41 exhibited positive adsorption properties towards ethyl acetate but negative behaviours towards toluene. Compared to the MCM-41, the larger quantity of toluene retained by SBA-15 and the higher desorption temperature for toluene relative to MCM-41 were ascribed to the higher adsorption potential existing in the secondary pores of SBA-15.