Abstract:

Palladium catalysts with different contents of palladium supported by activated Al2O3 were prepeared by means of ultrasonic impregnation to eliminate trace oxygen from hydrogen. The effects of the palladium content and the H2 space velocity on the O2 content after the reaction were then discussed. Moreover, the reaction region on the catalyst bed was detected by means of infrared thermal imaging. The results show that the conversion of O2 decreases with the increase of H2 space velocity, and that two inflection points occur at the H2 space velocities of 10 - 12s^{- 1} and 15 - 17s^-1, respectively, which become more acuate at a higher palladium content. It is thus concluded that the internal diffusion is the controlling step of the catalytic reaction, that the reaction is not sensititive to the palladium content more than 0. 20%, and that the catalytic reaction becomes more effective in the conditions of low palladium content, small catalyst particle size and large catalyst dosage.

Key words: palladium catalyst, hydrogen, oxygen, space velocity, diffusion