Low-temperature complete oxidation of BTX on Pt/activated carbon catalysts

The catalytic destruction of volatile organic compound (VOC) benefits from a low oxidation temperature due to less energy consumption. In this study, activated carbon-supported Pt catalysts were prepared for benzene, toluene and xylene (BTX) deep oxidation at below 200 degreesC. Activated carbon can serve as a media for concentrating VOC. The carbon supports were heated to 400 or 800 degreesC under N-2 how and washed with HF acid to remove surfac e impurities and/or minerals. The similar to0.3 wt.% Pt/activated carbon ca talysts were prepared by the incipient wetness method, followed by H-2 redu ction at 300 degreesC for 2 h. The catalytic oxidation was conducted with a BTX concentration ranging from 640 to 2000 ppmv in air at volume hour spac e velocity (VHSV) of approximately 21 000 h(-1). The light-off curves were very steep and the light-off temperatures ranged between 130 and 150 degree sC, well below those of the Pt/Al2O3 catalyst. The oxidation activity was p romoted because of a higher surface BTX concentration due to the adsorption capability of activated carbons. Moisture reduces the activity only slight ly due to the hydrophobicity of activated carbon. Generally, the Pt catalys ts with thermally-treated activated carbon had lower ignition temperatures. Experimental results indicated that high-temperature pretreatment of activ ated carbon could effectively increase the catalyst activity. Meanwhile, X- ray photoelectron spectroscopy (XPS)/secondary ion mass spectroscopy (SIMS) investigation revealed that the graphitized surface might play a role in c atalytic activity. Finally, this work suggested a reaction mechanism based on the adsorption-migration of hydrocarbons to reveal the enhanced activity of activated carbon support. (C) 2000 Elsevier Science B.V. All rights res erved.