Catalytic Decomposition of Low-Level Ozone by Au/AC Prepared by a Sol Immobilization Method

Highly dispersed gold nanoparticles were supported on coal-based activated carbon by the sol immobilization method,and their catalytic activity for low-level ozone decomposition at ambient temperature was investigated.Nitrogen adsorption-desorption,scanning elec-tron microscopy,and X-ray photoelectron spectroscopy were used to characterize the catalysts before and after ozone decomposition.The results showed that the supported gold nanoparticles prepared by the microwave heating method were much smaller and more uniformly dispersed on the activated carbon than those prepared by the traditional conduction heating method,exhibiting higher catalytic activity for ozone decomposition.The pH value of gold precursor solution significantly influenced the catalytic activity of supported gold for ozone decomposition,and the best was at pH = 8.Decreasing gas space velocity and correspondingly extending contact time between ozone and catalyst can improve the catalytic activity for the reaction.In the case of space velocity at 120 000 h-1,the ozone removal ratio of the catalyst after treating about 1 g ozone decreased to 78.6%,while it kept at 93.3% after treating 1.25 g ozone in the case of space velocity at 60 000 h-1.After ozone decomposition,the surface carbon of the catalyst was partly oxidized and the oxygen content accordingly increased,while its specific surface area and pore volume only decreased a little.Ozone was mainly catalytically decomposed by supported-gold itself.