Catalytic hydrogenation of nitrate on Cu-Pd supported on titanate nanotube and the experiment after aging, sulfide fouling and regeneration procedures

摘要

Although catalytic nitrate reduction is efficient for water treatment, catalysts are sensitive to other components in the environment. In this study, the catalytic performance of Cu-Pd/TNTs (palladium-copper/titanate nanotubes) toward nitrate reduction was investigated for their nitrate reduction ability in CO2-saturated condition. The inhibiting effects due to catalyst aging and sulfide fouling were also investigated. The results showed that TNTs-supported bimetallic catalysts were more resistant to catalyst poisoning than TiO2-supported ones. This could be due to the fact that the specific geometry of TNTs shelter bimetallic catalyst from oxidation as the valence state of the catalysts is evidenced by the XPS analysis. Regarding the regeneration methods, Cu-Pd/TNTs showed higher nitrate reduction rates than Cu-Pd/TiO2 after aging, sulfide fouling and regeneration procedures. The valence state of the catalyst analyzed by XPS revealed that metals on the TNTs were slightly more oxidized than metals on TiO2. Therefore TNTs can prevent the supported metals from being oxidized. Moreover, heated NaBH4-saturated nitrogen gas (403 °K) could effectively revive the nitrate reduction rates of sulfide-fouled catalysts.