Carbon nanotubes containing oxygenated decorating defects as metal-free catalyst for selective oxidation of H2S

In this study, we report on the influence of gaseous HNO3 treatment, with various time and temperature, on the creation of defects decorated with oxygenated functional groups on the CNTs side-wall. The gaseous acid treatment leads to a significant increase of the oxygenated functional groups and defects on the tube wall along with a specific surface area improvement. The as-synthesized catalyst was further used as a metal-free catalyst in the selective oxidation of H2S in the waste effluents. According to the results the defects decorated with oxygenated groups are extremely active for performing partial oxidation of H2S into elemental sulfur. The desulfurization activity is extremely high and stable as a function of time on stream which indicates the high efficiency of these oxidized un-doped carbon nanotubes as metal-free for the selective oxidation process. The high catalytic performance was attributed to both the presence of structural defects on the carbon nanotubes wall which acting as a dissociative adsorption center for the oxygen and the oxygenated functional groups which could play the role of active sites. (C) 2016 Elsevier B.V. All rights reserved.