UV-assisted functionalization of carbon nanotube for synthesis of efficient desulfurization catalysts (NH2/COOH)-MWNT/MoO3

Abstract

In this study, multiwall carbon nanotubes (MWNTs) surface was directly functionalized with the -NH2 and -COOH groups via radical media by using the UV light radiation at room temperature. For this purpose, the suspension of CNTs and solution of functional groups (NH4OH and H2O2) irradiated by UV light at varying exposure duration and light intensity. The photo-functionalized CNTs were characterized by FT-IR, Raman, TGA, XRD, SEM, and XPS analysis. Consequently, the functionalized CNTs are used to synthesize the grafted MoO3 catalysts. CNT/MoO3 catalysts were prepared using oxodiperoxo molybdenum complex and were characterized by XRD, FTIR, SEM, TEM, and TGA analysis. Then the efficient synthesized catalysts were evaluated in oxidative desulfurization of a model fuel in the presence of H2O2 as an oxidant. These works indicated that the activity of catalysts can be improved by using functionalized CNTs/MoO3 hybrids under mild condition. The best DBT conversion obtained in the presence of acetonitrile as extractive solvent. The sulfur removal can be enhanced by using the catalyst containing carboxyl functional groups. According to the mechanism, it seems that the higher electron density in peroxo group of O-MWNT/MoO3 catalyst can increase the DBT conversion compared to N-MWNT/MoO3 catalyst with amino groups.