Enhanced catalytic activity towards formaldehyde oxidation over Ag catalysts supported on carbon nanotubes

Abstract

In this paper, highly active Ag catalysts supported on carbon nanotubes (CNTs) were synthesized by impregnation and two kinds of simple one step co-reduction methods with reducing agents of glycerol and dimethyl sulfoxide (denoted as IM, GL and DMSO sample). The catalysts were characterized by N2 adsorption–desorption, X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy, transmission electron microscopy, UV–visible spectrometer, infrared spectrometry, X-ray photoelectron spectroscopy (XPS) and H2 temperature programmed reduction (H2-TPR). DMSO sample showed the high reaction activity, above 90% HCHO conversion at 150 °C, whereas its surface Ag content is only less than ten times of IM sample in DMSO sample. The XRD, SEM, BET analysis, XPS and H2-TPR results revealed that the highly dispersed Ag/CNTs prepared by chemical reduction method in DMSO sample showed a smaller silver particles size, high surface areas and the enriched surface oxygen species. In general, the highest activity of DMSO samples in HCHO oxidation was associated with its higher silver dispersion and the strong interaction between Ag and CNTs, thereby increasing the effectiveness of oxygen mobility.