Synthesis and characterization of nanosilver catalysts supported on the nitrogen-incorporated-SBA-15 for the low-temperature selective CO oxidation

Abstract

Nitrogen-incorporated molecular sieve materials were obtained by the modification of SBA-15 with NH3 under different nitridation temperatures, and the as-prepared SBA-15-N materials were used as supports for the nanosilver catalysts by the impregnation method. Some technologies such as transmission electron microscope, elemental analysis, X-ray photoelectron spectroscopy, physical adsorption–desorption of nitrogen, carbon dioxide temperature programmed desorption and X-ray diffraction were used to characterize the structure of the supports and nanosilver catalysts. The selective CO oxidation reaction was carried out to investigate the catalytic activity and selectivity of the silver catalysts Ag/SBA-15-N under low temperature from 25 to 65 °C, and the stability of Ag/SBA-15-N-1000 catalyst was also tested under 55 °C for 15 h. The results suggested that the nitrogen content of the SBA-15-N material was increased with the increasing of nitriding temperature. When the nitriding temperature was kept at 1000 °C for 20 h, the nitrogen content of the SBA-15-N support could reach to 13.7 %, and the CO conversion and the CO2 selectivity of Ag/SBA-15-N-1000 catalyst were both better than those of Ag/SBA-15 catalyst without nitridation treatment, respectively. This might be due to the –NHx groups in the SBA-15-N skeleton, which led to the strong interaction between –NHx groups and silver particles and gave rise to a good dispersion of nanosilver particles to the channels of SBA-15-N support.