The synthesis, characterization and application of Ag–SiO 2–Al 2O 3 sol–gel composites

Abstract

A new type of tertiary Ag–SiO 2–Al 2O 3 sol–gel composite with various silver concentrations has been prepared and characterized using combined spectroscopic techniques of XRD, XPS, TPR, UV–VIS, DRS and SEM. It was found that the homogeneous Ag–SiO 2–Al 2O 3 glass composites with transparent appearance could be obtained when the silver content is controlled below 20 wt.%. The silver ion species are found to be highly dispersed in the framework of the glass composites and exhibited a unique thermal stability in air. In addition, the use of the Ag–SiO 2–Al 2O 3 sol–gel composite material as promising silver catalysts for the catalytic oxidation of methanol to formaldehyde was demonstrated.