A simple synthesis of catalytically active,high surface area ceria aerogels

A simple synthetic route for preparing high surface area, structurally stable ceria aerogels is presented. Ceria aerogels were doped with 1% palladium: a water-gas shift (WGS) active metal. A reduced Pd/ceria aerogel and an as-prepared Pd/ceria aerogel are compared to determine the effect of pretreatment conditions on WGS activity. The BET surface area of the as-prepared ceria aerogel was 345 m²/g. CO chemisorption data and high-resolution TEM images indicate that the particle size of palladium on the reduced Pd/ceria sample was approximately 15 nm. X-ray photoelectron spectroscopy (XPS) data establish that the fraction of Ce³⁺ from Ce₂O₃ was approximately the same for both reduced and as-prepared samples. XPS data also indicate that approximately 44% of the palladium on the reduced Pd/ceria sample was converted to the metallic form. Each catalyst was tested for WGS activity. The reduced Pd/ceria sample exhibited the greatest WGS activity as compared with the other samples used in this study.