Enhanced Stability of CaO and/or La(2)O(3) Promoted Pd/Al(2)O(3) Egg-Shell Catalysts in Partial Oxidation of Methane to Syngas

An egg-shell Pd/Al(2)O(3) catalyst showed higher activity than a regular Pd/Al(2)O(3) catalyst in the partial oxidation of methane to syngas, but a common problem of this reaction is the catalyst deactivation on stream. We attempted to modify the egg-shell catalyst via impregnation with some metal oxide additives. Although the addition of MgO did not show any beneficial effect, the addition of CaO and/or La(2)O(3) significantly improved the stability due to the suppression of carbon deposition and phase transformation of the Al(2)O(3) support. The catalysts were characterized by X-ray diffraction (XRD), N(2) adsorption-desorption, and thermogravimetric analysis (TGA).