CATALYST COMPOSITION AND STRUCTURE FOR A DIESEL-FUELED REFORMER CONFIGURED IN AN EXHAUST STREAM

摘要

The invention relates to catalysts comprising precious metals supported on La stabilized refractory metal oxides. The La is provided on the surface of the refractory metal oxide in an amount to form at least about a monolayer, preferably about 1 -2 mono-layers. Preferably, the La has no crystalline structure shown by X- ray diffraction. Nd and mixtures of La and Nd can be used in place of La. In one embodiment, the catalyst is a reforming catalyst comprising an effective amount of Rh on a ZrO2 support. Preferably, the Rh is provided in a relatively low concentration, typically about 0.5% or less based on the weight of the ZrO2 support. The inventors have found that if the Rh loading is kept sufficiently low, the Rh can be maintained in the form of small particles (less than 5 nm, typically about 2 nm or less) through lean rich cycling as a consequence of an effect involving the La.