| 摘要 |
A catalytic exhaust emission control device has a support which consists of a high-temperature resistant material and on its surfaces contacting the exhaust gases has a coating containing a catalytically active material. The coating has a surface area of at least 40 m<2>/g, preferably at least 75 m<2>/g, and an average pore diameter of at least 100 ANGSTROM , at least 75% of the surface area being present in pores having a diameter of above 100 ANGSTROM . The coating consists of aggregate particles having a coherent three-dimensional network structure and/or of colloidal particles, the catalytically active material being carried by these aggregate particles and/or colloidal particles. In the making of the catalytic exhaust emission control device, the catalytically active material or precursor thereof is concentrated in the coating of the catalyst support. This concentration may be achieved in that the aggregate particles and/or the colloidal particles by a sol or suspension technique or an emulsion technique are provided with a surface coating of the catalytically active material or a precursor thereof. In this manner, the catalytic exhaust emission control device will have a very large accessible surface of catalytically active material per unit of weight. |
