Improved ceramic coating for a catalyst support.

摘要

In a preferred method, particles of amorphous silica are used to provide a silica coating suitable for carrying thereon dispersed catalyst particles for the treatment of diesel engine exhaust emissions. The silica coating is formed from a mixture consisting essentially of two groups of the fine silica particles of respective average sizes and size ranges which are substantially non-overlapping. The particles of the first of the two groups have a first average size sufficient to permit the particles of the first group (smaller particle size group) to occupy voids between the particles of the second group (larger particle size group) in a packed arrangement, and the second group has a second average particle size which is at least 20 times greater than the first average particle size. Although particles of amorphous silica are preferred for use in forming a coating with improved adherence suitable for the treatment of diesel exhaust, the method of the invention could also be useful to improve the adherence of coatings formed of other ceramic materials, such as alumina, titania, zirconia and zeolite.