Inside the converter, catalysts are grouped in one or more separated layers. The catalytically active centers are exposed on the surface of these elements.

Their shape features many parallel channels which results in a very high surface area. The activity of catalysts is linked directly to the size of their surface.

Due to their shape the elements are often called honeycombs.

Under certain circumstances soot, dust and ashes may accumulate at the entry side of the catalysts. In such cases the dust blowing system will keep the catalysts clean by emitting shock waves periodically.