Catalytic converters for motor vehicle, gasoline-fueled, internal combustion engines must be designed to have a relatively long, trouble-free life and yet be capable of mass production at a low cost. They contain catalyst substrates formed of refractory materials that have a low coefficient of thermal expansion and are relatively brittle. The housing for the catalyst element is composed of metal having a relatively high coefficient of expansion compared to the refractory and the temperature differential between the metal and refractory can vary from zero to over 1000.degree. F. This large differential in combination with the very different rates of expansion creates difficult problems in properly mounting the catalyst element. On the one hand it is necessary to avoid clearance that would permit the catalyst element to move and be cracked, chipped, or extruded. On the other hand, it is also necessary to avoid interference which could cause the catalyst element to be cracked or crushed thereby leading to clearance and associated damage.
In addition to troublesome thermal conditions, the conditions under which a motor vehicle is operated can cause mechanical damage to an improperly mounted monolithic refractory catalyst element. Constant or excessive vibration, shock loads, etc., occur regularly in driving and it is necessary to insulate the catalyst element from them.
Further, in manufacturing, storage, installation, and general handling, the converter is likely to be dropped or thrown around in such a way as to be subjected to severe shock loads that are capable of damaging the brittle refractory.
These problems must be solved by practical means that can be incorporated in a converter capable of mass production.