oxidation catalyst a hydrocarbon trap catalyst or a selective catalytic reduction scr catalyst depending on the design intent moreover two or more types of catalyst 50 may be coated on the support 40 for example the lnt catalyst and the scr catalyst may be sequentially coated on the support 40 but the present disclosure is not limited thereto furthermore different types of catalyst 50 may be coated on one side and the other side of the support 40 also the catalyst 50 coated on the support 40 may be a different type from the catalyst 50 coated on the wall 30 meanwhile the support 40 is provided to hold the catalyst 50 in place rather than serving as a filter thus the support 40 is not necessarily made from a porous material that is the support 40 may be made from the same material as the porous wall 30 or a different material even in the case that the support 40 is made from a porous material exhaust gases mostly move along the support 40 and wall 30 without passing through the support 40 because there is little difference in pressure between the two parts of the channel 10 or 20 separated by the support 40 also the support 40 does not need to be thick since it is not required to serve as a filter that is the support 40 may be thinner than the wall 30 which minimizes an increase in back pressure for a support 40 made from a porous material the catalyst 50 is coated on the surface of the support 40 and on the micropores in the support 40 contrariwise for a support 40 made from a non porous material the catalyst 50 is coated on the surface of the support 40.