Abstract: The present invention relates to a catalyst carrier characterized by the fact that it comprises a substance which promotes a transition of an alumina that can be converted to .alpha.-alumina, which substance is located near the surface of a carrier composed mainly of alumina and which carrier is subjected to a heat treatment under appropriate conditions, thereby causing the transition of said alumina to .alpha.-alumina, with those pores near the surface made larger in diameter than those pores located more deeply within the carrier. The invention also includes a method of manufacturing said catalyst carrier.

Abstract: A catalyst for purifying exhaust gases, comprising a carrier composed mainly of active alumina, containing near its surface a component to promote the transformation of active alumina to .alpha.-alumina when said carrier is subjected to a heat treatment in order to make the diameters of the pores near its surface larger than those of the pores in its interior, impregnated with an active catalytic component which permeates further into a portion of the interior deeper than the layer having the alumina transformation-promoting component.

Abstract: The present invention relates to a catalyst carrier characterized by the fact that it comprises a substance which promotes a transition to .alpha.-alumina, which substance is located near the surface of a carrier composed mainly of alumina and which carrier is subjected to a heat treatment under appropriate conditions, thereby causing the transition of said alumina to .alpha.-alumina, with those pores near the surface made larger in diameter than those pores located more deeply within the carrier. The invention also includes a method of manufacturing said catalyst carrier.