A method of forming a catalytic region on a porous structure having an exterior surface and a plurality of pores, the method comprising: forming a supercritical dispersion, wherein the supercritical dispersion comprises a plurality of particles dispersed in a supercritical fluid; exposing the porous structure to the supercritical dispersion; and depositing the plurality of particles from the supercritical dispersion onto the porous structure, wherein each one of the deposited plurality of particles is catalytic, thereby forming one or more catalytic regions on the porous structure. The method is particularly well suited for creating catalytic regions within pre-formed microporous structures.