There is provided a substrate (1) capable of carrying uniformly dispersed, finely divided, particulate, solid particles, e. g., catalyst particles (10) and sustaining temperatures in excess of 1200 degrees F. The substrate comprises a top layer (2) for containing the particles (10) and composed of quartz fibers (4) with an average diameter of between about 0.1 and 4 microns and about 0 to 13% of microglass fibers having a softening point of about 1000 degrees F. A support layer (3) is composed of the fibers of the top layer and, in addition, bulk refractory, e. g., ceramic, fibers (6) having and average diameter of about 1 to 4 microns and 0 to 50% of chopped e-glass fiber (7). A method for producing the substrate is provided that includes wet laying the top and bottom layers in spaced apart times so that the juncture (8) between the two layers has intermingled fibers whereby the consolidated layers are not easily separated.