Method of preparing solid contact materials

Claim 1

A process for preparing a porous solid contact material which comprises the steps of: a. immersing a porous solid inorganic hydrophilic carrier material in a polar organic presoak liquid such that said presoak liquid substantially completely fills the pores of the carrier material, said presoak liquid being capable of (1) wetting said carrier material and (2) displacement by the impregnating solution used in step (b) at a rate slow enough to permit control of the depth of impregnation; b. separating the carrier material from the presoak liquid and, without substantial removal of presoak liquid from the pores of said carrier material, immersing the separated carrier material in an impregnating solution containing a compound which is decomposable into a desired active material for a time sufficient to permit the impregnating solution to displace a portion of the presoak liquid and thereby penetrate the carrier material to a controlled depth, the depth of penetration being controlled by the time during which said separated carrier material is immersed in said impregnating solution at any given set of impregnating conditions; and c. separating the impregnated carrier material from the impregnating solution, drying the carrier material and converting the decomposable compound to the desired active material, thereby yielding a contact material having a core of substantially unimpregnated carrier surrounded by an outer zone of carrier having said active material deposited thereon.