DeNOx catalysts for the reduction of NOx compounds and porous catalyst support materials are provided. The inventive catalysts comprise an active metal catalyst component and mixed TiO2/ZrO2 porous support particles that comprise a) a crystalline phase comprising titanium dioxide and/or a titanium/zirconium mixed oxide, b) an amorphous phase comprising zirconium, and c) a small amount of one or more metal oxide(s) or metalloid oxide(s) deposited on the amorphous outer layer. The inventive catalysts exhibit superior activity and ammonia selectivity.