Process for decoating a washcoat catalyst substrate

The invention relates to a process for decoating a used washcoat carrier substrate to produce a clean, inert carrier or substrate. In a preferred embodiment, a process according to the invention includes treating a washcoat catalyst substrate in an aqueous solution including a dispersant, an emulsifier, and at least one of an acid and a base. Alternatively, the first solution may include sodium hydroxide, sodium bicarbonate, or aluminum bicarbonate. The substrate is also subject to ultrasonic treatment, while treating the substrate in an aqueous solution preferably including a dispersant. The substrate may ultimately be rinsed, for example in deionized water. During treatment, solutions may be agitated, for example by air injection, directed stream of water or other agitation. Optional embodiments include heating prior to immersion, the addition of a solvent to solution; rinsing between steps, for example with DI water; treatment with acid to remove sodium before final rinsing, final rinsing in a cascade system, and drying.