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 an emulsifier. The substrate is also subject to ultrasonic treatment, while treating the substrate in an aqueous solution preferably including a dispersant. The substrate is ultimately rinsed, for example in deionized water. During treatment with the emulsifier, the solution can be agitated, for example by air injection. Likewise, during the ultrasonic treatment the solution can be agitated mechanically. Optional embodiments include the addition of an alkali to the emulsifier 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.