Recycling can recover valuable metals such as platinum, palladium, and rhodium. Crushing breaks the ceramic substrate into small particles, making the precious metals adhered to it more readily available for subsequent refining processes.
Crushing the catalyst honeycomb is a critical step in catalyst recycling. Through a stepwise process—from coarse reduction to fine grinding and optional cryogenic processes—the ceramic substrate is converted into a fine powder. This facilitates the subsequent chemical extraction of the precious metals and thus contributes to a sustainable recycling process.
Mechanical crushing breaks the ceramic substrate into small particles, making the precious metals adhering to it more readily available for subsequent refining processes (e.g. hydrometallurgical or pyrometallurgical processing).
In some cases, comminution is carried out under cryogenic conditions (e.g., using liquid nitrogen). This reduces any heating of the material, which could lead to undesirable changes in physical properties and clumping.
These three platinum group metals are the main components of the monolith and, depending on the catalyst type, make up 1–10 g of precious metal per catalyst .
Special catalysts sometimes also contain iridium, ruthenium, osmium or rhenium, which can also be recovered if necessary.
The outer steel casing is melted down separately and recycled as scrap steel.
The ceramic honeycomb structure can be crushed in some processes and used as a filler or binder in ceramic products.
