A catalyst classifiable under 3815 must be a preparation—meaning it is formulated or supported for catalytic use rather than being a chemically defined pure substance. A pure platinum sponge, for example, stays in Chapter 28, while platinum deposited on an alumina carrier for refinery use falls under 381512. The preparation character and the presence of a support material are the decisive factors.

Spent catalysts containing platinum-group metals may be subject to export controls, hazardous-materials shipping regulations, and contractual precious-metal accounting requirements. Importers and exporters should verify whether the spent material is classified as a waste or as a recoverable commodity, as that determination affects both the HTS classification and any applicable EPA or DOT requirements.