Disassembly of Small Engine Catalytic Converters and Analysis of Washcoat Material for Platinum Group Metals by X-Ray Fluorescence Spectrometry

The United States Environmental Protection Agency (U.S. EPA) National Enforcement Investigations Center (NEIC) has developed a test method for the analysis of washcoat material in small engine catalytic converters. Each small engine catalytic converter contains a metallic monolith. Each metallic monolith is removed from its outer casing, manually disassembled, and then separated into washcoat and substrate. The washcoat material is analyzed for platinum group metals (PGMs) using X-ray fluorescence (XRF) spectrometry. Results from the XRF analysis are used to calculate PGM ratios in the washcoat. During monolith disassembly, care is taken to minimize loss of washcoat or substrate, but some material is inevitably lost. The recovered washcoat mass does not necessarily equal the quantity of washcoat that was present in the intact catalytic converter. A maximum washcoat mass can be estimated by combining the masses of the recovered washcoat and the material loss during monolith disassembly. PGM concentrations, the recovered washcoat mass, the estimated maximum washcoat mass, and the monolith volume are used to calculate the PGM loading value range for the catalytic converter.