Formaldehyde Oxidation over Emission Control Catalysts

SCR and PGM-based oxidation catalysts are highly active for formaldehyde (HCHO) oxidation and removal. When designing a catalyst system for emissions control on a natural gas firing engine, it can be necessary, under certain conditions, to account for the inhibition effect of unburned hydrocarbons (i.e., alkenes and alkanes) on the HCHO oxidation rate. This paper will present experimental results that demonstrate that this apparent inhibition effect is due to the catalytic partial oxidation of these unburned hydrocarbons to HCHO as a primary product. This HCHO formation pathway, which can have an appreciable effect on the catalyst’s net removal efficiency for formaldehyde, needs to be accounted for in the catalyst system design to assure emissions compliance.