Phosphorus-Compound Effects on Catalyst Deterioration and Remedies

The effects of catalyst poisoning by phosphorus contained in engine oil and the associated parameters were investigated using catalysts aged in vehicles. The investigation revealed that automobile catalysts were suffering phosphorus poisoning via commercial SE engine oils, and a primary factor for that was glassy-surface phosphorus deposits on catalyst. The glassy surface was found attributable to catalyst temperature rise and formation of deposits which sinter at low temperatures (high phosphorus content). These parametric studies along with research for preventing deposit vitrification led to development and commercial realization of low-poison engine oils.