Regeneration of Aged Commercial Three-Way Catalytic Converters

Abstract

The present work demonstrates for the first time that rejuvenation of the catalytic activity of full-scale aged commercial three-way catalytic (TWC) converters is feasible after treatment with weak oxalic acid solution (0.1 M). Up to 50% reduction in CO, 75% in NO x and 32% in HC emissions was attained under warm engine driving conditions following regeneration of three aged TWC converters with 42,500, 156,000 and 165,000 km mileage. Efforts to expand the durability of aged commercial TWC converters installed in gasoline-driven cars after applying specific treatments with weak oxalic acid-based solutions appear to be a very promising starting point in recovering to a very large degree their performance.

Regeneration of three-way automobile catalysts using biodegradable metal chelating agent—S, S-ethylenediamine disuccinic acid (S, S-EDDS)

“…The increase in the BET surface area after washing was attributed to the uncovering of the pores and it was found that oxalic acid was more effective than citric acid [10]. The uncovering of pores results in regaining catalytic activity due to exposing more active sites that are responsible for CO and NO conversions [35,36]. It appears that the EDDS washing method fails to retrieve the large surface area and pore volume loss (around 50% loss) obtained after aging under real driving conditions and is probably the result of severe thermal sintering as reported [37].…”