Reactivation of an Aged Commercial Three-Way Catalyst by Oxalic and Citric Acid Washing
2006 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 40, 2030-2036 p.Article in journal (Refereed) Published
The efficiency of dilute oxalic and citric acid solutions on improving the oxygen storage capacity (OSC) and catalytic activity of a severely aged (83 000 km) commercial three-way catalyst (TWC) has been investigated. Washing procedures applied after optimization of experimental parameters, namely, temperature, flow-rate, and concentration of acid solution, led to significant improvements of OSC and catalytic activity (based on dynamometer test measurements) of the aged TWC. The latter was made possible due to the removal of significant amounts of various contaminants accumulated on the catalyst surface (e.g., P, S, Pb, Ca, Zn, Si, Fe, Cu, and Ni) during driving conditions, as revealed by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and X-ray Photoelectron Spectroscopy (XPS) analyses. For the first time, it is demonstrated that dilute oxalic acid solution significantly improves the catalytic activity of an aged commercial TWC toward CO, CxHy, and NOx conversions under real exhaust gas conditions (dynamometer tests) by two to eight times in the 250-450 degrees C range and the OSC quantity by up to 50%. Oxalic acid appears to be more efficient than citric acid in removing specifically P- and S-containing compounds from the catalyst surface, whereas citric acid in removing Pb- and Zn-containing compounds, thus uncovering surface active catalytic sites.
Place, publisher, year, edition, pages
2006. Vol. 40, 2030-2036 p.
oxygen storage, release properties, calcination temperature, exhaust catalysts, chemical-analysis, metal-oxides, supported rh, deactivation, phosphorus, oxidation
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-5635DOI: 10.1021/es052310tISI: 000236213900046ScopusID: 2-s2.0-33645220203OAI: oai:DiVA.org:kth-5635DiVA: diva2:10067
QC 201008122006-04-272006-04-272011-11-08Bibliographically approved