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Elucidation of Deterioration Mechanism and Improvement of Durability for Lean NOx Catalyst

Article of Honda R&D Technical Review Vol.25 No.1


The exhaust gas temperatures of diesel engines have been falling gradually due to engine efficiency improvement and body weight reduction. Thus, an NOx aftertreatment system that has high NOx conversion at lower temperature is required for these engines. To meet demand, the development of a new Lean NOx Catalyst with a new De-NOx mechanism has been carried out. However, it has recently been found that Lean NOx Catalyst has a durability issue during aging in an actual exhaust gas environment. The deterioration mechanism of Lean NOx Catalyst was clarified and durability enhancement of the material was conducted. As a result of an analysis using a combination of surface analysis and ab-initio calculation, it was found that the sulfur in exhaust gas was irreversibly adsorbed onto platinum in the form of sulfate, which reduced catalyst activity. A new Lean NOx Catalyst that has high durability even after aging with exhaust gas was developed by improving NO2 adsorption activity and NO2 reduction activity, which had been degraded by sulfur poisoning.


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Author (organization or company)

Yuichi MATSUO(Automobile R&D Center)、Shinya ISHIMARU(Automobile R&D Center)、Masanori HASHIMOTO(Automobile R&D Center)、Tetsuo ENDO(Automobile R&D Center)、Yoshiaki MATSUZONO(Automobile R&D Center)、Makoto NAGATA(N. E. CHEMCAT CORPORATION)

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