Low-Temperature Active Pt-catalysts Supported on Mesoporous Silica and Metal-Silicates for Cleaning Diesel-NOx Exhausts


  •  Tamikuni Komatsu    
  •  Keizo Tomokuni    
  •  Mitsuo Konishi    
  •  Takashi Shirai    

Abstract

New Pt-catalysts supported on mesoporous silica (MPS) and metal-silicates, which have high de-NOx capabilities over 70 % in NOx-conversion at temperatures around 170 under lean conditions, were developed. A new prototype honeycomb supporting Pt-catalyst allows high de-NOx of diesel-exhausts possible over the wide temperature range of 170-400. The low-temperature activities of the catalysts are well correlated with the Brønsted acidity of the support materials. In view of the reaction mechanism of the de-NOx processes, the Brønsted acid-sites of the supports probably stimulate the oxidation of NO into NO2, which is the rate-determining step of de-NOx processes, leading to the low-temperature activities.


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