Outstanding HC-SCR of Lean NOx Over Pt/Mesoporous-Silica Catalysts

Perfect de-NOx over a wide temperature range above 170 °C was achieved using a new Pt-catalyst supported on mesoporous silica (Pt/MPS) and a stoichiometric amounts of long-chain hydrocarbons as reducing agents for NOxpurification. Kinetic investigation of the HC-SCR of lean NOx over Pt/MPS, Pt/alumina and Pt/zirconia showed that such a remarkable activity of Pt/MPS is due to a large frequency factor but not to activation energy. Acid-treatment of the supports increased the activities of the catalysts and generated new IR-peaks in the range 1000-1200 cm-1, which suggests the support-effects on the catalyst-activities to be related to the special surface functional groups of the supports. The present HC-SCR must be very useful to remove diesel-NOx by means of pulse-injection of diesel fuel into the exhaust.