T. Tanaka et al., EFFECT OF THE ADDITION OF MO AND NA TO PT CATALYSTS ON THE SELECTIVE REDUCTION OF NO, Applied catalysis. B, Environmental, 16(3), 1998, pp. 199-208
The selective reduction of NOx by reductants such as C3H6 and CO in ox
idizing feedstreams simulated exhaust from automobile engine and three
-way behavior around the stoichiometric point have been investigated o
n trimetallic PtMoNa/SiO2 catalysts, over a wide range of temperatures
compared with bimetallic PtMo/SiO2 catalyst and monometallic Pt/SiO2
catalyst. The simultaneous addition of Mo and Na to Pt catalysts has b
een found to improve the following reaction characteristics on selecti
ve reduction of NOx and three-way activity of conventional Pt catalyst
. The temperature window on selective reduction of NOx on trimetallic
PtMoNa/SiO2 catalysts was found to be wider and to shift at higher tem
perature than that on bimetallic PtMo/SiO2 and monometallic Pt/SiO2 ca
talysts under lean static conditions. The redox ratio window, in which
three-way activity occurred on trimetallic PtMoNa/SiO2 catalysts, was
also found to be wider than that on bimetallic PtMo/SiO2 catalysts an
d monometallic Pt/SiO2 around stoichiometric point. On the other hand,
XPS, IR and CO adsorption data indicated that the oxidation of Pt on
PtMoNa/SiO2 catalysts was depressed by the added Mo and Na even under
excess oxygen conditions, so that the reaction characteristics of trim
etallic PtMoNa/SiO2 catalysts was improved. (C) 1998 Elsevier Science
B.V.