EFFECT OF LI, NA, K AND CS ON VACUUM DECOMPOSITION OF TETRAAMMINEPLATINUM(II) IN ZEOLITES - CATALYTIC ACTIVITY IN CO+NO REACTION

[Pt(NH3)(4)](2+) ions were exchanged for alkali (Li, Na, K and Cs) in -X and -Y zeolites and decomposed in vacuum. TPR after this decomposit ion showed that autoreduction accompanying this process reduced roughl y 2/3 of all Pt2+ to Pt-0. The extent of the autoreduction rose with t he ammonia pressure over the zeolite. The decomposition rate increased with increasing electropositivity of the alkali ion and this effect c ompletely overlapped that of the zeolite structure. The CO + NO reacti on rate also increased from Li to Cs, but -X zeolites were substantial ly more active than the -Y ones. Oxygen layer on the resulting Pt cata lyst affected positively the reaction rate. The dispersion of Pt parti cles was relatively low, when compared to that obtained by decompositi on of the Pr tetraammine complex in oxygen followed by hydrogen reduct ion. However, the reaction rate was higher.