On the effect of the preparation conditions on the location and the size of platinum particles on zeolite NaX

The effect of the calcination temperature, and of the reduction temperature on the location and the size of platinum particles on zeolite NaX was studied by EXAFS. The results showed that the tetramin platinum complex in the cationic sites of the zeolite is not completely decomposed after calcination at 633 K for 2 h. For this sample, some amine groups are still present after reduction at 633 K for 2h. Increasing the reduction temperature from 633 to 773 K caused the growth of the particles, the larger ones probably located on the outer surface of the zeolite crystals. On the other hand, for the samples calcined at 773 K for 2 h, the complex is completely decomposed and the reduction temperature did not affect the particle size significantly. For these samples, most of the particles are probably located inside the zeolite supercages.