Total and preferential CO oxidation on low-loaded Pt-HZSM-5 zeolites modified using laser electrodispersion

Platinum particles of 1.7 nm size were deposited on the external surface of HZSM-5 zeolites with Si/Al = 15, 28, and 40 using laser electrodispersion (LED) method. The obtained materials with low Pt loading (0.01–0.05 wt.%) were studied by transmission electron microscopy and X-ray photoelectron spectroscopy and tested in the catalytic oxidation of CO in the absence and in the presence of hydrogen The Pt/HZSM-5 catalyst modified by chemical impregnation was used as the reference sample. The best performance was found for the catalyst prepared by deposition of 0.05 wt.% Pt on the zeolite with the intermediate Si/Al ratio of 28. The CO conversion over this catalyst in the presence of hydrogen at 130 °C was 100%. The enhanced activity and selectivity of zeolites modified with Pt using LED are caused by the high degree of dispersion of particles, the pattern of particle distribution on the support surface, and the simultaneous presence of metallic and oxidized platinum on the surface.