Zinc Influence on the Formation and Properties of Pt/Mg(Zn)AlO x Catalysts Synthesized From Layered Hydroxides

Layered double hydroxides (LDH) containing Al3+, Mg2+ and Zn2+ cations in a ratio of Zn/(Mg+Zn) = 0, 0.05, 0.1, 0.2, 0.5, 0.7 and 1.0 were synthesized. The effect of zinc content on the phase composition of LDH and on the structural parameters, textural characteristics and acid-base properties of the corresponding mixed oxides were studied. This type of supports was used to obtain non-acid platinum catalysts Pt/Mg(Zn)AlOx. The formation of supported platinum particles, their composition, dispersion and electronic state were examined by means of TPR, TEM, XPS and EXAFS. The possibility to obtain bimetallic PtZn particles, whose structure and strength of interaction with the support depend on the zinc content of the support, was demonstrated. It was found that the presence of zinc atoms in the platinum environment decreases the particle size of active metal and stabilizes platinum in the active metallic state that ensures high activity of the catalyst in dehydrogenation of propane at a selectivity for propylene above 99%.