Ml. Casella et al., Surface characterization of Li-modified platinum/tin catalysts for isobutane dehydrogenation, LANGMUIR, 16(13), 2000, pp. 5639-5643
The superficial properties of different Pt/y-Al2O3 catalysts, modified by t
he addition of tin and/or lithium, were studied by X-ray photoelectron spec
troscopy (XPS), scanning electron microscopy, BET, and 2-propanol transform
ation. The results obtained were correlated with the behavior of the cataly
sts in applied reactions such as the dehydrogenation of isobutane. To obtai
n very well defined bimetallic superficial phases; tin was introduced by me
ans of surface organometallic chemistry on metals techniques and the nature
of the bimetallic-active sites so obtained was compared with the ones prep
ared by conventional procedures. XPS measurements indicate that tin is pres
ent in both zeroth valent and oxidized states. The addition procedure of bo
th tin and lithium has a marked influence on the characteristics of the sur
face of the catalysts. The order in which lithium is added generates solids
having different properties in relation to texture, dispersion, and cataly
tic behavior, for both Pt and PtSn systems.