n-Butane dehydrogenation on Pt, PtSn and PtGe supported on γ-Al2O3 deposited on spheres of α-Al2O3 by washcoating

In this paper the catalytic performance of Pt, PtSn and PtGe catalysts supported on gamma-Al2O3 (gamma-A) prepared by washcoating of spheres of alpha-Al2O3 (alpha-A) is studied in the n-butane dehydrogenation. For this purpose, the effect of the addition of Sn (0.3 and 0.5 wt.%) and Ge (0.18 and 0.3 wt.%) to Pt (0.3 wt.%) on the activity, selectivity and the catalytic stability was analyzed. The catalyst characterization was carried out by using cyclohexane dehydrogenation (CHD) and cyclopentane hydrogenolysis (CPH) reactions, and also temperature programmed reduction (TPR), H-2 chemisorption, X-ray photoelectron spectroscopy (XPS) and scanning electronic microscopy (SEM). Results show that important advances in the development of these catalysts were obtained. In this sense the PtSn(0.5)/gamma-A/alpha-A catalyst showed the best catalytic performance (activity, selectivity to all butenes and high stability) in n-butane dehydrogenation reaction. Results showed a different composition of the metallic phase according to the nature of the second metal (Sn or Ge). In fact, PtSn catalysts show a low electronic interaction between the two metals, with a surface segregation of Sn and oxidized Sn stabilized on the support. On the other hand, PtGe catalysts present strong PtGe interactions with probable alloys formation. (C) Published by Elsevier B.V.