Role of Sn and K on hydrogen spillover on Pt/gamma-Al2O3 catalyst

This paper studies the role of Sn and K on the hydrogen spillover on the Pt /gamma -Al2O3 catalyst. Four catalysts of Pt/gamma -Al2O3, Pt-Sn/gamma -Al2 O3, Pt-K/gamma -Al2O3 and Pt-Sn-K/gamma -Al2O3 were prepared, and various t echniques were employed to investigate the hydrogen spillover phenomena. Hy drogen temperature-programmed desorption (H-2-TPD) and temperature programm ed reduction (TPR) were used to display the hydrogen spillover effect of th e catalysts which was found to follow the sequence: Pt-Sn-K/gamma -Al2O3 > Pt-Sn/gamma -Al(2)O(3)approximate to Pt-K/gamma -Al2O3 > Pt/gamma -Al2O3. T he aromatization of n-hexane and the catalyst deactivation studies were use d to investigate the hydrogen spillover effect. It was found that the resul ts from both studies follow the trend obtained from the results of H-2-TPD and TPR. Furthermore, it was found that there is a synergistic effect; i.e. the catalyst life of the catalyst promoted with both Sn and K is longer th an that obtained from the summation of the catalyst life of the catalysts o btained from the promotion with Sn and K only. It was concluded that the pr omotion of Sn incorporated with K induces more hydrogen spillover on the Pt /gamma -Al2O3 than the promotion of either Sn or K.