Effect of Sn promoter on the performance of Pt-Sn/γ-Al2O3 catalysts for n-dodecane dehydrogenation

The effect of Sn promoters on the performance of Pt-Sn/γ-Al2O3 catalysts for the long-chain paraffins dehydrogenation to mono-olefins was studied by n-dodecane dehydrogenation. The catalysts were characterized by N2 adsorption-desorption, mercury intrusion porosimetry, CO pulse chemisorption, X-ray photoelectron spectroscopy and thermogravimetric analysis. Results show that the Pt-Sn/γ-Al2O3 catalysts exhibit the optimal catalytic performance when the Sn:Pt (mole ratio) of the catalysts is 3. While keeping on increasing the amount of Sn, the catalytic dehydrogenation activity of the catalysts is decreased with the formation of Sn0 and Pt-Sn alloy. Moreover, the catalytic stability of the catalysts is enhanced after the addition of Sn. And with the increasing of Sn loading, the selectivity to mono-olefins of the Pt-based γ-Al2O3 catalysts is also greatly increased.