Properties of the metallic phase of zinc-doped platinum catalysts for propane dehydrogenation

The influence of the zinc addition to alumina supported Pt and PtSn catalysts is analyzed in this paper, not only on the activity, selectivity and deactivation in the propane dehydrogenation reaction, but also on the characteristics of platinum metal phase. Zinc can give a remarkable improvement in dehydrogenation performance of catalysts. High propylene selectivity (≥97%) can be obtained over zinc-doped catalysts. Physicochemical technologies like BET, NH3-TPD, H2-TPR, H2-chemisorption, C3H6-TPD, CO-FTIR and TPO were used to characterize the metal phase of catalysts. The presence of zinc modifies the metallic phase, mainly by geometric and electronic modifications of the metallic phase. These modifications could be responsible for the improvement of catalytic performance.

The effects of Zn and Sn on the electronic environment of Pt atoms were different. Zn tended to increase the electronic density of the surface of Pt atoms which could be related to the formation of PtZn alloy. In contrast Sn resulted in a decrease in the electron density of Pt atoms, possibly due to the electron-attracting Sn(II) ions. Figure optionsDownload as PowerPoint slide