Effect of Sn promoter on the performance of Pt-Sn/γ-Al2O3 catalysts for n-dodecane dehydrogenation
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摘要: 以正十二烷烃临氢脱氢反应为探针，并结合氮气物理吸附脱附、压汞、CO脉冲化学吸附、原位X射线光电子能谱及热重等催化剂物化表征手段，研究了Sn助剂对于Pt-Sn/γ-Al2O3长链烷烃脱氢催化剂反应性能的影响。结果表明，当Pt-Sn/γ-Al2O3催化剂中Sn∶Pt原子比为3时，催化剂表现出最佳的反应初活性。继续增加Sn的含量，由于更多的零价锡生成，并与Pt形成合金反而使催化剂活性下降。此外，在催化剂中引入Sn组分后，催化剂的稳定性有所改善，并且随着Sn含量的增加，脱氢反应产物选择性明显提高。Abstract: The effect of Sn promoter on the performance of Pt-Sn/γ-Al2O3 catalysts for the long-chain paraffins dehydrogenation to monoolefins 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 (atomic ratio) of the catalyst 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.
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Key words:
- dehydrogenation /
- long chain paraffin /
- Pt-Sn catalysts /
- coking
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