氟对PtSnNaLa/ZSM-5催化剂丙烷脱氢反应性能的影响

在PtSnNaLa/ZSM-5催化剂中引入氟元素,制得用于丙烷脱氢反应的氟改性催化剂,利用X射线衍射(XRD)、NH₃吸脱附(NH₃-TPD)、红外(FT-IR) 、固体核磁(²⁷Al MAS NMR)和程序升温还原(H₂-TPR)等技术手段研究不同氟含量对催化剂的结构、表面酸性和丙烷脱氢反应性能的影响。 结果表明,氟能降低催化剂表面的弱酸强度,增强Pt与载体间的相互作用力,降低反应副产物的选择性,从而提高了产物丙烯的选择性,当氟的添加量为0.2%时,丙烯选择性可达到99.2%。 同时氟的加入易于载体骨架的脱铝,使得Sn组分的还原变得相对容易,但对催化剂结构没有明显的影响。

Effect of Fluorine on PtSnNaLa/ZSM-5 Catalyzed Dehydrogenation of Propane

Fluorine modified catalyst was prepared by introducing different content of fluorine during the preparation of PtSnNaLa/ZSM-5. These catalysts were used for the dehydrogenation of propane. The effect of fluorine addition on the structure, surface acidity and reaction performance of the catalysts were studied by means of XRD, NH₃-TPD, FT-IR, ²⁷Al MAS NMR and TPR. The results indicate that the addition of fluorine reduced the weak-acid strength of the catalyst, but had no obvious influence on the catalyst structure. Meanwhile, the existence of fluorine strengthened the interaction between Pt and the support, and caused the dealumination of the support to some extent. As a result, the reduction of Sn component becomes relatively easy. The influence of fluoride addition on the reaction performance is mainly concentrated on improving the selectivity to propene. As for the catalyst with 0.2% fluoride, the selectivity towards propene can reach 99.2% after the reaction for 7 h.