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通过X射线衍射(XRD)、N2吸附、透射电镜(TEM)、NH3程序升温脱附(NH3-TPD)、H2程序升温还原(H2-TPR)和O2程序升温氧化(O2-TPO)等多种表征手段及催化反应性能评价,研究了镁助剂的添加对PtNa/Sn-ZSM-5催化丙烷脱氢反应性能的影响.结果表明:适量Mg的添加(0.3%和0.5%,质量分数)能促进催化剂表面金属粒子的分散,减少反应过程中积碳的产生.Mg的引入能有效抑制催化剂中Sn组分的还原,使更多量的Sn组分以氧化态形式存在,有利于丙烷脱氢反应的进行.但是,过量Mg的加入导致催化剂表面金属颗粒易于发生团聚,高温下Sn组分易于被还原,不利于反应的进行.在本实验中,0.5%Mg加入后PtNa/Sn-ZSM-5催化剂显示出最佳的反应性能,反应7h后,丙烷转化率仍然高达38.7%,对应的丙烯选择性能够维持在95%以上.
The structures of the samples were characterized by XRD, N2 adsorption, TEM, NH3-TPD, H2-TPR and O2-TPO Characterization and evaluation of the catalytic performance of the catalyst were studied.The effect of addition of magnesium additive on the catalytic performance of PtNa / Sn-ZSM-5 in the dehydrogenation of propane was studied.The results showed that the addition of proper Mg (0.3% and 0.5%, mass fraction) Promote the dispersion of metal particles on the catalyst surface and reduce the carbon deposition during the reaction.The introduction of Mg can effectively restrain the reduction of Sn component in the catalyst and increase the amount of Sn component in the form of oxidation state, However, the addition of excessive Mg resulted in easy agglomeration of the metal particles on the surface of the catalyst, and the Sn component was easily reduced under high temperature, which was not conducive to the reaction.In this experiment, the addition of 0.5% Mg to the PtNa / Sn-ZSM- 5 catalyst showed the best reaction performance. After 7 hours of reaction, the conversion of propane was still as high as 38.7%, and the corresponding propylene selectivity could be maintained above 95%.