助剂对PtSn/SBA-15催化剂丙烷脱氢性能的影响

Effects of Additives on Catalytic Performances of Pt Sn/SBA-15 in Propane Dehydrogenation

考察了金属助剂K,Mg,Zn对Pt Sn/SBA-15催化剂催化丙烷脱氢性能的影响,并采用N2吸附-脱附、SEM、TG、H2-TPR和CO脉冲吸附原位漫反射红外光谱等方法对载体和催化剂进行了表征。实验结果表明,助剂对Pt Sn/SBA-15催化剂的丙烷脱氢性能有显著影响,K助剂对催化剂不利,而Mg和Zn助剂能显著改善Pt Sn/SBA-15催化剂的催化性能,含Mg或Zn的Pt Sn/SBA-15催化剂脱氢活性高、稳定性好。Mg和Zn助剂能提高催化剂的Pt分散度,且可能有部分活性组分进入分子筛孔道,同时Mg和Zn助剂能增加Pt粒子周围的电子密度,高的电子密度使得Pt与生成的烯烃双键之间的相互作用力减弱,从而使烯烃容易从催化剂表面脱附,提高催化剂的性能。

The effects of additives, namely K, Mg and Zn, on the performances of the PtSn/ SBA-15 catalysts in the propane dehydrogenation were investigated. The support and catalysts were characterized by means of N2 adsorption-desorption, SEM, TG, H2-TPR and in situ CO adsorption DRIFTS. The results showed that the additives affected the performances of the catalysts evidently. Mg and Zn could increase the activity and stability of the PtSn/SBA-15 catalysts because they improved the Pt dispersion and partly got into the pore of the support, while K would weaken the activity of the catalysts. It was showed that Mg and Zn could increase the electron cloud density around the Pt particles, which led to the easy desorption of the product from the catalyst surface.