Na2CO3处理制备复合孔ZSM-5分子筛及其丙烷脱氢制丙烯的催化性能

通过不同浓度的Na₂CO₃溶液处理合成的HZSM-5分子筛，并采用X射线衍射、N₂低温物理吸附和X射线荧光光谱分析仪对溶液处理前后的样品进行了表征。表征结果显示，适量浓度的Na₂CO₃溶液处理HZSM-5，能够形成介孔-微孔复合孔道，增加了分子筛介孔容积和外比表面积；同时不会明显破坏HZSM-5的MFI结构，从而保持较好的高温热稳定性。在上述碱处理后的载体上制备了Pt-Sn-K/HZSM-5分子筛催化剂，并在固定床反应器上考察了丙烷脱氢制丙烯的催化活性。结果表明，随着Na₂CO₃溶液浓度的增加，催化剂的初始活性增加，而稳定性先增加后减少。当采用Pt-Sn-K/HZSM-5（1.8）分子筛催化剂用于丙烷脱氢反应，其呈现了良好的脱氢活性和稳定性：反应100h后，其丙烷化率为35.53%，相比初始活性仅下降了2.8个百分点，丙烯选择为98.4%，基本保持不变。

Preparation of hierarchical ZSM-5 zeolites treated by Na2CO3 and its catalytic performance for propane dehydrogenation to propylene

HZSM-5 zeolites were treated with different concentrations of Na₂CO₃ solutions.The samples were characterized by XRD,N₂ adsorption and XRF.The characterizations showed that under suitable concentrations of Na₂CO₃ solution,the treatment could form meso-micropore channels,which enhanced the external surface area and mesoporous volume.At the same time,the MFI structure of HZSM-5 was not obviously destroyed,therefore better thermal stability was maintained.The Pt-Sn-K/HZSM-5 catalysts were prepared by subjecting HZSM-5 samples to alkali treatment,and their catalytic performances for propane dehydrogenation to propylene were evaluated in a fixed-bed reactor.The results showed that the initial activity of the catalyst increased with increasing Na₂CO₃ solution concentration,while the stability of the catalyst increased at first and then decreased.When Pt-Sn-K/HZSM-5(1.8) zeolite catalyst was used for propane dehydrogenation,it showed better activity and stability:after reacting for 100 hours,the conversion of propane only decreased by 2.8%,resulted in a conversion of 35.53%.The propylene selectivity maintained at 98.4% with no significant change.