铵离子交换后脱胺对β沸石脱铝及酸性和结构的影响

The Effects of De amine After the Ion Exchange with NH_4~ + on the Acidity, Structure and Dealuminum of Zeolite β

采用 Py- TPD、XRD、IR等主要实验方法 ,研究了 Naβ沸石原粉经 NH+ 4 交换后脱胺对β沸石表面酸性和结构的影响以及焙烧温度对 NH+ 4 - β沸石骨架脱铝的影响。结果表明 ,高温脱胺 ,β沸石有明显的骨架脱铝过程发生 ,而迁移到 β沸石表面酸性位上 ,使表面较体相富铝 ,脱铝导致其表面酸性的减弱 ;β沸石随焙烧脱胺温度的升高 ,其表面酸量逐渐减少 ,酸强度也逐渐降低 ,L酸主要来源于骨架三配位铝 ,它比非骨架铝酸强度高 ;随脱胺温度的提高 ,β沸石晶相结构和骨架结构破坏程度均加深 ,NH+ 4 在脱胺过程中对 β沸石的结晶度影响不大 ,而交换后的 NH+ 4 较 Na+

The effects of de amine after the ion exchange of Na β with NH + 4 on the surface acidity and structure of Zeolite β and the effects of calcination temperature on the dealumination of NH + 4 β Zeolite framework were investigated using Py TPD,XRD and IR.The results indicate that de amine at high temperature leads to the significant dealumination of β Zeolite framework and migration to surface acidic sites and results in the enrichment of aluminum on the outer surface than the body,the dealumination leads to the decrease of catalyst acidity;the higher the de amine temperature is,the lesser the acid amount and acid strength will be,L acid mainly results from the tetrahedral framework Al,the acid strength of the tetrahedral framework Al is stronger than nonframework Al;It is shown that the crystalline structure and framework structure decrease with the increase of the calcinations temperature,in the de amine process NH + 4 nearly has no significant effect on the crystallinity of β Zeolite,but the framework aluminum species with Na + are more difficult to detach from the framework than those with NH + 4;The thermal decomposition of NH + 4 is also one of the reasons causing the decrease of crystallinty.