关键词: 锌 , AEL 结构 , 铝磷酸盐分子筛 , 正己烷 , 催化裂解

Abstract: Zinc-substituted aluminophosphate molecular sieves (ZnAPO-11) containing different zinc contents were synthesized using the gel composition n(R)/n(ZnO)/n(Al2O3)/n(P2O5)/n(H2O)=1∶ x∶y∶1.1∶80 (0.5x+y=1) by static hydrothermal method. As-synthesized ZnAPO-11 molecular sieves were characterized by XRD, SEM, N2-adsorption, MAS-NMR and ICP-AES techniques.The results show that ZnAPO-11 molecular sieves with AEL topology are prepared in the range of 0≤n(ZnO)/n(Al2O3)≤0.04. And resultant ZnAPO-11 molecular sieves are of high crystallinity and purity. A regular platelet morphology is observed for the as-synthesized ZnAPO-11 molecular sieves. Experimental data show that Zn as heteroatom is successfully incorporated into the framework of AlPO4-11 and substituted for Al. The n-hexane cracking over ZnAPO-11 was examined under different reaction conditions. It is found that ZnAPO-11 molecular sieves exhibited a significant activity for the n-hexane cracking at 475~550 ℃. Conversion level of n-hexane increased with increasing contact time, and the apparent rates increased with increasing reaction temperature.The first order was determined of the n-hexane concentration. In addition, the dependence of the rates on reaction temperature can be expressed in terms of Arrhenius formula in the whole cracking temperature range.

Key words: Zinc , AEL topology , Aluminophosphate molecular sieves , n-Hexane , Catalytic cracking