Ultrafast Synthesis and Regulating Al Status of Mesoporous ZSM-48 Zeolite via a Pretreated-Seed-Solution-Assisted Strategy

Abstract

Ultrafast synthesis of nanocrystal assembled mesoporous ZSM-48 zeolite spheres of highly crystalline was achieved within 1.5 h by using pretreated-seed-solution-assisted strategy. Interestingly, by altering the introducing sequence of aluminum source (in the pretreated seed solution or in the synthesis gel), the obtained ZSM-48 with similar particle size and total acid sites exhibited quite different crystallization behavior and acid property in terms of Al distribution and acid strength, because of the distinct local microenvironment (Al-rich or Al-free) in the pretreated seed solution. The HZ48-Al-pre (introduce an Al source to the pretreated seed solution) had more framework Al(IV) content and stronger acid strength than that of the HZ48-Al-post (synthesized by the Al-free pretreated seed solution). The corresponding Pt supported catalysts showed a great difference in the n-C12 hydroisomerization reation. The Pt/HZ48-Al-pre catalyst had a very low selectivity (41.1%), and the maximum iso-yield was only 35.5%. However, the ultrafast synthesizedPt/HZ48-Al-post-1.5h catalyst exhibited a superior selectivity (90.1%) with a total i-C12 yield of 82.3% at 330 °C, which was a high level in the exist literature reports.