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

Ultrafast (1.5 h) synthesis of nanocrystal assembled ZSM-48spheres and regulating the corresponding acidity were successfullyachieved by pretreated-seed-solution-assisted strategy. The resultedproduct was an excellent acid support in the hydroconversion of long-chainalkanes. Ultrafast synthesis of nanocrystal assembled mesoporousZSM-48zeolite spheres of highly crystalline was achieved within 1.5 h byusing pretreated-seed-solution-assisted strategy. Interestingly, byaltering the introducing sequence of aluminum source (in the pretreatedseed solution or in the synthesis gel), the obtained ZSM-48 with similarparticle size and total acid sites exhibited quite different crystallizationbehavior 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 Alsource to the pretreated seed solution) had more framework Al(IV)content and stronger acid strength than that of the HZ48-Al-post (synthesizedby the Al-free pretreated seed solution). The corresponding Pt supportedcatalysts showed a great difference in the n-C-12 hydroisomerization reation. The Pt/HZ48-Al-pre catalysthad a very low selectivity (41.1%), and the maximum iso-yield wasonly 35.5%. However, the ultrafast synthesizedPt/HZ48-Al-post-1.5hcatalyst exhibited a superior selectivity (90.1%) with a total i-C-12 yield of 82.3% at 330 degrees C, which wasa high level in the exist literature reports.