TUD-C: A tunable, hierarchically structured mesoporous zeolite composite

J Wang, Wenbo Yue, Wuzong Zhou, M.-O. Coppens

Research output: Contribution to journalArticlepeer-review

46 Citations (Scopus)

Abstract

TUD-C is a new type of hierarchically structured composite with ZSM-5 nanocrystals embedded in a well-connected mesoporous matrix. It is synthesized by employing only one organic templating/scaffolding molecule (TPAOH) through a two-step procedure involving gelation and crystallization. Both the Si/Al ratio and crystallization time are important factors influencing the acidity and the micro- and mesopore structures of TUD-C. A lower Si/Al ratio results in slower formation of zeolite crystals and weaker acidity. Nevertheless, when Si/Al > 50, the mesopore size can only be tuned inside a narrower range. The tuning of the mesopore size by crystallization is identified as primarily due to a thermal effect, rather than to crystal growth. SEM reveals the intriguing formation of clusters consisting of nanoparticles during the crystallization of samples with Si/Al = 30. Micropore structure analysis by At sorption and TEM shows the formation of a pre-formed microporous structure before the zeolite structure appears. This sheds light on the formation mechanism of zeolite crystals through a solid-phase transformation. Compared with TUD-M, TUD-C is more hydrothermally stable, more acid, and the mesopore size is more easily tuned. However, the method to synthesize TUD-M can be applied to a wider range of zeolite types. The choice between TUD-C and TUD-M depends on the application. (C) 2008 Elsevier Inc. All rights reserved.

Original languageEnglish
Pages (from-to)19-28
Number of pages10
JournalMicrop. Mesop. Mater.
Volume120
DOIs
Publication statusPublished - 1 Apr 2009

Keywords

  • Hierarchical structure
  • Solid-phase crystallization
  • Zeolite
  • Mesopores
  • Templating
  • MICRO/MESOPOROUS COMPOSITES
  • ZSM-5 COMPOSITES
  • SINGLE-CRYSTALS
  • CATALYSTS
  • ACID
  • NANOPARTICLES
  • NANOCRYSTALS
  • NETWORKS
  • SILICA
  • PHASE

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