Mesopore Formation in USY and Beta Zeolites by Base Leaching: Selection Criteria and Optimization of Pore-Directing Agents
2012; American Chemical Society; Volume: 12; Issue: 6 Linguagem: Inglês
10.3929/ethz-a-010788570
ISSN1528-7505
AutoresDanny Verboekend, Gianvito Vilé, Javier Pérez‐Ramírez,
Tópico(s)Chemical Synthesis and Characterization
ResumoMolecular criteria for the selection of organic pore-directing agents (PDAs) in NaOH leaching, that is, desilication, were investigated on USY and beta zeolites of distinct aluminum contents (Si/Al = 15–385). PDAs prove particularly useful for FAU and BEA topologies since they serve a dual purpose: tailoring the mesopore structure while preventing realumination and amorphization of the crystals. An efficient PDA is positively charged and contains ca. 10–20 carbon atoms, for example, TPA+ or CTA+. Compositional, textural, morphological, structural, and acidity studies performed on selected hierarchical zeolites confirmed the presence of extensive secondary porosity coupled to well-preserved zeolitic properties. Inclusion of TPA+ in the alkaline solution led to the largest preservation of the intrinsic zeolite properties, whereas CTA+ facilitates the reassembly of dissolved species during alkaline treatment. Finally, we report the preparation of mesoporous zeolites in a continuous-mode using a tubular react...
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