Probing the Design Rationale of a High‐Performing Faujasitic Zeotype Engineered to have Hierarchical Porosity and Moderated Acidity

Porosity and acidity are influential properties in the rational design of solid‐acid catalysts. Probing the physicochemical characteristics of an acidic zeotype framework at the molecular level can provide valuable insights in understanding intrinsic reaction pathways, for affording structure–activi...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2020-10, Vol.59 (44), p.19561-19569
Main Authors: Chapman, Stephanie, Carravetta, Marina, Miletto, Ivana, Doherty, Cara M., Dixon, Hannah, Taylor, James D., Gianotti, Enrica, Yu, Jihong, Raja, Robert
Format: Article
Language:English
Subjects:
acid catalysis
Acidity
Catalysts
Coking
Deactivation
Design
heterogeneous catalysis
hierarchical porosity
Magnetic resonance spectroscopy
NMR
NMR spectroscopy
Nuclear magnetic resonance
Porosity
Positron annihilation
probe-based techniques
Spectroscopy
Spectrum analysis
structure–activity relationships
Transport properties
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Summary:Porosity and acidity are influential properties in the rational design of solid‐acid catalysts. Probing the physicochemical characteristics of an acidic zeotype framework at the molecular level can provide valuable insights in understanding intrinsic reaction pathways, for affording structure–activity relationships. Herein, we employ a variety of probe‐based techniques (including positron annihilation lifetime spectroscopy (PALS), FTIR and solid‐state NMR spectroscopy) to demonstrate how a hierarchical design strategy for a faujasitic (FAU) zeotype (synthesized for the first time, via a soft‐templating approach, with high phase‐purity) can be used to simultaneously modify the porosity and modulate the acidity for an industrially significant catalytic process (Beckmann rearrangement). Detailed characterization of hierarchically porous (HP) SAPO‐37 reveals enhanced mass‐transport characteristics and moderated acidity, which leads to superior catalytic performance and increased resistance to deactivation by coking, compared to its microporous counterpart, further vindicating the interplay between porosity and moderated acidity. A design‐led dual‐templating approach was used to create a hierarchical zeotype catalyst with superior mass transport properties. Advanced probe‐based characterization (including positron annihilation lifetime spectroscopy and probe‐based IR spectroscopy) shows how the siliceous mesoporogen modulates the porosity and moderates the acidity of the zeotype framework, leading to enhanced catalytic performance.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202005108