Effect of hydrophobic character of diammonium-capping agents for the synthesis of nanocrystalline MOR zeolite

IF 4.7 3区材料科学 Q1 CHEMISTRY, APPLIED

Microporous and Mesoporous Materials Pub Date : 2025-07-29 DOI:10.1016/j.micromeso.2025.113784

Gayoung Lee , Jong Yeon Lim , Jeong-Chul Kim , Changbum Jo

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Abstract

Multiammonium surfactants are known to act as effective capping agents in the synthesis of zeolite nanoparticles. While the attractive interactions between ammonium head groups and zeolite surfaces play a critical role in capping, the influence of the surfactant tail structures remains poorly understood. In this study, a series of diammonium surfactants with different tail lengths (i.e., C_nH_2n+1-N⁺(CH₃)₂-C₆H₁₂-N⁺(CH₃)₂-C_mH_2m+1, 4 ≤ n, m ≤ 22) were systematically tested to investigate the effect of hydrophobic character on the morphology of mordenite (MOR) zeolite nanocrystals. Capping efficiency was assessed using X-ray diffraction, nitrogen adsorption-desorption isotherms, and scanning electron microscopy. The results showed that surfactants with a moderate hydrophilic/hydrophobic balance—quantified by the carbon-to-nitrogen (C/N⁺) ratio—exhibited the highest capping efficiency, resulting in smaller particle sizes and larger external surface areas. Furthermore, non-Gemini surfactants (i.e., n ≠ m) demonstrated significantly enhanced capping efficiency, compared to symmetric Gemini surfactants (i.e., n = m). These findings offer valuable insights into the molecular design of surfactants in the controlled synthesis of zeolite nanoparticles.

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包覆剂疏水特性对纳米晶MOR分子筛合成的影响

在沸石纳米颗粒的合成中，多铵表面活性剂被认为是有效的封盖剂。虽然铵头基团与沸石表面之间的相互吸引作用在封盖中起着关键作用，但表面活性剂尾部结构的影响仍然知之甚少。本研究系统测试了一系列尾长不同的二铵表面活性剂(CnH2n+1- n+ (CH3)2-C6H12-N+(CH3)2-CmH2m+ 1,4≤n, m≤22)，研究疏水特性对丝光沸石纳米晶形貌的影响。利用x射线衍射、氮吸附-解吸等温线和扫描电镜对封盖效率进行了评估。结果表明，以碳氮比（C/N+）衡量，具有中等亲疏水平衡的表面活性剂表现出最高的封盖效率，从而产生更小的粒径和更大的外表面积。此外，与对称Gemini表面活性剂（n = m）相比，非Gemini表面活性剂（即n≠m）的封井效率显著提高。这些发现为沸石纳米颗粒受控合成中表面活性剂的分子设计提供了有价值的见解。

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来源期刊

Microporous and Mesoporous Materials 化学-材料科学：综合

CiteScore

10.70

自引率

5.80%

发文量

649

审稿时长

26 days

期刊介绍： Microporous and Mesoporous Materials covers novel and significant aspects of porous solids classified as either microporous (pore size up to 2 nm) or mesoporous (pore size 2 to 50 nm). The porosity should have a specific impact on the material properties or application. Typical examples are zeolites and zeolite-like materials, pillared materials, clathrasils and clathrates, carbon molecular sieves, ordered mesoporous materials, organic/inorganic porous hybrid materials, or porous metal oxides. Both natural and synthetic porous materials are within the scope of the journal. Topics which are particularly of interest include: All aspects of natural microporous and mesoporous solids The synthesis of crystalline or amorphous porous materials The physico-chemical characterization of microporous and mesoporous solids, especially spectroscopic and microscopic The modification of microporous and mesoporous solids, for example by ion exchange or solid-state reactions All topics related to diffusion of mobile species in the pores of microporous and mesoporous materials Adsorption (and other separation techniques) using microporous or mesoporous adsorbents Catalysis by microporous and mesoporous materials Host/guest interactions Theoretical chemistry and modelling of host/guest interactions All topics related to the application of microporous and mesoporous materials in industrial catalysis, separation technology, environmental protection, electrochemistry, membranes, sensors, optical devices, etc.