Scholarlink

<p>This study utilizes advanced solid-state NMR spectroscopy to elucidate the spatial distribution, coordination behavior, and inter-nuclear interactions of boron species in B-MFI zeolites. Through <sup>13</sup>C-{<sup>11</sup>B} symmetry-based resonance-echo saturation-pulse double-resonance (S-RESPDOR) NMR experiment, we reveal that boron incorporation is preferentially directed by tetrapropylammonium (TPA<sup>+</sup>) structure-directing agents, with boron predominantly occupying both sinusoidal and straight channels rather than channel intersections. Quantitative analysis further indicates a closer proximity to terminal methyl groups of TPA<sup>+</sup> in sinusoidal channels (B-C<sub><i>γ</i></sub>′: <i>ca.</i> 2.8 Å) (1 Å=0.1 nm) compared to straight channels (B-C<sub><i>γ</i></sub>: <i>ca.</i> 3.1 Å). Upon dehydration, two-dimensional (2D) <sup>11</sup>B multiple-quantum magic-angle spinning (MQMAS) NMR, together with a 2D <sup>1</sup>H-{<sup>11</sup>B} dipolar-based heteronuclear multiple quantum correlation (D-HMQC) experiment, identifies two distinct trigonal boron species, attributed to framework boron perturbed by proximal silanols, highlighting microenvironmental heterogeneity. Our findings establish that boron siting is template-directed and that dehydration induces distinct speciation, providing atomic-scale insights that are crucial for the rational design of zeolites.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Probing Framework Boron Speciation and Spatial Distribution in MFI Zeolites by Solid-state NMR

  • 期刊论文

  • 发表日期：

    2025年10月11日

查看全文
  • Junze Li,
  • Yongxiang Wang,
  • Han Bao,
  • Shuangqin Zeng,
  • Xiuzhi Gao,
  • Xiaowu He,
  • Mingji Zheng,
  • Ningdong Feng,
  • Qiang Wang,
  • Jun Xu,
  • Feng Deng

摘要

This study utilizes advanced solid-state NMR spectroscopy to elucidate the spatial distribution, coordination behavior, and inter-nuclear interactions of boron species in B-MFI zeolites. Through 13C-{11B} symmetry-based resonance-echo saturation-pulse double-resonance (S-RESPDOR) NMR experiment, we reveal that boron incorporation is preferentially directed by tetrapropylammonium (TPA+) structure-directing agents, with boron predominantly occupying both sinusoidal and straight channels rather than channel intersections. Quantitative analysis further indicates a closer proximity to terminal methyl groups of TPA+ in sinusoidal channels (B-Cγ′: ca. 2.8 Å) (1 Å=0.1 nm) compared to straight channels (B-Cγ: ca. 3.1 Å). Upon dehydration, two-dimensional (2D) 11B multiple-quantum magic-angle spinning (MQMAS) NMR, together with a 2D 1H-{11B} dipolar-based heteronuclear multiple quantum correlation (D-HMQC) experiment, identifies two distinct trigonal boron species, attributed to framework boron perturbed by proximal silanols, highlighting microenvironmental heterogeneity. Our findings establish that boron siting is template-directed and that dehydration induces distinct speciation, providing atomic-scale insights that are crucial for the rational design of zeolites.