Chemical Research in Chinese Universities ›› 2026, Vol. 42 ›› Issue (1): 134-142.doi: 10.1007/s40242-025-5137-2

• Research Articles • Previous Articles     Next Articles

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

LI Junze1, WANG Yongxiang2,4, BAO Han1, ZENG Shuangqin3, GAO Xiuzhi3, HE Xiaowu1, ZHENG Mingji2,4, FENG Ningdong2,4, WANG Qiang2,4, XU Jun2,4, DENG Feng2,4   

  1. 1. School of Mathematics and Physics, North China Electric Power University, Beijing 102206, P. R. China;
    2. National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Imaging, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China;
    3. SINOPEC Research Institute of Petroleum Processing, Beijing 100083, P. R. China;
    4. University of Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2025-07-08 Online:2026-02-01 Published:2026-01-28
  • Contact: HE Xiaowu,E-mail:hxw2008@ncepu.edu.cn;WANG Qiang,E-mail:qiangwang@wipm.ac.cn;XU Jun,E-mail:xujun@wipm.ac.cn E-mail:hxw2008@ncepu.edu.cn;qiangwang@wipm.ac.cn;xujun@wipm.ac.cn
  • Supported by:
    This work was supported by the Project of the National Energy R&D Center of Petroleum Refining Technology (RIPP, SINOPEC), the National Key R&D Program of China (No. 2024YFE0115300), the National Natural Science Foundation of China (Nos. 22161132028, 22225205, 22320102002, 22172177, 22127801), the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDB0540000), the International Partnership Program of the Chinese Academy of Sciences (No. 314GJH2022022FN), the Hubei International Scientific and Technological Cooperation Program, China (No. 2024EHA043) and Base (No. SH2303).

Abstract: 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 magicangle spinning (MQMAS) NMR, together with a 2D 1H-{11B} dipolarbased 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.

Key words: Borosilicate zeolite, MFI topology, Solid-state NMR, Internuclear distance, Boron speciation