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MOF 卓越的孔隙率和表面积

2004
  • Omar M. Yaghi
Researcher analyzing Metal-Organic Frameworks in a laboratory setting, focusing on porosity and surface area.

(图片仅供参考)

金属有机框架(MOF)的一个显著特征是其极高的内表面积和孔隙率。有序的晶体结构形成了清晰的孔隙和通道,使得其Brunauer-Emmett-Teller(BET)比表面积可超过7000 m²/g。这一数值远超沸石或活性炭等传统多孔材料,使得巨大的内表面积易于分子接触。 adsorption.

The high surface area in MOFs is a direct consequence of their low-density crystalline structure. Unlike amorphous materials like activated carbon, which have a wide distribution of irregular pores, MOFs possess uniform, precisely engineered cavities. The surface area is calculated from gas adsorption isotherms, typically using nitrogen or argon at cryogenic temperatures, and applying the BET theory. The formula for the BET surface area is [latex]S_{BET} = \frac{v_m N_A s}{V_M}[/latex], where [latex]v_m[/latex] is the monolayer volume of the adsorbate gas, [latex]N_A[/latex] is Avogadro’s number, [latex]s[/latex] is the adsorption cross-section of the gas molecule, and [latex]V_M[/latex] is the molar volume of the gas.

The ability to design MOFs with very long organic linkers and low-density metal nodes allows for the creation of frameworks with extremely large void fractions, sometimes exceeding 90% of the crystal volume. For example, MOF-5, one of the archetypal MOFs, has a BET surface area of around 3,000 m²/g. Later developments, such as MOF-177 and the NU series (e.g., NU-110), pushed these values to over 7,000 m²/g and even 10,000 m²/g, respectively. This immense internal ‘real estate’ is crucial for applications that rely on surface interactions, such as gas storage, where molecules are physisorbed onto the framework’s interior surfaces, and catalysis, where active sites can be distributed throughout the material’s volume.

UNESCO Nomenclature: 2211
– Solid state physics

类型

Physical Property

中断

重大的

用法

广泛使用

前体

  • 布鲁诺尔-埃米特-特勒(BET)理论用于表面积测量
  • 气体吸附分析技术的发展
  • 沸石和活性炭等早期多孔材料的合成
  • 了解物理吸附和化学吸附现象

应用程序

  • 车辆高密度氢气和甲烷储存
  • 碳捕获 and sequestration (CCS) from flue gas
  • 工业气体净化
  • 多相催化 with high active site density
  • 色谱分离

专利:

NA

潜在创新理念

  • 用于洁净室和航天器的超高容量空气过滤器
  • 用于高选择性石油泄漏清理的海绵
  • 用于固定酶等大型生物分子而不会变性的支架
  • 精准农业的缓释肥料系统
  • 从电子废弃物中提取贵金属的材料
  • high-performance supercapacitor electrodes
  • 固态电解质使电池更安全
  • protective coatings that adsorb and neutralize chemical warfare agents
  • 医学成像(MRI)造影剂
  • 研究密闭空间内单分子反应的平台
Related to: surface area, porosity, bet theory, gas adsorption, physisorption, MOF-5, mof-177, porous material, void fraction, crystal density.

历史背景

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2015-09-14

(如果日期未知或不相关,例如“流体力学”,则提供其显著出现的近似估计)

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