BETisotherm types The Brunauer–Emmett–Teller (BET) theory and its practical application, the BET analysis, stand as cornerstone techniques for characterizing the surface properties of porous materials, with a particular emphasis on metal-organic frameworks (MOFs).作者：F Ambroz·2018·被引用次数：767—In this review, the suitability of theBETmethod is discussed forMOFsthat have a diverse range of pore widths below the diameters of N2 or Ar ... These highly versatile crystalline compounds, constructed from metal ions or clusters coordinated to organic ligands, possess exceptionally high surface areas and tunable pore structures, making them promising candidates for a diverse array of applications. Understanding and quantifying these surface characteristics through BET analysis is crucial for optimizing their performance.
The BET analysis is widely recognized as the standard method for determining surface areas from gas adsorption isotherms. Specifically, it quantizes the amount of gas molecules that physically adsorb onto the surface of a materialScreening the Specific Surface Area for Metal-Organic .... The core principle of the Brunauer–Emmett–Teller (BET) theory itself is to explain the multilayer physical adsorption of gas molecules on a solid surfaceEvaluation of the BET method for determining surface .... This theoretical framework allows for the calculation of the specific surface area, a critical parameter for evaluating the potential of materials like MOFs in gas storage, separation, catalysis, and sensing.Bismuth and lead based metal organic frameworks
MOFs are renowned for their extraordinarily large surface areas, which can range from hundreds to thousands of square meters per gram. This dwarfs the surface areas of many traditional porous materials. The BET analysis provides an experimental estimate of these high BET surface areas, which are often experimentally determined by applying the BET theory to measured gas adsorption isotherms. For instance, research has shown that MOFs of a larger surface area have been found to significantly correlate with greater storage capacity, such as for methane.
While the BET analysis is a commonly used method, its applicability and accuracy for certain MOFs have been a subject of ongoing research作者：KS Walton·2007·被引用次数：1296—The BET analysis is the standard method for determining surface areasfrom nitrogen adsorption isotherms and was originally derived for multilayer gas .... Specifically, the evaluation of the BET method for determining surface areas of MOFs that contain "ultra-micropores" (less than 7 Å in diameter) requires careful consideration作者：HR Abid·2024·被引用次数：94—The highestBETwas observed in high-valenceMOFs... We conclude that TGAanalysisand thermalMOFstability are important factors in the .... The traditional BET model, derived for multilayer gas adsorption on non-porous surfaces, may present limitations when dealing with extremely small pores or complex pore geometries prevalent in some MOFs.作者：YS Bae·2010·被引用次数：421—The BET analysis iscommonly used for determining surface areas of metal-organic frameworks (MOFs) and zeolites that contain ultra-micropores. Studies have explored the suitability of the BET method for MOFs with a diverse range of pore widths, especially those below the diameters of common probe gases like nitrogen (N₂) or argon (Ar)B.E.T. surface area and total pore volume of synthesized ....
The most frequent approach for performing BET analysis on MOFs involves nitrogen adsorption at cryogenic temperatures, typically 77 K. This is because nitrogen is a readily available and cost-effective adsorbate, and its adsorption behavior at low temperatures provides detailed information about the porous structure. The process involves measuring the amount of nitrogen gas adsorbed by the MOF sample at various relative pressures. From this data, the BET specific surface area and micropore volume can be determined.
However, researchers have also investigated other adsorbates and modified BET analysis techniques to overcome potential limitations. For example, the adsorption of hydrogen (H₂) has been studied to complement nitrogen adsorption resultsBET specific surface area and pore structure of MOFs .... Furthermore, advancements in computational tools have emerged to address issues related to manual BET fitting, such as the development of a computational tool called BET surface identification (BETSI), aiming to improve the reproducibility and accuracy of BET surface area calculations.
The analysis of microstructure properties of MOFs, often performed using techniques like SEM (Scanning Electron Microscopy) and TGA (Thermogravimetric Analysis) alongside BET analysis, provides a comprehensive understanding of the material作者：HR Mahdipoor·2021·被引用次数：74—Characterization of the synthesizedMOFswere performed byBET, SEM, and TGA methods. While the temperature resistance of MIL-53(Fe) was .... TGA analysis, for instance, coupled with BET analysis, helps in understanding thermal MOF stability, which is an important factor for practical applications.Ultrahigh Surface Area Zirconium MOFs and Insights into ...
Several factors can influence the resulting BET surface area obtained from MOFs:
* Degassing Conditions: The temperature and duration of degassing (outgassing) the MOF sample before the adsorption experiment are critical. Increasing the degassing temperature, as long as it does not alter the crystal structure of the MOF or lead to decomposition, can often increase the measured surface area.B.E.T. surface area and total pore volume of synthesized ... This is because effective removal of adsorbed species from the pores is essential for accurate gas adsorption measurements.
* Pore Size Distribution: As mentioned, very small micropores can pose challenges for the standard BET analysis. The applicability of the BET method for the characterization of meso and microporous MOFs is an area of active investigation.
* Adsorbate Choice: While nitrogen is standard, the interaction of different gas molecules with the internal pore surfaces can vary, potentially leading to different apparent surface areasEvaluation of the BET Theory for the Characterization ....
* MOF Structure: The inherent porosity, pore size, and connectivity within the MOF structure directly impact the gas adsorption behavior and thus the BET results.Screening the Specific Surface Area for Metal-Organic ... For example, studies on bismuth and lead based metal organic frameworks have utilized BET analysis to characterize their adsorptive potentialApplicability of the BET method for determining surface ....
* Synthesis and Post-Synthetic Modification: The synthesis method can influence the final crystal structure and pore accessibility.作者：HR Mahdipoor·2021·被引用次数：74—Characterization of the synthesizedMOFswere performed byBET, SEM, and TGA methods. While the temperature resistance of MIL-53(Fe) was ... Post-synthetic modifications, such as introducing specific functional groups or altering the metal-ligand ratios (e.gWhat can affect the amount of BET surface area in MOFs?., adjusting the Ni/Fe molar ratio in some Ni-Fe MOFs), can significantly impact the BET surface area and selectivity2022年2月12日—Increasing the degassing temperature as long as it does not change the structure of theMOFsample can increase in the surface area..
While BET analysis is primarily used for surface area determination, it also provides insights into pore volume and distribution.Surface area determination with theBrunauer–Emmett–Teller (BET) methodis a widely used characterization technique for metal–organic frameworks (MOFs). The type of adsorption isotherm observed during the BET analysis can offer clues about the pore structure.BET specific surface area and pore structure of MOFs ... Different isotherm types (e.g., Type I, II, III, IV, V) are associated with different pore geometries and adsorption mechanisms.
The BET analysis is not performed in isolation.作者：T Evans·2023·被引用次数：15—The table includes a summary of the key values obtained from theBET analysisin the range of P/P0 of 0.01-0.05 for theMOFUiO-66. The positive ... It is often a part of a comprehensive characterization suite.BET theory For instance, before conducting BET analysis, characterizing your MOF by PXRD (Powder X-ray Diffraction) and indexing is essential to confirm its crystalline phase and porosity. This ensures that the MOF is indeed porous and suitable for such surface area measurements.2.3: BET Surface Area Analysis of Nanoparticles
In conclusion, MOFs BET analysis is an indispensable technique for unlocking the potential of these advanced materials.Bismuth and lead based metal organic frameworks While the Brunauer–Emmett–Teller (BET) method serves as a robust foundation, continued research into its nuances, especially concerning ultra-microporous MOFs, ensures its relevance and accuracy in characterizing the diverse and complex world of metal-organic frameworks.Evaluation of the BET method for determining surface ... The insights gained from BET analysis of MOF samples are vital for designing materials with tailored properties for emerging technologies.
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