vacuum-pressure-swing-adsorption-for-hydrogen-purification-with

Vacuum Pressure Swing Adsorption for Hydrogen Purification with Zeolite 5A

Pressure swing adsorption (PSA) is widely used for gas purification, and its performance depends strongly on the adsorbent properties and the cycle ...

University of Stavanger

Metal-organic frameworks (MOF) hold great promise for CO adsorption due to their high surface areas, tunable pore sizes, and the ability to modify their chemical properties to enhance CO affinity. MOFs tagged with functional groups either at linker or metal sites have shown improved CO uptake capacity and selectivity. This study focuses on investigating the potential of selective CO adsorption using amino functionalization of linker forming Ce-UiO-66. The physicochemical properties and characteristics of MOFs to determine the degree of amino functionalization and structural stability were examined using powder X-ray diffraction (PXRD), Fourier transformer infra-red (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and N porosimetry and specific surface area (BET). This work unveils a novel array of results on CO, N and water vapour adsorption on Ce-UiO-66-NH. The amino-functionalized Ce-UiO-66-NH shows 63 % higher CO uptake and 84 % higher CO/N selectivity at 273 K and 1 bar over Ce-UiO-66. Ce-UiO-66-NH also shows excellent structural stability after gas and vapour sorption making Ce-UiO-66-NH potential adsorbent for CO capture.

Amino-Functionalizing Ce-Based MOF UiO-66 for Enhanced CO Adsorption and Selectivity.

Metal-organic frameworks (MOFs) with a Zr-oxo cluster [(ZrO(OH))] are exceptionally stable and offer vast potential for a wide range of applications. Synthesis parameters strongly affect the quality, stability, morphology, , of the MOFs. In this study, we present an experimental set-up that allows following  element-specific chemical transformations during synthesis and the effect of various reaction parameters on the reaction products. Zr-fumarate formation was monitored using X-ray absorption spectroscopy (XAS) in ZrCl-DMF-based solutions. We have studied (i) the local (∼2-5 Å) environment around Zr ions in the early stages of the Zr-oxo cluster formation and MOF-synthesis reaction, (ii) kinetics of the synthesis reaction and its dependence on water and modulator concentrations, and (iii) the effect of the reaction parameters on MOF product quality. XAS data have provided direct evidence that the increased amounts of water and modulator accelerate the reaction. It has also confirmed that water is essential for MOF formation in DMF. Zr-cluster formation and the synthesis reaction were not observed in the absence of water in ZrCl-DMF and ZrCl-DMF-linker-modulator solutions. According to the EXAFS data, Zr ions are octahedrally coordinated by chlorine atoms in anhydrous solutions with and without the linker. In contrast, the Zr-oxo clusters and MOFs were formed only in the presence of water. The results of the  experiments were correlated with post-synthetic characterization of the resultant MOF products.

Exploring cluster formation in Zr-MOF synthesis  using X-ray absorption spectroscopy.

The synthesis of Ce-fumarate and Zr-fumarate metal-organic framework (MOF) is monitored for the first time with in situ Raman spectroscopy in custom-built solvothermal reactors. Several synthesis conditions were explored for Ce-fumarate at room temperature. The use of the method for high-temperature synthesis of Zr-fumarate is also demonstrated. In situ Raman monitoring provided insights into both the solution and crystalline phases of the reaction medium, revealing the dynamic interplay among precursors, modulators, and the forming MOF structure. The reaction kinetics was determined by following the characteristic peak at 1666 cm. The conversion was in good agreement with the reaction kinetics determined via in situ synchrotron powder diffraction. The resulting MOF products were further characterized using ex situ X-ray powder diffraction, scanning electron microscopy, thermogravimetry, and surface area measurements. This study demonstrates a simple and industrially scalable method for monitoring MOF synthesis in situ, which can provide insights into the stages and mechanisms of formation of MOFs and other compounds.

Article	Year
Amino-Functionalizing Ce-Based MOF UiO-66 for Enhanced CO Adsorption and Selectivity. ChemPlusChem\| PubMed ID: 38708570	2024
Exploring cluster formation in Zr-MOF synthesis using X-ray absorption spectroscopy. Physical chemistry chemical physics : PCCP\| PubMed ID: 39428857	2024
Probing Ce- and Zr-Fumarate Metal-Organic Framework Formation in Aqueous Solutions with In Situ Raman Spectroscopy and Synchrotron X-ray Diffraction. ACS omega\| PubMed ID: 39524665	2024

Sachin Maruti Chavan

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