scholarly journals The impact of crystal size and temperature on the adsorption-induced flexibility of the Zr-based metal-organic framework DUT-98

2019 ◽  
Author(s):  
Simon Krause ◽  
Volodymyr Bon ◽  
Hongchu Du ◽  
Rafal E Dunin-Borkowski ◽  
Ulrich Stoeck ◽  
...  
Keyword(s):  
Crystal Size ◽  
Metal Organic Framework ◽  
Type I ◽  
Adsorption Behaviour ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Adsorption Of Nitrogen ◽  
Metal Organic ◽  
The Impact ◽  
Organic Framework

In this contribution we analyse the influence of adsorption cycling, crystal size, and temperature on the switching behaviour of the flexible Zr-based metal-organic framework DUT-98. We observe a shift in the gate opening pressure upon cycling of adsorption experiments of micro meter-sized crystals and assign this to a fragmentation of the crystals. In a series of modulated syntheses we downsize the average crystal size of DUT-98 crystals from 120 µm to 50 nm and characterize the obtained solids by X-ray diffraction, infrared spectroscopy, as well as scanning and transmission electron microscopy. We analyse the adsorption behaviour by nitrogen and water adsorption at 77 K and 298 K, respectively and show that adsorption-induced flexibility is only observed for micro meter-sized crystals. Nanometer-sized crystals were found to exhibit reversible type I adsorption behaviour upon adsorption of nitrogen and exhibit a crystal-size dependent steep water uptake of up to 20 mmol g-1 at 0.5 p/p 0 with potential for water harvesting and heat pump applications. We furthermore investigate the temperature-induced structural transition by in situ PXRD. At temperatures beyond 110 °C the open pore state of nano meter-sized DUT-98 crystals are found to irreversibly transform in a closed pore state. The connection of crystal fragmentation upon adsorption cycling and the crystal size-dependence of the adsorption-induced flexibility is an important finding for evaluation of these materials in future adsorption-based applications. This work thus extends the limited amount of studies on crystal size effects in flexible MOFs and hopefully motivates further investigations into this field.

scholarly journals The impact of crystal size and temperature on the adsorption-induced flexibility of the Zr-based metal–organic framework DUT-98

2019 ◽  
Vol 10 ◽  
pp. 1737-1744 ◽  
Author(s):  
Simon Krause ◽  
Volodymyr Bon ◽  
Hongchu Du ◽  
Rafal E Dunin-Borkowski ◽  
Ulrich Stoeck ◽  
...  
Keyword(s):  
Crystal Size ◽  
Metal Organic Framework ◽  
Adsorption Behavior ◽  
Switching Behavior ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metal Organic ◽  
The Impact ◽  
Organic Framework

In this contribution we analyze the influence of adsorption cycling, crystal size, and temperature on the switching behavior of the flexible Zr-based metal–organic framework DUT-98. We observe a shift in the gate-opening pressure upon cycling of adsorption experiments for micrometer-sized crystals and assign this to a fragmentation of the crystals. In a series of samples, the average crystal size of DUT-98 crystals was varied from 120 µm to 50 nm and the obtained solids were characterized by X-ray diffraction, infrared spectroscopy, as well as scanning and transmission electron microscopy. We analyzed the adsorption behavior by nitrogen and water adsorption at 77 K and 298 K, respectively, and show that adsorption-induced flexibility is only observed for micrometer-sized crystals. Nanometer-sized crystals were found to exhibit reversible type I adsorption behavior upon adsorption of nitrogen and exhibit a crystal-size-dependent steep water uptake of up to 20 mmol g−1 at 0.5 p/p 0 with potential for water harvesting and heat pump applications. We furthermore investigate the temperature-induced structural transition by in situ powder X-ray diffraction. At temperatures beyond 110 °C, the open-pore state of the nanometer-sized DUT-98 crystals is found to irreversibly transform to a closed-pore state. The connection of crystal fragmentation upon adsorption cycling and the crystal size dependence of the adsorption-induced flexibility is an important finding for evaluation of these materials in future adsorption-based applications. This work thus extends the limited amount of studies on crystal size effects in flexible MOFs and hopefully motivates further investigations in this field.

scholarly journals Morphology and adsorption of chromium ion on uranium 1,2,4,5-benzenetetracarboxylic acid metal organic framework (MOF)

2016 ◽  
Vol 70 (5) ◽  
pp. 565-572 ◽  
Author(s):  
Remy Vala ◽  
Donbebe Wankasi ◽  
Ezekiel Dikio
Keyword(s):  
Electron Microscopy ◽  
Porous Structure ◽  
Metal Organic Framework ◽  
Tetracarboxylic Acid ◽  
X Ray Diffraction ◽  
Kinetic Determination ◽  
Transmission Electron ◽  
Metal Organic ◽  
Organic Framework

In this paper, we report the synthesis of metal organic framework of uranium 1,2,4,5-benzene tetracarboxylic acid (U-H4btec MOF) by solvothermal method. The obtained MOF was characterized by Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), Energy dispersive spectroscopy (EDS), thermogravimetric and differential thermogravimetric analysis (TGA/DTA). The morphology of the uranium 1,2,4,5-benzene tetracarboxylic acid MOF observed by SEM, revealed the presence of flaky porous structure. Adsorption of Cr3+ from aqueous solution onto the uranium 1,2,4,5-benzene tetracarboxylic acid MOF was systematically studied. Langmuir and Freundlich adsorption isotherms were applied to determine the adsorption capacity of the MOF to form a monolayer. Kinetic determination of the adsorption of Cr3+ suggested both chemisorption and physisorption probably due to the presence of carbonyl groups within the MOF and its porous structure.

scholarly journals Testing Metal–Organic Framework Catalysts in a Microreactor for Ethyl Paraoxon Hydrolysis

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1159
Author(s):  
Palani Elumalai ◽  
Nagat Elrefaei ◽  
Wenmiao Chen ◽  
Ma’moun Al-Rawashdeh ◽  
Sherzod T. Madrahimov
Keyword(s):  
Crystal Size ◽  
Metal Organic Framework ◽  
Catalyst Stability ◽  
Reaction Yield ◽  
Process Conditions ◽  
Chemical Agent ◽  
Testing Metal ◽  
Metal Organic ◽  
The Impact ◽  
Organic Framework

We explored the practical advantages and limitations of applying a UiO-66-based metal–organic framework (MOF) catalyst in a flow microreactor demonstrated by the catalytic hydrolysis of ethyl paraoxon, an organophosphorus chemical agent. The influences of the following factors on the reaction yield were investigated: a) catalyst properties such as crystal size (14, 200, and 540 nm), functionality (NH2 group), and particle size, and b) process conditions: temperature (20, 40, and 60 °C), space times, and concentration of the substrate. In addition, long-term catalyst stability was tested with an 18 h continuous run. We found that tableting and sieving is a viable method to obtain MOF particles of a suitable size to be successfully screened under flow conditions in a microreactor. This method was used successfully to study the effects of crystal size, functionality, temperature, reagent concentration, and residence time. Catalyst particles with a sieved fraction between 125 and 250 µm were found to be optimal. A smaller sieved fraction size showed a major limitation due to the very high pressure drop. The low apparent activation energy indicated that internal mass transfer may exist. A dedicated separate study is required to assess the impact of pore diffusion and site accessibility.

Synthesis and Structure of a Clathrated Two-Dimensional Metal-Organic Framework: [Cd(4,4'-bpy)2(H2O)2](ClO4)2·(L)2·H2O (L = Bis(1-pyrazinylethylidene)hydrazine)

2008 ◽  
Vol 73 (1) ◽  
pp. 24-31
Author(s):  
Dayu Wu ◽  
Genhua Wu ◽  
Wei Huang ◽  
Zhuqing Wang
Keyword(s):  
Metal Organic Framework ◽  
Channel Structure ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Square Planar ◽  
Metal Organic ◽  
Aqueous Meoh ◽  
Organic Framework

The compound [Cd(4,4'-bpy)2(H2O)2](ClO4)2·(L)2 was obtained by the reaction of Cd(ClO4)2, bis(1-pyrazinylethylidene)hydrazine (L) and 4,4'-bipyridine in aqueous MeOH. Single-crystal X-ray diffraction has revealed its two-dimensional metal-organic framework. The 2-D layers superpose on each other, giving a channel structure. The square planar grids consist of two pairs of shared edges with Cd(II) ion and a 4,4'-bipyridine molecule each vertex and side, respectively. The square cavity has a dimension of 11.817 × 11.781 Å. Two guest molecules of bis(1-pyrazinylethylidene)hydrazine are clathrated in every hydrophobic host cavity, being further stabilized by π-π stacking and hydrogen bonding. The results suggest that the hydrazine molecules present in the network serve as structure-directing templates in the formation of crystal structures.

scholarly journals Construction of Silver Quantum Dot Immobilized Zn-MOF-8 Composite for Electrochemical Sensing of 2,4-Dinitrotoluene

2019 ◽  
Vol 9 (22) ◽  
pp. 4952 ◽  
Author(s):  
Sushma Rani ◽  
Bharti Sharma ◽  
Shivani Kapoor ◽  
Rajesh Malhotra ◽  
Rajender S. Varma ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Limit Of Detection ◽  
Metal Organic Framework ◽  
Linear Sweep Voltammetry ◽  
Electrochemical Sensing ◽  
Amperometric Determination ◽  
Transmission Electron ◽  
Electro Catalysis ◽  
Metal Organic ◽  
Organic Framework

In the present study, we report a highly effective electrochemical sensor for detecting 2,4-dinitrotoluene (2,4-DNT). The amperometric determination of 2,4-DNT was carried out using a gold electrode modified with zinc–metal organic framework-8 and silver quantum dot (Zn-MOF-8@AgQDs) composite. The synthesized nanomaterials were characterized by using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The synthesized nanocomposite proved to be efficient in electro-catalysis thereby reducing the 2,4-DNT. The unique combination present in Zn-MOF-8@AgQDs composite offered an excellent conductivity and large surface area enabling the fabrication of a highly sensitive (−0.238 µA µM−1 cm−2), selective, rapid and stable 2,4-DNT sensor. The dynamic linear range and limit of detection (LOD) was about 0.0002 µM to 0.9 µM and 0.041 µM, respectively. A 2,4-DNT reduction was also observed during the linear sweep voltammetry (LSV) experiments with reduction peaks at −0.49 V and −0.68 V. This is an unprecedented report with metal organic framework (MOF) composite for sensing 2,4-DNT. In addition, the presence of other species such as thiourea, urea, ammonia, glucose, and ascorbic acid displayed no interference in the modified electrode suggesting its practicability in various environmental applications.

Single Crystal X-ray Diffraction Studies of Carbon Dioxide and Fuel-Related Gases Adsorbed on the Small Pore Scandium Terephthalate Metal Organic Framework, Sc2(O2CC6H4CO2)3

Langmuir ◽  
2009 ◽  
Vol 25 (6) ◽  
pp. 3618-3626 ◽  
Author(s):  
Stuart R. Miller ◽  
Paul A. Wright ◽  
Thomas Devic ◽  
Christian Serre ◽  
Gérard Férey ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Single Crystal ◽  
Metal Organic Framework ◽  
X Ray Diffraction ◽  
X Ray ◽  
Small Pore ◽  
Metal Organic ◽  
Organic Framework

scholarly journals Exceptional adsorption-induced cluster and network deformation in the flexible metal–organic framework DUT-8(Ni) observed by in situ X-ray diffraction and EXAFS

2015 ◽  
Vol 17 (26) ◽  
pp. 17471-17479 ◽  
Author(s):  
Volodymyr Bon ◽  
Nicole Klein ◽  
Irena Senkovska ◽  
Andreas Heerwig ◽  
Jürgen Getzschmann ◽  
...  
Keyword(s):  
Metal Organic Framework ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gate Opening ◽  
Metal Organic ◽  
Flexible Metal ◽  
Organic Framework

The “gate opening” mechanism in flexible MOF Ni2(2,6-ndc)2dabco was elucidated in detail.

A Mn(II) Metal-Organic Framework Constructed from a Tetrahedral Silicon-Cored Ligand

2013 ◽  
Vol 275-277 ◽  
pp. 2367-2370
Author(s):  
Qing Yu Ma ◽  
Rui Fang Guan ◽  
Guo Zhong Li ◽  
Deng Xu Wang
Keyword(s):  
Single Crystal ◽  
Metal Organic Framework ◽  
Diffusion Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Slow Diffusion ◽  
Sheet Structure ◽  
Metal Organic ◽  
1D Chains ◽  
Organic Framework

A novel metal-organic framework, MnCl2(BIPS)2•2CH3OH•2H2O (1) were synthesized from MnCl2 and a tetrahedral silicon-cored ligand, Me2Si(p-C6H4-imdazol-1-yl)2 (BIPS) under the slow diffusion method. The structure was determined by single-crystal X-ray diffraction. Complex 1 is a 2D sheet structure constructed from 1D chains with 34-atom metallamacrocycles.

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