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Open Access
Abstract: The purification of light olefins is one of the most important chemical separations globally and consumes large amounts of energy. Porous materials have the capability to improve the efficiency of this process by acting as solid, regenerable adsorbents. However, to develop translational systems, the underlying mechanisms of adsorption in porous materials must be fully understood. Herein, we report the adsorption and dynamic separation of C2 and C3 hydrocarbons in the metal–organic framework MFM-300(In), which exhibits excellent performance in the separation of mixtures of ethane/ethylene and propyne/propylene. Unusually selective adsorption of ethane over ethylene at low pressure is observed, resulting in selective retention of ethane from a mixture of ethylene/ethane, thus demonstrating its potential for a one-step purification of ethylene (purity > 99.9%). In situ neutron powder diffraction and inelastic neutron scattering reveal the preferred adsorption domains and host–guest binding dynamics of adsorption of C2 and C3 hydrocarbons in MFM-300(In).
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Jun 2022
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I11-High Resolution Powder Diffraction
|
Shanshan
Liu
,
Yinlin
Chen
,
Bin
Yue
,
Chang
Wang
,
Bin
Qin
,
Yuchao
Chai
,
Guangjun
Wu
,
Jiangnan
Li
,
Xue
Han
,
Ivan
Da Silva
,
Pascal
Manuel
,
Sarah J.
Day
,
Naijia
Guan
,
Stephen P.
Thompson
,
Sihai
Yang
,
Landong
Li
Diamond Proposal Number(s):
[29649]
Abstract: The development of cost-effective sorbents for direct capture of trace CO 2 (<1%) from the atmosphere is an important and challenging task. Natural or commercial zeolites are promising sorbents, but their performance in adsorption of trace CO 2 has been poorly explored to date. Herein, we report a systematic study on capture of trace CO 2 by commercial faujasite zeolites, where we found that the extra-framework cations played a key role on their performance. Under dry conditions, Ba-X displays high dynamic uptake of 1.79 and 0.69 mmol g -1 at CO 2 concentrations of 10000 and 1000 ppm, respectively, and shows excellent recyclability in the temperature-swing adsorption processes. K-X exhibits perfect moisture resistance, and >95 % dry CO 2 uptake can be preserved under relative humidity of 74%. In situ solid-state NMR spectroscopy, synchrotron X-ray diffraction and neutron diffraction reveal two binding sites for CO 2 in these zeolites, namely the basic framework oxygen atoms and the divalent alkaline earth metal ions. This study unlocks the potential of low-cost natural zeolites for applications in direct air capture.
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Jun 2022
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B18-Core EXAFS
B22-Multimode InfraRed imaging And Microspectroscopy
|
Yujie
Ma
,
Wanpeng
Lu
,
Xue
Han
,
Yinlin
Chen
,
Ivan
Da Silva
,
Daniel
Lee
,
Alena M.
Sheveleva
,
Zi
Wang
,
Jiangnan
Li
,
Weiyao
Li
,
Mengtian
Fan
,
Shaojun
Xu
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Yongqiang
Cheng
,
Svemir
Rudic
,
Pascal
Manuel
,
Mark D.
Frogley
,
Anibal J.
Ramirez-Cuesta
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[19850]
Open Access
Abstract: The presence of active sites in metal–organic framework (MOF) materials can control and affect their performance significantly in adsorption and catalysis. However, revealing the interactions between the substrate and active sites in MOFs at atomic precision remains a challenging task. Here, we report the direct observation of binding of NH3 in a series of UiO-66 materials containing atomically dispersed defects and open Cu(I) and Cu(II) sites. While all MOFs in this series exhibit similar surface areas (1111–1135 m2 g–1), decoration of the −OH site in UiO-66-defect with Cu(II) results in a 43% enhancement of the isothermal uptake of NH3 at 273 K and 1.0 bar from 11.8 in UiO-66-defect to 16.9 mmol g–1 in UiO-66-CuII. A 100% enhancement of dynamic adsorption of NH3 at a concentration level of 630 ppm from 2.07 mmol g–1 in UiO-66-defect to 4.15 mmol g–1 in UiO-66-CuII at 298 K is observed. In situ neutron powder diffraction, inelastic neutron scattering, and electron paramagnetic resonance, solid-state nuclear magnetic resonance, and infrared spectroscopies, coupled with modeling reveal that the enhanced NH3 uptake in UiO-66-CuII originates from a {Cu(II)···NH3} interaction, with a reversible change in geometry at Cu(II) from near-linear to trigonal coordination. This work represents the first example of structural elucidation of NH3 binding in MOFs containing open metal sites and will inform the design of new efficient MOF sorbents by targeted control of active sites for NH3 capture and storage.
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May 2022
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B22-Multimode InfraRed imaging And Microspectroscopy
|
Lixia
Guo
,
Xue
Han
,
Yujie
Ma
,
Jiangnan
Li
,
Wanpeng
Lu
,
Weiyao
Li
,
Daniel
Lee
,
Ivan
Da Silva
,
Yongqiang
Cheng
,
Svemir
Rudic
,
Pascal
Manuel
,
Mark D.
Frogley
,
Anibal Javier
Ramirez-Cuesta
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[30398]
Open Access
Abstract: To understand the exceptional adsorption of ammonia (NH3) in MFM-300(Sc) (19.5 mmol g−1 at 273 K and 1 bar without hysteresis), we report a systematic investigation of the mechanism of adsorption by a combination of in situ neutron powder diffraction, inelastic neutron scattering, synchrotron infrared microspectroscopy, and solid-state 45Sc NMR spectroscopy. These complementary techniques reveal the formation of reversible host-guest supramolecular interactions, which explains directly the observed excellent reversibility of this material over 90 adsorption-desorption cycles.
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Apr 2022
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[18786, 25166]
Abstract: The layered oxide chalcogenides Ba3-xSrxFe2O5Cu2Ch2 (x = 0, 1, 2; Ch = S, Se) and BaCa2Fe2O5Cu2S2 are reported here for the first time. They are isostructural with the previously reported Sr3Fe2O5Cu2Ch2, crystallising in the I4/mmm space group. This structure is related to the n = 2 Ruddlesden-Popper type structure which is common for oxides and contains Sr3Fe2O5 perovskite-related slabs intergrown with Cu2Ch2 layers which resemble fragments of the antifluorite structure. In the oxide slabs, a double layer of FeO5 pyramids is formed by the sharing of apical oxide ions. Structural analysis shows a clear partial ordering of the alkaline earth cations of different sizes over the available 12 and 8-coordinate sites which correlates with the size variation of the alkaline earth cations. Long range magnetic ordering on a √2a × √2a × c expansion of the nuclear cell reveals nearest neighbour Fe3+ moments coupling antiferromagnetically via all the Fe–O–Fe linkages. In Ba3Fe2O5Cu2Se2, the moments are oriented in the ab-plane, whereas in Ba3-xSrxFe2O5Cu2Ch2 (x = 2; Ch = S, Se), the Fe3+ moments are tilted towards the c-axis, reflecting that high spin d5 ions with no orbital angular momentum have only a weak preference for a particular spin direction.
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Dec 2021
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I11-High Resolution Powder Diffraction
|
Diamond Proposal Number(s):
[13284]
Open Access
Abstract: Preparing materials which simultaneously exhibit spontaneous magnetic and electrical polarisations is challenging as the electronic features which are typically used to stabilise each of these two polarisations in materials are contradictory. Here we show that by performing low-temperature cation-exchange reactions on a hybrid improper ferroelectric material, Li2SrTa2O7, which adopts a polar structure due to a cooperative tilting of its constituent TaO6 octahedra rather than an electronically driven atom displacement, a paramagnetic polar phase, MnSrTa2O7, can be prepared. On cooling below 43 K the Mn2+ centres in MnSrTa2O7 adopt a canted antiferromagnetic state, with a small spontaneous magnetic moment. On further cooling to 38 K there is a further transition in which the size of the ferromagnetic moment increases coincident with a decrease in magnitude of the polar distortion, consistent with a coupling between the two polarisations.
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Aug 2021
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I11-High Resolution Powder Diffraction
|
Abstract: Electronic phase separation into charge-ordered (CO) and charge-averaged (CA) phases in
Ca
Fe
3
−
x
M
x
O
5
samples for dopants
M
=
Mn
and Co has been investigated using powder neutron and x-ray diffraction, magnetization, and Mössbauer spectroscopy measurements. Electronic phase separation is observed in lightly doped
Ca
Fe
3
O
5
samples, where
4
–
10
%
Ca is replaced by Mn, Fe, or Co, and the CA ground state is stabilized at higher doping levels. The CO and CA phases are found to emerge below a common magnetic ordering temperature at
300
–
320
K
providing strong evidence for a lattice strain-driven mechanism that couples their magnetic transitions.
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Feb 2021
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I11-High Resolution Powder Diffraction
|
Tatchamapan
Yoskamtorn
,
Pu
Zhao
,
Xin-Ping
Wu
,
Kirsty
Purchase
,
Fabio
Orlandi
,
Pascal
Manuel
,
James
Taylor
,
Yiyang
Li
,
Sarah
Day
,
Lin
Ye
,
Chiu C.
Tang
,
Yufei
Zhao
,
S. C. Edman
Tsang
Abstract: Understanding structural responses of metal–organic frameworks (MOFs) to external stimuli such as the inclusion of guest molecules and temperature/pressure has gained increasing attention in many applications, for example, manipulation and manifesto smart materials for gas storage, energy storage, controlled drug delivery, tunable mechanical properties, and molecular sensing, to name but a few. Herein, neutron and synchrotron diffractions along with Rietveld refinement and density functional theory calculations have been used to elucidate the responsive adsorption behaviors of defect-rich Zr-based MOFs upon the progressive incorporation of ammonia (NH3) and variable temperature. UiO-67 and UiO-bpydc containing biphenyl dicarboxylate and bipyridine dicarboxylate linkers, respectively, were selected, and the results establish the paramount influence of the functional linkers on their NH3 affinity, which leads to stimulus-tailoring properties such as gate-controlled porosity by dynamic linker flipping, disorder, and structural rigidity. Despite their structural similarities, we show for the first time the dramatic alteration of NH3 adsorption profiles when the phenyl groups are replaced by the bipyridine in the organic linker. These molecular controls stem from controlling the degree of H-bonding networks/distortions between the bipyridine scaffold and the adsorbed NH3 without significant change in pore volume and unit cell parameters. Temperature-dependent neutron diffraction also reveals the NH3-induced rotational motions of the organic linkers. We also demonstrate that the degree of structural flexibility of the functional linkers can critically be affected by the type and quantity of the small guest molecules. This strikes a delicate control in material properties at the molecular level.
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Feb 2021
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B22-Multimode InfraRed imaging And Microspectroscopy
|
Xue
Han
,
Wanpeng
Lu
,
Yinlin
Chen
,
Ivan
Da Silva
,
Jiangnan
Li
,
Longfei
Lin
,
Weiyao
Li
,
Alena M.
Sheveleva
,
Harry G. W.
Godfrey
,
Zhenzhong
Lu
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Yongqiang
Cheng
,
Luke L.
Daemen
,
Laura J.
Mccormick Mcpherson
,
Simon J.
Teat
,
Mark D.
Frogley
,
Svemir
Rudic
,
Pascal
Manuel
,
Anibal J.
Ramirez-Cuesta
,
Sihai
Yang
,
Martin
Schroeder
Diamond Proposal Number(s):
[23782]
Abstract: Ammonia (NH3) is a promising energy resource owing to its high hydrogen density. However, its widespread application is restricted by the lack of efficient and corrosion-resistant storage materials. Here, we report high NH3 adsorption in a series of robust metal–organic framework (MOF) materials, MFM-300(M) (M = Fe, V, Cr, In). MFM-300(M) (M = Fe, VIII, Cr) show fully reversible capacity for >20 cycles, reaching capacities of 16.1, 15.6, and 14.0 mmol g–1, respectively, at 273 K and 1 bar. Under the same conditions, MFM-300(VIV) exhibits the highest uptake among this series of MOFs of 17.3 mmol g–1. In situ neutron powder diffraction, single-crystal X-ray diffraction, and electron paramagnetic resonance spectroscopy confirm that the redox-active V center enables host–guest charge transfer, with VIV being reduced to VIII and NH3 being oxidized to hydrazine (N2H4). A combination of in situ inelastic neutron scattering and DFT modeling has revealed the binding dynamics of adsorbed NH3 within these MOFs to afford a comprehensive insight into the application of MOF materials to the adsorption and conversion of NH3.
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Feb 2021
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I11-High Resolution Powder Diffraction
|
Henrik
Jacobsen
,
Hai L.
Feng
,
Andrew J.
Princep
,
Marein C.
Rahn
,
Yanfeng
Guo
,
Jie
Chen
,
Yoshitaka
Matsushita
,
Yoshihiro
Tsujimoto
,
Masahiro
Nagao
,
Dmitry
Khalyavin
,
Pascal
Manuel
,
Claire A.
Murray
,
Christian
Donnerer
,
James G.
Vale
,
Marco
Moretti Sala
,
Kazunari
Yamaura
,
Andrew T.
Boothroyd
Diamond Proposal Number(s):
[9839]
Abstract: We report on the structural, magnetic, and electronic properties of two new double-perovskites synthesized under high pressure,
Pb
2
CaOsO
6
and
Pb
2
ZnOsO
6
. Upon cooling below 80 K,
Pb
2
CaOsO
6
simultaneously undergoes a metal-to-insulator transition and develops antiferromagnetic order.
Pb
2
ZnOsO
6
, on the other hand, remains a paramagnetic metal down to 2 K. The key difference between the two compounds lies in their crystal structures. The Os atoms in
Pb
2
ZnOsO
6
are arranged on an approximately face-centered cubic lattice with strong antiferromagnetic nearest-neighbor exchange couplings. The geometrical frustration inherent to this lattice prevents magnetic order from forming down to the lowest temperatures. In contrast, the unit cell of
Pb
2
CaOsO
6
is heavily distorted up to at least 500 K including antiferroelectriclike displacements of the Pb and O atoms despite metallic conductivity above 80 K. This distortion relieves the magnetic frustration, facilitating magnetic order which, in turn, drives the metal-insulator transition. Our results suggest that the phase transition in
Pb
2
CaOsO
6
is spin driven and could be a rare example of a Slater transition.
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Dec 2020
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