I19-Small Molecule Single Crystal Diffraction
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William J. F.
Trenholme
,
Daniil I.
Kolokolov
,
Michelle
Bound
,
Stephen P.
Argent
,
Jamie A.
Gould
,
Jiangnan
Li
,
Sarah A.
Barnett
,
Alexander J.
Blake
,
Alexander G.
Stepanov
,
Elena
Besley
,
Timothy L.
Easun
,
Sihai
Yang
,
Martin
Schroeder
Abstract: The desolvated (3,24)-connected metal–organic framework (MOF) material, MFM-160a, [Cu3(L)(H2O)3] [H6L = 1,3,5-triazine-2,4,6-tris(aminophenyl-4-isophthalic acid)], exhibits excellent high-pressure uptake of CO2 (110 wt% at 20 bar, 298 K) and highly selective separation of C2 hydrocarbons from CH4 at 1 bar pressure. Henry’s law selectivities of 79:1 for C2H2:CH4 and 70:1 for C2H4:CH4 at 298 K are observed, consistent with ideal adsorption solution theory (IAST) predictions. Significantly, MFM-160a shows a selectivity of 16:1 for C2H2:CO2. Solid-state 2H NMR spectroscopic studies on partially deuterated MFM-160-d12 confirm an ultra-low barrier (∼2 kJ mol–1) to rotation of the phenyl group in the activated MOF and a rotation rate 5 orders of magnitude slower than usually observed for solid-state materials (1.4 × 106 Hz cf. 1011–1013 Hz). Upon introduction of CO2 or C2H2 into desolvated MFM-160a, this rate of rotation was found to increase with increasing gas pressure, a phenomenon attributed to the weakening of an intramolecular hydrogen bond in the triazine-containing linker upon gas binding. DFT calculations of binding energies and interactions of CO2 and C2H2 around the triazine core are entirely consistent with the 2H NMR spectroscopic observations.
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Feb 2021
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B18-Core EXAFS
B22-Multimode InfraRed imaging And Microspectroscopy
I11-High Resolution Powder Diffraction
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Shaojun
Xu
,
Xue
Han
,
Yujie
Ma
,
Thien D.
Duong
,
Longfei
Lin
,
Emma K.
Gibson
,
Alena
Sheveleva
,
Sarayute
Chansai
,
Alex
Walton
,
Duc-the
Ngo
,
Mark D.
Frogley
,
Chiu C.
Tang
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
C. Richard A.
Catlow
,
Christopher
Hardacre
,
Sihai
Yang
,
Martin
Schroeder
Open Access
Abstract: Efficient catalytic conversion of NO2 to non-harmful species remains an important target for research. State-of-the-art deNOx processes are based upon ammonia (NH3)-assisted selective catalytic reduction (NH3-SCR) over Cu-exchanged zeolites at elevated temperatures. Here, we describe a highly efficient non-thermal plasma (NTP) deNOx process catalyzed by a Cu-embedded metal-organic framework, Cu/MFM-300(Al), at room temperature. Under NTP activation at 25°C, Cu/MFM-300(Al) enables direct decomposition of NO2 into N2, NO, N2O, and O2 without the use of NH3 or other reducing agents. NO2 conversion of 96% with a N2 selectivity of 82% at a turnover frequency of 2.9 h−1 is achieved, comparable to leading NH3-SCR catalysts that use NH3 operating at 250°C–550°C. The mechanism for the rate-determining step (NO→N2) is elucidated by in operando diffuse reflectance infrared Fourier transform spectroscopy, and electron paramagnetic resonance spectroscopy confirms the formation of Cu2+⋯NO nitrosylic adducts on Cu/MFM-300(Al), which facilitates NO dissociation and results in the notable N2 selectivity.
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Feb 2021
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B22-Multimode InfraRed imaging And Microspectroscopy
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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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B22-Multimode InfraRed imaging And Microspectroscopy
I11-High Resolution Powder Diffraction
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Lydia
Briggs
,
Ruth
Newby
,
Xue
Han
,
Christopher
Morris
,
Mathew
Savage
,
Cristina
Perez
,
Timothy L.
Easun
,
Mark
Frogley
,
Gianfelice
Cinque
,
Claire A.
Murray
,
Chiu C.
Tang
,
Sihai
Yang
,
Junliang
Sun
,
Martin
Schroeder
Diamond Proposal Number(s):
[22137, 22138]
Open Access
Abstract: We report the adsorption of C2H2, CO2 and SO2 in a new, ultra-stable Cr(III)-based MOF, MFM-300(Cr), {[Cr2(OH)2(L)], H4L = biphenyl-3,3',5,5'-tetracarboxylic acid}. MFM-300(Cr) shows uptakes of 7.37, 7.73 and 8.59 mmol g-1 for CO2, C2H2 and SO2, respectively, at 273 K, 1.0 bar, and shows a higher selectivity for SO2/CO2 compared with the Al(III) analogue MFM-300(Al) (selectivity of 79 vs. 45). In order to monitor the effects of changing metal centre on gas uptake and to integrate the properties of the homometallic analogues, the mixed metal MFM-300(Al0.67Cr0.33), [Al1.34Cr0.66(OH)2L] has been synthesised. In situ synchrotron micro-FTIR spectroscopy has identified distinct CO2 binding environments on Al-O(H)-Al, Cr-O(H)-Cr and Al-O(H)-Cr bridges in MFM-300(Al0.67Cr0.33), and we have determined the binding domains for these gases by in situ synchrotron X-ray diffraction in both MFM-300(Cr) and MFM-300(Al0.67Cr0.33). The capability of these materials for gas separation has been confirmed by dynamic breakthrough experiments. The incorporation of Al(III) and Cr(III) within the same framework allows tuning of the host-guest and guest-guest interactions within these functional porous materials.
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Feb 2021
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I11-High Resolution Powder Diffraction
I20-EDE-Energy Dispersive EXAFS (EDE)
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Longfei
Lin
,
Mengtian
Fan
,
Alena M.
Sheveleva
,
Xue
Han
,
Zhimou
Tang
,
Joseph H.
Carter
,
Ivan
Da Silva
,
Christopher
Parlett
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
German
Sastre
,
Svemir
Rudic
,
Hamish
Cavaye
,
Stewart F.
Parker
,
Yongqiang
Cheng
,
Luke L.
Daemen
,
Anibal J.
Ramirez-cuesta
,
Martin P.
Attfield
,
Yueming
Liu
,
Chiu C.
Tang
,
Buxing
Han
,
Sihai
Yang
Diamond Proposal Number(s):
[2359]
Open Access
Abstract: Optimising the balance between propene selectivity, propene/ethene ratio and catalytic stability and unravelling the explicit mechanism on formation of the first carbon–carbon bond are challenging goals of great importance in state-of-the-art methanol-to-olefin (MTO) research. We report a strategy to finely control the nature of active sites within the pores of commercial MFI-zeolites by incorporating tantalum(V) and aluminium(III) centres into the framework. The resultant TaAlS-1 zeolite exhibits simultaneously remarkable propene selectivity (51%), propene/ethene ratio (8.3) and catalytic stability (>50 h) at full methanol conversion. In situ synchrotron X-ray powder diffraction, X-ray absorption spectroscopy and inelastic neutron scattering coupled with DFT calculations reveal that the first carbon–carbon bond is formed between an activated methanol molecule and a trimethyloxonium intermediate. The unprecedented cooperativity between tantalum(V) and Brønsted acid sites creates an optimal microenvironment for efficient conversion of methanol and thus greatly promotes the application of zeolites in the sustainable manufacturing of light olefins.
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Feb 2021
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I11-High Resolution Powder Diffraction
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Xi
Chen
,
Zhongyue
Zhang
,
Jin
Chen
,
Sergei
Sapchenko
,
Xue
Han
,
Ivan
Da Silva
,
Ming
Li
,
Inigo
Vitorica-yrezabal
,
George
Whitehead
,
Chiu C.
Tang
,
Kunio
Awaga
,
Sihai
Yang
,
Martin
Schroeder
Diamond Proposal Number(s):
[22138]
Abstract: MFM-722(Pb)-DMA undergoes a single-crystal-to-single-crystal (SCSC) transformation to give MFM-722(Pb)-H2O via ligand substitution upon exposure to water vapour. In situ single crystal impedance spectroscopy reveals an increase in proton conductivity due to this structural transition, with MFM-722(Pb)-H2O showing a proton conductivity of 6.61×10-4 S cm-1 at 50 °C and 98% RH. The low activation energy (Ea = 0.21 eV) indicates that the proton conduction follows a Grotthuss mechanism.
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Nov 2020
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I11-High Resolution Powder Diffraction
I19-Small Molecule Single Crystal Diffraction
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Stephen P.
Argent
,
Ivan
Da Silva
,
Alex
Greenaway
,
Mathew
Savage
,
Jack
Humby
,
Andrew J.
Davies
,
Harriott
Nowell
,
William
Lewis
,
Pascal
Manuel
,
Chiu C.
Tang
,
Alexander J.
Blake
,
Michael W.
George
,
Alexander V.
Markevich
,
Elena
Besley
,
Sihai
Yang
,
Neil R.
Champness
,
Martin
Schroeder
Diamond Proposal Number(s):
[861, 11622, 15833, 9443]
Open Access
Abstract: Designing porous materials which can selectively adsorb CO2 or CH4 is an important environmental and industrial goal which requires an understanding of the host–guest interactions involved at the atomic scale. Metal–organic polyhedra (MOPs) showing permanent porosity upon desolvation are rarely observed. We report a family of MOPs (Cu-1a, Cu-1b, Cu-2), which derive their permanent porosity from cavities between packed cages rather than from within the polyhedra. Thus, for Cu-1a, the void fraction outside the cages totals 56% with only 2% within. The relative stabilities of these MOP structures are rationalized by considering their weak nondirectional packing interactions using Hirshfeld surface analyses. The exceptional stability of Cu-1a enables a detailed structural investigation into the adsorption of CO2 and CH4 using in situ X-ray and neutron diffraction, coupled with DFT calculations. The primary binding sites for adsorbed CO2 and CH4 in Cu-1a are found to be the open metal sites and pockets defined by the faces of phenyl rings. More importantly, the structural analysis of a hydrated sample of Cu-1a reveals a strong hydrogen bond between the adsorbed CO2 molecule and the Cu(II)-bound water molecule, shedding light on previous empirical and theoretical observations that partial hydration of metal−organic framework (MOF) materials containing open metal sites increases their uptake of CO2. The results of the crystallographic study on MOP–gas binding have been rationalized using DFT calculations, yielding individual binding energies for the various pore environments of Cu-1a.
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Oct 2020
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B22-Multimode InfraRed imaging And Microspectroscopy
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Jiangnan
Li
,
Zhengyang
Zhou
,
Xue
Han
,
Xinran
Zhang
,
Yong
Yan
,
Weiyao
Li
,
Gemma L.
Smith
,
Yongqiang
Cheng
,
Laura J.
Mcormick Mpherson
,
Simon J.
Teat
,
Mark D.
Frogley
,
Svemir
Rudic
,
Anibal J.
Ramirez-cuesta
,
Alexander J.
Blake
,
Junliang
Sun
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[22137]
Abstract: Structural transitions of host systems in response to guest binding dominate many chemical processes. We report an unprecedented type of structural flexibility within a meta-rigid material, MFM-520, which exhibits a reversible periodic-to-aperiodic structural transition resulting from a drastic distortion of a [ZnO4N] node controlled by the specific host–guest interactions. The aperiodic crystal structure of MFM-520 has no three-dimensional (3D) lattice periodicity but shows translational symmetry in higher-dimensional (3 + 2)D space. We have directly visualized the aperiodic state which is induced by incommensurate modulation of the periodic framework of MFM-520·H2O upon dehydration to give MFM-520. Filling MFM-520 with CO2 and SO2 reveals that, while CO2 has a minimal structural influence, SO2 can further modulate the structure incommensurately. MFM-520 shows exceptional selectivity for SO2 under flue-gas desulfurization conditions, and the facile release of captured SO2 from MFM-520 enabled the conversion to valuable sulfonamide products. MFM-520 can thus be used as a highly efficient capture and delivery system for SO2.
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Oct 2020
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Samer
Abdulridha
,
Rongxin
Zhang
,
Shaojun
Xu
,
Aleksander
Tedstone
,
Xiaoxia
Ou
,
Jiacheng
Gong
,
Boyang
Mao
,
Mark
Frogley
,
Carlo
Bawn
,
Zhaoxia
Zhou
,
Xinran
Zhang
,
Sarayute
Chansai
,
Stuart M.
Holmes
,
Christopher
Hardacre
,
Arthur A.
Garforth
,
Sihai
Yang
,
Yilai
Jiao
,
Xiaolei
Fan
Abstract: We report a low-cost, highly energy efficient microwave-assisted chelation (MWAC) method, which enabled the post-synthetic modification of synthetic zeolites for adopting hierarchical structures within minutes. Exemplified by Zeolite Y, hierarchical Y zeolites prepared in this way showed exceptional specific external surface areas of >300 m2 g−1 and mesopore volumes of >0.46 cm3 g−1. Comparative assessments revealed that developed zeolites have shown significantly improved catalytic activities for catalysis involving large substrates, such as catalytic cracking and hydrocracking of plastics.
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Oct 2020
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B22-Multimode InfraRed imaging And Microspectroscopy
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Xinchen
Kang
,
Bin
Wang
,
Kui
Hu
,
Kai
Lyu
,
Xue
Han
,
Ben F.
Spencer
,
Mark D.
Frogley
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Robert A. W.
Dryfe
,
Buxing
Han
,
Sihai
Yang
,
Martin
Schroeder
Diamond Proposal Number(s):
[19171]
Open Access
Abstract: Efficient electro-reduction of CO2 over metal–organic framework (MOF) materials is hindered by the poor contact between thermally synthesized MOF particles and the electrode surface, which leads to low Faradaic efficiency for a given product and poor electrochemical stability of the catalyst. We report a MOF-based electrode prepared via electro-synthesis of MFM-300(In) on an indium foil, and its activity for the electrochemical reduction of CO2 is assessed. The resultant MFM-300(In)-e/In electrode shows a 1 order of magnitude improvement in conductivity compared with that for MFM-300(In)/carbon-paper electrodes. MFM-300(In)-e/In exhibits a current density of 46.1 mA cm–2 at an applied potential of −2.15 V vs Ag/Ag+ for the electro-reduction of CO2 in organic electrolyte, achieving an exceptional Faradaic efficiency of 99.1% for the formation of formic acid. The facile preparation of the MFM-300(In)-e/In electrode, coupled with its excellent electrochemical stability, provides a new pathway to develop efficient electro-catalysts for CO2 reduction.
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Sep 2020
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