B22-Multimode InfraRed imaging And Microspectroscopy
I11-High Resolution Powder Diffraction
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Jiangnan
Li
,
Gemma L.
Smith
,
Yinlin
Chen
,
Yujie
Ma
,
Meredydd
Kippax-Jones
,
Mengtian
Fan
,
Wanpeng
Lu
,
Mark D.
Frogley
,
Gianfelice
Cinque
,
Sarah
Day
,
Stephen P.
Thompson
,
Yongqiang
Cheng
,
Luke L.
Daemen
,
Anibal J.
Ramirez-Cuetos
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[28497, 29649]
Open Access
Abstract: We report reversible high capacity adsorption of SO2 in robust Zr-based metal-organic frameworks (MOFs). Zr-bptc (H4bptc = biphenyl-3,3’,5,5’-tetracarboxylic acid) shows a high SO2 uptake of 6.2 mmol g-1 at 0.1 bar and 298 K, reflecting excellent capture capability and removal of SO2 at low concentration (2500 ppm). Dynamic breakthrough experiments confirm that the introduction of amine, atomically-dispersed Cu(II) or heteroatomic sulphur sites into the pores enhance the capture of SO2 at low concentrations. The captured SO2 can be converted quantitatively to a pharmaceutical intermediate, aryl N-aminosulfonamide, thus converting waste to chemical values. In situ X-ray diffraction, infrared micro-spectroscopic and inelastic neutron scattering enable the visualisation of the binding domains of adsorbed SO2 molecules and host-guest binding dynamics in these materials at the atomic level. The refinement of pore environment plays a critical role in designing efficient sorbent materials.
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Jun 2022
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I11-High Resolution Powder Diffraction
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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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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[24092]
Open Access
Abstract: Marine archaeological artefacts contain unexpected compounds due to prolonged exposure to the sea. These can remain dormant and embedded within materials until a change in their surrounding environment, such as exposure to oxygen, prompts a transformation. These changes can pose a problem, as acidic compounds are formed which disintegrate the material, or crystals form which physically break the artefact apart. The extent of these transformations is highly heterogeneous due to its dependence on the ability for oxygen to reach and catalyse these reactions. Additionally, these transformations are heavily dependent on the environment the artefact is exposed to, and the pathways available for ingress, either naturally or through previous degradation. This results in materials with a range of different compounds which are often co-located on the macro, micro and nano-scale. Trying to de-convolute these compounds is challenging, and usually requires a suite of complementary techniques to achieve. Here we report on damaging salts found within marine archaeological bricks and show how it is only possible to qualitatively and quantitatively understand what is present by employing a range of analytical techniques, such as XRD, SEM-EDS and SR-XPD. The marine archaeological bricks studied were found to contain a range of different sulfate-based salts, which had grown crystals in preferred orientations. This provides information which will guide further conservation strategies such as how these bricks are stored, conserved and protected in the future.
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May 2022
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I11-High Resolution Powder Diffraction
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Shanshan
Liu
,
Yinlin
Chen
,
Bin
Yue
,
Yuanxin
Nie
,
Yuchao
Chai
,
Guangjun
Wu
,
Jiangnan
Li
,
Xue
Han
,
Sarah J.
Day
,
Stephen P.
Thompson
,
Naijia
Guan
,
Sihai
Yang
,
Landong
Li
Diamond Proposal Number(s):
[31365]
Abstract: Adsorptive separation of light hydrocarbons by porous solids provides an energy-efficient alternative to state-of-the-art cryogenic distillation. However, an optimal balance between the cost, performance and stability of the sorbent material is yet to be achieved for industrial applications. Here, we report the efficient separation of C2 and C3 hydrocarbons by a faujasite zeolite (Na-X, Si/Al=1.23). A tandem configuration of two fixed-beds packed with Na-X affords complete dynamic separation of the ternary mixture of C2H2/C2H4/C2H6 (1/49.5/49.5; v/v/v) under ambient conditions. Pressure-swing desorption on the latter fixed-bed gives ethylene (>99.50%, 1.80 mmol g-1) and ethane (>99.99%, 1.41 mmol g-1). In situ synchrotron X-ray powder diffraction revealed the binding sites for C2H2 and C2H4 in Na-X. This study highlights the potential application of commercial zeolites for challenging industrial separations.
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May 2022
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I11-High Resolution Powder Diffraction
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Tianxiang
Chen
,
Yong
Wang
,
Qi
Xue
,
Ching Kit Tommy
Wun
,
Pui Kin
So
,
Ka Fu
Yung
,
Tai-Sing
Wu
,
Yun-Liang
Soo
,
Keita
Taniya
,
Sarah
Day
,
Chiu C.
Tang
,
Zehao
Li
,
Bolong
Huang
,
Shik Chi Edman
Tsang
,
Kwok-Yin
Wong
,
Tsz Woon Benedict
Lo
Diamond Proposal Number(s):
[26404]
Open Access
Abstract: The large-scale synthesis of supported multinuclear catalysts with controllable metal nuclearity and constituent composition remains a formidable challenge. We report the stepwise assembly of supported atom-precise bimetallic ligand-mediated metal ensembles (LMMEs) by exploiting the underlying principles of coordination chemistry and solid-state chemistry. Lewis di-basic 2-methylimidazole is used to bridge multiple Cu2+ and M2+ (M = Co, Ni, Cu, and Zn) ions within ZSM-5 zeolites. We observe the metal constituent composition of the LMMEs by mass spectroscopy. The adjacent metal nuclei in the LMMEs offer substantial synergistic effects that enhance the catalytic performance by at least an order of magnitude in the model catalytic “click” reaction. It is envisaged that this stepwise assembly approach to develop supported multinuclear catalysts with atom precision could effectively bridge homogeneous and heterogeneous catalysis.
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Apr 2022
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I11-High Resolution Powder Diffraction
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Open Access
Abstract: Zeolites have found tremendous applications in the chemical industry. However, it is unclear about the dynamic nature of their active sites under the flow of adsorbate molecules for adsorption and catalysis, especially in operando conditions, which could be different from the as-synthesized structures. In the present study, we report a structural transformation of the adsorptive active sites in SAPO-34 zeolite by using acetone as a probe molecule under various temperatures. The combination of solid-state nuclear magnetic resonance, in-situ variable-temperature synchrotron x-ray diffraction, and in-situ diffuse-reflectance infrared Fourier-transform spectroscopy allow a clear identification and quantification that the chemisorption of acetone can convert the classical Brønsted acid site adsorption mode to an induced Frustrated Lewis Pairs adsorption mode at increasing temperatures. Such facile conversion is also supported by the calculations of ab-initio molecular-dynamics simulations. This work sheds new light on the importance of the dynamic structural alteration of active sites in zeolites with adsorbates at elevated temperatures.
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Apr 2022
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[27557]
Abstract: Soluble additives are widely used to control crystallization processes, modifying the morphologies, sizes, polymorphs, and physical properties of the product crystals. Here, a simple and versatile strategy is shown to significantly enhance the potency of soluble additives, ranging from ions and amino acids to large dye molecules, enabling them to be effective even at low concentrations. Addition of small amounts of miscible organic co-solvents to an aqueous crystallization solution can yield enhanced morphological changes and an order of magnitude increase of additive incorporation within single crystals─a level that cannot be achieved in pure aqueous solutions at any additive concentration. The generality of this strategy is demonstrated by application to crystals of calcium carbonate, manganese carbonate, and strontium sulfate, with a more pronounced effect observed for co-solvents with lower dielectric constants and polarities, indicating a general underlying mechanism that alters water activity. This work increases the understanding of additive/crystal interactions and may see great application in industrial-scale crystal synthesis.
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Nov 2021
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[10025]
Open Access
Abstract: The precipitation of hydrated phases from a chondrite-like Na–Mg–Ca–SO4–Cl solution is studied using in situ synchrotron X-ray powder diffraction, under rapid- (360 K h−1, T = 250–80 K, t = 3 h) and ultra-slow-freezing (0.3 K day−1, T = 273–245 K, t = 242 days) conditions. The precipitation sequence under slow cooling initially follows the predictions of equilibrium thermodynamics models. However, after ∼50 days at 245 K, the formation of the highly hydrated sulfate phase Na2Mg(SO4)2·16H2O, a relatively recent discovery in the Na2Mg(SO4)2–H2O system, was observed. Rapid freezing, on the other hand, produced an assemblage of multiple phases which formed within a very short timescale (≤4 min, ΔT = 2 K) and, although remaining present throughout, varied in their relative proportions with decreasing temperature. Mirabilite and meridianiite were the major phases, with pentahydrite, epsomite, hydrohalite, gypsum, blödite, konyaite and loweite also observed. Na2Mg(SO4)2·16H2O was again found to be present and increased in proportion relative to other phases as the temperature decreased. The results are discussed in relation to possible implications for life on Europa and application to other icy ocean worlds
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Oct 2021
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I11-High Resolution Powder Diffraction
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Open Access
Abstract: Neutral ketene is a crucial intermediate during zeolite carbonylation reactions. In this work, the roles of ketene and its derivates (viz., acylium ion and surface acetyl) associated with direct C–C bond coupling during the carbonylation reaction have been theoretically investigated under realistic reaction conditions and further validated by synchrotron radiation X-ray diffraction (SR-XRD) and Fourier transformed infrared (FT-IR) studies. It has been demonstrated that the zeolite confinement effect has significant influence on the formation, stability, and further transformation of ketene. Thus, the evolution and the role of reactive and inhibitive intermediates depend strongly on the framework structure and pore architecture of the zeolite catalysts. Inside side pockets of mordenite (MOR), rapid protonation of ketene occurs to form a metastable acylium ion exclusively, which is favorable toward methyl acetate (MA) and acetic acid (AcOH) formation. By contrast, in 12MR channels of MOR, a relatively longer lifetime was observed for ketene, which tends to accelerate deactivation of zeolite due to coke formation by the dimerization of ketene and further dissociation to diene and alkyne. Thus, we resolve, for the first time, a long-standing debate regarding the genuine role of ketene in zeolite catalysis. It is a paradigm to demonstrate the confinement effect on the formation, fate, and catalytic consequence of the active intermediates in zeolite catalysis.
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Sep 2021
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Abstract: We report the guest-anion-induced photoluminescence enhancement of metal–organic frameworks (UiO-66-NH2), first based upon diffraction and computational evidence. We found that only limited anions, namely, carbonate and fluoride, can lead to a significant enhancement in photoluminescence, whereas their related anions, such as acetate and chloride, cannot. The optimized crystal structures reveal that the guest carbonate and fluoride ions interact with four framework amino functional groups through hydrogen bonding (ca. 1.6–1.7 Å) that ultimately forms a quaternary (−N(H))4···X– molecular bridge around the nodal center. Hence, the hydrogen-bonded molecular bridge not only restricts the intermolecular C–C rotation of the linker molecules but also greatly perturbs the electronic densities between the guest anions and the framework amino groups.
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Jul 2021
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