B18-Core EXAFS
|
Abstract: Industrial W-based olefin metathesis catalysts use silica as the support and generally show low activities. This is due to the difficulty in dispersing W species and in maintaining the structural integrity of W active centers on the silica surface. These catalysts also have poor W redox kinetics and slow olefin adsorption at reaction temperatures, which prohibits high reaction rates. Here, for the first time, we systematically demonstrate the dramatic multiple contributions from zeolite Y to the overall catalytic activity when it is used as the catalyst support. The high surface area and porous nature of zeolite Y can provide the isolation, immobilization, and confinement of W active centers. Isolated W active centers in zeolite Y show faster redox kinetics, which is crucial for olefin metathesis. Zeolite Y also facilitates rapid adsorption and isomerization of olefin substrates by its Brønsted acid sites for synergetic catalysis with W active centers.
|
Jun 2026
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
|
Pascal
Kolodzeiski
,
Benjamin M.
Gallant
,
Lennard
Richter
,
Mario Antonio T.
Ongkiko
,
Carlo
Franke
,
Aleksander
Kostka
,
Wen-Long
Xue
,
Chinmoy
Das
,
Jan-Benedikt
Weiss
,
Elena
Kolodzeiski
,
Thomas
Kress
,
Gregor
Kieslich
,
Tong
Li
,
Andrew J.
Morris
,
Dominik
Kubicki
,
Sebastian
Henke
Diamond Proposal Number(s):
[31642]
Open Access
Abstract: Modifying glass compositions is key to creating silicate-based glasses for technologies including optical fibres, catalytic supports, protective coatings and separation membranes. Here we extend this concept to metal–organic framework (MOF) glasses by modifying the MOF glass former ZIF-62 with Li(bim) and Na(bim) as compatible glass modifiers (benzimidazolate, bim−). Melt-quenching of physical mixtures with increasing Na(bim) content yields modified MOF glasses that exhibit a systematic decrease in the glass transition temperature (Tg), accompanied by increased liquid fragility, configurational heat capacity at Tg and density: paralleling silicate glass chemistry through partial network depolymerization. Structural and spectroscopic analysis, coupled with density-functional theory calculations, confirm that Na(bim) is incorporated homogeneously into the MOF glass framework rather than the pores and reveal the presence of undercoordinated sodium ion environments. Finally, extraction of the modifier by water treatment increases glass porosity, akin to established borosilicate glass processes. This work introduces a transferable approach for tailoring the structure and properties of MOF glasses.
|
May 2026
|
|
I11-High Resolution Powder Diffraction
|
Diamond Proposal Number(s):
[16358]
Open Access
Abstract: In aluminosilicate zeolites, the atomic-scale insights into catalytic performance are tied to Brønsted acid sites (BASs), the primary active sites generated by the substitution of aluminum (Al) for silicon (Si) in the tetrahedral framework, with a proton (H⁺) compensating for the resultant charge imbalance. The profound influence of Al distribution on BAS density, spatial arrangement, and acidity is well established. Yet, the precise atomic positions of these Al atoms remain poorly resolved. Using silver (Ag) as a molecular probe, this study combines synchrotron X-ray diffraction (SXRD) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) to reveal the specific locations of Al atoms in ZSM-5, a prototypical zeolite catalyst. Statistical analysis of HAADF-STEM images unambiguously identifies the crystallographic adsorption sites of Ag at T4, T6, and T8, linking their distribution directly to the predominant framework Al sites, which correlates perfectly with the predominant Al sites identified by our previous work. By mapping these Al sites, we establish an atomic-scale model for single atom catalysis within the zeolite framework. This work develops methodologies further to elucidate the structure-activity relationship of industrially relevant zeolite catalysts, providing the foundational knowledge for rationally designing zeolite catalysts with optimised active sites and enhanced performance.
|
Mar 2026
|
|
B18-Core EXAFS
|
Diamond Proposal Number(s):
[19850, 29271]
Open Access
Abstract: Understanding the active site dynamics and redox behavior of copper species in zeolite catalysts is critical for advancing the understanding of catalytic methane-to-methanol conversion. These catalysts are also used for the selective catalytic reduction of NOx in diesel engines. Here, we present the first application of muon spin spectroscopy (μSR) to study transition metal-exchanged SSZ-13 (Cu-SSZ-13) zeolites and highlight the potential of μSR. This technique reveals unique insights into the local magnetic and electronic environments of Cu species, inaccessible via conventional spectroscopies. Temperature-dependent transverse field μSR measurements show a clear conversion of paramagnetic muonium (Mu0) to diamagnetic muon (Mu+) states, with distinct differences between Cu-loaded and pure SSZ-13 systems. This transformation is thermally activated, with Arrhenius analysis yielding activation energies of ∼3.3–5 meV, consistent with ionization processes of shallow donor states. Longitudinal field measurements confirm 2D muonium diffusion within Cu-SSZ-13 and support a model where muonium reacts with mono(μ-oxo)dicopper species, inducing comproportionation (2Cu2+ → 2Cu1.5+). DFT simulations validate this mechanism, reproducing the experimentally determined hyperfine coupling constants. At low temperatures (≤25 K), μSR also detects the onset of static magnetism in Cu clusters, consistent with Cu(II)-based multinuclear motifs. These results establish μSR as a powerful, underutilized probe for catalytic systems and provide compelling evidence for a multistep oxidation mechanism involving the initial reduction of Cu centers prior to methanol formation. This approach opens new avenues for real-time, local investigation of redox-active catalytic materials.
|
Mar 2026
|
|
B18-Core EXAFS
I11-High Resolution Powder Diffraction
|
Zhaodong
Zhu
,
Xin
Lian
,
Xue
Han
,
Zi
Wang
,
Siyu
Zhou
,
Meng
He
,
Tianze
Zhou
,
Yuting
Chen
,
Mengtian
Fan
,
Wenyuan
Huang
,
Yuhang
Yang
,
Shaojun
Xu
,
Yongqiang
Cheng
,
Luke L.
Daemen
,
Jeff
Armstrong
,
Svemir
Rudic
,
William
Thornley
,
Evan
Tillotson
,
Daniel
Lee
,
Sarah
Haigh
,
Shiyu
Fu
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Sihai
Yang
Diamond Proposal Number(s):
[37887, 31729, 36450]
Abstract: Catalytic hydrodeoxygenation (HDO) is critical for bio-oil upgrading, yet the selective cleavage of stable C(sp2)–OH bonds in lignin-derived substrates under aqueous conditions remains a challenge. Here, we report a heteroatomic zeolite catalyst, RuFA/SAPO-34-Nb, featuring few-atom Ru clusters on a Nb(V)-modified SAPO-34 framework, which achieves highly efficient HDO of lignin-derived creosol (2-methoxy-4-methylphenol) in water. Under mild conditions (250 °C, 7 bar H2, 24 h), this catalyst delivers quantitative conversion of creosol to toluene (99.2% conversion, 99.6% selectivity), fully preserving the aromaticity of lignin-derived feedstocks─a key requirement for sustainable production of chemicals. Synchrotron X-ray diffraction, X-ray absorption spectroscopy, and inelastic neutron scattering, combined with theoretical modeling, elucidate the cooperative mechanism: the Nb(V) sites selectively cleave the strong C–O bonds, while the few-atom Ru cluster generates hydrogen species with an exceptionally low rotational barrier of 65 cm–1. This synergistic interaction enables the direct and selective HDO of C(sp2)–O bonds without saturation of the aromatic ring. This work establishes a promissing strategy for aqueous-phase HDO catalysis and provides a general approach for designing bimetallic zeolite catalysts to convert lignin-derived compounds to value-added aromatic chemicals, advancing sustainable biorefinery processes.
|
Jan 2026
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
I20-EDE-Energy Dispersive EXAFS (EDE)
|
Diamond Proposal Number(s):
[30676, 30178]
Abstract: Zeolitic imidazolate frameworks (ZIFs), a subclass of metal–organic frameworks (MOFs), combine high porosity and chemical tunability with a resistance to harsh conditions. Understanding their response to extreme pressure and heat is critical for application development due to the conditions under which they may be required to work or for predicting their response to any processing before use. In this study, we characterize long- and short-range order in ZIF-8 and ZIF-62 under compression using Bragg X-ray diffraction and pair distribution function (PDF) analysis for a large pressure range (up to ∼5 GPa) previously attempted in very few works. X-ray absorption fine structure analysis was carried out under high-pressure-temperature conditions to probe the medium-range order, a novelty in MOFs. ZIF-8 demonstrated a crystalline–crystalline phase transition above 0.36 GPa but no full amorphization. In ZIF-62, pore intrusion of the silicone oil pressure-transmitting medium (PTM) was observed through negative compressibility and by retention of its open-pore configuration. Full amorphization was achieved, with heating lowering the amorphization threshold. Finally, a unique distortion in both MOFs was suggested by the spectroscopic data. These results provide insight into the thermomechanical stability of crystalline ZIFs and the mechanism underlying their amorphization.
|
Dec 2025
|
|
B18-Core EXAFS
|
Diamond Proposal Number(s):
[38597]
Open Access
Abstract: Extra-large-pore Ge-containing GTM chiral zeolite catalysts have recently proved useful asymmetric catalysts, with chirality emerging from their chiral confined nanospace. However, so far these exceptional materials have suffered from low framework stability in the presence of water and moderate catalytic enantioselectivity in the ring-opening of chiral trans-stilbene oxide with 1-butanol used as a test reaction. Here, we report that these chiral zeolite catalysts can be easily stabilized upon exposure of the calcined material to 1-butanol, providing stability against water and, most importantly, prompting a preactivation of the chiral active sites that boosts their enantioselective properties, reaching unprecedented enantiomeric excesses up to 88% where one enantiomer reacts 16 times more than the other. A range of physicochemical studies, including in situ Fourier transform infrared (FTIR) and X-ray absorption spectroscopy, indicates that framework Ge sites increase their coordination environment upon interaction with 1-butanol molecules, which after a thermal treatment above 100 °C remain irreversibly bound to Ge as a consequence of a condensation and dehydration reaction, providing a route to easily functionalize these materials. These preactivated GTM asymmetric catalysts act similarly to enzymes by controlling the confinement of the chiral reactants in particular orientations through coordination with Ge and development of H-bonds with nearby hydroxyl groups, thus attaining enantioselective catalytic activities close to those reached by enzymatic systems but with the crucial advantage associated with heterogeneous catalysts and, notably, the possibility of preparing both enantiomeric versions of the catalyst by using an easily accessible alkaloid.
|
Oct 2025
|
|
B18-Core EXAFS
|
Diamond Proposal Number(s):
[34632]
Open Access
Abstract: The removal of trace acetylene from ethylene feedstocks is essential for polyethylene production, yet current hydrogenation catalysts often suffer from over-hydrogenation or require scarce noble metals. Here, a Pd-free single-atom catalyst comprising isolated Ni atoms anchored in zeolite Beta (Ni1/BEA) synthesized via incipient wetness impregnation on Na-exchanged BEA zeolite is reported for selective acetylene hydrogenation. Comprehensive characterization confirmed the atomic dispersion of Ni within the BEA framework, with no evidence of Ni nanoparticle formation. Under optimized conditions (160 °C, H2/C2H2 = 16, residence time = 0.46 s), Ni1/BEA achieves complete acetylene conversion with 89% ethylene selectivity, which remain stable over 24 hours with no coke formation. Ni1/BEA exceeds the TOFC2H2 achieved by previous zeolite-supported single-atom nickel catalysts by 12-fold. Ethylene selectivity improve upon removal of Brønsted acid sites via Na+ exchange, suppressing oligomerization. Ni1/BEA preserved the catalytic performance under industrially relevant feed containing excess ethylene, achieving 86% ethylene selectivity at full acetylene conversion. Kinetic analysis yielded consistent activation energies (≈67 kJ mol−1). TPD studies suggested a non-associative hydrogenation mechanism in which H2 activation precedes acetylene adsorption. This work demonstrates Ni1/BEA as a stable, cost-effective, and Pd-free single-atom catalyst for acetylene removal in ethylene purification.
|
Oct 2025
|
|
B18-Core EXAFS
|
Diamond Proposal Number(s):
[34510, 39677]
Open Access
Abstract: Excessive nitrogen fertiliser use has resulted in reactive nitrogen losses to the environment through gaseous N emissions, like N2O, resulting in agriculture being a major anthropogenic source of N2O gas emissions globally. Using engineered nanomaterials to deliver reactive nitrogen can aid in more efficient nutrient delivery to crops, maximising yield and crop quality, while minimising reactive losses to the environment. ZSM-5-15, a nano-zeolite, increased cumulative N2O emissions by 134% when applied in combination with a 50% dose of conventional nitrogen fertiliser. This is theorised to be through ion exchange of ZSM-5-15’s extra-framework NH4+ ion load being released, allowing nitrifying microbes to act on the newly released NH4+ and increase N2O emissions. BEA-19, a similar zeolite to ZSM-5-15 but with a slightly altered Si:Al ratio, size and charge, causes no increase in N2O emissions. While ZSM-5-15 increases reactive N emissions it also drives improved lettuce growth, with 13% more biomass accumulation compared to a half dose of conventional fertiliser. Ce0.75Zr0.25O2, a nano-metal oxide, improves growth by 6% and maintains the nutritive quality of lettuce, with higher Zn, Cu, Mg, K, Fe and Mn contents, without increasing N2O emissions. Nano-Ce0.75Zr0.25O2 transforms in soil to form CeO2 and Ce0.9Zr0.1O2, leaching Zr4+ ions some of which partly form ZrCl4. These compounds may then act on lettuce roots and soil microbes independently. These results indicate how nanomaterials may impact reactive nitrogen emissions through effects on soil microbial communities.
|
Sep 2025
|
|
I11-High Resolution Powder Diffraction
|
Lutong
Shan
,
Tianxiang
Chen
,
Shiyun
Li
,
Boya
Tang
,
Yuhang
Yang
,
Peng
Rao
,
Jiangnan
Li
,
Ching Kit Tommy
Wun
,
Daniel
Lee
,
Mufan
Li
,
Tsz Woon Benedict
Lo
,
Sihai
Yang
Diamond Proposal Number(s):
[37887]
Abstract: The concerted electron–proton transfer (CEPT) can substantially enhance the microkinetics of electrocatalysis by circumventing the formation of high-energy intermediates. Herein, we report the decoration of the MFI zeolite matrix with isolated Cu(II) sites in the proximity of intrinsic Brønsted acid sites (BASs), promoting the CEPT synergy in electrocatalysis. By modulating the spatial arrangement of “Cu-BAS” pairs in Cu-Z(23) zeolite, we show a Faradaic efficiency of 98% for electroreduction of nitrate to ammonia, achieving an exceptional yield of 103.1 mg h–1 cm–2 at a current density of 1.3 A cm–2. Cu-Z(23) also exhibits an excellent activity at low concentrations of nitrate (e.g., 50 ppm) and a high catalytic stability of 50 h. Synchrotron X-ray powder diffraction, solid-state nuclear magnetic resonance spectroscopy, and modeling studies reveal the critical role of the proximate “Cu-BAS” pairs in facilitating the CEPT process. This approach uncovers the overlooked capability of “electrical insulating” zeolites as effective electrocatalysts to drive future sustainable chemical synthesis.
|
Sep 2025
|
|
