B18-Core EXAFS
I15-1-X-ray Pair Distribution Function (XPDF)
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Shanshan
Xu
,
Matthew E.
Potter
,
Raquel
Simancas
,
Lucy
Costley-Wood
,
Boya
Qiu
,
Xuzhao
Liu
,
Cristina
Stere
,
M. Asuncion
Molina
,
Danial
Farooq
,
Floriana
Tuna
,
Dingyue
Zhang
,
Shuanglin
Zhang
,
Huanhao
Chen
,
Shengzhe
Ding
,
Xinrui
Wang
,
Sarayute
Chansai
,
Matthew
Lindley
,
Sarah J.
Haigh
,
Armando
Ibraliu
,
Lan
Lan
,
Piu
Chawdhury
,
Mariyam
Bi
,
Otis
Leahair
,
Yilai
Jiao
,
Min
Hu
,
Qiang
Liu
,
Toru
Wakihara
,
Xiaolei
Fan
,
Andrew M.
Beale
,
Christopher
Hardacre
Diamond Proposal Number(s):
[33381, 32971, 36241]
Open Access
Abstract: Methanol synthesis via non-thermal plasma (NTP) catalytic CO2 hydrogenation provides a sustainable approach to chemical and fuel production with potential in carbon emissions reduction. However, the underlying mechanisms remain unclear. Here we evaluate the mechanism of NTP-catalytic CO2 hydrogenation over Cu–Zn/ZSM-5 through operando X-ray absorption spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy and in situ X-ray pair distribution function. We found that Zn enhances Cu dispersion and reducibility, as well as forming active Cu/ZnO interfacial sites. Beyond the conventional formate pathway on metallic Cu, these interfaces enable an additional CO hydrogenation route, enhancing methanol yield. NTP also promotes gas-phase CO2 dissociation to CO, bypassing the reverse water–gas shift step required in thermal catalysis. No Cu/Zn alloy formation was observed, underscoring the importance of metallic Cu and Cu/ZnO interfaces under NTP conditions. Furthermore, NTP stabilizes reduced Cu species, preventing re-oxidation and ensuring sustained catalytic activity. These findings advance the mechanistic understanding of NTP-assisted catalysis.
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Feb 2026
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B18-Core EXAFS
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Diamond Proposal Number(s):
[34632]
Abstract: Bimetallic palladium (Pd) and gold (Au) systems are active for promoting the selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA), a key building block for producing polyethylene furanoate, a biobased polymer to substitute poly(ethylene terephthalate). Here, an FDCA yield of ∼99% was achieved over a physical mixture of 1.5 wt % Au/C and 1.5 wt % Pd/C (Pd/Au molar ratio of 5:1) under mild conditions (90 °C, 1 bar O2), outperforming bimetallic core–shell Au@Pd/C (∼90% FDCA yield) or alloyed AuPd/C (∼73% FDCA yield) systems. To gain insights into the synergy between the two monometallic catalysts, a series of kinetic studies were conducted employing either HMF or its intermediates as substrates in catalytic oxidation systems over either Pd/C or Au/C. The results show distinct selectivity preference of the two catalysts: Pd/C favors the 2,5-diformylfuran pathway (DFF), while Au/C follows the 5-hydroxymethyl-2-furancarboxylic acid (HFCA) pathway, as well as the presence of base-induced Cannizzaro disproportionation (CD) reactions. The advantage of the physical mixture system is largely attributed to the synergy between the two metals, which promotes the DFF pathway (over the HFCA route) and suppresses CD reactions, facilitating a more rapid progression of the overall oxidation cascade process. Catalyst recycling studies reveal deactivation of the physical mixture system (FDCA yield dropped to 62% after 3 cycles), with detailed comparative characterization of the fresh and used catalysts identifying operando Pd leaching and subsequent deposition onto Au/C, forming a core (Au)–shell (Pd) structure, as the origin of the diminished activity. Our findings challenge the conventional view regarding the alloy superiority in the selective oxidation of HMF, showing that systems based on simple physical mixtures of monometallic catalysts could be a more effective and practical strategy for progressing FDCA production via selective HMF oxidation.
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Jun 2025
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Open Access
Abstract: Furfural (Fur) represents an interesting bio-based platform chemical to pave the way to enhanced biorefinery integration in the modern chemicals industry. The production of this xylose- derived compound by its dehydration is catalysed by Brønsted acidity and has effectively been performed in biphasic systems using methyl isobutyl ketone (MIBK), where furfural is effectively partitioned. A selection of commercially available solid-acid catalysts were evaluated (different ion exchange resins, zeolites and sulfated zirconia), with top candidates being subjected to recycling experiments over six runs with carbon deposition removal and acid site regeneration. A sulfated zirconia (SO2/ZrO2-1) catalyst proved effective with maximum yield of Fur of 53.8% after 180 mins at 160 °C, with xylose conversion of 98.4%. A phenomenological approach to model developments was employed to describe the formation of each component of the reaction scheme and distribution in a biphasic system, with 18 separate kinetic models including both homo- and heterogeneous reaction pathways reported. The most optimal model, identified through statistical model discrimination (RMSE = 0.088), was a pseudohomogenous model with first order reaction kinetics for xylose conversion to Fur via a reactive intermediate and second order with respect to humin formation. Apparent activation energies for xylose dehydration were reported at 44.70 ± 7.89 kJ mol-−1, with results stating the formation of Fur proceeded preferentially through this reactive intermediate.
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Jan 2025
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Shengzhe
Ding
,
Dario Luis
Fernandez Ainaga
,
Min
Hu
,
Boya
Qiu
,
Ushna
Khalid
,
Carmine
D’agostino
,
Xiaoxia
Ou
,
Ben
Spencer
,
Xiangli
Zhong
,
Yani
Peng
,
Nicole
Hondow
,
Constantinos
Theodoropoulos
,
Yilai
Jiao
,
Christopher
Parlett
,
Xiaolei
Fan
Open Access
Abstract: Spatial control over features within multifunctional catalysts can unlock efficient one-pot cascade reactions, which are themselves a pathway to aviation biofuels via hydrodeoxygenation. A synthesis strategy that encompasses spatial orthogonality, i.e., one in which different catalytic species are deposited exclusively within discrete locations of a support architecture, is one solution that permits control over potential interactions between different sites and the cascade process. Here, we report a Pd doped hierarchical zeolite, in which Pd nanoparticles are selectively deposited within the mesopores, while acidity is retained solely within the micropores of ZSM-5. This spatial segregation facilitates hydrodeoxygenation while suppressing undesirable decarboxylation and decarbonation, yielding significant enhancements in activity (30.6 vs 3.6 moldodecane molPd−1 h−1) and selectivity (C12:C11 5.2 vs 1.9) relative to a conventionally prepared counterpart (via wet impregnation). Herein, multifunctional material design can realise efficient fatty acid hydrodeoxygenation, thus advancing the field and inspiring future developments in rationalised catalyst design.
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Sep 2024
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I20-EDE-Energy Dispersive EXAFS (EDE)
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Diamond Proposal Number(s):
[28203]
Abstract: Understanding nature of intermediates/active species in reactions is a major challenge in chemistry. This is because spectator species typically dominate the experimentally derived data and consequently active phase contributions are masked. Transient methods offer a means to bypass this difficulty. In particular, modulation excitation with phase-sensitive detection (ME-PSD) provides a mechanism to distinguish between spectator and reacting species. Herein, modulation excitation (ME) time-resolved (energy dispersive) X-ray absorption spectroscopy, assisted by phase sensitive detection (PSD) analysis, has been applied to the study of a liquid phase process; in this case the classic ferrocyanide/ferricyanide redox couple. Periodic switches of the electrical potential (anodic/cathodic) enabled the use of the ME approach. Structural changes at fractions as low as 2% of the total number of electroactive species were detected within the X-ray beam probe volume containing ~30 pmol of Fe(II)/Fe(III).
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Aug 2024
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Open Access
Abstract: Synthesis of 2,5-furandicarboxylic acid (FDCA) can be achieved via catalytic oxidation of 5-hydroxymethylfurfural (5-HMF), in which both base and catalyst play important roles. This work presents the development of a simple synthesis method (based on a commercial parent 10 wt.% Pd/C catalyst) to prepare the bimetallic AuPd alloy catalysts (i. e., AuPd/C) for selective 5-HMF oxidation to FDCA. When using the strong base of NaOH, Pd and Au cooperate to promote FDCA formation when deployed either separately (as a physical mixture of the monometallic Au/C and Pd/C catalysts) or ideally alloyed (AuPd/C), with complete 5-HMF conversion and FDCA yields of 66 % vs 77 %, respectively. However, NaOH also promoted the formation of undesired by-products, leading to poor mass balances (<81 %). Comparatively, under weak base conditions (using NaHCO3), an increase in Au loading in the AuPd/C catalysts enhances 5-HMF conversion and FDCA productivity (due to the enhanced carbonyl oxidation capacity) which coincides with a superior mass balances of >97 %. Yet, the excessive Pd content in the AuPd/C catalysts was not beneficial in promoting FDCA formation.
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Oct 2023
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B18-Core EXAFS
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Run
Zou
,
Sarayute
Chansai
,
Shaojun
Xu
,
Bing
An
,
Shima
Zainal
,
Yangtao
Zhou
,
Ruojia
Xin
,
Pan
Gao
,
Guangjin
Hou
,
Carmine
D’agostino
,
Stuart M.
Holmes
,
Christopher
Hardacre
,
Yilai
Jiao
,
Xiaolei
Fan
Diamond Proposal Number(s):
[29271]
Open Access
Abstract: Stabilisation of metal species using hydroxyl-rich dealuminated zeolites is a promising method for catalysis. However, insights into the interactions between the hydroxyl groups in zeolite and noble metals and their effects on catalysis are not yet fully understood. Herein, comparative studies were conducted using Pt catalysts supported on hydroxyl-rich dealuminated Beta (deAl-Beta) and the pristine proton-form Beta (H-Beta) for catalytic oxidation of toluene. The findings suggest that during impregnation the Pt precursor (i.e., Pt(NH3)4(NO3)2) interacted with different sites on deAl-Beta and H-Beta, leading to the formation of supported Pt nanoparticles with different physicochemical properties. The resulting Pt/deAl-Beta exhibited improved activity and anti-coking ability than Pt/H-Beta in catalytic toluene oxidation. According to toluene-TPD, 1H NMR relaxation and in situ DRIFTS characterisation, the enhanced performance of Pt/deAl-Beta could be ascribed to (i) the active Pt-O sites stabilised by hydroxyl groups, which interact with toluene easily for conversion, and (ii) the acid-free feature of the deAl-Beta support, which avoids the formation of coke precursors (such as benzoate species) on the catalyst surface. Findings of the work can serve as the design guidelines for making effective supported metal catalysts using zeolitic carriers.
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Sep 2023
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Open Access
Abstract: Realising sustainability within the chemical industry necessitates a shift from the traditional linear approach, based on crude oil, to a circular economy using alternative feedstock such as biomass, from which 5-hydroxymethylfurfural (HMF) is a potentially highly interesting platform chemical. While its production is relatively straightforward via the dehydration of fructose, derived from either saccharides or lignocellulosic biomass, its production is hindered by undesirable side reactions, which diminish overall HMF yield. Here we report a green, highly selective approach to producing 5-hydroxymethylfurfural (HMF) from fructose based on the co-deployment of a biphasic reaction media, microwave radiation, and a commercial solid acid catalyst (FAU Y zeolites). Following an initial evaluation of catalyst-solvent interactions and diffusion, a hierarchical mesoporous Y zeolite was chosen and deployed within a range of reaction media and process conditions for process optimisation, identifying a biphasic system consisting of ((6:4 Water:DMSO) / (7:3 MIBK:2-BuOH)) as the optimal reaction media. This solvent combination facilitated an HMF yield of ~73.9 mol% with an excellent selectivity of ~86.1 % at 160 ℃ after only 45 minutes under the microwave condition. These, in turn, result in optimal energy efficiency and excellent green credentials relative to conventional heating.
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Jul 2023
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Open Access
Abstract: In this paper we carry out a surface study of promising supported solid acid catalysts commonly used for the production of high value chemicals derived from glycerol. In particular, γ, θ and α alumina (Al2O3) were modified by (i) grafting with 5 wt% zirconia, (ii) doping with 30 wt% silicotungstic acid (STA), and (iii) using both zirconia and STA. The aim is to rationalise the effect of these different parameters on structural properties and surface adsorption through a comprehensive multi-technique approach, including recently developed NMR relaxation techniques. XRD and laser Raman spectroscopy confirmed a strong interaction between STA and the γ-/θ-Al2O3 resulting in a distortion of the supported STA Keggin structure relative to that of bulk STA. Conversely, a much weaker interaction between the supported STA and α-Al2O3 was measured. NMR relaxation demonstrated that the STA doping increases the adsorption properties of the catalyst, particularly for γ-/θ-Al2O3. For catalysts based on α-Al2O3, such effect was negligible. Thermogravimetric/differential thermogravimetry (TGA/DTG) analysis suggested that zirconia-grafted and non-grafted θ-Al2O3 and γ-Al2O3 are suitable materials for increasing the thermal stability of STA whereas α-Al2O3 (both grafted and non-grafted) does not improve the thermal stability of STA.
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Dec 2022
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E01-JEM ARM 200CF
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Shanshan
Xu
,
Thomas J. A.
Slater
,
Hong
Huang
,
Yangtao
Zhou
,
Yilai
Jiao
,
Christopher M. A.
Parlett
,
Shaoliang
Guan
,
Sarayute
Chansai
,
Shaojun
Xu
,
Xinrui
Wang
,
Christopher
Hardacre
,
Xiaolei
Fan
Diamond Proposal Number(s):
[29468]
Open Access
Abstract: The stability of catalysts in dry reforming of methane (DRM) is a known issue. In this paper an encapsulation strategy has been employed to improve the stability compared with conventional impregnation methods. Herein, nickel nanoparticles encapsulated in silicalite-1 were prepared using a range of methods including post treatment, direct hydrothermal and seed-directed methods to investigate the effect of synthesis protocol on the properties of catalysts, such as degree of encapsulation and Ni dispersion, and anti-coking/-sintering performance in DRM. The Ni@SiO2-S1 catalysts obtained by the seed-directed synthesis presented the full encapsulation of Ni NPs by the zeolite framework with small particle sizes (∼2.9 nm) and strong metal-support interaction, which could sterically hinder the migration/aggregation of Ni NPs and carbon deposition. Therefore, Ni@SiO2-S1 showed stable CO2/CH4 conversions of 80% and 73%, respectively, with negligible metal sintering and coking deposition (∼0.5 wt.%) over 28 h, which outperformed the other catalysts prepared. In contrast, the catalysts developed by the post-treatment and ethylenediamine-protected hydrothermal methods showed the co-existence of Ni phase on the internal and external surfaces, i.e. incomplete encapsulation, with large Ni particles, contributing to Ni sintering and coking. The correlation of the synthesis-structure-performance in this study sheds light on the design of coking-/sintering-resistant encapsulated catalysts for DRM.
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Jun 2022
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