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34 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4 [Next/Last]

Instruments / Technical Area	Publication Details	Published
	Dehydration of xylose to furfural in a biphasic system: catalyst selection and kinetic modelling discrimination Dominik Soukup-Carne , Ben Hillman , Christopher M. A. Parlett , Xiaolei Fan , Jesus Esteban Reaction Chemistry & Engineering DOI: 10.1039/D4RE00572D Open Access Show Abstract ▼ 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.	Jan 2025
	Spatial segregation of catalytic sites within Pd doped H-ZSM-5 for fatty acid hydrodeoxygenation to alkanes 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 Nature Communications 15 DOI: 10.1038/s41467-024-51925-2 Open Access Show Abstract ▼ 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.	Sep 2024
	Promotion of manganese on Fe-based catalyst for the production of carbon nanotubes (CNTs) from plastics Su He , Chunchun Li , Hongman Sun , Christopher Parlett , Yuanting Qiao , Youhe Wang , Yikai Xu , Ningbo Gao , Chunfei Wu Chemical Engineering Journal 279 DOI: 10.1016/j.cej.2024.152306 Show Abstract ▼ Abstract: Manganese (Mn) is an effective promoter of Fe-based catalysts to increase the production of carbon nanotubes (CNTs) from waste plastics but suffers from the lack of insights into how Mn affects the catalytic performance of CNTs production. Herein, we systematically investigate the promotion mechanism of Mn in Fe-based catalysts by varying the adding order of Mn and Fe during one or two-step impregnation methods. The results show that α-(Fe1-xMnx)2O3 is formed and uniformly distributed in Fe crystals when Mn and Fe are simultaneously added by the one-step impregnation method ((Mn + Fe)/MgO), resulting in the highest gas (66.3 mmol/gplastic), and CNTs (235 mg/gplastic) yields. While α-(Fe1-xMnx)2O3 in FeMn/MgO (Fe is added first and followed by Mn by two-step impregnation method) exhibited a poor distribution resulting in reduced gas and CNTs yields compared to (Mn + Fe)/MgO. For MnFe/MgO prepared by the two-step impregnation method and Mn is added first, the formed α-(Fe1-xMnx)2O3 is entirely not inserted into Fe crystals, and the corresponding catalyst exhibits lower gas and CNTs yields. The best catalytic performance of (Mn + Fe)/MgO is owing to the well-dispersed α-(Fe1-xMnx)2O3, which increases the carbon solubility capacity of the Fe crystals and regulates the equilibrium of carbon dissolution and precipitation, promoting the thermal cracking and carbon formation reactions, thereby improving the catalytic performance of CNTs and gas production.	May 2024
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS	In situ formation of suspended graphene windows for lab-based XPS in liquid and gas environments Elizabeth Jones , Charalampos Drivas , Joshua Gibson , Jack Swallow , Leanne Jones , Thomas Bricknell , Matthijs Van Spronsen , Georg Held , Mark Isaacs , Christopher Parlett , Robert S. Weatherup Chemcatchem DOI: 10.1002/cctc.202400239 Diamond Proposal Number(s): [30358] Open Access Show Abstract ▼ Abstract: Environmental cells sealed with photoelectron-transparent graphene windows are promising for extending X-ray photoelectron spectroscopy (XPS) to liquid and high-pressure gas environments for in situ and operando studies. However, the reliable production of graphene windows that are sufficiently leak-tight for extended measurements remains a challenge. Here we demonstrate a PDMS/Au(100 nm)-supported transfer method that reliably produces suspended graphene on perforated silicon nitride membranes without significant contamination. A yield of ~95% is achieved based on single-layer graphene covering >98% of the holes in the silicon nitride membrane. Even higher coverages are achieved for stacked bilayer graphene, allowing wet etching (aqueous KI/I2) of the Au support to be observed in a conventional lab-based XPS system, thereby demonstrating the in situ formation of leak-tight, suspended graphene windows. Furthermore, these windows allow gas-phase measurements at close to atmospheric pressure, showing future promise for XPS under higher-pressure gas environments in conventional lab-based systems.	Apr 2024
B18-Core EXAFS E02-JEM ARM 300CF	Impact of ceria support morphology on Au single‐atom catalysts for benzyl alcohol selective oxidation Xinyue Zhou , Aristarchos Mavridis , Mark A. Isaacs , Charalampos Drivas , Carmine D’agostino , Christopher M. A. Parlett Chemcatchem DOI: 10.1002/cctc.202301673 Diamond Proposal Number(s): [19850] Open Access Show Abstract ▼ Abstract: Alcohol oxidations are a key industrial chemical transformation, with aldehydes and ketones finding use in an array of applications. Nobel metals are known for their activity towards this chemoselective transformation, however, sustainable catalyst synthesis requires optimal utilisation of these scarce elements. Here, we report Au catalytic systems based on the deposition of isolated Au sites on different morphologies of ceria in which different surface facets of the support are exposed. Through tailoring the support morphology and from extensive catalyst characterisation, it is shown that the exposed facet is critical for controlling the formation (or not) of isolated Au sites. Both the 110 and 111 facets are capable of this feat, yielding single-atom sites for rod, octahedron, and polyhedron morphologies. In contrast, the 100 facet is not, resulting in Au nanoparticles on cubic ceria. This dictation over Au species is critical to benzyl alcohol oxidation capacity at mild conditions and in the absence of a soluble base, with only single-atom catalyst (SAC) systems demonstrating activity. Furthermore, the exposed surface facet also governs the degree of surface oxygen vacancies, which is critical to catalyst activity and arises from its control over substrate adsorption strength, as revealed through T1/T2 NMR relaxation measurements.	Apr 2024
I18-Microfocus Spectroscopy	Operando synchrotron-based X-ray study and intervention approaches of graphene-related-materials for investigating the performance and durability of HT-PEMFC Jianuo Chen , Maria Perez-Page , Christopher M. A. Parlett , Zunmin Guo , Xiaochen Yang , Zeyu Zhou , Heng Zhai , Stuart Bartlett , Thomas S. Miller , Stuart M. Holmes Chemical Engineering Journal 297 DOI: 10.1016/j.cej.2024.150670 Diamond Proposal Number(s): [25932, 30031] Open Access Show Abstract ▼ Abstract: The application of high-temperature proton exchange membrane fuel cells (HT-PEMFCs) addresses challenges in water management, fuel purity, and overheating under high current density. However, phosphoric acid (PA) migration hinders their development. This study uses synchrotron-based X-ray fluorescence spectroscopy to investigate PA and catalyst migration. Interventions with single-layer graphene and electrochemically exfoliated graphene oxide improve performance and durability. X-ray absorption spectroscopy provides insights into relevant mechanisms, advancing understanding of membrane electrode assembly preparation and the intricate influences of PA and catalyst migration on performance and durability in HT-PEMFCs.	Mar 2024
	A facile synthesis route to AuPd alloys for the selective oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid Yani Peng , Boya Qiu , Shengzhe Ding , Min Hu , Yuxin Zhang , Yilai Jiao , Xiaolei Fan , Christopher M. A. Parlett Chempluschem 14 DOI: 10.1002/cplu.202300545 Open Access Show Abstract ▼ 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.	Oct 2023
	Impact of porous silica nanosphere architectures on the catalytic performance of supported sulphonic acid sites for fructose dehydration to 5-hydroxymethylfurfural Cameron-Alexander H. Price , Antonio Torres-Lopez , Robert Evans , Nicole S Hondow , Mark A. Isaacs , Aina Syahida Jamal , Christopher M. A. Parlett Chempluschem DOI: 10.1002/cplu.202300413 Open Access Show Abstract ▼ Abstract: 5-hydroxymethylfurfural represents a key chemical in the drive towards a sustainable circular economy within the chemical industry. The final step in 5-hydroxymethylfurfural production is the acid catalysed dehydration of fructose, for which supported organoacids are excellent potential catalyst candidates. Here we report a range of solid acid catalysis based on sulphonic acid grafted onto different porous silica nanosphere architectures, as confirmed by TEM, N2 porosimetry, XPS and ATR-IR. All four catalysts display enhanced active site normalised activity and productivity, relative to alternative silica supported equivalent systems in the literature, with in-pore diffusion of both substrate and product key to both performance and humin formation pathway. An increase in-pore diffusion coefficient of 5-hydroxymethylfurfural within wormlike and stellate structures results in optimal productivity. In contrast, poor diffusion within a raspberry-like morphology decreases rates of 5-hydroxymethylfurfural production and increases its consumption within humin formation.	Oct 2023
	Hierarchical zeolite catalysed fructose dehydration to 5-hydroxymethylfurfural within a biphasic solvent system under microwave irradiation Huaizhong Xiang , Shima Zainal , Henry Jones , Xiaoxia Ou , Carmine D'Agostino , Jesus Esteban , Christopher Parlett , Xiaolei Fan Rsc Sustainability DOI: 10.1039/D3SU00162H Open Access Show Abstract ▼ 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.	Jul 2023
	Synthesis and catalytic advantage of a hierarchical ordered macroporous KIT-6 silica Sabina Siles-Quesada , Christopher M. A. Parlett , Alexander C. Lamb , Jinesh C. Manayil , Yang Liu , Jim Mensah , Hamidreza Arandiyan , Karen Wilson , Adam F. Lee Materials Today Chemistry 30 DOI: 10.1016/j.mtchem.2023.101574 Open Access Show Abstract ▼ Abstract: Ordered mesoporous silicas are important technological materials in catalysis, sorption and separation science, however new architectures are desired to improve in-pore accessibility. Here we report the first synthesis of an ordered macroporous KIT-6, obtained by optimizing the ratios of Pluronic P123: sodium dodecyl sulfate cosurfactants, and a 400 nm polystyrene nanosphere macropore template. The macroporous KIT-6 possesses 370 nm macropores in a face-centered cubic arrangement, surrounded by a silica framework comprised of cubic Ia d three-dimensional, intertwined 5 nm mesopore channels. Propylsulfonic acid (PrSO3H) functionalization affords a macroporous KIT-6 solid acid catalyst whose hierarchical pore network permits rapid diffusion and esterification of fatty acids, conferring a five-fold enhancement for palmitic acid esterification compared with a conventional mesoporous PrSO3H/KIT-6, and 33% rate enhancement vs. an ordered macroporous PrSO3H/SBA-15.	Jun 2023

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