Publications
240 results found
Brandt-Talbot A, Murphy R, Leak D, et al., 2014, Treatment, US2014073016 (A1)
The present invention relates to a method for treating a lignocellulose biomass in order to dissolve the lignin therein, while the cellulose does not dissolve. The cellulose pulp obtained can be used to produce glucose. In addition the lignin can be isolated for subsequent use in the renewable chemical industry as a source for aromatic platform chemicals.
Eminov S, Wilton-Ely JDET, Hallett JP, 2014, Highly selective and near-quantitative conversion of fructose to 5-hydroxymethylfurfural using mildly acidic ionic liquids, ACS Sustainable Chemistry & Engineering, Vol: 2, Pages: 978-981, ISSN: 2168-0485
Claudio AFM, Swift L, Hallett JP, et al., 2014, Extended scale for the hydrogen-bond basicity of ionic liquids, Physical Chemistry Chemical Physics, Vol: 16, Pages: 6593-6601, ISSN: 1463-9084
In the past decade, ionic liquids (ILs) have been the focus of intensive research regarding their use as potential and alternative solvents in many chemical applications. Targeting their effectiveness, recent investigations have attempted to establish polarity scales capable of ranking ILs according to their chemical behaviours. However, some major drawbacks have been found since polarity scales only report relative ranks because they depend on the set of probe dyes used, and they are sensitive to measurement conditions, such as purity levels of the ILs and procedures employed. Due to all these difficulties it is of crucial importance to find alternative and/or predictive methods and to evaluate them as a priori approaches capable of providing the chemical properties of ILs. Furthermore, the large number of ILs available makes their experimental characterization, usually achieved by a trial and error methodology, burdensome. In this context, we firstly evaluated COSMO-RS, COnductor-like Screening MOdel for Real Solvents, as an alternative tool to estimate the hydrogen-bond basicity of ILs. After demonstrating a straight-line correlation between the experimental hydrogen-bond basicity values and the COSMO-RS hydrogen-bonding energies in equimolar cation–anion pairs, an extended scale for the hydrogen-bond accepting ability of IL anions is proposed here. This new ranking of the ILs' chemical properties opens the possibility to pre-screen appropriate ILs (even those not yet synthesized) for a given task or application.
Verdia P, Brandt A, Hallett JP, et al., 2014, Fractionation of lignocellulosic biomass with the ionic liquid 1-butylimidazolium hydrogen sulfate, Green Chemistry, Vol: 16, Pages: 1617-1627, ISSN: 1744-1560
The application of the protic ionic liquid 1-butylimidazolium hydrogen sulfate in the deconstruction (aka pretreatment) and fractionation of lignocellulosic biomass has been investigated. A cellulose rich pulp and a lignin fraction were produced. The pulp was subjected to enzymatic saccharification which allowed recovery of up to 90% of the glucan as fermentable glucose. The influence of the solution acidity on the deconstruction of Miscanthus giganteus was examined by varying the 1-butylimidazole to sulfuric acid ratio. Increased acidity led to shorter pretreatment times and resulted in reduced hemicellulose content in the pulp. Addition of water to the ionic liquid resulted in enhanced saccharification yields. The ability to tune acidity through the use of protic ionic liquids offers a significant advantage in flexibility over dialkylimidazolium analogues.
Boot-Handford ME, Abanades JC, Anthony EJ, et al., 2014, Carbon capture and storage update, Energy and Environmental Science, Vol: 7, Pages: 130-189, ISSN: 1754-5692
In recent years, Carbon Capture and Storage (Sequestration) (CCS) has been proposed as a potential method to allow the continued use of fossil-fuelled power stations whilst preventing emissions of CO2 from reaching the atmosphere. Gas, coal (and biomass)-fired power stations can respond to changes in demand more readily than many other sources of electricity production, hence the importance of retaining them as an option in the energy mix. Here, we review the leading CO2 capture technologies, available in the short and long term, and their technological maturity, before discussing CO2 transport and storage. Current pilot plants and demonstrations are highlighted, as is the importance of optimising the CCS system as a whole. Other topics briefly discussed include the viability of both the capture of CO2 from the air and CO2 reutilisation as climate change mitigation strategies. Finally, we discuss the economic and legal aspects of CCS.
Graesvik J, Hallett JP, Trang QT, et al., 2014, A quick, simple, robust method to measure the acidity of ionic liquids, CHEMICAL COMMUNICATIONS, Vol: 50, Pages: 7258-7261, ISSN: 1359-7345
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- Citations: 23
Hallett JP, Brandt-Talbot A, Zahari SMSNS, 2013, Low-Cost Ionic Liquids for the Delignification of Lignocellulosic Biomass, AIChE
Polizzi KM, Hallett JP, Kontoravdi C, et al., 2013, Frontier manufacturing: Scaling up synthetic biology
Brandt A, Grasvik J, Hallett JP, et al., 2013, Deconstruction of lignocellulosic biomass with ionic liquids, Green Chem., Vol: 15, Pages: 550-583-550-583
This paper reviews the application of ionic liquids to the deconstruction and fractionation of lignocellulosic biomass, in a process step that is commonly called pretreatment. It is divided into four parts: the first gives background information on lignocellulosic biomass and ionic liquids; the second focuses on the solubility of lignocellulosic biomass (and the individual biopolymers within it) in ionic liquids; the third emphasises the deconstruction effects brought about by the use of ionic liquids as a solvent; the fourth part deals with practical considerations regarding the design of ionic liquid based deconstruction processes.
Salari H, Hallett JP, Padervand M, et al., 2013, Systems designed with an ionic liquid and molecular solvents to investigate the kinetics of an S<sub>N</sub>Ar reaction, PROGRESS IN REACTION KINETICS AND MECHANISM, Vol: 38, Pages: 157-170, ISSN: 1468-6783
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- Citations: 4
Mota A, Butenko N, Hallett JP, et al., 2012, Application of V<SUP>IV</SUP>O(acac)<sub>2</sub> type complexes in the desulfurization of fuels with ionic liquids, CATALYSIS TODAY, Vol: 196, Pages: 119-125, ISSN: 0920-5861
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- Citations: 11
Brandt A, Erickson JK, Hallett JP, et al., 2012, Soaking of pine wood chips with ionic liquids for reduced energy input during grinding, Green Chemistry, Vol: 14, Pages: 1079-1085, ISSN: 1463-9262
Ionic liquids are of great interest as potential solvents/catalysts for the production of fuels and chemicals from lignocellulosic biomass. Attention has focused particularly on the pretreatment of lignocellulose to make the cellulose more accessible to enzymatic hydrolysis. Any biomass processing requires a reduction in the size of the harvested biomass by chipping and/or grinding to make it more amenable to chemical and biological treatments. This paper demonstrates that significant energy savings can be achieved in the grinding of pine wood chips when the ionic liquid is added before the grinding operation. We show that this is due to the lubricating properties of the ionic liquids and not to physico-chemical modifications of the biomass. A brief impregnation of the chipped biomass results in higher savings than a longer treatment.
Niedermeyer H, Hallett JP, Villar-Garcia IJ, et al., 2012, Mixtures of ionic liquids, CHEMICAL SOCIETY REVIEWS, Vol: 41, Pages: 7780-7802, ISSN: 0306-0012
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- Citations: 485
Ab Rani MA, Brandt A, Crowhurst L, et al., 2011, Erratum: Understanding the polarity of ionic liquids (Physical Chemistry Chemical Physics (2011) DOI: 10.1039/c1cp21262a), Physical Chemistry Chemical Physics, Vol: 13, ISSN: 1463-9076
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- Citations: 5
Dowell NM, Hallett JP, Vilaseca O, et al., 2011, Towards green bioprocessing: Ionic liquids for biomass deconstruction
The sustainable production of both biofuels and chemicals depends largely on the cost effective access to cellulose. Current best-practice methods for biomass deconstruction are largely derived from the pulp and paper industry, and are energy intensive and require the use of large quantities of organic solvents. As such, these processes are capital and energy intensive. As an alternative, ionic liquids-based processes provide a promising near-term option for the digestion of lingocellulosic biomass. Unfortunately, the majority of ionic liquids for which data are available are not themselves suitable for processing owing to their poor chemical instability - many of them are hydrolytically unstable, corrosive or both. However, other ionic liquids such as 1-butyl-3-methylimidazolium methylsulfate ([C4C1im][C1SO4]) and 1-butyl-3-methylimidazolium hydrogensulfate ([C4C1im][HSO4]) are promising ionic liquids for biomass deconstruction. They act by reducing the crystallinity of the cellulose fibrils, rendering them open to enzymatic attack. Importantly, these ionic liquids don't degrade into dangerous products, making them suitable for biomass processing. Ionic liquids-based process engineering is still very much in its infancy. One important limiting factor is the limited availability of thermophysical property data for ionic liquids. Thus, physically based methods for the prediction of thermophysical properties relevant to process engineering are required. One such method is the soft-SAFT equation of state. The soft-SAFT approach has previously been successfully applied to ionic liquids with applications in CO 2 capture. Following previous work, we represent the ionic liquids as associating Lennard-Jones chains. This model represents the ion pairs (anion plus cation) as a single chain molecule with the usual SAFT-type association sites used to describe the short-ranged anisotropic interactions. All molecular parameters were obtained by fitting to available density-temper
Hallett JP, Welton T, 2011, Room-Temperature Ionic Liquids: Solvents for Synthesis and Catalysis. 2, CHEMICAL REVIEWS, Vol: 111, Pages: 3508-3576, ISSN: 0009-2665
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- Citations: 3031
Mota A, Hallett JP, Kuznetsov ML, et al., 2011, Structural characterization and DFT study of V<SUP>IV</SUP>O(acac)<sub>2</sub> in imidazolium ionic liquids, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 13, Pages: 15094-15102, ISSN: 1463-9076
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- Citations: 20
Ab Rani MA, Brant A, Crowhurst L, et al., 2011, Understanding the polarity of ionic liquids, Phys. Chem. Chem. Phys., Vol: 13, Pages: 16831-16840-16831-16840
The polarities of a wide range of ionic liquids have been determined using the Kamlet-Taft empirical polarity scales [small alpha], [small beta] and [small pi]*, with the dye set Reichardt’s Dye, N,N-diethyl-4-nitroaniline and 4-nitroaniline. These have been compared to measurements of these parameters with different dye sets and to different polarity scales. The results emphasise the importance of recognising the role that the nature of the solute plays in determining these scales. It is particularly noted that polarity scales based upon charged solutes can give very different values for the polarity of ionic liquids compared to those based upon neutral probes. Finally, the effects of commonplace impurities in ionic liquids are reported.
Ab Rani MA, Brandt A, Crowhurst L, et al., 2011, Understanding the polarity of ionic liquids (vol 13, pg 16831, 2011), PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 13, Pages: 21653-21653, ISSN: 1463-9076
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- Citations: 4
Lui MY, Crowhurst L, Hallett JP, et al., 2011, Salts dissolved in salts: ionic liquid mixtures, Chem. Sci., Vol: 2, Pages: 1491-1496-1491-1496
Hallett J, Polizzi K, 2010, ORGANOSILICON-FUNCTIONAL PHASE TRANSFER CATALYSTS, US2010197892 (A1)
Organosilicon-functional phase transfer catalysts (PTCs) and methods for transferring immiscible molecules into a silicon-functional phase employing an organosilicon-functional PTC are provided.
Mac Dowell N, Florin N, Buchard A, et al., 2010, An Overview of CO2 capture technologies, Energy and Environmental Science, Vol: 3, Pages: 1645-1669
Hart R, Pollet P, Marus G, et al., 2010, Design and development of a sustainable DMSO substitute: Piperylene sulfone, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, Vol: 239, ISSN: 0065-7727
Niedermeyer H, Ab Rani MA, Lickiss PD, et al., 2010, Understanding siloxane functionalised ionic liquids, Phys. Chem. Chem. Phys., Vol: 12, Pages: 2018-2029-2018-2029
Brandt A, Hallett JP, Leak DJ, et al., 2010, The effect of the ionic liquid anion in the pretreatment of pine wood chips, Green Chem., Vol: 12, Pages: 672-679-672-679
The effect of the anion of ionic liquids on air-dried pine (Pinus radiata) has been investigated. All ionic liquids used in this study contained the 1-butyl-3-methylimidazolium cation; the anions were trifluoromethanesulfonate, methylsulfate, dimethylphosphate, dicyanamide, chloride and acetate. Using a protocol for assessing the ability to swell small wood blocks (10 [times] 10 [times] 5 mm), it was shown that the anion has a profound impact on the ability to promote both swelling and dissolution of biomass. Time course studies showed that viscosity, temperature and water content were also important parameters influencing the swelling process. We used Kamlet-Taft parameters to quantify the solvent polarity of the ionic liquids and found that the anion basicity described by the parameter [small beta] correlated with the ability to expand and dissolve pine lignocellulose. It is shown that 1-butyl-3-methylimidazolium dicyanamide dissolves neither cellulose nor lignocellulosic material.
Wells TP, Hallett JP, Williams CK, et al., 2009, ORGN 201-Esterification in ionic liquids: The influence of solvent basicity, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, Vol: 237, ISSN: 0065-7727
Hallett JP, Liotta CL, Ranieri G, et al., 2009, Charge Screening in the S<sub>N</sub>2 Reaction of Charged Electrophiles and Charged Nucleophiles: An Ionic Liquid Effect, JOURNAL OF ORGANIC CHEMISTRY, Vol: 74, Pages: 1864-1868, ISSN: 0022-3263
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- Citations: 84
Hallett JP, Welton T, 2009, How polar are ionic liquids?, Pages: 33-38, ISSN: 1938-5862
Ionic liquids have recently become extremely popular solvents for a wide range of applications from electrochemistry to synthesis. From a solvation standpoint, ionic liquids are generally considered to be 'very polar' solvents. However, attempts to quantify the polarity of ionic liquids have yielded a confusing mixture of results - moderate dielectric constants, mixed solvatochromic parameters and adjustable water solubilities defy a simple classification of the polarity of ionic liquids. We attempt to clarify this confusing and conflicting picture by using the Kamlet-Taft polarity scales to shed light on the solution behaviour and explain how ionic liquids interact with a variety of solutes. Using these various parameters, different solution behaviours can be quantified and correlated, thus painting a descriptive picture of what 'polarity' means for an ionic solvent. ©The Electrochemical Society.
Wells TP, Hallett JP, Williams CK, et al., 2009, Esterification in ionic liquids: The influence of solvent basicity, Pages: 103-106, ISSN: 1938-5862
The rate of esterification is reported in a range of ionic and molecular solvents. The effects of solvent on esterification rate are examined by using a linear solvation energy relationship based on the Kamlet-Taft solvent polarity descriptors (α, β, and π*). It is shown that the basicity (β) of the solvent is the major factor in determining esterification rate and that the highest rates are observed in low basicity solvents. ©The Electrochemical Society.
Hallett JP, Liotta CL, Ranieri G, et al., 2009, In search of an "ionic liquid effect", Pages: 81-87, ISSN: 1938-5862
The application of liquids that are salts at room temperature to chemicals synthesis has become a hugely exciting field of study. Thousands of papers are now generated each year and several industrial chemicals processes are now running. The greatest promise that these ionic liquids hold is that they might offer process advantages, even novel behaviors that cannot be achieved in molecular solvents. However, until now no behavior that is unique to ionic liquids has been observed. For such an "ionic liquid effect" to be seen it would need to be the result of the medium being composed solely of ions in motion. We have been searching for an ionic liquid effect, which we can now report here, for most the last decade. We demonstrate that when two dissolved salts react with each other in ionic liquids they follow a fundamentally different pathway to when the same salts react in any molecular solvent. ©The Electrochemical Society.
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