Publications
256 results found
Clough M, Geyer K, Hunt P, et al., 2015, Ionic liquids: Not always innocent solvents for cellulose, Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Matthews RP, Welton T, Hunt PA, 2015, Hydrogen bonding and π-π interactions in imidazolium-chloride ionic liquid clusters, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 17, Pages: 14437-14453, ISSN: 1463-9076
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- Citations: 104
George A, Brandt A, Tran K, et al., 2014, Design of low-cost ionic liquids for lignocellulosic biomass pretreatment, Green Chemistry, Vol: 17, Pages: 1728-1734, ISSN: 1744-1560
The cost of ionic liquids (ILs) is one of the main impediments to IL utilization in the cellulosic biorefinery, especially in the pretreatment step. In this study, a number of ionic liquids were synthesized with the goal of optimizing solvent cost and stability whilst demonstrating promising processing potential. To achieve this, inexpensive feedstocks such as sulfuric acid and simple amines were combined into a range of protic ionic liquids containing the hydrogen sulfate [HSO4]− anion. The performance of these ionic liquids was compared to a benchmark system containing the IL 1-ethyl-3-methylimidazolium acetate [C2C1im][OAc]. The highest saccharification yields were observed for the triethylammonium hydrogen sulfate IL, which was 75% as effective as the benchmark system. Techno-economic modeling revealed that this promising and yet to be optimized yield was achieved at a fraction of the processing cost. This study demonstrates that some ILs can compete with the cheapest pretreatment chemicals, such as ammonia, in terms of effectiveness and process cost, removing IL cost as a barrier to the economic viability of IL-based biorefineries.
Clough MT, Crick CR, Grasvik J, et al., 2014, A physicochemical investigation of ionic liquid mixtures, Chemical Science, Vol: 6, Pages: 1101-1114, ISSN: 2041-6539
Ionic liquids have earned the reputation of being ‘designer solvents’ due to the wide range of accessible properties and the degree of fine-tuning afforded by varying the constituent ions. Mixtures of ionic liquids offer the opportunity for further fine-tuning of properties. A broad selection of common ionic liquid cations and anions are employed to create a sample of binary and reciprocal binary ionic liquid mixtures, which are analysed and described in this paper. Physical properties such as the conductivity, viscosity, density and phase behaviour (glass transition temperatures) are examined. In addition, thermal stabilities of the mixtures are evaluated. The physical properties examined for these formulations are found to generally adhere remarkably closely to ideal mixing laws, with a few consistent exceptions, allowing for the facile prediction and control of properties of ionic liquid mixtures.
Clough MT, Geyer K, Hunt PA, et al., 2014, Ionic liquids: not always innocent solvents for cellulose, Green Chemistry, Vol: 17, Pages: 231-243, ISSN: 1744-1560
The decomposition pathways of a series of carbohydrates dissolved in carboxylate ionic liquids have been investigated in detail using a broad range of thermal and chromatographic techniques. Mixtures of the carboxylate ionic liquid 1-ethyl-3-methylimidazolium acetate with carbohydrates were found to undergo reaction of the C2 carbon of the imidazolium ring with the aldehyde functionality on the open chain sugar, yielding an imidazolium adduct with a hydroxylated alkyl chain. Subsequently, degradation of the hydroxyalkyl chain occurs by sequential loss of formaldehyde units, to yield a terminal adduct species, 1-ethyl-2-(hydroxymethyl)-3-methylimidazolium acetate. Identities of the final and intermediate adduct species, and the reaction mechanisms connecting adducts, were elucidated by NMR, HPLC and LCMS techniques. Factors affecting the rate and quantity of adduct formation were explored. Changing the ionic liquid cation and anion, the acid number, sugar concentration and temperature influenced the rate of formation and relative quantities of the adduct species. Formation of adducts could not be entirely prevented when employing carboxylate ionic liquids. By contrast, 1-butyl-3-methylimidazolium chloride was identified as an ionic liquid capable of dissolving a significant quantity of cellulose, yet without reacting with carbohydrates.
Holloczki O, Malberg F, Welton T, et al., 2014, On the origin of ionicity in ionic liquids. Ion pairing <i>versus</i> charge transfer, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 16, Pages: 16880-16890, ISSN: 1463-9076
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- Citations: 175
De Gregorio GF, Welton T, Hallett JP, 2014, Elucidating the mechanism of lignin depolymerisation using acidic ionic liquids: A focus on ether cleavage, 248th National Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Ismail NL, Trang QT, Hallett JP, et al., 2014, Nucleophilic substitution of benzyl alcohol with hydrogensulfate ionic liquids, 248th National Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Cecchini MP, Turek VA, Demetriadou A, et al., 2014, Heavy Metal Sensing Using Self-Assembled Nanoparticles at a Liquid–Liquid Interface, Advanced Optical Materials
Matthews RP, Ashworth C, Welton T, et al., 2014, The impact of anion electronic structure: similarities and differences in imidazolium based ionic liquids, JOURNAL OF PHYSICS-CONDENSED MATTER, Vol: 26, ISSN: 0953-8984
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- Citations: 53
Mac Dowell N, Llovell F, Sun N, et al., 2014, New Experimental Density Data and soft-SAFT Models of Alkylimidazolium ([CnC₁im](+)) Chloride (Cl-), Methylsulfate ([MeSO4](-)), and Dimethylphosphate ([Me2PO4](-)) Based Ionic Liquids, JOURNAL OF PHYSICAL CHEMISTRY B, Vol: 118, Pages: 6206-6221, ISSN: 1520-6106
Chen L, Sharifzadeh M, Mac Dowell N, et al., 2014, Inexpensive ionic liquids: [HSO₄]¯-based solvent production at bulk scale, Green Chemistry, Vol: 16, Pages: 3098-3106, ISSN: 1463-9262
Through more than two decades’ intensive research, ionic liquids (ILs) have exhibited significant potential in various areas of research at laboratory scales. This suggests that ILs-based industrial process development will attract increasing attention in the future. However, there is one core issue that stands in the way of commercialisation: the high cost of most laboratory-synthesized ILs will limit application to small-scale, specialized processes. In this work, we evaluate the economic feasibility of two ILs synthesized via acid–base neutralization using two scenarios for each: conventional and intensification processing. Based upon our initial models, we determined the cost price of each IL and compared the energy requirements of each process option. The cost prices of triethylammonium hydrogen sulfate and 1-methylimidazolium hydrogen sulfate are estimated as $1.24 kg−1 and $2.96–5.88 kg−1, respectively. This compares favourably with organic solvents such as acetone or ethyl acetate, which sell for $1.30–$1.40 kg−1. Moreover, the raw materials contribute the overwhelming majority of this cost and the intensified process using a compact plate reactor is more economical due to lower energy requirements. These results indicate that ionic liquids are not necessarily expensive, and therefore large-scale IL-based processes can become a commercial reality.
Welton T, 2014, Introducing Ionic Liquids, Supported Ionic Liquids: Fundamentals and Applications, Pages: 11-36, ISBN: 9783527324293
This chapter summarizes the known physicochemical properties that are of particular interest for supported ionic liquid phases (SILPs). Any salt that is sufficiently thermally stable will form an ionic liquid when it melts. The most important property of an ionic liquid is whether it is a liquid or not in the required temperature range. Coulombic interactions between ions give rise to the largely periodic behavior (alternating cation-anion structures) that is seen in ionic liquids. Hydrogen bonding is an important structure forming factor in many pure ionic liquids and the degree of the short-range cation-anion interactions is dependent upon which ions the ionic liquid is composed of. It has been demonstrated that ionic liquids can have dramatic effects upon the products and rates of chemical reactions. Industrial chemists have been exploring ionic liquids' potential commercial uses, particularly as process solvents.
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.
Matthews RP, Welton T, Hunt PA, 2014, Competitive pi interactions and hydrogen bonding within imidazolium ionic liquids, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 16, Pages: 3238-3253, ISSN: 1463-9076
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.
Skarmoutsos I, Welton T, Hunt PA, 2014, The importance of timescale for hydrogen bonding in imidazolium chloride ionic liquids, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 16, Pages: 3675-3685, ISSN: 1463-9076
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- Citations: 71
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
Welton T, 2014, Introducing Ionic Liquids, SUPPORTED IONIC LIQUIDS: FUNDAMENTALS AND APPLICATIONS, Editors: Fehrmann, Riisager, Haumann, Publisher: WILEY-V C H VERLAG GMBH, Pages: 13-36, ISBN: 978-3-527-32429-3
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- Citations: 3
Ab Rani MA, Borduas N, Colquhoun V, et al., 2013, The potential of methylsiloxanes as solvents for synthetic chemistry applications, Green Chemistry, Vol: 16, Pages: 1282-1296, ISSN: 1744-1560
The potential use of volatile methylsiloxanes (VMSs) as solvents for chemicals synthesis has been explored. Assessment of the environmental impact of these VMS solvents is made and found to be significantly lower than those of the non-polar organic solvents that they have the potential to replace. The polarities of the VMSs, as expressed by empirical polarity measurements, and miscibilities with other liquids are found to be similar to those of alkane solvents. Finally, some uses of VMSs as solvents for both organic and inorganic transformations are described. The VMSs provide environmentally more sustainable (greener) alternatives to the nonpolar solvents that they have the potential to replace.
Deyko A, Cremer T, Rietzler F, et al., 2013, Interfacial Behavior of Thin Ionic Liquid Films on Mica, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 117, Pages: 5101-5111, ISSN: 1932-7447
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- Citations: 56
Smith AM, Lovelock KRJ, Gosvami NN, et al., 2013, Monolayer to Bilayer Structural Transition in Confined Pyrrolidinium-Based Ionic Liquids, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, Vol: 4, Pages: 378-382, ISSN: 1948-7185
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- Citations: 137
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.
Smith AM, Lovelock KRJ, Gosvami NN, et al., 2013, Quantized friction across ionic liquid thin films, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 15, Pages: 15317-15320, ISSN: 1463-9076
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- Citations: 122
Niedermeyer H, Ashworth C, Brandt A, et al., 2013, A step towards the <i>a priori</i> design of ionic liquids, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 15, Pages: 11566-11578, ISSN: 1463-9076
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- Citations: 55
Clough MT, Geyer K, Hunt PA, et al., 2013, Thermal decomposition of carboxylate ionic liquids: trends and mechanisms, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 15, Pages: 20480-20495, ISSN: 1463-9076
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- Citations: 196
Welton T, Westcott S, 2012, A finite resource: Helium, Manufacturing Chemist, Vol: 83, ISSN: 0262-4230
Baez JC, Baratin A, Freidel L, et al., 2012, Introduction, Publisher: AMER MATHEMATICAL SOC
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- Citations: 25
Bulut S, Ab Rani MA, Welton T, et al., 2012, Preparation of [Al(hfip)4]--Based Ionic Liquids with Siloxane-Functionalized Cations and Their Physical Properties in Comparison with Their [Tf2N]- Analogues, CHEMPHYSCHEM, Vol: 13, Pages: 1802-1805, ISSN: 1439-4235
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- Citations: 17
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