Publications
240 results found
Brogan APS, Heldman N, Hallett JP, et al., 2019, Thermally robust solvent-free biofluids of M13 bacteriophage engineered for high compatibility with anhydrous ionic liquids, Chemical Communications, Vol: 55, Pages: 10752-10755, ISSN: 1359-7345
Here, we demonstrate a chemical modification strategy to create biomaterials of the M13 bacteriophage with extraordinary thermal stability, and high compatibility with non-aqueous ionic liquids. The results provide a blueprint for developing soft materials with well-defined architectures that may find broad applicability in the next generation of flexible devices.
Tan SY, Payne DJ, Hallett JP, et al., 2019, Developments in electrochemical processes for recycling lead-acid batteries, Current Opinion in Electrochemistry, Vol: 16, Pages: 83-89, ISSN: 2451-9103
The lead-acid battery recycling industry is very well established, but the conventional pyrometallurgical processes are far from environmentally benign. Hence, recent developments of lead-acid battery recycling technologies have focused on low-temperature (electro-)hydrometallurgical processes, the subject of this review, covering modified electrolytes, improved reaction engineering, better reactor design and control of operating conditions.
Green SP, Payne AD, Wheelhouse KM, et al., 2019, Diazo transfer reagent 2-azido-4,6-dimethoxy-1,3,5-triazine (ADT) Displays highly exothermic decomposition comparable to tosyl azide, The Journal of Organic Chemistry, Vol: 84, Pages: 5893-5898, ISSN: 0022-3263
2-Azido-4,6-dimethoxy-1,3,5-triazine (ADT) was reported recently as a new “intrinsically safe” diazo-transfer reagent. This assessment was based on differential scanning calorimetry data indicating that ADT exhibits endothermic decomposition. We present DSC data on ADT that show exothermic decomposition with an initiation temperature (Tinit) of 159 °C and an enthalpy of decomposition (ΔHD) of −1135 J g–1 (−207 kJ mol–1). We conclude that ADT is potentially explosive and must be treated with caution, being of comparable exothermic magnitude to tosyl azide (TsN3). A maximum recommended process temperature for ADT is 55 °C.
Chambon CL, Chen M, Fennell PS, et al., 2019, Efficient fractionation of lignin- and ash-rich agricultural residues following treatment with a low-cost protic ionic liquid, Frontiers in Chemistry, Vol: 7, ISSN: 2296-2646
Agricultural residues from rice, wheat and sugarcane production are annually available at the gigaton-scale worldwide, particularly in Asia. Due to their high sugar content and ash compositions, their conversion to bioethanol is an attractive alternative to their present disposal by open-field burning and landfilling. In this work, we demonstrate application of the low-cost protic ionic liquid triethylammonium hydrogen sulfate ([TEA][HSO4]) for pretreatment of rice straw, rice husk, wheat straw and sugarcane bagasse. The feedstocks had high ash (up to 13 wt%) and lignin content (up to 28 wt%). Pretreatment effectiveness was examined at 150 and 170°C and an optimal pretreatment time was identified and characterized by glucose release following enzymatic saccharification (i.e., hydrolysis), biomass delignification observed by compositional analysis, and lignin recovery. The isolated lignin fractions were analyzed by 2D HSQC NMR to obtain insights into the structural changes occurring following ionic liquid pretreatment. After treatment at 170°C for 30–45 min, enzymatic hydrolysis of three agroresidues gave near-quantitative glucose yields approaching 90% while rice husk gave 73% yield. Glucose release from the pulps was enhanced by saccharifying wet pulps without an air-drying step to reduce hornification. According to pulp compositional analysis, up to 82% of lignin was removed from biomass during pretreatment, producing highly digestible cellulose-rich pulps. HSQC NMR of the extracted lignins showed that delignification proceeded via extensive cleavage of β-O-4′ aryl ether linkages which was accompanied by condensation reactions in the isolated lignins. The high saccharification yields obtained indicate excellent potential for valorization of low-cost agroresidues in large volumes, which is promising for commercialization of biofuels production using the ionoSolv pretreatment technology.
Hennequin L, Levers O, Hallett J, 2019, Ionic Liquids as Solvents for the Production of Materials from Biomass, Encyclopedia of Ionic Liquids, Editors: Zhang
Vriamont CEJJ, Chen T, Romain C, et al., 2019, From lignin to chemicals: Hydrogenation of lignin models and mechanistic insights into hydrodeoxygenation via low-temperature C-O bond cleavage, ACS Catalysis, Vol: 9, Pages: 2345-2354, ISSN: 2155-5435
The catalytic hydrogenation of a series of lignin model compounds, including anisole, guaiacol, 1,2-dimethoxybenzene, 4-propyl-2-methoxyphenol, and syringol, has been investigated in detail, using a Ru/C catalyst in acetic acid as the solvent. Both hydrogenation of the aromatic unit and C–O bond cleavage are observed, resulting in a mixture of cyclohexanes and cyclohexanols, together with cyclohexyl acetates due to esterification with the solvent. The effect on product composition of the reaction parameters temperature (80–140 °C), pressure (10–40 bar), and reaction time (0.5–4 h) has been evaluated in detail. The lignin model compound 4-propyl-2-methoxyphenol was converted to 4-propylcyclohexanol in 4 h at 140 °C and 30 bar of H2 pressure with 84% conversion and 63% selectivity. Mechanistic studies on the reactivity of reaction intermediates have shown that C–O bond cleavage under these relatively mild conditions does not involve a C–O bond hydrogenolysis reaction but is due to elimination and hydrolysis reactions (or acetolysis in acetic acid solvent) of highly reactive cyclohexadiene- and cyclohexene-based enols, enol ethers, and allyl ethers.
Sharifzadeh M, Sadeqzadeh M, Nejadghaffar Borhani T, et al., 2019, The multiscale challenges of biomass fast pyrolysis and bio-oil upgrading: review of the state of art and future research directions, Progress in Energy and Combustion Science, Vol: 71, Pages: 1-80, ISSN: 1873-216X
Biomass fast pyrolysis is potentially one of the cheapest routes toward renewable liquid fuels. Its commercialization, however, poses a multi-scale challenge, which starts with the characterization of feedstock, products and reaction intermediates at molecular scales, and continues with understanding the complex reaction network taking place in different reactor configurations, and in the case of catalytic pyrolysis and upgrading on different catalysts. In addition, crude pyrolysis oil is not immediately usable in the current energy infrastructure, due to undesirable properties such as low energy content and corrosiveness as a result of its high oxygenate content. It, therefore, needs to be upgraded and fractionated to desired specifications. While various types of pyrolysis reactors and upgrading technologies are under development, knowledge transfer and closing the gap between theory and application requires model development. In-depth understanding of the reaction mechanisms and kinetics should be combined with the knowledge of multi-scale transport phenomena to enable design, optimization, and control of complex pyrolysis reactors. Finally, underpinning economic and environmental impacts of biofuel production requires expanding the system boundaries to include the overall process and supply chain. The present contribution aims at providing a comprehensive multi-scale review that discusses the state of the art of each of these aspects, as well as their multi-scale interactions. The study is mainly focused on fast pyrolysis, although reference to other types of pyrolysis technologies is made for the sake of comparison and knowledge transfer.
Gschwend F, Chambon C, Biedka M, et al., 2019, Quantitative glucose release from softwood after pretreatment with low-cost ionic liquids, Green Chemistry, Vol: 21, Pages: 692-703, ISSN: 1463-9262
Softwood is an abundantly available feedstock for the bio-based industry, however, achieving cost-effective sugar release is particularly challenging owing to its guaiacyl-only lignin. Here, we report the highly effective pretreatment of the softwood pine (Pinus sylvestris) using ionoSolv pretreatment, a novel ionic liquid-based lignocellulose fractionation technology. Three protic, low-cost ionic liquids, 1-butylimidazolium hydrogen sulfate, triethylammonium hydrogen sulfate and N,N-dimethylbutylammonium hydrogen sulfate, were used to fractionate the biomass into a carbohydrate-rich pulp and a lignin. The carbohydrate-rich pulp was hydrolysed into fermentable sugars by enzymatic saccharification. Under the most successful pretreatment conditions, quantitative glucose release from the pulp was achieved, which equates to a projected glucose release of 464 mg per gram of pine wood entering the process. We further intensified the process by increasing the solid to solvent ratio up to 1:2 g/g while maintaining saccharification yields of 75% of the theoretical maximum. We also demonstrate for the first time that N,N-dimethylbutylammonium hydrogen sulfate, [DMBA][HSO4] is an excellent low-cost pretreatment solvent, surpassing the pretreatment effectiveness of its symmetrically substituted analogue triethylammonium hydrogen sulfate. This shows that ionoSolv pretreatment with protic hydrogen sulfate ionic liquids is a truly feedstock-independent pretreatment option, further increasing the commercial potential of this pretreatment technology.
Baaqel H, Guillén-Gosálbez G, Diaz I, et al., 2019, Estimating “true” cost of ionic liquids (ILs) using monetization
Ragauskas AJ, Williams CK, Davison BH, et al., 2018, The path forward for biofuels and biomaterials, Renewable Energy: Four Volume Set, Pages: 271-283, ISBN: 9781844078677
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- Citations: 6
Chambon C, Mkhize T, Reddy P, et al., 2018, Pretreatment of South African sugarcane bagasse using a low-cost protic ionic liquid: a comparison of whole, depithed, fibrous and pith bagasse fractions, Biotechnology for Biofuels, Vol: 11, ISSN: 1754-6834
BackgroundSugarcane bagasse is an abundant and geographically widespread agro-industrial residue with high carbohydrate content, making it a strong candidate feedstock for the bio-based economy. This study examines the use of the low-cost protic ionic liquid triethylammonium hydrogen sulfate ([TEA][HSO4]) to fractionate a range of South African sugarcane bagasse preparations into a cellulose-rich pulp and lignin. The study seeks to optimize pretreatment conditions and examine the necessity of applying a depithing step on bagasse prior to pretreatment.ResultsPretreatment of five bagasse preparations, namely whole, industrially depithed, laboratory depithed (short and long fiber) and pith bagasse with [TEA][HSO4]:[H2O] (4:1 w/w) solutions produced highly digestible cellulose-rich pulps, as assessed by residual lignin analysis and enzymatic hydrolysis. Pretreatment under the optimized condition of 120 °C for 4 h produced a pretreated cellulose pulp with up to 90% of the lignin removed and enabled the release of up to 69% glucose contained in the bagasse via enzymatic hydrolysis. Glucose yields from whole and depithed bagasse preparations were very similar. Significant differences in lignin recovery were obtained for laboratory depithed bagasse compared with whole and industrially depithed bagasse. The silica-rich ash components of bagasse were seen to partition mainly with the pulp, from where they could be easily recovered in the post-hydrolysis solids.ConclusionsThe five bagasse preparations were compared but did not show substantial differences in composition or cellulose digestibility after pretreatment. Evidence was presented that a depithing step appears to be unnecessary prior to ionoSolv fractionation, potentially affording significant cost and energy savings. Instead, lignin re-deposition onto the pulp surface (and, in turn, particle size and shape) appeared to be major factors affecting the conditioning of bagasse with the applied IL. We show that pith ba
Gschwend FJV, Brandt-Talbot A, Malaret FJ, et al., 2018, Rapid pretreatment of Miscanthus using the low-cost ionic liquid triethylammonium hydrogen sulfate at elevated temperatures, Green Chemistry, Vol: 20, Pages: 3486-3498, ISSN: 1463-9262
Deconstruction with low-cost ionic liquids (ionoSolv) is a promising method to pre-condition lignocellulosic biomass for the production of renewable fuels, materials and chemicals. This study investigated process intensification strategies for the ionoSolv pretreatment of Miscanthus X giganteus using the low-cost ionic liquid triethylammonium hydrogen sulfate ([TEA][HSO4]) in the presence of 20 wt% water, using high temperatures and a high solid to solvent loading of 1:5 g/g. The temperatures investigated were 150, 160, 170 and 180°C. We discuss the effect of pretreatment temperature on lignin and hemicellulose removal, cellulose degradation and enzymatic saccharification yields. We report that very good fractionation can be achieved across all investigated temperatures, including an enzymatic saccharification yield exceeding 75% of the theoretical maximum after only 15 min of treatment at 180°C. We further characterised the recovered lignins which established some tunability of the hydroxyl group content, subunit composition, connectivity and molecular weight distribution in the isolated lignin while maintaining maximum saccharification yield. This drastic reduction of pretreatment time at increased biomass loading without a yield penalty is promising for the development of a commercial ionoSolv pretreatment process.
Brogan APS, Bui-Le L, Hallett JP, 2018, Non-aqueous homogenous biocatalytic conversion of polysaccharides in ionic liquids using chemically modified glucosidase, Nature Chemistry, Vol: 10, Pages: 859-865, ISSN: 1755-4330
The increasing requirement to produce platform chemicals and fuels from renewable sources means advances in biocatalysis are rapidly becoming a necessity. Biomass is widely used in nature as a source of energy and as chemical building blocks. However, recalcitrance towards traditional chemical processes and solvents provides a significant barrier to widespread utility. Here, by optimizing enzyme solubility in ionic liquids, we have discovered solvent-induced substrate promiscuity of glucosidase, demonstrating an unprecedented example of homogeneous enzyme bioprocessing of cellulose. Specifically, chemical modification of glucosidase for solubilization in ionic liquids can increase thermal stability to up to 137 °C, allowing for enzymatic activity 30 times greater than is possible in aqueous media. These results establish that through a synergistic combination of chemical biology (enzyme modification) and reaction engineering (solvent choice), the biocatalytic capability of enzymes can be intensified: a key step towards the full-scale deployment of industrial biocatalysis.
Hallett J, Fennell P, Gschwend F, et al., 2018, Process for the extraction of metal pollutants from treated cellulosic biomass, CN108291033 (A)
The present invention relates to a process for extracting oxidised metal pollutants from treated cellulosic or lignocellulosic biomass to recover the metal. The treatment also generates a cellulosic or lignocellulosic biomass which can to be used as a feedstock for biofuel, for making cellulose containing materials, and provides a source of other renewable chemicals.
Mac Dowell N, Hallett JP, 2018, Challenges and opportunities for the utilisation of ionic liquids as solvents for CO2 capture, Molecular Systems Design & Engineering, Vol: 3, Pages: 560-571, ISSN: 2058-9689
Ionic Liquids have been extensively investigated as promising materials for several gas separationprocesses, including CO2capture. They have the potential to outperform traditional solvents, interms of their capacity, selectivity, regenerability and stability. In fact, hundreds of ionic liquidshave been investigated as potential sorbents for CO2capture. However, most studies focus onenhancing equilibrium capacity, and neglect to consider other properties, such as transport prop-erties, and hence ignore the effect that the overall set of properties have on process performance,and therefore on cost. In this study, we propose a new methodology for their evaluation using arange of monetised and non-monetised process performance indices. Our results demonstratethat whilst most research effort is focused on improving CO2solubility, viscosity, a transport prop-erty, and heat capacity, a thermochemical property, might preclude the use of ionic liquids, eventhose which are highly CO2-philic, and therefore increased effort on addressing the challengesassociated with heat capacity and viscosity is an urgent necessity. This work highlights a rangeof potential challenges that ionic liquids will face before they can be applied at process scale, andidentifies some key research opportunities.
Ballantyne AD, Hallett JP, Riley DJ, et al., 2018, Lead acid battery recycling for the twenty-first century, Royal Society Open Science, Vol: 5, Pages: 171368-171368, ISSN: 2054-5703
There is a growing need to develop novel processes to recover lead from end-of-life lead-acid batteries, due to increasing energy costs of pyrometallurgical lead recovery, the resulting CO2 emissions and the catastrophic health implications of lead exposure from lead-to-air emissions. To address these issues, we are developing an iono-metallurgical process, aiming to displace the pyrometallurgical process that has dominated lead production for millennia. The proposed process involves the dissolution of Pb salts into the deep eutectic solvent (DES) Ethaline 200, a liquid formed when a 1 : 2 molar ratio of choline chloride and ethylene glycol are mixed together. Once dissolved, the Pb can be recovered through electrodeposition and the liquid can then be recycled for further Pb recycling. Firstly, DESs are being used to dissolve the lead compounds (PbCO3, PbO, PbO2 and PbSO4) involved and their solubilities measured by inductively coupled plasma optical emission spectrometry (ICP-OES). The resulting Pb2+ species are then reduced and electrodeposited as elemental lead at the cathode of an electrochemical cell; cyclic voltammetry and chronoamperometry are being used to determine the electrodeposition behaviour and mechanism. The electrodeposited films were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). We discuss the implications and opportunities of such processes.
Bui M, Adjiman CS, Bardow A, et al., 2018, Carbon capture and storage (CCS): the way forward, Energy and Environmental Science, Vol: 11, Pages: 1062-1176, ISSN: 1754-5692
Carbon capture and storage (CCS) is broadly recognised as having the potential to play a key role in meeting climate change targets, delivering low carbon heat and power, decarbonising industry and, more recently, its ability to facilitate the net removal of CO2 from the atmosphere. However, despite this broad consensus and its technical maturity, CCS has not yet been deployed on a scale commensurate with the ambitions articulated a decade ago. Thus, in this paper we review the current state-of-the-art of CO2 capture, transport, utilisation and storage from a multi-scale perspective, moving from the global to molecular scales. In light of the COP21 commitments to limit warming to less than 2 °C, we extend the remit of this study to include the key negative emissions technologies (NETs) of bioenergy with CCS (BECCS), and direct air capture (DAC). Cognisant of the non-technical barriers to deploying CCS, we reflect on recent experience from the UK's CCS commercialisation programme and consider the commercial and political barriers to the large-scale deployment of CCS. In all areas, we focus on identifying and clearly articulating the key research challenges that could usefully be addressed in the coming decade.
Corbett PJ, Mclntosh AJS, Gee M, et al., 2018, Use of ionic liquids to remove harmful M2+ contaminants from hydrocarbon streams, MOLECULAR SYSTEMS DESIGN & ENGINEERING, Vol: 3, Pages: 408-417, ISSN: 2058-9689
Zinc contaminants have been identified as suspects leading to nozzle deposit formation and copper contaminants quickly reduce the oxidation stability of diesel fuel. Ionic liquids (ILs) are commonly referred to as ‘designer solvents’ due to the great degree of fine-tuning of physical and chemical properties afforded by modification of the constituent cation and anion. The tunable properties of the IL ions allows the ‘design’ to meet the requirements for a particular application, making ILs an ideal potential candidate for the extraction of trace (ppb to ppm) amounts of zinc and copper heavy metals from diesel fuel. We report for the first time that ILs can extract up to 99.3% of zinc at a zinc concentration of just 2 mg kg−1 and copper can be extracted up to 99.7% at copper concentration of just 1 mg kg−1 from a model diesel fuel. Factors affecting the extent of extraction were investigated via correlation with experimental descriptors. 23Na NMR was used in the determination of donor number (DN) and Kamlet–Taft parameters were gathered for each IL providing information of possible hydrogen-bond acidity/basicity (α/β), and dipolarity/polarizability effects (π*). In addition, the non-random two liquid (NRTL) model was applied to determine τ parameters for each of the ILs. We determined that the extraction is controlled strongly by the hydrogen bond basicity of the IL which is directly related to the ability of the anion of the IL to complex Zn2+ and Cu2+ thus removing it from the fuel. DN, τ parameters and β, in addition to density and viscosity values, provide further information on the extraction mechanisms and predict performance, informing chemical design of ILs that are ideal for fuel purification.
Corbett PJ, McIntosh AJS, Gee M, et al., 2018, Use of ionic liquids to minimize sodium induced internal diesel injector deposits (IDIDs), MOLECULAR SYSTEMS DESIGN & ENGINEERING, Vol: 3, Pages: 397-407, ISSN: 2058-9689
Trace amounts of dissolved sodium has been identified as one possible cause leading to the formation of internal diesel injector deposits (IDIDs) which prove problematic by reducing fuel efficiency in high pressure diesel injectors. We demonstrate the successful extraction of ppm levels of Na+ from a model diesel fuel. A range of ionic liquids (ILs) with a variety of cations and anions were examined for their effectiveness at different loadings of IL relative to the model diesel fuel. Results provide several clear trends with some exceptional capabilities of the ILs in the extractions. ILs are commonly referred to as ‘designer solvents’, due to the great degree of fine-tuning of physical and chemical properties afforded by modification of the constituent cation and anion. The tunable properties of the ILs ions allow the ‘design’ to meet the requirements for a particular target and here provide several potential candidates for the extraction of the ppm levels of sodium from diesel fuel. We report for the first time that ILs can extract up to 99.1% of Na+ from a model diesel fuel at a Na+ concentration of just 3 mg kg−1 in the fuel; factors affecting the extent of extraction were investigated via correlation with experimental solvent descriptors. 23Na NMR was used in the determination of donor number (DN), and Kamlet–Taft parameters were gathered for each IL providing information of possible hydrogen-bond acidity/basicity (α/β) and dipolarity/polarizability solvent strength (π*). In addition, the non-random two liquid model (NRTL) was applied to correlate the experimental extraction results and determine τ parameters for each of the ILs. We determined that the extraction is controlled strongly by the Lewis basicity of the IL which is directly related to the ability of the anion of the IL to complex Na+ and thereby remove it from the fuel. DN, τ parameters and β, in addition to interfacial tension and visco
Clarke CJ, Tu W-C, Levers O, et al., 2018, Green and Sustainable Solvents in Chemical Processes, CHEMICAL REVIEWS, Vol: 118, Pages: 747-800, ISSN: 0009-2665
Sustainable solvents are a topic of growing interest in both the research community and the chemical industry due to a growing awareness of the impact of solvents on pollution, energy usage, and contributions to air quality and climate change. Solvent losses represent a major portion of organic pollution, and solvent removal represents a large proportion of process energy consumption. To counter these issues, a range of greener or more sustainable solvents have been proposed and developed over the past three decades. Much of the focus has been on the environmental credentials of the solvent itself, although how a substance is deployed is as important to sustainability as what it is made from. In this Review, we consider several aspects of the most prominent sustainable organic solvents in use today, ionic liquids, deep eutectic solvents, supercritical fluids, switchable solvents, liquid polymers, and renewable solvents. We examine not only the performance of each class of solvent within the context of the reactions or extractions for which it is employed, but also give consideration to the wider context of the process and system within which the solvent is deployed. A wide range of technical, economic, and environmental factors are considered, giving a more complete picture of the current status of sustainable solvent research and development.
Brandt-Talbot A, Hallett JP, Gschwend FJV, 2018, Ultra-low cost ionic liquids for waste wood biorefining, Pages: 47-54
The BioFlex process is a lignocellulose fractionation process that can treat many different lignocellulosic input materials in a one-size-fits-all system. This now includes low value metal polluted waste wood. We have demonstrated high metal extraction can be achieved with ultra-low cost BioFlex ILs. The ionic liquid solution based on 1-methylimidazolium chloride was shown to be particularly effectively in removing heavy metals from waste wood while affording a cellulose pulp that results in high glucose yields after enzymatic saccharification. It has further been shown that copper can be deposited from BioFlex ionic liquids. The presence of biomass degradation products from pretreatment did not alter the deposition behaviour. Ionic liquid based pretreatment therefore represents a promising platform for the decontamination of metal contaminated waste wood while concomitantly producing intermediate fractions that can be used for biorefining. Our techno-economic estimate shows that the BioFlex process with metal polluted waste wood is economically attractive at a small commercial scale. The next focus is finding suitable applications for the BioFlex process outputs.
Hallett J, Welton T, Brandt-Talbot A, 2017, Treatment, EP3244371 (A1)
The present disclosure relates to an improved 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.
Mac Dowell N, Hallett J, Mota Martinez M, 2017, Solvent selection and design for CO2 capture - how we might have been missing the point, Sustainable Energy & Fuels, Vol: 1, Pages: 2078-2090, ISSN: 2398-4902
Carbon capture and storage (CCS) is a vital technology for the cost-effective mitigation of anthropogenic CO2 emissions. However, a key obstacle to its deployment on a large scale remains its cost – both capital and operating costs. In this context, the development of improved sorbents is a key research priority. Consequently, there is a vast global effort to develop new materials for this purpose, with literally thousands of new materials having been proposed since the beginning of the millennium. One common element of these contributions is that they focus on the equilibrium capacity of the material to absorb CO2 and rarely, if ever, other key factors such as transport properties. To date, the majority of this effort has cost significant amounts of time and resources and has almost exclusively focused on developing sorbents with increased CO2 capacity and/or reduced heat of regeneration. Given that sorbent regeneration largely dictates operational cost, this would, on the surface, appear rational. However, it is vital to recall that the cost structure of $ per MWh of electricity generated is composed of contributions from both capital and operational costs. Consequently, this single-minded focus on equilibrium CO2 capacity and heat of regeneration excludes the contribution of transport and kinetic properties which determine the equipment size and thus the capital cost. Therefore, in order to develop sorbents which will result in a non-negligible cost reduction, it is essential to move beyond equilibrium-based metrics of sorbent performance. In this paper, we present a new methodological approach for sorbent screening which explicitly includes rate-based phenomena. Our approach uses both monetised and non-monetised performance indicators. Our results suggest that whilst equilibrium CO2 capacity is a key determinant of process performance, transport properties (e.g., viscosity) and other thermophysical properties (e.g., heat capacity) have a significant effect
Daud NMAN, Bakis E, Hallett JP, et al., 2017, Evidence for the spontaneous formation of N-heterocyclic carbenes in imidazolium based ionic liquids, Chemical Communications, Vol: 53, Pages: 11154-11156, ISSN: 1359-7345
We present a study of the reactions of aldehydes in ionic liquids which gives evidence for the spontaneous formation of N-heterocyclic carbenes in ionic liquids based on 1,3-dialkyl substituted imidazolium cations from the lack of a deuterium isotope effect on the reaction of these ionic liquids with aldehydes.
Gschwend FJV, Brandt-Talbot A, Chambon CL, et al., 2017, Ultra-Low Cost Ionic Liquids for the Delignification of Biomass, Ionic Liquids: Current State and Future Directions, Editors: Shiflett, Scurto, Publisher: American Chemical Society, Pages: 209-223, ISBN: 9780841232136
Low-cost pretreatment of lignocellulosic biomass is an essential next step toward large-scale deployment as renewable liquid fuels, materials or chemicals. Ionic liquids (ILs) are highly effective at pretreatment, but high IL cost has hindered commercial viability. We have recently developed low-cost (ca. $1/kg) ILs, such as triethylammonium hydrogen sulphate, for pretreatment. In this chapter we discuss the fractionation of the grass Miscanthus x giganteus, wherein we deconstruct the lignocellulosic matrix into a cellulose-rich pulp, a recovered lignin fraction and an organic distillate. More than 80% of the lignin and quantitative hemicelluloses are removed during extraction. This results in 70-90% glucose release during enzymatic saccharification. The IL can also be successfully recovered and reused, with >99% IL recovery and minimal effects on efficiency of extraction. A detailed mass balance of all components and subsequent economic analysis revealed this efficient pretreatment with an ultra-low cost IL could result in an economically viable pretreatment process.
Argyropoulos D, Bitter H, Brandt-Talbot A, et al., 2017, Conversion technologies: general discussion, FARADAY DISCUSSIONS, Vol: 202, Pages: 371-389, ISSN: 1359-6640
Brogan APS, Hallett JP, 2017, Protein-polymer surfactant nanoconjugates for biocatalysis in anhydrous ionic liquids, 19th IUPAB Congress / 11th EBSA Congress, Publisher: SPRINGER, Pages: S362-S362, ISSN: 0175-7571
Mota-Martinez MT, Hallett J, Mac Dowell N, 2017, Screening solvents properties for CO2 capture based on the process performance, 13th International Conference on Greenhouse Gas Control Technologies (GHGT), Publisher: ELSEVIER SCIENCE BV, Pages: 1551-1557, ISSN: 1876-6102
Fennell PS, hallett J, Brandt-Talbot A, et al., 2017, An economically viable ionic liquid for the fractionation of lignocellulosic biomass, RSC Green Chemistry, Vol: 19, Pages: 3078-3102, ISSN: 1757-7047
Cost-effective fractionation (pretreatment) of lignocellulosic biomass is necessary to enable its large-scale use as a source of liquid fuels, bio-based materials and bio-derived chemicals. While a number of ionic liquids (ILs) have proven capable of highly effective pretreatment, their high cost presents a barrier to commercial viability. In this study, we investigate in detail the application of the low-cost (ca. $1 kg−1) ionic liquid triethylammonium hydrogen sulfate for the fractionation of the grass Miscanthus x giganteus into a cellulose rich pulp, a lignin and a distillate. We found that up to 85% of the lignin and up to 100% of the hemicellulose were solubilized into the IL solution. The hemicellulose dissolved mainly in monomeric form, and pentoses were partially converted into furfural. Up to 77% of the glucose contained in the biomass could be released by enzymatic saccharification of the pulp. The IL was successfully recovered and reused four times. A 99% IL recovery was achieved each time. Effective lignin removal and high saccharification yields were maintained during recycling, representing the first demonstration that repeated IL use is feasible due to the self-cleaning properties of the non-distillable solvent. We further demonstrate that furfural and acetic acid can be separated quantitatively from the non-volatile IL by simple distillation, providing an easily recoverable, valuable co-product stream, while IL degradation products were not detected. We further include detailed mass balances for glucose, hemicellulose and lignin, and a preliminary techno-economic estimate for the fractionation process. This is the first demonstration of an efficient and repeated lignocellulose fractionation with a truly low-cost IL, and opens a path to an economically viable IL-based pretreatment process.
Weigand L, Mostame S, Brandt-Talbot A, et al., 2017, Effect of pretreatment severity on the cellulose and lignin isolated from Salix using ionoSolv pretreatment, Faraday Discussions, Vol: 202, Pages: 331-349, ISSN: 1359-6640
The ionoSolv pretreatment is a new technique employing protic low-cost ionic liquids and has previously been applied to successfully fractionate switchgrass and the grass Miscanthus giganteus. This study investigates the effect of using the protic ionic liquid solution [N2220][HSO4]80% with two different acid/base ratios (1.02 and 0.98) at 120, 150 and 170 °C on the pretreatment outcome of the hardwood willow. The ionic liquid solution was able to fractionate willow, and a pulp and lignin fraction were recovered after treatment. The pretreatment success was determined via enzymatic hydrolysis of the pulp, which showed that the ionoSolv pretreatment was able to increase enzymatic glucose yields compared to untreated willow biomass. The pretreatment produced a cellulose-rich pulp with high hemicellulose and lignin removal. The pulp composition and glucose yield after saccharification were greatly influenced by the acidity of the ionic liquid solution, temperature and pretreatment time. The extracted lignin was analysed via 2-D HSQC NMR spectroscopy and GPC to investigate the changes in the lignin structure induced by the pretreatment severity. The lignin structure (in terms of inter-unit linkages and S/G ratio) and molecular weight varied significantly depending on the pretreatment conditions used.
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