Reactive and Reversible Ionic Liquids for CO<sub>2</sub>Capture and Acid Gas Removal

Shannon, Matthew S.; Bara, Jason E.

doi:10.1080/01496395.2011.630055

Cited by 99 publications

(76 citation statements)

References 14 publications

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“…However, as SO 2 scrubbing from low pressure (i.e., ∼1 atm) flue gas at coal-fired power plants typically is performed at an inlet SO 2 concentration of 2000 ppm to as low as 50−100 ppm of SO 2 , there is a need to focus on ILs that exhibit stronger chemical interactions with SO 2 . 23 Shiflett and Yokozeki also studied SO 2 absorption in ILs with an imidazolium cation ([C 4 27 However, this guanidine-based polymer exhibited a high viscosity >13 000 cP, which would make it impractical for conventional process equipment. ILs with formate (HCOO − ) ions have also shown utility for enhancing SO 2 complexation via a 1:1 reaction.…”

Section: Introductionmentioning

confidence: 97%

Chemical and Physical Absorption of SO₂ by N-Functionalized Imidazoles: Experimental Results and Molecular-level Insight

Shannon

Irvin

Liu

et al. 2014

Ind. Eng. Chem. Res.

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Sulfur dioxide (SO 2 ) removal is a key component of many industrial processes, especially coal-fired power generation. Controlling SO 2 emissions is vital to maintaining environmental quality, as SO 2 is a contributor to acid rain, but has value as a chemical feedstock. Although a number of novel solvents/materials including ionic liquids (ILs) have recently been proposed for alternatives to limestone scrubbing for SO 2 capture/removal from point sources, the imidazole architecture presents a convenient, inexpensive and efficient class of low volatility and low viscosity solvents to accomplish this goal. On the basis of our prior work with imidazoles for CO 2 capture, we have extended our interests toward understanding the relationship between imidazole structure and SO 2 absorption. Using a series of imidazole compounds with various substituents at the 1, 2 and/or 4(5) positions of the five-membered ring, SO 2 absorption via both chemical and physical mechanisms was observed. The chemical absorption product is a relatively stable 1:1 SO 2 −imidazole complex, while physical absorption of SO 2 is dependent on pressure and temperature. Because imidazoles are relatively small molecules, they are an efficient absorption medium for SO 2 and can form adducts wherein the mass fraction of bound SO 2 is >40 wt %. The SO 2 −imidazole complexes were also observed to produce distinct color and/or phase changes that are associated with the nature of the substituents present. The chemically bound SO 2 can be released under vacuum at moderate temperature (∼100°C) and vacuum, yielding the original neat solvent, while the physically dissolved SO 2 can be readily removed at ambient temperature under vacuum. This behavior corresponds to a much smaller enthalpy of absorption for physical dissolution (−4 to −13 kJ/mol) as determined via thermodynamic relationships compared to the binding energies of chemical complexation (−35 to −42 kJ/mol) as determined via density functional theory calculations. Increasing chemical complexation energies are correlated with increased substitution on the imidazole ring. Simulations were also employed to gain insight into the structures of the SO 2 −imidazole complexes, illustrating changes in partial charge distribution before and after complexation as well as confirming a charge transfer complex is formed based on the N−S bond length.

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Section: Introductionmentioning

confidence: 97%

Chemical and Physical Absorption of SO₂ by N-Functionalized Imidazoles: Experimental Results and Molecular-level Insight

Shannon

Irvin

Liu

et al. 2014

Ind. Eng. Chem. Res.

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“…Owing to their exceptional combination of properties (negligible vapor pressure [2], high ion conductivity [3], high thermal stability [4], and low flammability [5]), ILs have been used to promote more efficient processes or develop novel functional materials in a plethora of different technological fields such as electrochemistry [6], biotechnology [7], analytical chemistry [8], catalysis [9], energy [10], nanotechnology [11], among others. In particular, ILs have attracted much attention as alternative media for CO 2 capture and separation processes [12][13][14][15][16][17][18][19], not only due to their low volatility, but also to their highly tunable nature which allows for the design of specific ILs with remarkable affinity for CO 2 over other flue gases [20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Novel pyrrolidinium-based polymeric ionic liquids with cyano counter-anions: High performance membrane materials for post-combustion CO2 separation

Tomé

Işık

Freire

et al. 2015

Journal of Membrane Science

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“…As such, they are emerging as important materials for drug delivery (4), lubrication (5), and electrolytes (6), including those for lithium ion (7) and lithium sulfur batteries (8). ILs have also found utility as heat transfer media for solar thermal systems (9), carbon capture (10), and biodiesel production (11). Among the industrial applications with highest potential volume requirements of these remarkable solvents is the processing of lignocellulosic biomass, and subsequent fermentation, to produce specialty and commodity chemicals including advanced biofuels (12)(13)(14)(15).…”

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confidence: 99%

Efficient biomass pretreatment using ionic liquids derived from lignin and hemicellulose

Socha

Parthasarathi

Shi

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

283

213

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Ionic liquids (ILs), solvents composed entirely of paired ions, have been used in a variety of process chemistry and renewable energy applications. Imidazolium-based ILs effectively dissolve biomass and represent a remarkable platform for biomass pretreatment. Although efficient, imidazolium cations are expensive and thus limited in their large-scale industrial deployment. To replace imidazolium-based ILs with those derived from renewable sources, we synthesized a series of tertiary amine-based ILs from aromatic aldehydes derived from lignin and hemicellulose, the major byproducts of lignocellulosic biofuel production. Compositional analysis of switchgrass pretreated with ILs derived from vanillin, p-anisaldehyde, and furfural confirmed their efficacy. Enzymatic hydrolysis of pretreated switchgrass allowed for direct comparison of sugar yields and lignin removal between biomass-derived ILs and 1-ethyl-3-methylimidazolium acetate. Although the rate of cellulose hydrolysis for switchgrass pretreated with biomassderived ILs was slightly slower than that of 1-ethyl-3-methylimidazolium acetate, 90-95% glucose and 70-75% xylose yields were obtained for these samples after 72-h incubation. Molecular modeling was used to compare IL solvent parameters with experimentally obtained compositional analysis data. Effective pretreatment of lignocellulose was further investigated by powder X-ray diffraction and glycome profiling of switchgrass cell walls. These studies showed different cellulose structural changes and differences in hemicellulose epitopes between switchgrass pretreatments with the aforementioned ILs. Our concept of deriving ILs from lignocellulosic biomass shows significant potential for the realization of a "closed-loop" process for future lignocellulosic biorefineries and has far-reaching economic impacts for other IL-based process technology currently using ILs synthesized from petroleum sources. renewable chemicals | bioenergy | lignocellulose conversion | saccharification | green chemistry

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Reactive and Reversible Ionic Liquids for CO₂Capture and Acid Gas Removal

Cited by 99 publications

References 14 publications

Chemical and Physical Absorption of SO₂ by N-Functionalized Imidazoles: Experimental Results and Molecular-level Insight

Chemical and Physical Absorption of SO₂ by N-Functionalized Imidazoles: Experimental Results and Molecular-level Insight

Novel pyrrolidinium-based polymeric ionic liquids with cyano counter-anions: High performance membrane materials for post-combustion CO2 separation

Efficient biomass pretreatment using ionic liquids derived from lignin and hemicellulose

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Reactive and Reversible Ionic Liquids for CO2Capture and Acid Gas Removal

Cited by 99 publications

References 14 publications

Chemical and Physical Absorption of SO2 by N-Functionalized Imidazoles: Experimental Results and Molecular-level Insight

Chemical and Physical Absorption of SO2 by N-Functionalized Imidazoles: Experimental Results and Molecular-level Insight

Novel pyrrolidinium-based polymeric ionic liquids with cyano counter-anions: High performance membrane materials for post-combustion CO2 separation

Efficient biomass pretreatment using ionic liquids derived from lignin and hemicellulose

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Reactive and Reversible Ionic Liquids for CO₂Capture and Acid Gas Removal

Chemical and Physical Absorption of SO₂ by N-Functionalized Imidazoles: Experimental Results and Molecular-level Insight

Chemical and Physical Absorption of SO₂ by N-Functionalized Imidazoles: Experimental Results and Molecular-level Insight