Direct analysis of cellulose in polar ionic liquids (original) (raw)
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Catalysis Communications
The effect of eight metal ions, Cr3+, Mn2+, Fe3+, Co2+ Ni2+, Cu2+, Zn2+ and La3+ on 1-(1-propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed hydrolysis of cellulose in water was studied at 140-170 °C. Mn2+, Fe3+, and Co2+ as co-catalysts produced significant enhancements in total reducing sugar (TRS) yields, with Mn2+ showing the highest activity. Mn2+ as co-catalyst produced 91.8, and 91.9 % TRS yields, whereas samples without Mn2+ gave 28.0 and 28.7 % yields at 160 and 170 °C respectively. The observed activation energies for cellulose hydrolysis without a co-catalyst and with Mn2+ co-catalyst are 78.1±1.4 and 32.8±4.9 kJ.mol-1 respectively.
The Hydrolysis of Cellulosic Materials in Ionic Liquids
BioResources, 2013
This study's main objective was the dissolution of cellulose from biomass using ionic liquids to obtain saccharides by prehydrolysis. Raw materials were exposed to the ionic liquids (ILs) 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium chloride, 1-ethyl-2,3-dimethylimidazolium chloride, and 3-(2-methoxy-2-oxoethyl)-1-(3-methoxy-3-oxopropyl)-imidazolium bromide at 105 °C for 6 h. The sugar content of the liquid phase was characterized by high-performance liquid chromatography (HPLC). The vegetal materials after treatments were characterized by Fourier transform infrared spectroscopy (FTIR). Glucose was the main reducing sugar product in each case. Different ILs were found to be most effective, depending on what sample was being dissolvedmicrocrystalline cellulose or rapeseed stalk.
Chemical Engineering Journal, 2009
Recent studies on the application of room temperature ionic liquids (RTILs) in cellulose chemistry have made great progresses. This has been providing a new and versatile platform for the wide utilization of cellulose resources and creation of novel functional materials. In this paper, the research progress in the field of dissolution, regeneration and derivatization of cellulose with RTILs are reviewed. And the perspective of RTIL application in cellulose industry is also discussed.
Green Chemistry, 2010
New strategies are needed to efficiently convert non-food biomass to glucose as a platform chemical. One promising approach is to use ionic liquids to first dissolve lignocellulose. Yet, in the presence of such solvents, the enzymes that catalyze cellulose hydrolysis become compromised in their activity. However, this decreased cellulase activity has not been examined in detail. Thus, the aim of this study was to investigate how the ionic liquid precisely affects cellulase activity and stability with regard to different cellulose substrates. Hereby, four ionic liquids were screened to identify which one best minimized the loss of enzyme activity. Then, this best ionic liquid was tested on one insoluble and two soluble cellulose substrates. Subsequently, the relevant parameters of solution viscosity and ionic strength were evaluated with respect to enzyme activity and stability. Finally the residual ionic liquid concentration from the precipitation of a-cellulose was varied. The best ionic liquid was found to be 1,3-dimethylimidazolium dimethylphosphate with the highest retained activity of 30% on the a-cellulose substrate in the presence of 10% (v/v) ionic liquid. Most importantly, an increase in viscosity and ionic strength contributed to the decrease in enzyme activity which nonetheless retained their stability. The hydrolysis of precipitated a-cellulose from ionic liquid showed significant higher reaction rates but reduced sugar yields when residual ionic liquid was present. None the less, it should be possible to effectively produce glucose from precipitated cellulose without needing to wash off all residual ionic liquid when optimized cellulase mixtures are used.
Efficient acid-catalyzed hydrolysis of cellulose in organic electrolyte solutions
Polymer Degradation and Stability, 2012
A novel method for cellulose hydrolysis catalyzed by mineral acids in the ionic liquid 1butyl-3-methylimidazolium chloride ([C 4 mim]Cl) has been developed that facilitates the hydrolysis of cellulose with dramatically accelerated reaction rates at 100 8C under atmospheric pressure and without pretreatment.
Regenerating cellulose from ionic liquids for an accelerated enzymatic hydrolysis
Journal of …, 2009
The efficient conversion of lignocellulosic materials into fuel ethanol has become a research priority in producing affordable and renewable energy. The pretreatment of lignocelluloses is known to be key to the fast enzymatic hydrolysis of cellulose. Recently, certain ionic liquids (ILs) were found capable of dissolving more than 10 wt% cellulose. Preliminary investigations [Dadi, A.P., Varanasi, S., Schall, C.A., 2006. Enhancement of cellulose saccharification kinetics using an ionic liquid pretreatment step. Biotechnol. Bioeng. 95, 904–910; Liu, L., Chen, H., 2006. Enzymatic hydrolysis of cellulose materials treated with ionic liquid [BMIM]Cl. Chin. Sci. Bull. 51, 2432–2436; Dadi, A.P., Schall, C.A., Varanasi, S., 2007. Mitigation of cellulose recalcitrance to enzymatic hydrolysis by ionic liquid pretreatment. Appl. Biochem. Biotechnol. 137–140, 407–421] suggest that celluloses regenerated from IL solutions are subject to faster saccharification than untreated substrates. These encouraging results offer the possibility of using ILs as alternative and non-volatile solvents for cellulose pretreatment. However, these studies are limited to two chloride-based ILs: (a) 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), which is a corrosive, toxic and extremely hygroscopic solid (m.p. ∼ 70 °C), and (b) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl), which is viscous and has a reactive side-chain. Therefore, more in-depth research involving other ILs is much needed to explore this promising pretreatment route. For this reason, we studied a number of chloride- and acetate-based ILs for cellulose regeneration, including several ILs newly developed in our laboratory. This will enable us to select inexpensive, efficient and environmentally benign solvents for processing cellulosic biomass. Our data confirm that all regenerated celluloses are less crystalline (58–75% lower) and more accessible to cellulase (>2 times) than untreated substrates. As a result, regenerated Avicel® cellulose, filter paper and cotton were hydrolyzed 2–10 times faster than the respective untreated celluloses. A complete hydrolysis of Avicel® cellulose could be achieved in 6 h given the Trichoderma reesei cellulase/substrate ratio (w/w) of 3:20 at 50 °C. In addition, we observed that cellulase is more thermally stable (up to 60 °C) in the presence of regenerated cellulose. Furthermore, our systematic studies suggest that the presence of various ILs during the hydrolysis induced different degrees of cellulase inactivation. Therefore, a thorough removal of IL residues after cellulose regeneration is highly recommended, and a systematic investigation on this subject is much needed.
ChemSusChem, 2014
This work describes a relatively simple methodology for efficiently deconstructing cellulose into monomeric glucose, which is more easily transformed into a variety of platform molecules for the production of chemicals and fuels. The approach undertaken here first involves the dissolution of cellulose in an ionic liquid (IL), followed by a second reconstruction step aided by an antisolvent. The regenerated cellulose exhibited strong structural and morphological changes, as revealed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. These changes dramatically affect the hydrolytic reactivity of the cellulose with dilute mineral acids. As a consequence, the glucose yield obtained from the deconstructed-reconstructed cellulose was substantially higher than that achieved via hydrolysis of the starting cellulose. Factors that affect the hydrolysis reaction include the type of cellulose substrate, the type of IL used in the pretreatment and the type of acid used in the hydrolysis step. The best results were obtained by treating the cellulose with IL and using phosphotungstic acid (0.067 mol/L) as a catalyst at 413 K. Under these conditions, the conversion of cellulose was almost complete (> 99 %), with a glucose yield of 87 % after only 5 h of reaction.
Cellulose processing with chloride-based ionic liquids
Ionic liquids (ILs, salts with a melting point below 100 °C) are discussed as solvents for cellulose with a potential for industrial applications. Several chloride containing ILs have been tested for their cellulose dissolving properties. Partly, strong cellulose degradation was observed, but could be prevented in some cases by addition of stabilisers. Cellulose degradation was compared for five chloride ILs. For three solvents, 1-butyl-3-methylimidazolium chloride, 1-allyl-3-methyl-imidazolium chloride and 1,3-diallylimidazolium chloride the temperature effect on degradation was studied. Fibres could be obtained by spinning the IL solutions into water; fibre characteristics are presented. The experimental cellulose spinning process with chloride containing ILs is compared to the well-known NMMO-based Lyocell process.