Modification of lignites via low temperature ionic liquid treatment

In order to improve the total sulfur removal rate in coal combustion, an acidic ionic liquid (IL) 1-carboxymethyl-3-methylimidazolium hydrogen sulfate ([HOOCCH 2 mim][HSO 4 ]) as the extractant combined with the oxidant 30% hydrogen peroxide (H 2 O 2 ) was applied to reduce the total sulfur content, and its microscopic mechanism of desulfurization was analyzed. The experimental results show that the desulfurization rate of the [HOOCCH 2 mim][HSO 4 ]–H 2 O 2 (1:10) solution was 45.12% and the organic sulfur removal rate was 16.26%, which were significantly higher than those of only H 2 O 2 or pure [HOOCCH 2 mim][HSO 4 ]. Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy analyses showed that the mercaptan −SH and disulfide −S–S– in coal decreased after being treated with IL–H 2 O 2 . In particular, the results of FTIR spectroscopy indicated that the relative proportion of −S–S–and −SH treated with IL–H 2 O 2 (1:10) decreased by 31.9 and 27.2%, respectively, compared with that of a pure IL. This is due to H 2 O 2 oxidation; −SH and −S–S– were oxidized to sulfoxide and then the sulfoxide transferred from the coal phase to the IL phase, which improved organic sulfur removal from coal. Therefore, the combination of an ionic liquid and H 2 O 2 could increase the total desulfurization rate. In addition, the thermogravimetric analysis of coal is divided into four different stages; the weight loss during the combustion stage and the residues show that the IL–H 2 O 2 could improve the coal combustion because of good previous swelling and destruction of bridge bonds and hydrogen bonding of coal. Besides, the fewer residues in IL–H 2 O 2 -treated coals also indicate that a less amount of inorganic substance is left in coal after IL–H 2 O 2 desulfurization, which is consistent with the desulfurization results.

show abstract

“…The swelling and destruction of ionic liquids on coal structures had been confirmed by many references so far. 45 − 48 …”

Section: Resultsmentioning

confidence: 99%

Experimental Study on Organic Sulfur Removal in Bituminous Coal by a 1-Carboxymethyl-3-methyl Imidazolium Bisulfate Ionic Liquid and Hydrogen Peroxide Solution

Liu

Xie

et al. 2020

ACS Omega

View full text Add to dashboard Cite

show abstract

“…The use of ionic liquids along with NMP for the extraction of a bituminous coal and lignite has been recently demonstrated by Sonmez et al The ILs (especially [BMIM]Cl) were found to be significantly effective in the extraction of lignite as compared to the bituminous coal. Lignites have also been treated by Cummings et al in various ILs but the most effective was found to be [EMIM][DCM] that resulted in a significant decrease in COOH and CO groups in the resulting IL treated lignite product inferring the ability of the IL to break the coal macromolecular structure. Pyrolysis pretreatment studies of lignites in ILs such as [BMIM]Cl and [BMIM]dihydrogen phosphate also show significant enhancement in the oil yield and increase in the arenes and phenolics in the oil.…”

Section: Use Of Ionic Liquids For Coal Dissolution and Extractionmentioning

confidence: 99%

Separative Refining of Coals through Solvolytic Extraction under Milder Conditions: A Review

Sharma

Dhawan

2018

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Not only cleaning but refining of coal has become an area of utmost importance both industrially and academically because of stringent environmental norms being imposed globally for arresting the climate change. However, coal is a polluting fuel, therefore, there is a grave need of deep refining of coal to obtain ashless coal for increasing its efficiency of utilization in order to minimize its impact on environment. The presence of ash in coal also greatly reduces the coal utility because of its deleterious effect on the boiler parts and gasification equipment. Solvent extraction (organo-refining) techniques produce Super Clean Coal (SCC) or Ultra Clean Coal (UCC) with almost zero ash content. The utilization of the SCC in the Integrated Gasification Combined Cycle (IGCC) Power Generation would increase the availability of this otherwise efficient and cleaner coal technology. Research work on different processes of solvent extraction of coal under varying conditions of temperature, pressure, and the nature of the solvent used and other parameters, their effect on the extraction yield have been discussed presently. Extraction of coal under milder ambient pressure conditions is desirable as this affords the recovery of coal without its fractionation, structural dislocations, or changes. The effect of the use of single solvent, mixture of two solvents (of solvent and cosolvent), i.e., synergism in enhancing the extraction yield under milder atmospheric pressure conditions have been reviewed. Utilization of high boiling solvents and coal derived solvents along with successive sequential solvent extractions for obtaining the enhanced extraction yields mainly under ambient pressure conditions have been discussed in the present paper. Hypercoal production under high pressure conditions, its characteristics, and utilization have also been described. Use of ionic liquids as potential solvents for coal extraction (especially of lignites) has also been discussed. Physical and chemical pretreatments greatly enhance the coal solvent extraction yield. Different potential uses of SCC such as in production of carbon nanotubes as a super clean fuel dust for car engines, synthesis of chemicals, etc. have been discussed. Separate discussion on nanotechnology of coals as related to solvent extraction of coal has also been included presently.

show abstract

“…Shah and co-workers 4 dissolved ∼22 wt% vitrinite-rich coal in [BMIM]Cl at 100 °C for 3 h but only 14 wt% inertinite-rich coal; they further confirmed that [BMIM]Cl was up to 10 times more effective than other ILs (i.e., [BuPy]Cl, [EMIM] [dca], [BMIM][C(CN) 3 ]; BuPy = N-butylpyridinium, EMIM = 1-ethyl-3methylimidazolium) in swelling and reducing the particle size of subbituminous and lignite coals. [34][35][36] Following treatment by [BMIM]Cl at 150 °C for 10 h, lignite was observed to have a more loose stacking structure based on SEM images, and reduced hydrogen bonds but more -CH 3 groups based on FT-IR spectra. 37 The Sönmez group 38 reported that including [BMIM]Cl as an additive (IL/coal (w/w) = 2; with 2 g coal) during coal extraction by NMP (30 mL) under reflux conditions (∼202 °C) improved the extraction yield of lignite from 26.1% to 43.9%.…”

Section: Introductionmentioning

confidence: 99%

Functionalized ionic liquids for lignite dissolution and treatment

Franklin

Larm

Baker

et al. 2021

J of Chemical Tech & Biotech

View full text Add to dashboard Cite

BACKGROUND: As a low-rank coal, lignite (frequently referred to as 'brown coal') has a high latent moisture content and low energy density and thus has low value as a solid fuel, often being burned at power stations close to where it is mined. For this reason, an effective pretreatment is essential to the better utilization of low-rank coal for energy and materials. Ionic liquids (ILs) are alternatives to conventional volatile organic solvents for pretreating coal due to their tailorable structures and physical properties, as well as their ability to partially dissolve/swell coal components. This study aimed to rationally design ionic liquids having a high hydrogen-bond basicity, based on the acetate anion, paired with ether-functionalized cations (especially the lessexpensive piperidinium) for lignite dissolution and treatment. RESULTS: Lignite treated by these functionalized ionic liquids at 105 °C led to the dissolution of 15.7-24.5 wt% lignite with a concomitant increase in coal aromaticity and rank, a reduction in coal decomposition residues, and the production of smaller and more uniform particles. The ether-functionalized N-(2-ethoxyethyl)-N-methylpiperidinium acetate is a particularly attractive alternative to conventional imidazolium ILs due to its lower cost, high hydrogen-bond basicity, and a strong capability for improving the coal aromaticity.CONCLUSION: Our results have demonstrated that pretreatment with functionalized ionic liquids can improve the coal aromaticity and rank, decrease coal decomposition residues, and yield smaller and more uniform particles, which enables a better utilization of low-rank coal for fuel and materials.

show abstract

Modification of lignites via low temperature ionic liquid treatment

Cited by 48 publications

References 41 publications

Experimental Study on Organic Sulfur Removal in Bituminous Coal by a 1-Carboxymethyl-3-methyl Imidazolium Bisulfate Ionic Liquid and Hydrogen Peroxide Solution

Experimental Study on Organic Sulfur Removal in Bituminous Coal by a 1-Carboxymethyl-3-methyl Imidazolium Bisulfate Ionic Liquid and Hydrogen Peroxide Solution

Separative Refining of Coals through Solvolytic Extraction under Milder Conditions: A Review

Functionalized ionic liquids for lignite dissolution and treatment

Contact Info

Product

Resources

About