Effect of Solvent on the Degradative Solvent Extraction of Low Rank

Subscriber access provided by TUFTS UNIV

Article

Effect of Solvent on the Degradative Solvent Extraction of Low Rank Coal Trairat Muangthong-on, Janewit Wannapeera, Supachai Jadsadajerm, Nakorn Worasuwannarak, Hideaki Ohgaki, and Kouichi Miura Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b02352 • Publication Date (Web): 23 Oct 2017 Downloaded from http://pubs.acs.org on October 27, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Energy & Fuels is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Effect of Solvent on the Degradative Solvent Extraction of Low Rank Coal

Trairat Muangthong-on1, Janewit Wannapeera1, 2, Supachai Jadsadajerm2, Nakorn Worasuwannarak 2, Hideaki Ohgaki1, and Kouichi Miura1,*

1

Institute of Advanced Energy, Kyoto University, Uji 611-0011, Japan

2

The Joint Graduate School of Energy and Environment, Center of Energy Technology and

Environment, King Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand

*Corresponding author. E-mail address: [email protected]

ACS Paragon Plus Environment

1

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 31

Abstract:

We have proposed a degradative solvent extraction method which upgrades as well as dewaters low rank coals and biomass wastes at 350 °C using 1-methlynaphthalene as a model solvent.

The

proposed solvent treatment is an effective method to produce high quality extracts having similar physical and chemical properties from several kinds of low rank coals and biomasses. Three solid fractions (Residue, Deposit, and Soluble) were fractionated and recovered after the solvent extraction. Soluble and Deposit are expected to be precursors for producing value added products. In this work the effects of solvent on the degradative solvent extraction of two low-rank coals, Loy Yang (LY) and Pendopo (PD), were examined by using four solvents: 1-methylnaphthalene (1-MN), Kerosene, 1 to 1 mixture of 1-MN and Kerosene, and a solvent rich in alkyl benzenes, A150. It was judged that solvent does not affect the degradation reaction at 350 °C, and hence the performance of this degradative solvent extraction method such as selective deoxygenation and effective dewatering is realized by all the solvents used. The yield distributions of extracted products were dominated by the solubility of solvent used as expected. The Hildebrand regular solution theory seems to represent the differences in the yields and elemental compositions of Soluble fractions. 1-MN, having 21.3 (J/cm3)1/2 of solubility parameter δ, gave the largest yield of Soluble followed by A150 (δ ≅ 18.8 (J/cm3)1/2 ), the mixed solvent (δ ≅ 19.1 (J/cm3)1/2 ), and Kerosene (δ ≅ 16.7 (J/cm3)1/2 ). Preparation of solvent treated coals (STCs) from different solvents gave the yields close to the sum of the yields of Soluble, Deposit, and Residue for all solvents used. Most of the heating values of solid products were over 29 MJ/kg and rather close to subbituminous coal. All Solubles were found to melt completely at rather low temperature. The properties of Solubles can be changed by solvents used. It was found that A150 may be utilized as a practical solvent when Soluble is the target product and that Kerosene is expected to be a practical solvent for preparing STC from low-rank coal.

Keywords: degradative solvent extraction, low rank coal, upgraded coal, solvent treated coal, kerosene


2

Page 3 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1. INTRODUCTION It is without question that coal is a valuable resource used not only as fuels but also as chemical feedstock in this century. However, the minable reserve of high grade coal, bituminous coal, has been depleting very rapidly due to the rapid increase of worldwide coal consumption. This inevitably requests us to utilize low-rank coals, brown coal/lignite, and sub-bituminous coal, instead of the high grade coal, because the minable reserve of the low-rank coal is as large as that of the high grade coal. L ow-rank coals are currently used just for power generation near coal mines because they have several drawbacks to be overcome for effective utilization. Brown coals, for example, contain a large amount of water (∼60%) and oxygen functional groups in general, resulting in low calorific value. When dewatered and/or dried, their propensity to spontaneous heating largely increases, which makes their storage and transportation extremely difficult.1-4 It is therefore essential to develop technologies for dewatering and/or upgrading low-rank coals for their effective utilization. Here upgrading means the treatment which not only increase the heating value but suppress the propensity to spontaneous heating of the low rank coals. Various methods have been proposed for dewatering and/or upgrading low-rank coals by many researc hers as reviewed by Katalambula.5 However, most of the works on low-rank coal dewatering and upgrading are aiming at using the treated coals as solid fuel. If we think of the low-rank coals as the fee dstock of chemicals and carbon materials, we might have to develop methods that enable to effectively extract precursors of chemicals and/or carbon materials from low-rank coals in addition to develop the methods for dewatering and/or upgrading.

Solvent extraction of coal may be one of the promising me

thods for the purpose. However, solvent extraction cannot upgrade but just extract low-molecular-weig ht compounds from the coals. Furthermore, the extraction yield is very low at room temperature when u sing nonpolar solvents from practical viewpoint. Using strong polar solvents increases the extraction yi eld, but it makes the separation of the extract from solvent difficult.6,7 Overcoming these drawbacks, the authors have recently presented the degradative solvent extraction method for dewatering and upgrading of low-rank coals and biomasses at 350 °C by using 1-methlynaphthalene (1-MN) as a solvent. 8-10 In this process, the solvent is expected not to take part in chemical reactions with a sample but to act simply as a dispersant for the sample. Low-rank coals and biomasses were not only dewatered but also upgraded by the selective removing of oxygen functional groups in the form of either H2O or CO2 during the treatment. The upgraded product was fractionated into three solid fractions: Soluble, Deposit, and Residue. The carbon based yield of Soluble reached as


3

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 31

high as 70 % for some biomass wastes. Solubles were free from water and mineral matters and their physical and chemical properties were almost independent of raw materials. Elemental compositions of Solubles, for example, were C = 81.8 – 84.8 wt %, H = 7.5 – 8.1 wt %, and O = 6.5 – 10.2 wt %. The Solubles were composed of low-molecular weight compounds having a molecular peak at ca. 300. Complete melting of the Solubles occurred below 100 °C, and 60 – 70 % of the Solubles were devolatilized below 400 °C.

Solubles having such unique properties were expected to be utilized as

raw materials of value added products. On the other hand, Residues produced from low-rank coals in 50 % yields were expected to be used as high quality solid fuels.11 However, there are still several problems to be solved for the practical application of the proposed extraction method. One of the examinations needed is the effect of solvent on the yields and properties of three solid extracts. Next examination needed is the search of practical solvent that is cheap and can be separated easily from the extract. In this study, the possibility of using a practical solvent for this extraction method was examined. Kerosene, which is easily obtained and has lower boiling point than 1-MN, was selected as one of practical solvents. Solvent having lower boiling point is expected to be easily separated and recovered from the upgraded product. 1-MN, 1 to 1 mixture of 1-MN and Kerosene, and a solvent rich in aromatic compounds were also used for comparison purpose. The three upgraded fractions, Soluble, Deposit, and Residue, were characterized in detail. If we intend to convert the low-rank coals to just high quality solid fuels, it is not necessary to separate the solvent treated product into three fractions. Then we also prepared “Solvent treated coal” (abbreviated to STC) under the same condition but without separating the upgraded coal into 3 fractions12, and the STCs prepared were also characterized in detail as were done for the three fractions.

2. EXPERIMENTAL SECTION 2.1 Materials and solvent used.

Two low-rank coals, an Australian brown coal, Loy Yang

(abbreviated to LY) and an Indonesian lignite, Pendopo (PD) , were used as coal samples. Their analyses are shown in Table 1. The coals were ground without drying and sieved to have a diameter less than 0.2 mm before serving to the experiments. Four kinds of solvents were selected in this study. A popular liquid fuel, kerosene (abbreviated to Kerosene), which was supplied from PTT Company (Thailand) was used as a practical solvent. A non-polar solvent, 1-methylnaphalene (1-MN) purchased from Tokyo Chemical Industry Company was selected as a model solvent. The 1 to 1 mixture of 1-MN


4

Page 5 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

and kerosene (abbreviated to 1-MN/Kerosene) and a solvent rich in aromatic compounds, which was supplied from PTT Company and is abbreviated to A150, were also used for comparison purpose. The boiling points of 1-MN, Kerosene, and A150 were respectively 234.5 °C, 169.2 – 239.0 °C and 176.1 – 218.4 °C. Figures 1a to 1c show GC-MS chromatograms for 1-MN, Kerosene, and A150. The chromatograms were obtained using a gas chromatography/mass spectrometer (GC-MS, Shimadzu GCMS-QP2010SE with FID-2010 Plus) with a ZB-5HT column (0.23 mm in diameter, 30 m in length, 0.1 mm in thickness). The flow rate of carrier gas (helium) was 50 mL/min, and the column was heated from 40 °C to 300 °C at a heating rate of 5 K/min for the analysis. Main components in Kerosene and A150 were characterized by referring to the MS library of the National Institute of Standard (NIST14). Fig. 1a shows that 1-MN is almost pure solvent. Fig. 1b shows that Kerosene consists of aliphatic hydrocarbons, and Fig.1c shows that A150 contains lots of alkyl benzenes. 2.2 Experimental procedure.

The detailed experimental procedure was given in the previous

papers.9,10 Main parts of the extraction system consist of a stainless steel autoclave reactor (130 mL in volume), a reservoir (130 mL in volume), a stainless steel filter (65 mm in O.D, 0.5 µm opening) that is attached at the bottom of the autoclave reactor, and an electric furnace. The autoclave reactor was connected with the reservoir by a ball valve. To start the experiment, about 5 g of coal in dry and ash free (d.a.f.) basis and 80 mL of solvent were carefully charged into the autoclave reactor with the connecting valve closed. Both the autoclave reactor and the reservoir were purged by 0.5 MPa of He for several times to ensure that the oxygen inside the vessel was completely removed. Then the sample was heated up to 350 °C at a constant heating rate of 5 K/min. An impeller magnetically connected to the agitator stirred the content of autoclave throughout the experiment. After 60 min of treatment at 350 °C, the connecting valve was opened, allowing the extract together with the solvent moving to the reservoir by a pressure difference. The extraction residue remaining in the autoclave is called Residue in this study. Cooling down the mixture of the extract and solvent to room temperature precipitates a part of extract as solid. It was separated by a vacuum filtration using a PTFE filter (0.5 µm opening). The solid extract above this filter was called Deposit in this study. Another extract dissolving in the solvent was also recovered as solid by removing the solvent using a rotary evaporator. It is called Soluble in this study. The operating temperature of the rotary evaporator was varied depending on the solvents as follows: 140 – 150 ˚C for 1-MN, 110 – 120 ˚C for Kerosene, and 130 – 140 ˚C for 1-MN/Kerosene and A150. The operating pressure and the time duration were respectively 20 mbar


5

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 31

and 1 h for all of the solvents. Residue, Deposit, and Soluble were dried at 160 °C for 8 h by using a vacuum oven. The experiment separating the upgraded product into fractions is abbreviated to “Fractionation scheme” hereinafter. To prepare the solvent treated coal (STC), the extraction apparatus was operated without the reservoir. The experiment was performed by following the exactly same procedure as Fraction scheme until the end of treatment at 350 °C. After 60 min of treatment at 350 °C, the autoclave was cooled down to room temperature, and then all the content in the autoclave was carefully collected. The solvent treated coal was recovered by only removing the solvent from the content by the rotary evaporator and by additional drying in the vacuum oven. The experiment recovering STC by just removing the solvent from the upgraded product is abbreviated to “Non-fractionation scheme” hereinafter. All the gaseous products were collected in a gas bag at room temperature by purging the reactor and reservoir with pressurized He before collecting the extracts. The purging of He was performed several times until the concentration of the product gas in the whole system will be reduced to less than 1%. The gaseous product was analyzed for CO2, CO, and small molecular-weight hydrocarbons using a micro gas chromatograph (Varian, CP4900).

2.3 Characterizations of upgraded products. Soluble, Deposit, and Residue obtained by Fractionation scheme and STC obtained by Non-fractionation scheme were carefully characterized by several techniques. First, each of their yields was estimated from its weight. The sum of the yields of Soluble, Deposit, Residue, and gaseous product for Fraction scheme and the sum of the yields of STC and gaseous product for Non-fraction scheme were less than 1 for most of experiments. The difference was called “Liquid” and it was assumed to consist of the fraction of smallest molecular weight compounds that were not separated from the solvent and water produced by the degradation reaction. The proximate and the ultimate analyses of the solid products were performed respectively by using a thermogravimetric analyzer (Shimadzu, TGA 50) and a CHN corder (Yanaco, CHN MT-6M). The higher heating values of the solid products on the d.a.f. basis were calculated by using the Dulong equation13 below: HHV (MJ/kg, d.a.f.) = (338.1C + 1441.8H – 180.2O)/100

(1)

where C, H, and O represent the weight percentages of carbon, hydrogen, and oxygen, respectively.


6

Page 7 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

3. RESULTS AND DISCUSSION 3.1 Effect of solvent on the degradative reaction and the product distributions.

Table 1 lists the

yields of Residue, Deposit, and Soluble for Fractionation scheme and the yield of STC for Non-fractionation scheme for all combinations of coal and extract solvent. Experiments using A150 were performed for only LY. The proximate analyses, elemental compositions, atomic ratios, and the higher heating values (HHVs) are also listed in the table. Figure 2 and 3 compare the product yield distributions

including

gaseous

product

and

Liquid

between

Fractionation

scheme

and

Non-fractionation scheme for LY and PD, respectively. The distribution of elements of C, H, and O to the products through the degradative solvent extraction was calculated from the analyses in Table 1 and the yields of gaseous product in Figure 3 for PD and is shown as Figure 4 to show schematically the element balance. We assume that the effect of solvent on the degradative solvent extraction method should be examined from two aspects. The first one is to examine if solvent affects the degradative reaction at 350 °C. The second one is to examine how the solubility of solvent affects the distribution of the extract. Answer to the first aspect can be made by comparing the yields of gaseous product. The gaseous product consisted of CO2 and trace amounts of CO and small molecular-weight hydrocarbons. For PD, the yields of gaseous product were almost same for all the solvents as shown in Fig. 3. For LY, the yields of gaseous product obtained using 1-MN/Kerosene seem to be slightly larger than those obtained using other solvents as shown in Fig. 2, but the differences are not so large, judging from the complicated experimental procedure and some errors involved. Then we may be able to conclude that the decomposition reactions at 350 °C in the four solvents are similar. To examine if the conclusion is valid, the product distributions and the properties of each fraction were examined. At first glance of Figs. 2and 3 we notice that the sum of the yields of three fractions obtained by Fractionation scheme is almost equal to the yield of STC obtained by Non-fractionation scheme for every combination of coal and solvent. Since the gas yields were almost independent of solvent used as stated above, the difference between Fractionation scheme and Non-fractionation scheme lies in whether the degraded solid product is separated or not. However, the sum of the yields of three fractions obtained by Fractionation scheme (≅ the yield of STC obtained by Non-fractionation) apparently decreased by the order of 1-MN, A150, 1-MN/Kerosene, and Kerosene. In other words, the yields of Liquid increased by the order of 1-MN, A150, 1-MN/Kerosene, and Kerosene. Then let us examine these changes by focusing on the yields of Residue, Soluble, and Liquid obtained by


7

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 31

Fractionation scheme for LY to make discussion simple. It was found that the extraction with 1-MN gave the highest yield of Soluble and the smallest yields of Residue and Liquid, and that Kerosene gave the smallest yield of Soluble and the highest yields of both Residue and Liquid. Meanwhile, as expected, the extract yields lay between the two solvents when using 1-MN/Kerosene or A150. In more details, the yields of Residue were 55.6 % from 1-MN extraction, 66.1 % from 1-MN/Kerosene, 71.2 % from Kerosene, and 66.8 % from A150. The yields of Soluble obtained from 1-MN, 1-MN/Kerosene, Kerosene, and A150 extractions were, respectively, 20.2 %, 12.0 %, 4.8 %, and 14.5 %. Although the so called regular solution theory of Hildebrand may not be applied to the extraction of low-rank coal itself14, but it is well expected to be applicable to the extraction of the Solubles in the solvents used. The solubility parameter of 1-MN δ (1-MN) is calculated to be 21.3 (J/cm3)1/2 by following Van Krevelen15. The solubility parameters of Kerosene, 1-MN/Kerosene, and A150 may be respectively assumed to be δ (Kerosene) ≅ 16.7 (J/cm3)1/2 = δ (cyclohexane), δ (1-MN/Kerosene) ≅ 19.1 (J/cm3)1/2 = {0.5δ 2 (1-MN)+ 0.5δ 2 (Kerosene)}1/2, and δ (A150) ≅ 18.8 (J/cm3)1/2 =δ (C6H6). The yields of LY Solubles mentioned above beautifully correlate with the solubility parameter values, indicating that the regular solution theory is applicable to the extraction of Solubles. 1-MN extracted aromatic rich components and Kerosene extracted aliphatic rich components from the upgraded product. These are also clearly shown by the ultimate analyses of Solubles given in Table 1. For example, it is clearly shown that the atomic H/C ratios of the Solubles obtained from Kerosene are 1.51 for LY and 1.48 for PD, indicating that the Solubles consist of aliphatic rich compounds. Since the Soluble yield using 1-MN was the largest, the upgraded product is judged to be rich in aromatic compounds. These

yield

values

indicate

that

Liquid

obtained

from

Kerosene

must

contain

small-molecular-weight hydrocarbon compounds that could not be separated from Kerosene. It was rather easy to remove Kerosene from either the mixture of Soluble and solvent or the mixture of STC and solvent, but Kerosene inevitably accompanied small-molecular-weight compounds of Soluble fraction when it evaporates at rather high rate. The element balance shown in Fig. 4 also indicates that Liquid obtained from Kerosene must contain compounds consisting of C and H: hydrocarbons. To confirm that small-molecular-weight compounds are contained in Liquid fraction obtained from Kerosene, the GC-MS chromatogram of the mixture of Kerosene and Soluble fraction is shown in Figure 5. The components that appear at the retention time less than 30 min are well judged to be the small-molecular-weight compounds involved in Liquid fraction. The discussion for LY well holds for PD as the product distribution in Fig. 3 show. Then the effect


8

Page 9 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

of solvent examined from two aspects stated above is summarized as follows. Solvents used in this work are assumed to affect little the degradation reaction at 350 °C. Solvents mainly change the distribution of the extract product by following the regular solution theory. For example, using 1-MN that has strongest affinity to aromatic compounds (δ (1-MN) = 21.3 (J/cm3)1/2) gives highest Soluble yield and using Kerosene that has weakest affinity to aromatic compounds (δ (Kerosene) ≅ 16.7 (J/cm3)1/2) gives smallest Soluble yield and largest Residue yield. Next, we will examine the properties of Solubles, Residues, and STCs obtained using different solvents. 3.2 Properties of Solubles obtained using different solvents. Solubles are expected to be a precursor of carbon materials including carbon fiber.16,17 Their molecular weight distributions and thermal properties are essential information on examining the potential utility of Solubles as a precursor of carbon materials.

Figure 6 compares the molecular weight distributions (MWDs) of Solubles

prepared using four different solvents for LY. Figure 7 shows similar comparison using three solvents for PD. The LDI-TOFMS measurement used small amounts but almost same amounts of samples for different samples. Then the intensities obtained are multiplied by the yields of Soluble to construct the figures. This was done so as to make the comparison among the solvents rather quantitative. The MWDs of all Solubles ranged from 200 to 600 in molecular weight with a peak molecular weight at around 300, showing that the molecular weights of Solubles are much larger than the solvents used (see Fig. 1). These results show that the solvents are not incorporated in Solubles. Let us focus on the MWDs of Solubles prepared using 1-MN and Kerosene for LY first. The MWD obtained from Kerosene extraction is well incorporated in the MWD obtained from 1-MN extraction in either the intensity or the range of molecular weights. The MWD obtained from Kerosene extraction misses both the small- molecular-weight compounds and large-molecular-weight compounds from the MWD obtained from 1-MN extraction. This is also the case for PD as the MWDs of Solubles in Fig. 5 shows. The missing of the large-molecular-weight compounds can be explained by the difference in solubility between 1-MN and Kerosene, and the missing of the small-molecular-weight compounds is due to the loss of those compounds with Kerosene during the evaporation process of Kerosene as discussed above. It is also shown that the MWDs obtained using 1-MN/Kerosene are incorporated in the MWDs obtained using 1-MN and they incorporate the MWDs obtained using Kerosene. Thus the MWD measurement well supports the above discussion based on the yield distribution. Figures 8 and 7 compare the thermogravimetric (TG) curves of raw coal and Solubles, respectively, for LY and PD. The solid lines are the TG curves on Soluble basis and the broken lines are the TG


9

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 31

curves on raw coal basis. Since the weight decrease below 400 °C is solely due to the evaporation of small-molecular-weight compounds, TG curves also show that all Solubles are rich in small-molecular-weight compounds. Let us focus on the TG curves for PD. The TG curves shown on Soluble basis (solid lines) seem to be strange at a glance. The weight decrease of Soluble obtained using Kerosene starts at higher temperature than the weight decrease of Soluble obtained using either 1-MN or 1-MN/Kerosene and the TG curve of Soluble obtained using Kerosene intersects with both of the TG curves obtained using 1-MN and 1-MN/Kerosene. The TG curves shown on raw coal basis (broken lines), however, clearly show that the Soluble prepared from Kerosene can be regarded as a part of the Solubles prepared using either 1-MN or 1-MN/Kerosene. These results well reflect the MWDs shown in Fig. 5, and show that the Soluble properties can be changed by the solvent used. Figures 10 and 11 compare the melting behaviors of Solubles for LY and PD, respectively. TMA profiles were rather similar among the Solubles obtained from different solvents. Soluble obtained using 1-MN shows the highest melting point whereas Soluble obtained using Kerosene shows the rather low melting point as was expected. In addition, TMA profiles of all Solubles finally reached −1, showing their complete melting at less than 200 °C. The discussion above suggests that solvent may adjust MWD, thermal decomposition characteristics, and thermoplastic properties of Solubles so as to meet the requirement of specific use of Soluble. 3.3 Possibility of using Residue and STC as high quality solid fuel. As listed in Table 1, the yields of Residues obtained Fractionation scheme were 55.6 to 66.8 % for LY and 54.3 to 60.7 % for PD. The yields of STCs were 77.1 to 84.6 % for LY and 72.6 to 81.3 % for PD. The carbon contents of Residues were 76.4 to 78.9 % for LY and 74.3 to 77.4 % for PD. The carbon contents of STCs were 75.2 to 81.9 % for LY and 74.3 to 77.4 % for PD.

All Residues and STCs are free from water. These results

show that both Residue and STC prepared are really upgraded coals from the viewpoints of elemental composition and the degree of dewatering. Table 1 also lists the higher heating values (HHVs) of three solid fractions obtained by Fractionation scheme and STC obtained by Non-fractionation scheme for all combinations of coal and solvent. It was found that the sample basis HHVs of Soluble, Deposit, Residue, and STC were all much higher than those of corresponding raw coals. The HHVs of Residues were respectively 28.3 to 30.1 MJ/kg and 27.3 to 29.2 MJ/kg for LY and PD. The HHVs of STCs were respectively as high as 28.7 to 32.9 MJ/kg and 30.9 to 31.8 MJ/kg for LY and PD. These HHVs well correspond to the HHVs of subbituminous or bituminous coals on d.a.f. basis. In a separate paper we have shown that the propensity to spontaneous


10

Page 11 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

combustion of both Residues and STCs are much less than those of raw coals.18 These results clearly show that Residues and STCs obtained by the degradative solvent extraction can be utilized as high quality solid fuels. One of the purposes of upgrading technologies of low-rank coal is to increase the heating value of the upgraded solid product. In this sense the HHVs given above show the validity of the proposed degradative solvent extraction method. However, the heating value recovered in the solid products from raw coal is more informative from the practical viewpoint. It can be examined by using the HHVs converted to the unit weight of raw coal by using the yield values and HHVs given in Table 1. Figures 12 and 13 show the HHVs converted to the values per 1 kg of raw coal (d.a.f.) respectively for LY and PD. The heating values recovered were slightly larger than the heating values of the raw coal for LY. Since elemental analysis of each fraction is rather accurate, the apparent increase of the heating value is judged to come from the complicated experimental procedure and some errors involved for estimating the yield of fractions. For PD, on the other hand, the heating values recovered using 1-MN and 1-MN/Kerosene were almost equal to the heating value of raw coal, because good mass and element balances could be established for these combinations. Although some errors are inevitably involved, the loss of heating value through the degradative solvent are small. The small recovery ratio for Kerosene treatment comes from the fact that the small-molecular-weight compounds of the extract is retained in Liquid as stated above. Thus, the proposed degradative solvent extraction method was found to be effective not only to produce clean and high heating value product, but to transfer the heating value of the raw coals to the extract products very effectively. 3.4 Discussion on the role of solvents for coal extraction.

We assumed that the effect of solvent on

this degradative solvent extraction method should be examined from two aspects as stated above. The first one was to examine if solvent affects the degradation reaction at 350 °C. The second one is to examine how solvent affects the product distribution. In other words, we assumed that solvent has two roles in the proposed solvent extraction method. Its first role is a media to disperse raw material during the solvent treatment at 350 °C and hence it is expected not to react with the raw material. The second role is to act as extraction solvent to dissolve decomposed and upgraded product by its solubility at 350 °C. Therefore, the product distribution, the yield ratios of Residue, Deposit, and Soluble, are dependent on the kinds of solvent in principle. For both coals, the Soluble yield was highest using 1-MN, and smallest using Kerosene as expected. Another examination in this work was to examine the possibility of Kerosene as a practical solvent.


11

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 31

The sum of the yields of Residue, Deposit, and Soluble (≅ the yield of STC) obtained using Kerosene was smallest. This was judged to come from the difficulty in removing Kerosene selectively from either Soluble or STC. Some small-molecular-weight compounds were judged to be removed with Kerosene during the solvent removing process due to high volatility of Kerosene. This suggests that Kerosene is not suitable for recovering a large amount of Soluble. Another practical solvent, A150, which was tested for only LY may be utilized when Soluble is the target product. Preparation of STC was intended to convert low rank coal to high quality solid fuel. The properties of STC are little affected by the treating solvent as shown in Table 1. Since Kerosene has advantages such as cheap and common practical solvent and the easiness of separation from the upgraded product, it can be a candidate of a practical solvent for preparing STC from low rank coal. Although we are still far away from performing accurate feasibility study of the proposed degradative solvent extraction technology, we will mention our future plan. When the target product is Soluble, which can be used for the carbon fibre production, we may be able to use high quality extraction solvent to maximise the yield of high quality Soluble. On the other hand, we must use a cheap and locally available solvent when the target product is STC.

Using the coal derived

small-molecular-weight compounds produced by this process as the extraction solvent is another option. We have just constructed a bench scale plant to examine such possibilities and to realize our method practically in the future.

4. CONCLUSIONS The effects of solvent on the degradative solvent extraction of two low-rank coals, Loy Yang (LY) and Pendopo (PD), were examined by using four solvents: 1-MN, Kerosene, 1 to 1 mixture of 1-MN and Kerosene, and a solvent rich in alkyl benzenes, A150. It was judged that solvent does not affect the degradation reaction at 350 °C, and hence the performance of this degradative solvent extraction method such as selective deoxygenation and effective dewatering is realized by all the solvents used. The yield distributions of extracted products were dominated by the solubility of solvent used as expected. The Hildebrand regular solution theory seems to represent the differences in the yields and elemental compositions of Soluble fractions. 1-MN, having 21.3 (J/cm3)1/2 of solubility parameter δ, gave the largest yield of Soluble, followed by A150 (δ ≅ 18.8 (J/cm3)1/2 ), the mixed solvent (δ ≅ 19.1 (J/cm3)1/2 ), and Kerosene (δ ≅ 16.7 (J/cm3)1/2 ) . The preparation of STCs from different solvents also gave the yields close to the sum of the yields of Soluble, Deposit, and Residue for all solvents used.


12

Page 13 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Most of the heating values of solid products were over 29 MJ/kg and rather close to subbituminous coal. All Solubles were found to melt completely at rather low temperature. The properties of Solubles can be changed by solvents used. A150 may be utilized as a practical solvent when Soluble is the target product. Kerosene, having advantages such as cheap and common practical solvent and the easiness of separation from the upgraded product, was expected to be a candidate of a practical solvent for preparing STC from low rank coal.

ACKNOWLEDGEMENTS This work was performed under the JICA-JST project of science and technology research partnership for sustainable development (SATREPS) project: Development of Clean and Efficient Utilization of Low-Rank Coals and Biomass by Solvent Treatment. The authors are grateful to Drs. K. Matsuoka and M. Morimoto from AIST for their measurement of the molecular weight distributions shown in Figs. 4 and 5.

REFERENCES (1)Kim, A.G. Laboratory studies on spontaneous heating of coal. A summary of information in the literature. U.S. Dept of the Interior, Bureau of Mines Information Circular 8756 1977. (2) Carras, J.N.; Young, B.C. Self-heating of coal and related materials: Models, application and test methods. Prog. Energy Combust. Sci. 1994, 20, 1-15. (3) Wang, H.; Dlugogorski, B. Z.; Kennedy, E. M. Coal oxidation at low temperatures: oxygen consumption, oxidation products, reaction mechanism and kinetic modelling. Progress in energy and Combustion Science 2003, 29, 487-513. (4) Nelson, M.I.; Chen, X.D. Survey of experimental work on the self-heating and spontaneous combustion of coal. 31-83 in Geology of Coal Fires: Case Studies from Around the World. Reviews in Engineering Geology XVIII 2007, Stracher, G.B. (Ed), The Geological Society of America. (5) Katalambula, H.; Gupta, R. Low grade coals: A review of some prospective technologies. Energy Fuels 2009, 23, 3392−3405. (6) Makgato, M. H.; Moitsheki, L. J.; Shoko, L.; Kgobane, B. L.; Morgan, D. L.; Focke, W. W. Alkali-assisted coal extraction with polar aprotic solvents. Fuel Process. Technol. 2009, 90, 591− 598. (7) Iino, M.; Takanohashi, T.; Ohsuga, H.; Toda, K. Extraction of coals with CS2-N-methly-2pyrrolidinone mixed solvent at room temperature. Fuel 1988, 67, 1639−1647. (8) Ashida, R.; Morimoto, M.; Makino, Y.; Umemoto, S.; Nakagawa, H.; Miura, K.; Saito, K.; Kato, K. Fractionation of brown coal by sequential high temperature solvent extraction. Fuel, 2009, 88, 1485–1490. (9) Wannapeera, J.; Li, X.; Worasuwannarak, N.; Ashida, R.; Miura, K. Production of high-grade carbonaceous materials and fuel having similar chemical and physical properties from various types of biomass by degradative solvent extraction. Energy Fuels. 2012, 26, 4521−4531. (10) Li, X.; Ashida, R.; Miura, K. Preparation of high-grade carbonaceous materials having similar chemical and physical properties from various low-rank coals by degradative solvent extraction. Energy Fuels. 2012, 26, 6897-6904.


13

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 31

(11) Li, X.; Ashida, R.; Makino, M; Nishida, A.; Yao, H.; Miura, K. Enhancement of Gasiﬁcation Reactivity of Low-Rank Coal through High-Temperature Solvent Treatment. Energy Fuels 2014, 28, 5690−5695. (12) Fujitsuka, H.; Ashida,R.; Miura, K. Upgrading and dewatering of low rank coals through solvent treatment at around 350 °C and low temperature oxygen reactivity of the treated coals. Fuel, 2013, 114, 16–20. (13) Mott, R. A.; Spooner, C. E. The calorific value of carbon in coal: the Dulong relationship. Fuel Science Practice, 1940, 19, 226−231, 242−251. (14) Larsen, J. W.; Shawver, S. Solvent Swelling Studies of Two Low-Rank Coals. Energy Fuels, 1990, 4, 74−77. (15) van Krevelen, D. W. Coal, 2nd ed.; Elsevier Scientific: New York, 1981; pp 485-603. (16) Li, X.; Zhu, X.; Okuda, K.; Zhang, Z.; Ashida, R.; Yao, H.; Miura, K. Preparation of carbon fibers from low-molecular-weight compounds obtained from low-rank coal and biomass by solvent extraction. New Carbon Materials. 2017, 32, 41-47. (17) Wannapeera, J.; Ashida, R.; Ohgaki, H.; Miura, K. Production of carbon fiber and activated carbon fiber from the extract produced from the degradative solvent extraction of biomass. 2017 International Conference on Coal Science & Technology and 2017 Australia-China Symposium on Energy. Paper No. O9-5, Beijing, China. (18) Muangthong-on, T.; Wannapeera, J.; Ohgaki, H.; Miura, K. Examination of interactions of solvent treated coal with oxygen and water vapor at over 100 °C using TG-DSC for examining propensity to spontaneous heating of the solvent treated coal. Energy Fuels, DOI: 10.1021 /acs.energyfuels.7b01906.


14

Page 15 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Table 1. Analyses of coal used and their extract products.

Coal

Yield [wt %, d.a.f.]

Loy Yang (LY) Extraction in 1-MN

Ultimate analysis [wt %, d.a.f.a]

Proximate analysis Atomic ratio [wt %, d.b.b] (-)

HHV [MJ/kg, d.a.f.]

C

H

N

O (diff.)

VM

FC

ash

O/C

H/C

66.6

4.5

0.5

28.4

50.0

47.8

2.2

0.32

0.81

23.9

Residue

55.6

76.4

4.0

0.9

18.7

36.7

60.4

2.9

0.18

0.63

28.3

Deposit

7.5

77.9

5.0

0.9

16.2

40.2

58.9

0.9

0.16

0.77

30.6

Soluble 20.2 81.4 7.4 0.5 10.7 STC 84.6 78.5 4.8 0.9 15.8 Extraction in mixture of 1-MN and kerosene (mixed solvent) Residue 67.1 78.9 4.2 0.8 16.1

74.9

24.5

0.6

0.10

1.09

36.3

42.4

55.7

1.9

0.12

0.73

30.9

32.2

65.6

2.2

0.15

0.64

29.9

Deposit

8.1

74.8

5.7

0.8

18.8

49.4

49.9

0.7

0.19

0.91

30.1

Soluble

12.0

80.5

8.7

0.3

10.5

83.0

16.9

0.1

0.10

1.30

37.9

STC 83.2 Extraction in Kerosene Residue 71.2 Deposit 1.8

80.1

5.0

0.9

14.0

41.2

56.6

2.1

0.13

0.75

31.8

77.7 75.2

4.2 6.1

1.7 1.7

16.5 16.9

30.6 70.7

67.2 28.8

2.2 0.5

0.16 0.17

0.65 0.97

29.3 31.2

Soluble

4.8

84.9 10.7 0.4

4.0

89.0

10.9

0.1

0.04

1.51

43.4

STC Extraction in A150 Residue Deposit

77.1

75.2

4.7

0.7

19.4

37.6

59.9

2.6

0.19

0.75

28.7

66.8 5.0

78.4 77.8

4.5 5.8

0.8 0.8

16.2 15.6

34.3 50.1

63.8 49.6

1.9 0.3

0.15 0.15

0.69 0.90

30.1 31.9

Soluble

14.5

82.1

8.7

0.3

8.9

83.8

16.1

0.1

0.08

1.27

38.7

STC

83.6

81.9

5.2

0.8

12.2

39.0

58.7

2.3

0.11

0.76

32.9

67.5

5.1

0.8

26.6

49.4

38.0

12.6

0.30

0.91

25.4

Pendopo (PD) Extraction in 1-MN Residue

54.3

76.5

4.5

1.2

17.7

40.1

42.4

17.4

0.15

0.71

29.2

Deposit

4.1

81.1

5.4

1.5

12.0

44.8

54.2

0.9

0.11

0.80

33.0

Soluble

23.2

83.8

7.6

0.7

7.9

76.3

23.4

0.3

0.07

1.09

37.9

STC 81.3 78.7 5.1 1.2 15.0 Extraction in mixture of 1-MN and kerosene (mixed solvent)

41.6

45.8

12.5

0.14

0.78

31.3

Residue

59.7

77.4

4.4

1.3

16.9

30.1

53.8

16.1

0.16

0.68

29.4

Deposit

4.8

76.7

5.7

1.2

16.5

49.3

50.0

0.7

0.16

0.89

31.2

Soluble STC

15.9 76.3

80.5 79.4

8.5 5.2

0.4 1.2

10.6 14.2

87.1 38.3

11.8 49.2

0.6 12.5

0.10 0.14

1.27 0.79

37.6 31.8


15

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 31

Table 1. Continued. Yield [wt %, d.a.f.]

Coal

Ultimate analysis [wt %, d.a.f.a]

Proximate analysis Atomic ratio [wt %, d.b.b] (-)

HHV [MJ/kg, d.a.f.]

C

H

N

O (diff.)

VM

FC

ash

O/C

H/C

Pendopo (PD) Extraction in Kerosene

67.5

5.1

0.8

26.6

49.4

38.0

12.6

0.30

0.91

25.4

Residue

60.7

74.3

4.3

1.2

20.2

31.6

57.5

11.1

0.20

0.69

27.3

Deposit

2.0

78.6

7.3

0.9

13.2

69.6

30.2

0.2

0.13

1.11

34.7

Soluble

8.9

83.6 10.3 0.3

5.7

94.7

5.2

0.1

0.05

1.48

42.1

72.6

76.5

5.6

16.8

44.0

44.3

11.7

0.16

0.88

30.9

STC a

1.0

b

Dry, ash-free. Dry basis.


16

Page 17 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Figure captions Figure 1. GC-MS chromatograms of solvents used. 1a 1-MN, 1b Kerosene, 1c A150 Figure 2. Comparison of the product yield distributions between Fractionation scheme and Non-fractionation scheme for LY. Figure 3. Comparison of the product yield distributions between Fractionation scheme and Non-fractionation scheme for PD. Figure 4.

Distribution of C, H, and O through the degradative solvent extraction for LY coal.

Figure 5. GC-MS chromatogram of of the mixture of Kerosene and Soluble fraction for LY. Figure 6. Molecular weight distributions of Solubles prepared using three solvents for LY. Figure 7. Molecular weight distributions of Solubles prepared using three solvents for PD. Figure 8. TG curves of solid products and raw coal for LY. The solid line shows the results on sample basis while the broken line shows the results on raw coal basis. Figure 9. TG curves of solid products and raw coal for PD. The solid line shows the results on sample basis while the broken line shows the results on raw coal basis. Figure 10. TMA profiles of Solubles and raw coal for LY. Figure 11. TMA profiles of Solubles and raw coal for PD. Figure 12. Comparison of HHVs among raw coal, solid extracts, and STC for LY on raw coal basis. Figure 13. Comparison of HHVs among raw coal, solid extracts, and STC for PD on raw coal basis.


17

Energy & Fuels

Total ion current [-]

1-Methylnaphthalene

1-MN 0

10

20

30

40

Retention time [min]

1a. 1-MN. Nonane with methyl group Decane with methyl group Undecane with methyl group Dodecane with methyl group

Decane (C10H22) Undecane (C11H24)


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 31

Benzene with alkyl groups Dodecane (C12H26)

Tridecane (C13H28) Nonane (C9H20) Tritradecane (C14H30)

0

10

20

Kerosene 30

40


1b. Kerosene.


18

Page 19 of 31

Benzene, 1-ethyl-3,5-dimethyl-


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Benzene, 1,2,3-trimethylBenzene, 1,2,3,5-tetramethyl-

Mestitylene (C9H12) Benzene, 1-methyl-3-propyl-

Benzene, 2-ethyl-1,4-dimethyl-

Benzene, 1,2,3,4-tetramethyl-

A150 0

10

20

30

40


1c. A150.

Figure 1. GC-MS chromatograms of solvents used.


19

Energy & Fuels

100

Other gas CO

Liquid

CO2

80 Deposit

Soluble

60 Loy Yang 40

20

a ti on

No

n-f ra

ctio

1-MN/Kerosene Kerosene

cti on

na tio n

Residue

a ti on

n-f ra

ctio n

na tio n ctio

a ti on ctio n

na tio n

STC

No

No

No

n-f ra

cti o

a ti on Fra

cti on

na tio n

n-f ra

cti o Fra

1-MN

STC Residue

Residue

Residue

0

STC

Fra

STC

Fra

Product yield [ wt.% ]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 31

A150

Figure 2. Comparison of the product yield distributions between Fractionation scheme and Non-fractionation scheme for LY.


20

Page 21 of 31

100

Liquid

Other gas CO CO2

80

Product yield [ wt.% ]

Soluble

60

Deposit

Pendopo

40

20 STC

Residue

1-MN

cti on

a ti on

na tio n

n-f ra

cti o Fra

cti on

1-MN/Kerosene

No

No

No

n-f ra

cti o Fra

cti on n-f ra

a ti on

na tio n

Residue

a ti on

na tio n

cti o

0

STC

STC

Residue

Fra

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Kerosene

Figure 3. Comparison of the product yield distributions between Fractionation scheme and Non-fractionation scheme for PD.


21

Energy & Fuels

7 6

Pendopo

Pendopo

1-MN

1-MN/Kerosene

Raw sample

Gas

Gas

Kerosene Raw sample Gas

5

Liquid

Soluble

Soluble

4

Liquid

Liquid

Deposit Deposit Soluble

3

Deposit

2 STC Residue

STC

C

H

O

Residue

Residue

C

STC

STC

STC

STC

STC

H

O

Fra ctio na tio No n n-f rac tio na tio n Fra ctio na tio No n n-f rac tio na tio n Fra cti on ati o No n n-f rac tio na tio n

STC

STC

1 0

Figure 4.

Pendopo

Raw sample

Fra ctio na tio No n n-f rac tio na tio n Fra ctio na tio No n n-f rac tio na tio n Fra cti on ati on No n-f rac tio na tio n

Element distribution [kmol/100 kg-coal, d.a.f.]

8

Fra ctio na tio No n n-f rac tio na tio n Fra ctio na t ion No n-f rac tio na tio n Fra cti on ati on No n-f rac tio na tio n

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 31

C

H

O

Distribution of C, H, and O through the degradative solvent extraction for LY coal.


22

Page 23 of 31

Extracted compounds in recovered Kerosene

LY Cut-off solvent (Kerosene)

Total icon current [-]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

H

0 H

O

H O

H

H

0 H

H

H

HO

H

O

OH

O OH

O

O O

O

O

O

O

20

30

40

50

60


Figure 5. GC-MS chromatogram of of the mixture of Kerosene and Soluble fraction for LY.


23

Energy & Fuels

Loy Yang 1-MN Soluble Yield = 20.0%

Intensity [a.u.]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 31

1-MN/Kerosene Soluble Yield = 12.0%

Kerosene Soluble Yield = 4.8%

A150 Soluble Yield = 14.5%

0

200

400

600

800

1000

Figure 6. Molecular weight distributions of Solubles prepared using three solvents for LY.


24

Page 25 of 31

Pendopo 1-MN Soluble Yield = 23.2%

Intensity [a.u.]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

1-MN/Kerosene Soluble Yield = 15.9%

Kerosene Soluble Yield = 8.9%

0

200

400

600

800

1000

Mass/charge

Figure 7. Molecular weight distributions of Solubles prepared using three solvents for PD.


25

Energy & Fuels

1.0

Loy Yang Heated at 10 K/min in N2

0.8

1-MN

0.8

Raw

0.6

0.6 1-MN/Kerosene

Kerosene

A150

0.4

0.4 Soluble basis Raw coal basis

0.2

0.0

0.2

0

200

400

600

Relative weight [kg/kg-raw coal, d.a.f.]

1.0

Relative weight [kg/kg-Soluble, d.a.f.]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 31

0.0 800

Temperature [ºC]

Figure 8. TG curves of solid products and raw coal for LY. The solid line shows the results on Soluble basis while the broken line shows the results on raw coal basis.


26

Page 27 of 31

1.0

Pendopo Heated at 10 K/min in N2

0.8

0.8

Raw 0.6

0.6 1-MN

0.4

0.4

Soluble basis Raw coal basis

1-MN/Kerosene Kerosene

0.2

0.0

0

200

400

600

0.2

Relative weight [kg/kg-raw coal, d.a.f.]

1.0

Relative weight [kg/kg-Soluble, d.a.f.]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

0.0 800

Temperature [ºC]

Figure 9. TG curves of solid products and raw coal for PD. The solid line shows the results on Soluble basis while the broken line shows the results on raw coal basis.


27

Energy & Fuels

0.0 Raw

Normalized displacement [-]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 31

-0.2

-0.4

1-MN

-0.6 1-MN/Kerosene A150

-0.8

Kerosene

Loy Yang Heated at 10 K/min in N2

-1.0

0

100

200

300

400

500

600

Temperature [°C]

Figure 10. TMA profiles of Solubles and raw coal for LY.


28

Page 29 of 31

0.0

Normalized displacement [-]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

-0.2 Raw -0.4 1-MN -0.6

1-MN/Kerosene -0.8

Pendopo

Kerosene

Heated at 10 K/min in N2 -1.0

0

100

200

300

400

500

600

Temperature [°C]

Figure 11. TMA profiles of Solubles and raw coal for PD.


29

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 30 of 31

Figure 12. Comparison of HHVs among raw coal, solid extracts, and STC for LY on raw coal basis.


30

Page 31 of 31

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Figure 13. Comparison of HHVs among raw coal, solid extracts, and STC for PD on raw coal basis.


31

Effect of Solvent on the Degradative Solvent Extraction of Low Rank

Recommend Documents