Energy & Fuels 1990,4, 452-455
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The quantity (C/H)(dT/dX? defines the Rebinder number, Rb, as a dimensionless group. It determines the ratio of heat used to raise the temperature of the wet material to the heat used to evaporate the moisture present in the material. The Rebinder numbers calculated for these coals are also tabulated in Table 11. Previously obtained5 heat capacity data were used to calculate Rb.
Acknowledgment. The material in this paper was part of the data presented at the Pacifichem89 conference.1° The work was supported by a grant from CUNY and by the E. I. du Pont de Nemours and Co. R.A. also received support from the School of Engineering of City College to perform this work in partial fulfillment of the requirements of the Masters of Chemical Engineering degree.
Extraction of Argonne Premium Coal Samples with CS2-N-Methyl-2-pyrrolidinoneMixed Solvent at Room Temperature and ESR Parameters of Their Extracts and Residues Toshimasa Takanohashi and Masashi Iino* Chemical Research Institute of Non- Aqueous Solutions, Tohoku University, Katahira, Aoba-ku, Sendai 980, Japan Received May 2, 1990. Revised Manuscript Received July 23, 1990
The eight Argonne Premium Coal Samples were extracted a t room temperature with CS2-Nmethyl-2-pyrrolidinone(NMP) mixed solvent. Upper Freeport, Pittsburgh No. 8, Blind Canyon, Illinois No. 6, and Lewiston-Stockton coals gave high yields, i.e., 59.4, 39.0, 33.6, 33.1, and 27.1 wt 70 (daf), respectively. On the other hand, Pocahontas No. 3, Wyodak-Anderson, and Beulah-Zap coals gave only low yields, i.e., 2.8,9.9, and 2.3 wt % (daf), rsepectively. The extracts obtained were fractionated with acetone and pyridine, respectively. For the extract from the Upper Freeport coal, a considerable amount of pyridine-insoluble fraction, i.e., a heavier extract fraction than preasphaltene, was obtained. ESR parameters of spin concentration, line width, and g value for the raw coals and their extracts and residues were determined. The spin concentration was the order of extract fractions < raw coal < residue for all coals used. The extract fractions also had larger line widths than those of the residues.
Introduction The heterogeneous and complex nature of coal often gives us much trouble. The chemical and physical properties of coals depend critically on the sample history of the coal, i.e., place of mining and how it was mined, transported, and stored.'P2 Many researchers in coal chemistry around the world are using the Argonne Premium Coal Samples. These samples donated through this program are chemically and physically as identical and free ~ or weathering of coals of oxidation as p ~ s s i b l e . Oxidation has been reported to decrease extractability with organic solvent^.^^ The Argonne Samples are expected to give the "true" extractability with little effect of oxidation. CS2-N-methyl-2-pyrrolidinone (NMP) mixed solvent gave high extraction yields (40-65 wt 70,daf) a t room temperature for many bituminous No occurrence (1) Klein, R.; Wellek, R. Sample Selection, Aging, and Reactiuity of Coal; Wiley-Interscience: New York, 1989. (2) Monthiony, M.; Landais, P. Fuel 1987,66, 1703-1708. (3) Vorres, K. S. Prepr. Pap.-Am. Chem. SOC.,Diu.Fuel Chem. 1987, 32 (4), 221-226. (4) Buchanan, D. H.; Osborne, K. R.; Warfel, L. C.; Mai, W.; Lucas, D. Energy Fuels 1988,2, 163-170. (5) Seki, H.; Ito, 0.: Iino, M. Fuel 1990, 69, 317-321. (6) Isaacs, J. J.; Liotta, R. Energy Fuels 1987, I , 349-351. (7) Iino, M.; Kumagai, J.; Ito, 0. J . Fuel SOC.Jpn. 1985, 64, 210-212. (8) Iino, M.; Takanohashi, T.; Ohsuga, H.; Toda, K. Fuel 1988, 67, 1639-1647. (9) Iino, M.; Takanohashi, T.; Obara, H.; Tsueta, H. Fuel 1989, 68, 1588-1593.
of significant reaction between a coal and the solvents was reported.* The characterization of the chemical structure of the extracts and residues from five bituminous coals, including Upper Freeport coal, which is one of the Argonne Premium Coal Samples, was carried The measurements of ESR parameters, i.e., spin concentration, line width, g value, spin-spin relaxation time, and spin-lattice relaxation time, for various coals and the extracts and residues after extraction have been performed to obtain information about the coal Yokokawa'O reported a decrease in the spin concentration of coals after solvent treatment. Duber et a1.l' also reported a decrease in the spin concentration for the extracts and the residues after extraction. They suggested that these decreases in spin concentration were a t least partly attributable to the recombination of coal radicals. On the other hand, Seehra and co-workers12 reported that the weight-average spin concentration of the extracts and residues after extraction with NMP at 202 "C are nearly equal compared to that of the raw coals, unlike the cases in the above literature.lOJ1 This may be attributed to the difference in the extraction temperature (202 " C ) com(10)Yokokawa, C. Fuel 1969, 48, 29-40. (11) Duber, S.; Wieckowski, A. B. Fuel 1984, 63, 1641-1644. (12) Seehra, M. S.; Ghosh, B.; Zondlo, J. W.; Mintz, E. A. FuelProcess. Technol. 1988, 18, 279-286. (13) Ito, 0.; Seki, H.; Iino, M. Bull. Chem. SOC.J p n . 1987, 60, 2967-2975.
0887-0624/90/2504-0452$02.50/0 0 1990 American Chemical Society
Energy & Fuels, Vol. 4, No. 5, 1990 453
Extraction of Argonne P r e m i u m Coal S a m p l e s
coal Pocahontas No. 3 Upper Freeport Pittsburgh No. 8 Lewiston-Stockton Blind Canyon Illinois No. 6 Wyodak-Anderson Beulah-Zap a By
Table I. Ultimate and Proximate Analyses of Coals ultimate anal., wt % (daf) proximate C H N S 0 0 VM 89.7 4.5 1.1 0.7 4.0 17.6 4.6 28.2 86.2 5.1 1.9 2.2 2.4 82.6 5.5 2.1 7.4 38.3 10.2 30.0 0.9 82.0 5.3 1.6 0.6 79.4 5.9 2.0 12.1 45.5 5.6 10.1 38.6 76.9 5.5 1.9 0.7 73.6 5.4 1.1 19.2 43.3 71.6 4.8 1.0 0.9 21.7 42.2
anal., wt % (db) ash FC 4.8 77.6 13.1 58.7 8.7 53.0 19.6 50.4 4.5 50.0 15.0 46.4 8.7 48.0 9.6 48.2 ~~
difference.
I CS,-NMP
extraction
Extract Acetone
Pyridine
Pyridine
Pyridine insoluble
F i g u r e 1. Fractionation procedure of extracts with CS,-NMP mixed solvent (1:l by volume).
pared to room temperature which was used in the above literature.lOJ1 We preliminarily measured9 the spin concentrations of the extracts and residues from the three coals that gave high extraction yields with the mixed solvent, but the weight-average spin concentrations of the extract fractions and residues were higher or lower than the spin concentration of the corresponding raw coals, depending on the kinds of coals used. In the present study, the eight Argonne Premium Coal Samples were extracted with CS,-NMP mixed solvent at room temperature, and the extracts obtained were fractionated. The ESR parameters for raw coals and the extract fractions and residues were determined and discussed.
Experimental Section Materials. The eight Argonne Coal Samples, which were already ground
