liquefaction pathways of bituminous subbituminous coals andtheir

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The carbon-13 NMR spectra of all extracts and extraction residues were obtained according to the procedure of Solum, et a1.7 High resolution NMR data was obtained on a Varian VXR-500 spectrometer using dimethyl sulfoxide as solvent. It was noted that the solubility of the extracts varied with the coal and that solubilization was not complete for any of the coals. The NMR spectra exhibited the characteristics of high resolution with line widths that would be typical of compounds with molecular weights of several hundred daltons. RESULTS The amount of extract obtained from each of the 8 Argonne Premium coals is given in Table 1. The duplicate extractions were run in parallel and the reproducibility of the results appears to be quite adequate. It is noted that a mass closure of at least 94% was obtained on each sample. Figure 1 portrays the extract yield together with the fraction of total carbons that are protonated aromatic carbons in the pyridine extracts and residues. In each case this parameter is found to be higher in the extract than in the residue, indicating that the residue contains a higher fraction of substituted carbons than the extract. In Figure 2, the coordination number of the residues is higher than the extracts with the single exception of the Illinois Mi in which no distinction can be made. The number of bridges and loops in the residues and extracts are shown in Figure 3. This parameter is a measure of the cross link structure that exists between individual aromatic clusters. As one might expect, the residues exhibit a greater number of bridges than are found in the extracts. The single exception, again, is the Illinois #6 coal in which no distinction can be made between the two. In Figure 4, the average aromatic cluster size is given and in each case the size of the extract is less than that of the residue, with the single exception of Illinois #6 where no clear distinction can be made. Figure 5 pomays the number of side chains per cluster in the extracts and residues. From this data no consistent trend can be observed. Figure 6 contains the aromatic characteristics of the extracts from the Argonne coals. As expected, both the carbon and proton aromaticity of the extracts increase with rank with the single exception of the Pocahontas extract. The carbon aromaticity of the residue is also plotted for comparison purposes. Using the proton structural definitions reported by Fletcher, et al.? it is possible to approximate the contributions 1,2, and 3-ring aromatic species in the coal extracts. These data are also shown in Figure 6. In Figure 7, the contributions of total a-hydrogens, a-methyls, a- CH2 groups, and y-methyls for the pyridine extracts are given. It is interesting to note that the total a-hydrogen and a-CH2 groups pass through a maximum, as a percent of the total hydrogen in the samples, in the high volatile bituminous coal. As expected, the contributions of y-methyl groups decrease from lignite through the high volatile bituminous coal range and then increase slightly in the Upper Freepon and Pocahontas extracts. CONCLUSIONS Comparing the l3C NMR data on the extracts and residues, it becomes apparent why material is extracted from the parent coal. While the C PMS spectra of both the extracts and residues are quite similar, an examination of the details of the structure provide the subtle differences in structural detail that are important in describing the extraction process. While one must recognize that we are observing the averages of all the components present in the extracts, the extracted material appears to have many of the structural features that are observed in the macromolecular structure of the coal. The 648
differences lie in the fact that the number of cross links is reduced and the number of substituents on the aromatic rings is lower in the extracts than in the residues. Hence, these data are consistent with the fact that this material can be extracted since it is not extensively incorporated by means of covalent bonds into the macromolecular structure. The proton NMR data shows that the amount of 2- and 3-ring components present in the extracts increases with the rank of the coal. The aliphatic region of the proton NMR data indicates that: a) the amount of a-methyl groups is essentially the same in all extracts, b) the amount of y-methyl groups decreases with rank, and c) the amount of a-hydrogen goes through a maximum at the high volatile bituminous rank range. These data on the extracts will be used to compare the pyridine extractable material that is obtained as these coals are pyrolyzed. Experiments that are now underway in our laboratories together with the results presented herein will be useful in our future work on modeling the transformation that occur during devolatilization and char formation. ACKNOWLEDGMENT' This work was supported by the National Science Foundation through the Advanced Combustion Engineering Research Center at Brigham Young University and the University of Utah. REFERENCES 1. 2. 3. 5. 6. 7. T.H. Fletcher, A.R. Kerstein, R.J. Pugmire, and D.M. Grant, A Chemical Percolation Model for Devolatilization: 3. Chemical Structure as a Function of Coal Type, Energy & Fuels, 1992,6,414. T.H. Fletcher, M.S. Solum, D.M. Grant, S. Critchfield, and R.J. Pugmire, Solid State 13C and 1H NMR Studies of the Evolution of the Chemical Structure of Coal Char and Tar During Devolatilization, 23rd Symposium (International) on Combustion, The Combustion Institute, 1990,1231. R.J. Pugmire, M.S. Solum, D.M. Grant, S. Critchfield, and T.H. Fletcher, Structural Evolution of Matched Tar/Char Pairs in Rapid Pyrolysis Experiments, Fuel, 1991,zQ. 414. W.S. Fong, W.A. Peters, and J. Howard, Fuel, 1986, a, 251. D.H. Buchanan, Am. Chem. Soc., Div. of Fuel Preprints, 32, No. 4, p. 293. M.S. Solum, R.J. Pugmire, and D.M. Grant, 13C Solid State NMR of the Argonne Premium Coals, Energy & Fuels, 1989,3, 187. 649 /
Page 1 and 2:
LIQUEFACTION PATHWAYS OF BITUMINOUS
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the conversion of A+P and O+G with
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Asphaltcncs PrCasphaltenCS Cwr%, da
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NEW DIRECTIONS TO PRECONVERSION PRO
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ecause of incorporation of the coal
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should be considered more. The step
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17 18 Run no. 0 cys I ToS-CyS TS-To
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INTRODUCTION Effects of Thermal and
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apid decline in modulus. The loss m
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-0.01- . 04 5 -0.03- E 6 -0.0s- c)
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Assessment of Small Particle Iron O
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yields are calculated by subtractin
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conversion is greater than the corr
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Table 3. Effect of Superfine Iron O
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EFFECT OF A CATALYST ON THE DISSOLU
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inherent volatility of Mo(CO), perm
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Analysis of the quantity and compos
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$ EO .- 0 m L 0 c 0 0 > 40 300 350
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0 0 0 0 0.000 0.005 0.010 0.015 0.0
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of these studies indicate that cont
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Different levels of adsorption occu
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Nominal 2 Table 1. Concentration of
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- iF m 1.6 1.4 1.2 - - - 1- 0 0.8 -
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RESULTS AND DISCUSSION Swelling of
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. . % . . 9 'HF 0 0 0 *. . 0 . . 0
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1.50 KQ 1.00 0.50 I / ' 02 525 I 1
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hydrogen atoms. The hydrogen atoms
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D to generate more D atoms. It is r
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12. a. Poutsma, M. L.; Dyer, C. W.
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Figure 3. Minimum Steps to Explin D
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Apoaratus and Procedure Microflow R
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Model ComDound Test Figure 5 shows
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Figure 1. High resolution gas chrom
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Figure 5. Product distribution for
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THQ at somewhat higher temperatures
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areas of the particles and the SEM
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Experimental Catalyst Precursors an
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impregnating solvent. Table 3 shows
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of MoCo-TC2 at the level of 0.5 wt%
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Table 4. Effect of Temperature Prog
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In the past, chemical treatments in
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The effect of Corn20 preaatment on
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Reaction Time Figure 1 - Schematic
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DISSOLUTION OF THE ARGONNE PREMIUM
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A much more def~tive trend is seen
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EFFECT OF CHLOROBENZENE TREATMENT O
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same conditions and an extraction t
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ACKNOWLEDGEMENT The authors thank t
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THE STRUCTURAL &=RATION OF HUMINlTE
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to be originally derived from demet
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145 30 I --/---Jh I , , I I , 250 2
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THE EFFECTS OF MOISTURE AND CATIONS
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1 for the Zap lignite. These result
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content of the samples ion-exchange
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Table 1. F'yrolysis Results of Vacu
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585 I
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EFFECT OF TEMPERATURE, SAMPLE SI2E
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of some of the thermobalance runs.
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2. The mechanism of drying is a uni
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Influence of Drying and Oxidation 0
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"c gives W conversion mpared to the
Page 123 and 124: Table 1. Products dismbutions (dmmf
Page 125 and 126: - 50 45 40 E 35 2 30 E T) 25 ap 20
Page 127 and 128: Influence of Drying and Oxidation o
Page 129 and 130: FTIR . . of the L m To investigate
Page 131 and 132: CONCLUSIONS The characexizntion of
Page 133 and 134: A b S 0 r b a n C e A b s 0 r b a n
Page 135 and 136: An NMR Investigation of the Effd of
Page 137 and 138: for determining the area of the pea
Page 139 and 140: of the ronl roniponcnte nnd (2) the
Page 141 and 142: 2w 180 160 9 140 120 P loo f 80 P O
Page 143 and 144: 25 I 20 ' + 0 Drying lime, hours Fi
Page 145 and 146: substructure have been identified a
Page 147 and 148: Pyridine extraction showed that 60
Page 149 and 150: Figure 1. Reflected white-light pho
Page 151 and 152: Table 3. Pyridine Extraction Sample
Page 153 and 154: A bang-bang control strategy was us
Page 155 and 156: increased from 120°C to 135”C, r
Page 157 and 158: * wt% based on the amount of naphth
Page 159 and 160: Use of Biocatalysts for the Solubil
Page 161 and 162: Results Enzyme Modification with Di
Page 163 and 164: Conclusions Reducing enzymes can be
Page 165 and 166: Dynamics of the Extract Molecular-W
Page 167 and 168: where yi = (x-xi !/pi. The zero mom
Page 169 and 170: satisfactory agreement between theo
Page 171 and 172: 0.8 0.6 0.4 0.2 “E \ bo Y, - 1 0
Page 173: The Use of Solid State C-13 NMR Spe
Page 177 and 178: I- z W 0 K W n PROTONATED AROMATIC
Page 179 and 180: ZAP WIO SIDE CHAINS IN PYRIDINE EXT
Page 181 and 182: ORGAFlIC VOLATILE MATER AND ITS SUL
Page 183 and 184: (Figure 1). They indicated that the
Page 185 and 186: Table 3. Elemental analysis of arom
Page 187: 1- 700'C Figure 3. GClFID chromatog
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