liquefaction pathways of bituminous subbituminous coals andtheir

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30 20 10 0 Table I. Conversion data for hydrous pyrolysis experiments. # time temceratu converso 1 240hrs loooC 29.3 2 .5 hrs 3oooc 29.8 3 2 hrs 3oooc 30.6 4 3hrs 35w 39.1 * Phenols -0- Benzenes * Guaiacols -f- Catechols - Potapsco 10 days 200 C0.5 brs 300 C 2 hrs 300 C 3hrs 350 C Increasing Thermal Alteration Figure 2. Relative Yields of Flash Pyrolysis Products from Aquathermolysis Residues 576
THE EFFECTS OF MOISTURE AND CATIONS ON LIQUEFACTION OF LOW RANK COALS M.A. Serio, E. Kroo, H. Teng, and P.R. Solomon Advanced Fuel Research, Inc. 87 Church Street East Hartford, CT 06108 Keywords: Coal liquefaction, Cations, Low rank coals INTRODUCTION The role of calcium in reducing liquefaction yields from low rank coals has been suggested in previous work by Whitehurst et al. (1) and Mochida et al. (2). It is also consistent with work which shows an effect of calcium on reducing pyrolysis tar yields (3-7). The role of calcium may be to provide a nascent crosslink site in the coal by allowing coordination of groups like carboxyl and hydroxyl which are prone to such reactions. Otherwise, these sites would be more likely to coordinate with water (through hydrogen bonding) then with each other. There have been no studies of the effects of cation type and the associated moisture on liquefaction yields. Studies were done on samples of Argonne Zap Lignite and Wyodak subbituminous coals which have been demineralized and then exchanged with calcium, barium or potassium cations. Two sets of samples were prepared: 1) vacuum-dried; 2) exposed to water vapor until an equilibrium moisture content was reached. The samples were characterized by FT-IR transmission analysis in KBr pellets, programmed pyrolysis in aTG-FTIR system and liquefaction in donor solvent. The pyrolysis and liquefaction results are discussed in the current paper. EXPERIMENTAL In order to subject coals to a variety of modifications and avoid exposure to the ambient air, an apparatus fur continuous-flow, controlled-atmosphere demineralization and controlled pH ion- exchange of coals was designed and constructed. A closed system is used, where instead of stimng the batch reactor contents, a continuous flow of solvent through the sample is used. By utilizing valves, it is possible to change solvents without opening the reactor. The different solvents are held in separate reservoirs which are all equipped with sparge valve systems to deoxygenate the solvents before use (with N, or He as needed). Demlneralization - The procedure is similar to that described in the work of Bishop and Ward (8). The coal samples used in this study are the Zap lignite and Wyodak subbituminous coals from the Argonne premium sample bank (9). The sample sizes were all -100 mesh. Before starting the acid treatment, the samples were thoroughly wetted by mixing with de-ionized water under a nitrogen environment. Demineralization involved washing the coal with a flow of 2M HCI for 45 minutes, 50% HF for 45 minutes, 2M HCI for 45 minutes, and de-ionized water for 120 minutes. The process was performed at 80 'C. After demineralization, the sample was dried in vacuum for at least 20 hours at room temperature. The vacuum dried samples were kept in a nitrogen box for subsequent analysis and liquefaction experiments. Ion-Exchange of Carboxyl Groups with Metal Cations - The acidity constant (kJ of carboxylic acids is around lU5, and that of phenols is around 10"'. Theoretically, almost all carboxyl OH can be exchanged with cations at pH 8, whereas the phenolic-OH can remain in the acid form, according to the equation: [A- ] / [HA] = k, / [H'], where HA is either the carboxyl or phenolic group in acid form. At pH 8, (A]/[HA] would be a value of order lo3 for carboxyl groups, and 10' for phenols. Schafer's experimental results also suggest that the carboxyl groups in coal can be completely exchanged with cations at pH around 8-8.5, along with ortho-dihydroxy groups (10). In the case of barium, a 1N barium acetate solution, which has a pH value around 8.2, was used for ion-exchange with carboxyl groups. Roughly 3 g of demineralized coal was 577
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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
Page 51 and 52: 1.50 KQ 1.00 0.50 I / ' 02 525 I 1
Page 53 and 54: hydrogen atoms. The hydrogen atoms
Page 55 and 56: D to generate more D atoms. It is r
Page 57 and 58: 12. a. Poutsma, M. L.; Dyer, C. W.
Page 59 and 60: Figure 3. Minimum Steps to Explin D
Page 61 and 62: Apoaratus and Procedure Microflow R
Page 63 and 64: Model ComDound Test Figure 5 shows
Page 65 and 66: Figure 1. High resolution gas chrom
Page 67 and 68: Figure 5. Product distribution for
Page 69 and 70: THQ at somewhat higher temperatures
Page 71 and 72: areas of the particles and the SEM
Page 73 and 74: Experimental Catalyst Precursors an
Page 75 and 76: impregnating solvent. Table 3 shows
Page 77 and 78: of MoCo-TC2 at the level of 0.5 wt%
Page 79 and 80: Table 4. Effect of Temperature Prog
Page 81 and 82: In the past, chemical treatments in
Page 83 and 84: The effect of Corn20 preaatment on
Page 85 and 86: Reaction Time Figure 1 - Schematic
Page 87 and 88: DISSOLUTION OF THE ARGONNE PREMIUM
Page 89 and 90: A much more def~tive trend is seen
Page 91 and 92: EFFECT OF CHLOROBENZENE TREATMENT O
Page 93 and 94: same conditions and an extraction t
Page 95 and 96: ACKNOWLEDGEMENT The authors thank t
Page 97 and 98: THE STRUCTURAL &=RATION OF HUMINlTE
Page 99 and 100: to be originally derived from demet
Page 101: 145 30 I --/---Jh I , , I I , 250 2
Page 105 and 106: 1 for the Zap lignite. These result
Page 107 and 108: content of the samples ion-exchange
Page 109 and 110: Table 1. F'yrolysis Results of Vacu
Page 111 and 112: 585 I
Page 113 and 114: EFFECT OF TEMPERATURE, SAMPLE SI2E
Page 115 and 116: of some of the thermobalance runs.
Page 117 and 118: 2. The mechanism of drying is a uni
Page 119 and 120: Influence of Drying and Oxidation 0
Page 121 and 122: "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
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A bang-bang control strategy was us
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increased from 120°C to 135”C, r
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* wt% based on the amount of naphth
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Use of Biocatalysts for the Solubil
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Results Enzyme Modification with Di
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Conclusions Reducing enzymes can be
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Dynamics of the Extract Molecular-W
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where yi = (x-xi !/pi. The zero mom
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satisfactory agreement between theo
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0.8 0.6 0.4 0.2 “E \ bo Y, - 1 0
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The Use of Solid State C-13 NMR Spe
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differences lie in the fact that th
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I- z W 0 K W n PROTONATED AROMATIC
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ZAP WIO SIDE CHAINS IN PYRIDINE EXT
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ORGAFlIC VOLATILE MATER AND ITS SUL
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(Figure 1). They indicated that the
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Table 3. Elemental analysis of arom
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1- 700'C Figure 3. GClFID chromatog
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