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Analysis of Five U.S. Coals Pyrolysis Gas Chromatography—Mass Spectrometry— Computer and T h e r m a l Gravimetry—Mass Spectrometry—Computer Methods E. J. GALLEGOS Chevron Research Company, Richmond, CA 94802
Pyrolysis gas chromatography-mass spectrometry (py-GC MS) and thermal gravimetry-mass spectrometry (TGA-MS), in conjunction with a dedicated computer, are used to analyze five U.S. coals under identical conditions. Data presented graphically correlate relative concentrations of various identified components with the geochemical history of the coals. The C and C -C hopanes were identified in all five coals along with several C sesquiterpanes. The concentration ratio of the 17-βΗ isomer to the 17-αH hopane decreases with geothermal stress experienced by the coal deposit. Other biomarker hydrocarbons, including cadalene CH, were identified in some of the coals. These and other details are discussed. 27
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30
15
15
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'"phis paper describes the results of a detailed analysis of five U.S. coals of differing geological history using the technique of pyrolysis gas chromatography-mass spectrometry computer (py-GG-MS-C) and thermal gravimetry-mass spectrometry computer (TGA-MS-C). All data were acquired using the INCOS data system. This paper demonstrates the fantastic power of p y - G C - M S - C and T G A - M S - C for analysis of complex, nonvolatile systems such as coal. These techniques make it possible to obtain both qualitative and quanti tative information on saturates, aromatics, and some hetero compounds without any prior treatment. These are on-line techniques, i.e., pyrolysis is followed by chromatographic or weight analysis which is followed by mass analysis without interruption. 0-8412-0395-4/78/33-170-013$06.00/l © 1978 American Chemical Society In Analytical Chemistry of Liquid Fuel Sources; Uden, P., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1978.
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ANALYTICAL CHEMISTRY OF LIQUID FUEL SOURCES
Table I.
Classification of Coals by Rank
0
Btu/Lb I.
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II.
fed
III.
IV.
Anthracite 1. Metaanthracite 2. Anthracite 3. Semianthracite Bituminous 1. LowVolative 2. Medium Volatile 3. High Volatile A 4. High Volatile Β 5. High Volatile C Subbituminous 1. A 2. Β 3. C Lignite 1. A
VI.
'Réf. 9.
a
ο Ο α bD Ο
S3
03
14,000 13,000
03
11,500 10,500 7,500
r—I
!> bJO .S
W
9,500 8,300
2. Β V.
-Ρ
Brown Coal Peat
Since these are the first py-GC-MS and T G A - M S results on a series of coals, it is probably worthwhile to place the importance of coals in perspective with respect to other organic sediments as shown in Figure 1 (J). These world estimates are given in trillions of tons. Coal is by far the most common form of concentrated organic sediment. The United Table II. Era
Period
Quaternary
Phanerozoic Time Scale (3) Epoch
Pleistocene Pliocene Miocene
8 Ο
Tertiary
Oligocène Eocene Paleocene
Beginning of Interval (Million Years) 1.5-2 7
-0
26 37-38 53-54 65
In Analytical Chemistry of Liquid Fuel Sources; Uden, P., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1978.
-50
2.
GALLEGOS
Analysis of Five U.S. Coals
15
Table II. Continued Cretaceous
Upper
100
Lower
136
Upper
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ο
Jurassic
162
Middle
Permian
190-195
Upper Middle Lower
205 215
Upper
240
345
Upper Middle
359 370
Lower
-350
395 -400
Silurian
430-440
2 Upper Ordovician
-300
325
Ο ^ Mississippian
PH
-250 260
Jj § Pennsylvanian
ο
-200
225
Lower
Devonian
-150
172
Lower
Triassic
-100
445
Lower
-450
500 Upper
-500
515
Middle
540
Cambrian Lower
-550 570
Precambrian
-600 The Encyclopedia of Geochemistry and Environmental Sciences IVA
In Analytical Chemistry of Liquid Fuel Sources; Uden, P., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1978.
16
ANALYTICAL CHEMISTRY OF LIQUID FUEL SOURCES Organic Sediments
Diluted
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Concentrated
Petroleum
Asphalts
Coals
Hydrocarbons
Bitumen
Kerogen
0.6
0.3
7.0
60
100
3200
Numbers in 1 0
Figure 1.
12
Tons
World estimates organic sediments distribution
States is estimated to have ~ 1.5 Χ 10 tons of coal or ca. one-fifth of the world supply. In the discussion of the results given in this chapter, correlations are made with respect to coal rank and geothermal stress which, in the case of the five coals studied here, coincides with geological age. Table I gives the latest ranking of coals (2) and Table II (3) gives the geo logical time scale. 12
Pyrolyzer Septum
I njection Port
I
Control
/
Computer
χ
