Analysis of Five US Coals - American Chemical Society

Upper. Lower. Jj § Pennsylvanian. Ο ^ Mississippian ο. 2. PH. Devonian. Silurian. Ordovician. Upper. Middle. Lower. Upper. Lower. 100. 162. 172. 20...
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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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'"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.



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

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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.

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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.

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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