Organic Chemistry of Coal - American Chemical Society

Solvent Separation. Coal liquefaction products were solvent separated (1) by ..... 5. 17-2. 1. 19-2. 2. 17-2. 1. Azabenzo[ghi]fluoranthene s. -2. 7. 1...
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18 Heteroatom Species in Coal Liquefaction Products F. K. SCHWEIGHARDT, C. M . WHITE, S. FRIEDMAN, and J. L. SHULTZ U.S. Department of Energy, Pittsburgh Energy Research Center, 4800 Forbes Avenue, Pittsburgh, PA 15213

An assessment of the nitrogen and oxygen heteroatom species in coal-derived products is a complex yet important analytical problem in fuel chemistry. Principally, this is because the system is a multifarious molecular mixture that does not easily lend itself to direct analysis of any one component or functional group. Albeit this problem is not new, the characterization of these heteroatoms is of immediate importance to further processing of these fuels. Methods and techniques used to rapidly isolate and/or characterize both nitrogen and oxygen heteromolecular species are described. Utilization is made of solvent separations, functional group type separation, chemical derivatization, HCl salt formation and the use of chromatographic and spectrometric analytical methods to quantitate results. Specifically, the kind and distribution of nitrogen and oxygen heteromolecules in a coal liquefaction product and in a recycle solvent used in solvent refined coal (SRC) processing were determined. The coal liquefaction product was first solvent separated into oils, asphaltenes, preasphaltenes and ash, while low boiling oils (light oils) trapped from knock-out tanks and the SRC recycle solvent were treated directly. Nitrogen bases were complexed as HCl adducts or separated on ionexchange resins. Hydroxyl-containing species from the separated fractions were quantitated by infrared spectroscopy or by formation of a trimethylsilyl ether (TMS) and subsequent analysis by H NMR and mass spectrometry. Hydroxyl species were also isolated on ion-exchange resins or by selective gradient elution from silica gel. EXPERIMENTAL Solvent Separation Coal liquefaction products were solvent separated (1) by 0-8412-0427-6/78/47-071-240$05.00/0 This chapter not subject to U.S. copyright. Published 1978 American Chemical Society

18.

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Heteroatom

Species

241

f i r s t f r e e z i n g the c o a l l i q u i d s i n l i q u i d n i t r o g e n and g r i n d i n g them to f i n e p a r t i c l e s . T h i s f r o z e n o i l can be e a s i l y t r a n s ­ f e r r e d to a s t a i n l e s s s t e e l c e n t r i f u g e tube. P e s t i c i d e grade solvents were then used to s o l u b i l i z e s p e c i f i c f r a c t i o n s — o i l s (pentane), asphaltenes (benzene), preasphaltenes (2) ( t e t r a h y drofuran) and c o a l - d e r i v e d ash ( i n s o l u b l e i n a l l solvents used). By s t a r t i n g with a 3-4 gram sample, one (1) l i t e r of each solvent i n four or f i v e 200 ml p o r t i o n s was u s u a l l y s u f f i c i e n t to e x t r a c t tlje s o l u b l e s . Insolubles were removed by c e n t r i f u g a t i o n at 10 rpm at 6°C f o r 10 minutes. Solvents were removed by n i t r o g e n f l u s h on a Rotovap using a water bath (65-85°C). Asphaltenes were treated d i f f e r e n t l y at the f i n a l solvent r e ­ moval step; a 20 ml s o l u t i o n of benzene/asphaltenes was s w i r l e d i n a f l a s k and flaslji frozen i n l i q u i d n i t r o g e n , and the solvent was sublimed at 10 -10 t o r r f o r 2-3 hours. HC1

Treatment

The o b j e c t i v e of t h i s procedure was to separate and/or concentrate both n i t r o g e n heteromolecules and hydroxyl-containing species from c o a l - d e r i v e d m a t e r i a l (3). Gaseous HC1 was bubbled through a benzene or pentane s o l u t i o n of the c o a l product to form an i n s o l u b l e HC1 adduct with molecules c o n t a i n i n g a b a s i c n i t r o g e n atom. The adduct, a f t e r being washed f r e e of other components, was back t i t r a t e d with d i l u t e NaOH s o l u t i o n to f r e e the base n i t r o g e n i n t o an organic phase, u s u a l l y d i e t h y l ether, methylene c h l o r i d e or benzene. The two f r a c t i o n s recovered c o n t a i n a c i d / n e u t r a l and n i t r o g e n base m a t e r i a l , r e s p e c t i v e l y . Hydroxyl S i l y l a t i o n O i l s , asphaltenes and preasphaltenes were treated with hexamethlydisilazane (HMDS) to form a t r i m e t h y l s i l y l ether (TMS) of a c t i v e hydroxyl groups (4,5). A 50 mg sample of c o a l - d e r i v e d product was d i s s o l v e d i n 25 ml of benzene containing 50 μΐ of p y r i d i n e - d . To t h i s s o l u t i o n 500 μΐ each of HMDS and N - t r i methylsilyldimethylamine were added. This mixture was main­ tained as a closed system except f o r a small Bunsen v a l v e and m i l d l y r e f l u x e d f o r one hour with o c c a s i o n a l s w i r l i n g of the f l a s k . A f t e r the r e a c t i o n was completed, solvents and unreacted reagents were removed under n i t r o g e n f l u s h on a Rotovap and f i n a l l y f r e e z e d r i e d from 5 ml of benzene f o r 30 minutes. A p o r t i o n of the f i n a l product was checked by i n f r a r e d s p e c t r o s ­ copy (IR) f o r disappearance of the OH band at 3590 cm ( 6 ) . The remaining sample was d i s s o l v e d i n benzene-d. and i t s proton NMR spectrum taken and i n t e g r a t e d . From the r e l a t i v e areas of the peaks i n the proton NMR spectrum, a percent H as OH was c a l c u l a t e d (Equation 1) ( 7 ) .

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ORGANIC CHEMISTRY OF COAL

TMS Area. 9 TMS

Area 9

)

+

χ

10

2

=

% H as OH

(1)

(Remaining Proton Area)

From an elemental a n a l y s i s of the o r i g i n a l sample, one can c a l c u l a t e the weight percent oxygen as OH on a moisture and ash f r e e b a s i s (MAF). Combined Gas Chromatography-Mass Spectrometry (GCMS) The combined GCMg analyses were performed u s i n g a Dupont 490 mass spectrometer i n t e r f a c e d to a V a r i a n 1700 Series gas chromatograph, equipped with an 80:20 g l a s s s p l i t t e r and a flame i o n i z a t i o n d e t e c t o r . The spectrometer was a l s o coupled to a Hewlett-Packard 2100A computer used f o r spectrometric data storage and r e d u c t i o n . The mass spectrometer was operated at a r e s o l u t i o n of 600 and an i o n i z i n g v o l t a g e of 70 eV. The i o n source, j e t separator and g l a s s l i n e from the chromatograph to the mass spectrometer were h e l d at 275°C. The chromatographic e f f l u e n t was continuously scanned at a r a t e of four seconds per decade by the mass spectrometer. The gas chromatographic separations were e f f e c t e d u s i n g a v a r i e t y of c o n d i t i o n s . The n i t r o g e n bases and a c i d f r a c t i o n s from the c o a l l i q u e f a c t i o n product were chromatographed on a 10 χ 1/4" OD g l a s s column packed with 100-120 mesh Supelcoport coated with 3% OV-17. Bases from the SRC product were chromato­ graphed on a 10' by 1/8" 0D g l a s s column packed w i t h 100-120 mesh Chromasorb-G coated w i t h 2% OV-17. Gas chromatographic s e p a r a t i o n of bases from the l i g h t o i l was achieved using a 10 χ 1/8" OD g l a s s column c o n t a i n i n g a c i d washed and s i l y l t r e a t e d 100-120 mesh Supelcoport coated with 3% Carbowax 20M. In each case the He flow r a t e was 30 cc/min and the analyses were per­ formed using a p p r o p r i a t e temperature programming c o n d i t i o n s . 1

1

Column Chromatographic Separation Coal-derived l i q u i d s , s o l u b l e i n pentane, were separated i n t o f i v e f r a c t i o n s : a c i d s , bases, n e u t r a l n i t r o g e n , s a t u r a t e hydrocarbons and aromatic hydrocarbons. Acids were i s o l a t e d using anion-exchange r e s i n s , bases with cation-exchange r e s i n s , and n e u t r a l n i t r o g e n by complexation with f e r r i c c h l o r i d e ad­ sorbed on Attapulgus c l a y . Those pentane s o l u b l e hydrocarbons remaining were separated on s i l i c a g e l to give the non-adsorbed saturates and the moderately r e t a i n e d aromatics. This method i s commonly r e f e r r e d to as the SARA technique (8). RESULTS AND

DISCUSSION

The c e n t r i f u g e d c o a l l i q u i d product (CLP) was

produced

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Heteroatom

243

Species

using I r e l a n d Mine, P i t t s b u r g h seam, West V i r g i n i a c o a l i n the 1/2 ton per day SYNTHOIL Process Development Unit (PDU) (9). Operating c o n d i t i o n s f o r t h i s experiment were 4000 p s i hydrogen pressure, 450°C and no added c a t a l y s t . The l i g h t o i l s were derived from a c a t a l y t i c experiment (Harshaw 0402T) using Homestead Mine, Kentucky c o a l , under 4000 p s i pressure and 450°C. The coal l i q u e f a c t i o n product was solvent separated by the method p r e v i o u s l y described to y i e l d the d i s t r i b u t i o n of f r a c t i o n s given i n Table I. F i g u r e 1 gives the atom weight percent d i s t r i b u t i o n of n i t r o g e n and oxygen i n the solvent separated f r a c t i o n s l i s t e d i n Table I . The pentane s o l u b l e o i l s were subsequently separated i n t o f i v e f r a c t i o n s using the SARA chromatographic scheme. Table II l i s t s the weight percents of the i n d i v i d u a l f r a c t i o n s . The asphaltenes were t r e a t e d with HC1 to form a c i d / n e u t r a l and base s u b f r a c t i o n s , 63 and 37 weight percent, r e s p e c t i v e l y . Table I.

Solvent Separation Weight Percent D i s t r i b u t i o n .

Solvent F r a c t i o n Oil Asphaltenes Preasphaltenes Ash Table I I .

Wt.

% of CLP 68.0 26 4 2

SARA Chromatography F r a c t i o n s , Weight Percent D i s t r i b u t i o n .

Chromatography F r a c t i o n Saturates Aromatics Acids Bases N e u t r a l Nitrogen Loss Total O i l

Wt.

% of

CLP

4.1 37.3 6.3 10.2 3.9 7.4 68.8

The a c i d and base f r a c t i o n s from the SARA s e p a r a t i o n of the o i l s were subjected to a n a l y s i s by combined GCMS and low v o l t a g e low r e s o l u t i o n mass spectrometry (LVLR). Figures 2 and 3 r e p r o duce the gas chromatograms of the base and a c i d f r a c t i o n s , r e s p e c t i v e l y . The oxygen c o n t a i n i n g species shown i n Figure 3 have been c l a s s i f i e d as a l k y l a t e d phenols, i n d a n o l s / t e t r a l i n o l s , phenylphenols, and cyclohexylphenols. Table I I I l i s t s the carbon number range and t e n t a t i v e compound type assignments f o r the n i t r o g e n heteromolecules i n the a c i d and base f r a c t i o n s as determined by LVLR mass spectrometry (10) . Table IV l i s t s the

244

ORGANIC CHEMISTRY OF COAL

Nitrogen

Figure 1.

Oxygen

Atom percent distribution of heteroatoms: (A) oils, (B) asphaltenes, (C) preasphaltenes, and (D) residue.

0

I

250°

52 4

250°

499

250°

47.4

250°

44.9 250

42.4 250°

39.9 240°

37.4 230°

34.9 220° 210° 200° TEMPERATURE ,*C

32.4 29.9 27.4 TIME, minutes 190°

24.9 180°

22.4 170°

19.9 160°

17.4 150°

14.9

9.9

140° 130°

12 4

120°

7.4

110°

4.9

e

0 1 0 0 100°

24

I

55.5

250°

I

58.0

250°

250°

53.0

I

250°

50 5

I

I

250°

45.5

Figure 3.

250°

48.0

I

I

250°

I

240°

38.0

I

230°

35.5

I

220°

33.0

I

I

I

TEMPERATURE, t

190

e

25.5 TIME, minutes

28.0 210° 200°

30.5

I

e

180

23.0

I

e

170

20.5

I

e

160

18.0

ι

ι

13.0 150° 140°

15.5

Gas chromatogram of acid fraction from a coal liquefaction product

250°

43.0 40.5

I

130°

10.5

ι

120°

8.0

ι

ι

3.0 110° 100°

5.5

ι

Gas chromatogram of nitrogen-base fraction from a coal liquefaction product. Table IV identifies major components.

250°

250°

Figure 2.

54 9

57 4

100°

0

ι

1

^

t"

- 5 - 7 - 9 -11 -13 -15 -17 -19 -21 -23 -25 -27 -29 -31 -33 -35 -37 -39

z#

Bases Typical Structural Nitrogen Analogs

Pyridines, Anilines Azaindans Dihydroquinolines, Indols Quinolines Phenylpyr i d ines Azafluorenes Acridines Benzo[ghi]azafluorenes Azapyrenes Benzacridines Benzo[ghi]azafluoranthenes Benzazapyrenes Dibenzacridines Azaanthanthrenes Dibenzazapyrenes Azacoronenes

— —

6-12 8-13 9-15 9-15 11-17 12-19 13-19 14-21 15-21 17-26 17-26 19-26 21-26 21-26 23-26 23-27

— —

— — — —

— — — — 12-20

—

20-29 22-29 22-29 24-29 26-29 28-29 28-30

—

Dibenzocarbazoles Naphthylcarbazoles Naphthobenzo[def]carbazoles Anthracenocarbazoles Anthranylcarbazoles Anthracenobenzo[def]carbazoles Dinaphthocarbazoles

Carbazoles Phenylindoles Benzo[def]carbazoles Benzocarbazoles Phenylcarbazoles

__

__

14-20 14-22 16-24 18-24

Acids Typical Structural Nitrogen Analogs

LRLV C# Range

Carbon Number D i s t r i b u t i o n f o r the Acid and Base F r a c t i o n s From SARA Chromatography Separation.

LRLV C# Range

Table I I I .

Ο *1

I

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SCHWEIGHARDT ET AL.

Heteroatom

Species

Table IV. Compounds Found i n the Nitrogen Base F r a c t i o n of Figure 2. Peak Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Compound Solvent (Carbon D i s u l f i d e ) Phenol Cresol Cresol Tetrahydroquinoline Quinoline 6-Methyltetrahydroquinoline Methylquinoline Isoquinoline Methylquinoline Methylquinoline C -Quinoline C^-Quinoline Octahydro-N-3-Ring (Octahydroacridine) Methyloctahydro-N-3-Ring (Methyloctahydroacr Phenanthridine + A c r i d i n e Methylacridine Azapyrene Methylazapyrene 2

American Chemicef Society Library 1155 15th St. N. W. Wwhrngton, D. C.

200S6

248

ORGANIC CHEMISTRY OF

COAL

compound types assigned to the base f r a c t i o n of the o i l s by GCMS. Table V l i s t s the carbon number range data from the high r e s o l u t i o n mass spectrometry (HRMS) a n a l y s i s of the asphaltenes and t h e i r a c i d / n e u t r a l and base s u b f r a c t i o n s . I t must be noted thag at the operating c o n d i t i o n s of the s o l i d s i n l e t , 300°C, 10 t o r r , l e s s than 50% of the these m a t e r i a l s could be v o l a ­ tilized. These p r e l i m i n a r y studies have a l s o i n d i c a t e d the presence of a l i m i t e d number of diaza-species from Ζ = -8 to -18, where Ζ i s the hydrogen d e f i c i e n c y i n the general formula, CH . The SYNTHOIL PDU contains s e v e r a l knock-out traps that condense low b o i l i n g components, l i g h t o i l s (11). Nitrogen bases i n the l i g h t o i l s were i s o l a t e d by t h e i r p r e c i p i t a t i o n with gaseous HC1 and back t i t r a t e d with NaOH i n t o d i e t h y l ether. These n i t r o g e n bases c o n s t i t u t e d 3% by weight of the l i g h t o i l s . The gas chromatographic p r o f i l e of these bases i s given i n Figure 4. An e a r l i e r study of these l i g h t o i l s c h a r a c t e r i z e d the s a t u r a t e s , aromatics and a c i d i c components separated by Fluorescence I n d i c a t o r A n a l y s i s (FIA) (12). The present i n v e s ­ t i g a t i o n has r e s u l t e d i n the f i r s t q u a n t i t a t i v e a n a l y s i s of p y r i d i n e s and a n i l i n e s i n an o i l produced by the hydrogénation of c o a l . Table VI summarizes the q u a n t i t a t i v e r e s u l t s from the chromatogram of Figure 4. I t i s of i n t e r e s t to point out that during t h i s i n v e s t i g a t i o n , though numerous s u b s t i t u t e d p y r i d i n e s were quantitated, no evidence f o r the parent was found. Because the techniques employed recovered components with b o i l i n g p o i n t s near that of p y r i d i n e i t i s suggested that t h i s observation may be s i g n i f i c a n t . I f f r e e p y r i d i n e was trapped w i t h i n the c o a l macromolecular s t r u c t u r e i t s u r e l y would have been found i n e i t h e r the l i g h t o i l s or the pentane s o l u b l e o i l s . I f , on the other hand, p y r i d i n e was attached exo-, v i a a s i n g l e C-C bond, to a more complex molecular network, the hydrogénation process should have freed i t i n t a c t . But i f the n i t r o g e n heteroatom was an i n t e g r a l part of the o r i g i n a l c o a l macromolecule, then hydrogénation would have cleaved a number of Ca-C3 bonds to produce a wide d i s t r i b u t i o n of methylpyridines. Table VI shows t h i s methyl s u b s t i t u t i o n trend. Q u a n t i t a t i v e r e s u l t s i n d i c a t e that 2,3,6-trimethylpyridine i s seven times more abundant than 2,3dimethylpyridine and approximately twice as abundant as any other methylpyridine. The source of a n i l i n e s and, i n p a r t i c u l a r , the observation of both the parent and the methyl s u b s t i t u t e d a n i l i n e s are of i n t e r e s t . A n i l i n e s can a r i s e from hydrogénation of the heteror i n g i n a fused r i n g system followed by breaking of the bond between n i t r o g e n and an a l i p h a t i c carbon (13). Therefore q u i n o l i n e and i t s a l k y l d e r i v a t i v e could be a source of the anilines. Table IV l i s t s seven q u i n o l i n e s found i n the o i l s that could be the p r e c u r s o r s . The presence of the parent a n i n

5-7 8-11 8-14 9-14 11-16 11-19 13-20 14-20 15-21 17-21 17-21 19-23 21-23 21-23 23,24

Asph

6,8,9 9-12 9-15 9-15 11,12,14-17 11,12,14-19 14-20 14-21 15-22 18-23 19-22 20-23 21-23 21,22

6 8-12 8-14 9-14 11-16 11-17 13-18 14-19 15-20 17-21 17-21 19-22 21 21,22

Asph A Asph Β Carbon Number Range

ions

Pyridines Azaindans Dihydroquinolines; Indoles Quinolines Phenylpyridines Azafluorenes; Carbazoles Acridines Azabenzo[ghi]fluorenes Azapyrenes; Benzocarbazoles Benzacridines Azabenzo[ghi]fluoranthenes Azabenzopyrenes; Dibenzocarbazo Dibenzacridines Azabenzoperylenes Azadibenzopyrenes

P o s s i b l e S t r u c t u r a l Types

Carbon Number Range Data f o r Nitrogen Heteromolecules i n Asphaltenes.

Formulas derived by HRMS represent isomers and fragment as w e l l as molecular ions.

- 5 - 7 - 9 -11 -13 -15 -17 -19 -21 -23 -25 -27 -29 -31 -33

z#

Table V.

J

14

I

16

I

I

18 20

I

22

I

24

I

26

I

28

I

I

32

I

34

Τ I M E , minutes

30

I

36

I

38

I

40

I

42

I

44

I

46

I

48

I

50

I

I

52 54

Figure 4.

Gas chromatogram of nitrogen bases from a coal liquefaction light oil

T E M P E R A T U R E ,°C

62° 70° 78° 86° 94° 102° 110° 118° 126° 134° 142° 150° 158° 166° 174° 182° 190° 198° 206° 214° 222° 230°

12

18.

SCHWEIGHARDT ET

AL.

Heteroatom

Species

251

l i n e , that should r e a d i l y be hydrodenitrogenated (13), i s s i g nificant. I f d e a l k y l a t i o n was the same f o r a l l s p e c i e s , why didn't we see any of the parent p y r i d i n e ? I t could mean that the p o t e n t i a l a n i l i n e moieties are l o c a t e d near the periphery of the c o a l macromolecule i n c o n t r a s t to the p y r i d i n e s . The quant i t a t i v e r e s u l t s i n d i c a t e that m e t h y l a n i l i n e s ( t o l u i d i n e s ) are i n abundance i n the order meta > ortho » para > parent a n i l i n e , and a l l are greater than the d i m e t h y l a n i l i n e s . These i n t e r p r e t a t i o n s are based upon the more d e t a i l e d a n a l y s i s of the light oils. To date d i r e c t evidence f o r the presence of s i g n i f i c a n t amounts of a l k y l a t e d a n i l i n e s and p y r i d i n e s i n the pentane s o l u b l e o i l s from the CLP have not been reported. To complete t h i s i n i t i a l i n v e s t i g a t i o n of n i t r o g e n s p e c i e s we chose to look at the n i t r o g e n compounds present i n the r e c y c l e solvent used f o r SRC processing and compare them with those found i n c o a l l i q u e f a c t i o n product o i l s . A f t e r e x t r a c t i n g the gross benzene s o l u b l e s , they were t r e a t e d with HC1 to i s o l a t e n i t r o g e n bases. T h i s p a r t i c u l a r sample had a s l i g h t r e s i d u e that was benzene i n s o l u b l e . F i g u r e 5 gives the gas chromatographic p r o f i l e of these n i t r o g e n bases and summarizes the prominent s t r u c t u r a l isomers. The base f r a c t i o n from the SRC solvent was l e s s complex than the n i t r o g e n bases found i n the l i q u e f a c t i o n o i l s , but the same p r i n c i p a l molecular species were found i n both samples. The presence of hydroxyl groups i n c o a l - d e r i v e d m a t e r i a l s has long been e s t a b l i s h e d . Our present i n t e r e s t i s to d e f i n e q u a n t i t a t i v e l y the OH as a percentage of the t o t a l oxygen. The s e p a r a t i o n methods described concentrate a high percentage of the hydroxyl groups by anion exchange r e s i n chromatography (acids) or the HC1 treatment ( a c i d / n e u t r a l ) . Once the s e p a r a t i o n / concentration has been made the sample i s t r e a t e d with a d e r i v a t i z i n g reagent to form a t r i m e t h y l s i l y l ether, Ar-O-Si(CH^)^. I t has been shown^that a l l of the hydroxyl groups c o n t r i buting to the 3590 cm i n f r a r e d band can be q u a n t i t a t i v e l y removed with the d e r i v a t i z i n g reagent ( 6 ) . The TMS ethers are next examined by proton NMR. The s i g n a l s near 0 ppm represent the t r i m e t h y l s i l y l (CH^) protons from each of the hydroxyl d e r i v a t i v e s . By i n t e g r a t i n g the area under the t o t a l proton spectrum and a l l o w i n g f o r the 9-fold i n t e n s i t y enhancement f o r the TMS area, the percent H as OH can be c a l c u l a t e d . Table VII l i s t s some r e p r e s e n t a t i v e determinations of hydroxyl content from o i l s and asphaltenes. The s i l y l d e r i v a t i z a t i o n q u a n t i t a t i o n of hydroxyls i n asphaltenes has been compared to the i n f r a red s p e c t r o s c o p i c method of standard a d d i t i o n s (14). Our r e s u l t s agreed to w i t h i n 10%. I n f r a r e d data, and those from others working on s i m i l a r f r a c t i o n s (15) i n d i c a t e s that there i s l i t t l e i f any carbonyl oxygen (C=0) present i n c o a l l i q u e f a c t i o n products produced i n the SYNTHOIL PDU. Therefore, we conclude that s u b s t a n t i a l l y a l l of the oxygen e x i s t s as e i t h e r hydroxyl (phenolic or b e n z y l i c ) or i n an ether linkage (e.g. f u r a n ) .

e

TEMPERATURE ,°C

Figure 5.

Gas chromât ο gram of nitrogen bases from an SRC recycle solvent: (l)N-3 (3) azapyrene, (4) and (5) methylazapyrene.

TIME, minutes

15.0

12.5

10.0 7.5

ring, e.g., acridine, (2) methyl-N-3-ring,

17.5

190° 180° 170° 160° 150° 140° 130° 120°

52.0 50.0 47.5 45.0 42.5 40.0 37.5 35.0 32.5 30.0 27.5 25.0 22.5 20.0

e

298 290 280° 270° 260° 250° 240° 230° 220° 210° 200°

Gas chromatographic profile of bases from Tacoma SRC product

18.

scHWEiGHARDT ET AL.

Table VI.

Peak # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Heteroatom

253

Species

GCMS Results of the A n a l y s i s of the Nitrogen Base Components (16). Wt. % of Base F r a c t i o n

Compound 2-Me t h y l p y r i d ine 2,6-Dimethylpyridine 2-Ethylpyridine 3-Methylpyridine and 4-Methylpyridine 2-Methyl-6-ethylpyridine 2,5-Dimethylpyridine 2,4-Dimethylpyridine 2,3-Dimethylpyridine 2,4,6-Trimethylpyridine 2,3,6-Trimethylpyridine 3,5-Dimethylpyridine 2-Methyl-5-Ethylpyridine Aniline o-Methylaniline p-Methylaniline m-Methylaniline 2,6-Dimethylaniline 2,4-Dimethylaniline 2,5-Dimethylaniline 2,3-Dimethylaniline 3,5-Dimethylaniline and quinoline C ^ - A n i l i n e and I s o q u i n o l i n e 1,2,3,4-Tetrahydroquinoline

0.1 0.5 0.4 0.3 1.2 1.2 2.2 1.7 2.4 3.5 1.5 1.5 6.4 12.8 8.1 15.1 4.9 5.7 5.3 3.2 7.6 2.4 2.2 90.2

These values are based on the assumption that a l l p y r i d i n e s have the same response f a c t o r as 2,4d i m e t h y l p y r i d i n e and a l l a n i l i n e s have the same response f a c t o r as a n i l i n e . The assumption may introduce a small e r r o r i n t o the q u a n t i t a t i v e data. Table V I I .

Hydroxyl D i s t r i b u t i o n i n Solvent Separated F r a c t i o n s Determined By TMS D e r i v a t i z a t i o n .

Fraction Oils Asphaltenes Asphaltenes A c i d / N e u t r a l Asphaltenes Base Preasphaltenes

% H as 0 H 1.2 2.0 2.0 1.5 3.0

± 5 %

% 0 as OH* 67 43 44 49 35

170 184 198 212 226 240 254

Acenaphthenol S e r i e s

Molecular Weights

94 108 122 136 150 164

Phenol Series

Molecular Weights

Table V I I I .

242 256 270 284 298 312 326

TMS Ether

166 180 194 208 222 236

TMS Ether

196 210 224 238 252 266 280

Fluorenol Series

268 282 296 310 324 338 352

TMS Ether

206 220 234 248 262 276

TMS Ether

Molecular Weights

134 148 162 176 190

Indanol S e r i e s

Molecular Weights

TMS D e r i v a t i z e d Hydroxyl Species i n Acid Components From SARA. Separation.

18.

SCHWEIGHARDT ET AL.

Heteroatom

255

Species

MASS 140

160

190

220

250

90

H(fi

Ί

370

340

310

280

100

400

'—'—I—'— —I—'—'—Γ 1

-

80

-

70

-

60

-

50

-

40

-

30

-

20

-

B

10 ~ mil

• Ιΐΐ1ΐι.1ιΐ1ι.ΐ1ι1ι..ΐ1ιιιιι1ΐΐι.111ίι..1ΐ1ΐι.ι111»ι.11ι1

niilii ι

»

100 90

-

80

-

70

-

60

-

50 40 30 20 10 liililllillilliilliliiillliillilililllliillllliillllllilliiiiiii

0 L 70

n

_L 100

130

160

190

220

250

280

310

MASS Figure 6.

Mass spectra of acids before (A) and after (B) TMS derivatization. Note change in mass scale.

ORGANIC CHEMISTRY OF COAL

256

A useful corroboration of the NMR data and of characterizing the acid fraction of the oils is its mass spectrum before and after TMS dérivâtization. Figure 6 A and Β shows the acid components from the pentane soluble oils before and after TMS derivatization, respectively. Note that the mass peaks are shifted 72 amu to give a nearly identical mass distribution. Table VIII lists those hydroxyl containing compounds that def­ initely formed a TMS ether. From the mass spectral data there was also evidence for trace amounts of indenol, naphthol and phenanthrol derivatives. ACKNOWLEDGEMENT The authors acknowledge the cooperation of the following PERC personnel: Sayeed Akhtar and Nestor Mazzocco for providing the coal liquefaction products and associated data, Dennis Finseth for taking the infrared spectra, Y. C. Fu for providing the SRC samples, Joseph Malli for providing the mass spectra, and Tljomas Link for taking the NMR spectra. By acceptance of this article, the publisher and/or recip­ ient acknowledges the U. S. Government's right to retain a non­ exclusive, royalty-free license in and to any copyright covering this paper. LITERATURE CITED 1. Schweighardt, F. K., ERDA-PERC/RI-77/3. 2. Sternberg, H. W., Raymond, R., and Schweighardt, F. Κ., Preprints, Div. Fuel Chem., (1976), 21(7), 1. 3. Sternberg, H. W., Raymond, R., and Schweighardt, F. K., Science, (1975), 188, 49. 4. Langer, S. H., Connell, S., and Wender, I., J. Org. Chem., (1958), 23, 50. 5. Friedman, S., Kaufman, M. L., Steiner, W. Α., and Wender, I., Fuel, (1961), 40, 33. 6. Brown, F. R., Makovsky, L. E., Friedman, S., and Schweig­ hardt, F. K., Appl. Spectrosc., (1977), 31, 241. 7. Schweighardt, F. K., Retcofsky, H. L., Friedman, S., and Hough, M., Anal. Chem., in press. 8. Jewell, D. Μ., Weber, J. H., Bunger, J. W., Plancher, H., and Latham, D. R., Anal. Chem., (1972), 44, 1391. 9. Yavorsky, P. Μ., Akhtar, S., and Friedman, S., Chem. Eng. Prog., (1973), 69, 51. 10. Shultz, J. L., White, C. M., and Schweighardt, F. K., ERDA­ -PERC/RI-77/7. 11. Schultz, H., Gibbon, G. Α., Hattman, Ε. Α., Booher, Η. B., and Adkins, J. W., ERDA-PERC/RI-77/2. 12. White C. M. and Newman, J. O. H., ERDA-PERC/RI-76/3. 13. Poulson, R. E., Preprints, Div. Fuel Chem., (1975), 20(2), 183.

18.

SCHWEIGHARDT ET AL.

Heteroatom

Species

14. Finseth, D. H., private communication. 15. Brown, F. R., private communication. 16. White, C. M., Schweighardt, F. K., and Shultz, J. L., Fuel Processing Technology, in press. RECEIVED February 10,

1978

257