Geochemistry and Chemistry of Oil Shales - American Chemical Society

28 Organic-Mineral Matter Interactions in Green River Oil Shale Downloaded by UNIV OF NEW SOUTH WALES on April 12, 2016 | http://pubs.acs.org Publication Date: August 1, 1983 | doi: 10.1021/bk-1983-0230.ch028

K. M. JEONG and T. P. KOBYLINSKI Gulf Research & Development Company, Pittsburgh, PA 15230

A chemical extraction procedure was used to preferentially disassociate the carbonate and silicate mineral matrices in Colorado Green River (Mahogany Zone) oil shale. The percentages of organic matter isolated in two sets of acid/ether extracts were determined. Approximately four times more bitumen-free organic matter appears to be associated with the silicate mineral matrix than the carbonate minerals. Benzene/methanol Soxhlet extraction results indicate that up to 21 wt% of the bitumen in these samples is trapped by the carbonate mineral matrix. The bitumen-free organic matter extracted in association with the two mineral types can be considered to be a portion of the interfacial layer between kerogen and the inorganic mineral matrix. Spectroscopic identification of the interlayer structures indicated several differences in the composition of the two acid/ether extracted organic fractions which suggest possible types of kerogen-mineral matter bonding effects. One major distinction is a larger concentration of ester functional groups in the ether extracted organic matter associated with the silicate mineral matrix. Relatively more olefins and branched paraffins were identified with the carbonate mineral matrix. These results are discussed in terms of possible chemical bonding and physisorption interactions. O i l shales contain large q u a n t i t i e s of insoluble organic matter, k e r o g e n , w h i c h upon p y r o l y s i s a t h i g h e r temperatures, y i e l d s o i l products. K e r o g e n , w h i c h u s u a l l y r e p r e s e n t s 80-90% o f the t o t a l o r g a n i c matter i n Green R i v e r o i l s h a l e s , i s n e i t h e r s o l u b l e i n aqueous a l k a l i n e / a c i d i c s o l v e n t s n o r i n t h e common 0097-6156/ 83/0230-0493S06.00/0 © 1983 A m e r i c a n C h e m i c a l S o c i e t y

Miknis and McKay; Geochemistry and Chemistry of Oil Shales ACS Symposium Series; American Chemical Society: Washington, DC, 1983.

Downloaded by UNIV OF NEW SOUTH WALES on April 12, 2016 | http://pubs.acs.org Publication Date: August 1, 1983 | doi: 10.1021/bk-1983-0230.ch028

494

GEOCHEMISTRY A N DCHEMISTRY OF OIL SHALES

o r g a n i c s o l v e n t s a t m i l d c o n d i t i o n s . The r e m a i n i n g 10-20% o f t h e o r g a n i c f r a c t i o n i n s h a l e i s e x t r a c t a b l e w i t h o r g a n i c s o l v e n t s and i s r e f e r r e d t o a s b i t u m e n . The m i n e r a l c o n s t i t u e n t s o f o i l s h a l e , g e n e r a l l y f a r more a b u n d a n t t h a n k e r o g e n , v a r y l a r g e l y a c c o r d i n g to types, but u s u a l l y i n c l u d e carbonate, c l a y , and s i l i c a t e minerals. R e l a t i v e l y l i t t l e i n f o r m a t i o n i s c u r r e n t l y a v a i l a b l e concerni n g t h e a s s o c i a t i o n between k e r o g e n o r bitumen and t h e m i n e r a l matter phase. The o b j e c t i v e o f t h i s s t u d y was t o f u r t h e r c h a r a c t e r i z e t h e n a t u r e o f t h e b o n d i n g between t h e s e s h a l e c o n s t i t u e n t s u s i n g a c h e m i c a l e x t r a c t i o n p r o c e d u r e f o l l o w e d by s p e c t r o s c o p i c s t u d i e s , F o u r i e r T r a n s f o r m I n f r a r e d ( F T I R ) and N u c l e a r M a g n e t i c R e s o n a n c e (NMR), o f t h e v a r i o u s s e p a r a t e d f r a c t i o n s . Additional i n f o r m a t i o n on t h e m i n e r a l and o r g a n i c m a t t e r composition i s o b t a i n e d from p a r t i c l e s i z e d i s t r i b u t i o n data. Although there have b e e n s e v e r a l s t u d i e s u s i n g a n a l o g o u s a n a l y t i c a l p r o c e d u r e s t o i n v e s t i g a t e m a r i n e s e d i m e n t s , (O studies of the a s s o c i a t i o n between o r g a n i c and m i n e r a l m a t t e r i n o i l s h a l e have been v e r y l i m i t e d . (2_-_5) T h i s i n f o r m a t i o n may a l s o be u s e f u l t o w a r d u n d e r s t a n d i n g t h e f o r m a t i o n o f o i l s h a l e d e p o s i t s and perhaps p r o v i d e insight into beneficiation and enrichment of the organic matter. (6) The m i n e r a l m a t t e r p h a s e i n s a m p l e s o f C o l o r a d o G r e e n R i v e r o i l s h a l e ( C - a t r a c t , Mahagony Zone) was p r e f e r e n t i a l l y d i s a s s o c i a t e d i n a s e r i e s o f a c i d e x t r a c t i o n s (HC1, HF) i n o r d e r t o s e p a r a t e l y i s o l a t e carbonate and s i l i c a t e m i n e r a l s . ( B i t u m e n was removed u s i n g t h e b e n z e n e / m e t h a n o l S o x h l e t e x t r a c t i o n method.) I t i s w e l l known t h a t a t v a r y i n g c o n c e n t r a t i o n s o v e r a r a n g e o f t e m p e r a t u r e s , HC1 d i s s o l v e s most c a r b o n a t e s and t h a t p u r e HF o r HF/HC1 m i x t u r e s e f f e c t i v e l y remove s i l i c a t e s , q u a r t z , a n d c l a y m i n e r a l s . (J_ S) A l t h o u g h t h e m i n e r a l s e n c a p s u l a t e d by k e r o g e n c a n n o t be e x t r a c t e d by a n a c i d t r e a t m e n t , p a r t i c l e s i z e d i s t r i b u t i o n d a t a a n d a s h c o n t e n t measurements i n d i c a t e t h i s t o be a m i n o r problem. The r e l a t i v e amounts o f a c i d / e t h e r e x t r a c t e d o r g a n i c s i s o l a t e d w i t h b o t h c a r b o n a t e s and s i l i c a t e s w e r e d e t e r m i n e d , a s was t h e f r a c t i o n o f b i t u m e n t r a p p e d by e a c h o f t h e s e m i n e r a l s . The d a t a a r e d i s c u s s e d i n t h e c o n t e x t o f o t h e r p u b l i s h e d r e s u l t s as w e l l a s p o s s i b l e t y p e s o f b o n d i n g b e t w e e n k e r o g e n and m i n e r a l matter. 9

Experimental Samples o f C o l o r a d o Green R i v e r o i l s h a l e were o b t a i n e d f r o m t h e C-a t r a c t , Mahagany Zone. The m i n e - r u n s a m p l e s o f 7.6 cm x 0.64 cm m a t e r i a l were s t a g e - c r u s h e d t o p a s s a 5.1 cm s c r e e n and were s c r e e n e d a t 0.64 cm t o remove f i n e s . Shales o f three d i f f e r e n t r i c h n e s s e s were i s o l a t e d by heavy m e d i a l i q u i d s g r a v i t a t i o n a l s e p a r a t i o n ( 9 ) a n d d e t e r m i n e d by F i s c h e r a s s a y t o h a v e a n o r g a n i c content of 104 L / t ( d e n s i t y >2.25 g c m " ) , 129 L / t ( d e n s i t y >1.65 g c m " ) , and 184 L / t ( d e n s i t y

Caf_ Fef_ K°_ Wt%

Orig

43

6.3

12.0

1.9

LTA

47

8.6

12.9

Orig

50

5.9

LTA

55

Orig

c

499

o i l shale

c

C

Mn ppm

P

S S i wt%

1.4

100

0.4

0.6 12.5

1.8

1.5

150

0.5

1.0 15.0

9.1

2.7

1.8

200

0.4

0.8 16.2

6.5

10.4

2.9

2.0

350

0.5

1.0 18.7

87

6.4

6.9

3.5

1.9

200

0.4

1.4 14.9

108

8.7

8.5

4.0

2.4

350

0.7

1.4 18.8

c

g


104

129

184 LTA

INAA = I n s t r u m e n t a l n e u t r o n a c t i v a t i o n a n a l y s i s DRES = DC A r c E m i s s i o n S p e c t r o s c o p y XRF = X - r a y f l u o r e s c e n c e a n a l y s i s

The HC1 e x t r a c t i o n p r e f e r e n t i a l l y s e p a r a t e d c a r b o n a t e m i n e r a l s from t h e remaining mineral matter matrix. As T a b l e I I I i n d i c a t e s f o r t h e 184 L / t o i l s h a l e , a p p r o x i m a t e l y 9 9 % o f t h e C a and a p p r o x i m a t e l y 9 6 % o f t h e Mg were removed a s e x p e c t e d . The bitumen- and c a r b o n a t e - f r e e f r a c t i o n i s a l s o found t o c o n t a i n about 28% l e s s A l w h i c h i s p r o b a b l y a s s o c i a t e d w i t h o t h e r m i n e r a l m a t t e r ( e . g . , a l b i t e a n d a n a l c i m e ) p a r t i a l l y s o l u b l e i n HC1. ( T h e r a t h e r l a r g e d e c r e a s e i n t h e F e c o n c e n t r a t i o n f r o m 3.7 w t % i n t h e b e n z e n e / m e t h a n o l t r e a t e d o i l s h a l e t o 1.2 w t % f o r t h e HC1 t r e a t e d s h a l e i s due t o m e c h a n i c a l m a g n e t i c s e p a r a t i o n d i s c u s s e d i n t h e e x p e r i m e n t a l s e c t i o n a n d d i s s o l u t i o n by HC1 o f m i n e r a l s s u c h a s a n k e r i t e and s i d e r i t e . ) The HC1 e x t r a c t i o n r e s u l t e d i n a w e i g h t l o s s o f 28.6 wt%. I t i s determined t h a t a t l e a s t 0.45 a n d 0.38 w t % o f t h e t o t a l o r g a n i c s i n t h e 104 a n d 184 L / t d r i e d o i l shale, respectively, are recoverable i n the HCl/ether extracts and, t h u s , a r e i n t i m a t e l y a s s o c i a t e d w i t h c a r b o n a t e m i n e r a l s . I n a d d i t i o n , t h e r e s u l t s o f t h e s e c o n d benzene/ m e t h a n o l S o x h l e t e x t r a c t i o n i n d i c a t e t h a t 3.40 a n d 3.65 w t % o f t h e t o t a l o r g a n i c s w h i c h a r e b i t u m e n i n t h e s e two s a m p l e s a r e r e l e a s e d when t h e c a r b o n a t e m i n e r a l s a r e removed f r o m t h e s h a l e .


500

GEOCHEMISTRY AND CHEMISTRY OF OIL SHALES

Table I I I

M u l t i e l e m e n t a l a n a l y s i s (wt%) o f o r i g i n a l and t r e a t e d G r e e n R i v e r o i l s h a l e s a m p l e s ' * * (104 L / t s a m p l e ) 3


Element Wt Fraction Al * As B Ba Ca Cr Cu Fe K Mg Mn Mo Na Ni Si Sr Ti

Original O i l Shale

Benzene/Methanol Treated O i l Shale

100.0 6.4 87.1 ppm 0.021 0.11 5.1 0.03 0.003 3.6 1.9 4.4 0.083 0.57 0.018 15 0.08 0.28

97.1 5.9 88.1 ppm 0.015 5.2 0.03 0.004 3.7 2.0 4.5 0.074 0.59 0.015 15 0.07 0.30

HCl-Treated O i l Shale

HF/HCl-Treated O i l Shale

68.6 4.6

29.6 0.64

0.013 0.08 0.04 0.01 0.003 1.2 1.2 0.18 0.013 0.04 0.009 14

0.05 0.04 0.01 0.003 0.96 0.23 0.17 0.006 0.005 0.04 0.003 0.62 0.01 0.07

DC A r c E m i s s i o n S p e c t r o s c o p y , v a l u e s g i v e n i n w t % Mahogany Zone C-a T r a c t , 100 x 200 mesh o i l s h a l e Instrumental Neutron A c t i v a t i o n A n a l y s i s

The HF/HCI e x t r a c t i o n r e s u l t s i n t h e r e m o v a l o f a p p r o x i m a t e l y 96% o f t h e e l e m e n t a l S i p r e s e n t as w e l l a s a p p r o x i m a t e l y 90% o f t h e A l ( s e e T a b l e I I I ) . The t o t a l amount o f H F / e t h e r e x t r a c t e d o r g a n i c s i s a t l e a s t 1.72 a n d 1.34 w t % o f t h e t o t a l o r g a n i c c o n t e n t i n t h e 104 a n d 184 L / t o i l s h a l e . A p p r o x i m a t e l y 1.64 a n d 2.00 w t % o f t h e t o t a l o r g a n i c s a r e t r a p p e d by t h e s i l i c a t e m i n e r a l s a s d e t e r m i n e d by t h e r e s u l t s o f t h e t h i r d b e n z e n e / m e t h a n o l S o x h l e t e x t r a c t i o n f o r t h e two d i f f e r e n t s h a l e r i c h n e s s e s . T h e above r e s u l t s a r e s u m m a r i z e d i n T a b l e I V . I n t h i s study, an e x t r a c t i o n approach t o t h e problem o f a t t r a c t i v e i n t e r a c t i o n s i n G r e e n R i v e r (Mahogany Zone) o i l s h a l e r e s u l t e d i n t h e p r e f e r e n t i a l d i s s o l u t i o n o f both carbonate and s i l i c a t e minerals. As t h e r e s u l t s i n T a b l e I V i n d i c a t e , t h e interfacial organic layer between k e r o g e n a n d t h e i n o r g a n i c m i n e r a l m a t r i x was a l s o s i m u l t a n e o u s l y s e p a r a t e d . Since t h e majority o f t h e b i t u m e n was removed i n t h e i n i t i a l b e n z e n e /


28.

JEONG AND KOBYLINSKI

Table

Organic-Mineral

Matter

Interactions

501

IV Organic matter d i s t r i b u t i o n o f t r e a t e d o i l shale e x t r a c t s based on wt% o f t o t a l o r g a n i c s 8

104 GPT O i l Shale I II III T o t a l Bitumen Downloaded by UNIV OF NEW SOUTH WALES on April 12, 2016 | http://pubs.acs.org Publication Date: August 1, 1983 | doi: 10.1021/bk-1983-0230.ch028

Bitumen

Carbonate A s s o c i a t e d E t h e r E x t r a c t I A/N Ether Extract I N Ether Extract I B Total Extracts I

129 L / t O i l Shale

184 L / t O i l Shale

13.48 3.40 1.64 18.52

16.14 3.44 0.05 19.63

11.80 3.65 2.00 17.45

0.15 0.21 0.09 0.45

0.18 0.19 0.11 0.48

0.18 0.13 0.07 0.38

1.33 0.09 0.30 1.72

0.26 0.17 0.02 0.45

0.50 0.62 0.22 1.34

Organics

S i l i c a t e Associated Organics E t h e r E x t r a c t I I A/N Ether Extract I IN Ether Extract I I B Total Extracts I I

T o t a l o r g a n i c c o n c e n t r a t i o n s based on e l e m e n t a l a n a l y s i s a r e d e t e r m i n e d t o be 1 3 . 5 , 1 6 . 2 , 22.9 w t % f o r 104, 1 2 9 , a n d 184 L / t o i l s h a l e s , r e s p e c t i v e l y . methanol Soxhlet e x t r a c t i o n s t e p , these i n t e r f a c i a l s t r u c t u r e s a s s o c i a t e d w i t h e i t h e r carbonate o r s i l i c a t e m i n e r a l s c a n be c o n s i d e r e d t o b e a f o r m o f k e r o g e n . Due t o t h e i n f l u e n c e o f t h e s e m i n e r a l bonding s i t e s and t h e i r d i s s o l u t i o n during t h e a c i d treatment, the acid/ether extracted organic matter may h a v e s l i g h t l y d i f f e r e n t p r o p e r t i e s than t h e bulk kerogen m a t e r i a l . I t i s d e t e r m i n e d t h a t a p p r o x i m a t e l y f o u r t i m e s more b i t u m e n f r e e o r g a n i c m a t t e r a p p e a r s t o be a s s o c i a t e d w i t h t h e s i l i c a t e mineral matrix than w i t h carbonate minerals. (The a n o m a l o u s l y l o w r e s u l t s f o r t h e 129 L / t sample a r e b e i n g r e - i n v e s t i g a t e d . ) This i s p r o b a b l y a l o w e r bound, b e c a u s e o f t h e i n h e r e n t p r o b l e m s o f s e p a r a t i n g k e r o g e n f r o m t h e m i n e r a l m a t r i x by a c i d leaching methods. The s p e c t r o s c o p i c d a t a d i s c u s s e d i n t h e n e x t s e c t i o n provide f u r t h e r i n s i g h t i n t o t h e composition o f t h e kerogenc a r b o n a t e / s i l i c a t e i n t e r f a c i a l l a y e r a n d what t y p e s o f i n t e r a c t i o n s may c o n t r i b u t e t o t h e b i n d i n g f o r c e s i n t h e s e o i l s h a l e samples• The b e n z e n e / m e t h a n o l S o x h l e t e x t r a c t i o n d a t a s u m m a r i z e d i n T a b l e I V i n d i c a t e t h a t 27 a n d 32 w t % o f t h e b i t u m e n f o r t h e 104 and 184 L / t o i l s h a l e i s t r a p p e d by t h e i n o r g a n i c m i n e r a l m a t r i x



502


and thus, n o t a c c e s s i b l e t o removal i n t h e i n i t i a l Soxhlet e x t r a c t i o n . The d a t a a l s o s u g g e s t t h a t t r a p p i n g o f b i t u m e n o c c u r s t o a g r e a t e r e x t e n t by t h e c a r b o n a t e m i n e r a l m a t r i x . A previous s t u d y (_3) o f c a r b o x y l i c a c i d s i n G r e e n R i v e r o i l s h a l e b i t u m e n h a s s u g g e s t e d t h a t a s t r o n g i n t e r a c t i o n e x i s t s between these a c i d s and the m i n e r a l m a t r i x , p a r t i c u l a r l y c a r b o n a t e m i n e r a l s . Further e v i d e n c e f o r t h e c o u p l i n g between m i n e r a l s and bitumen f a c i l i t a t e d by c a r b o x y l i c a c i d s i s p r o v i d e d by t h e r e s u l t s o f h i g h p r e s s u r e CO2 d i s a g g r e g a t i o n o f Green R i v e r o i l s h a l e (4_) a n d c a t i o n exchange e x p e r i m e n t s i n v o l v i n g u n t r e a t e d a n d a c i d t r e a t e d o i l s h a l e . (5_) A l t h o u g h t h e b i t u m e n f r a c t i o n s o b t a i n e d i n t h i s s t u d y were not s p e c t r o s c o p i c a l l y analysed f o r specific chemical c o n s t i t u e n t s , t h e d a t a summarized i n T a b l e I V i n d i c a t e a s t r o n g i n t e r a c t i o n , i n c l u d i n g t r a p p i n g , between bitumen and t h e c a r b o n a t e m i n e r a l m a t r i x i n agreement w i t h t h e p r e v i o u s s t u d i e s . Spectroscopic

A n a l y s i s and Organic Matter C h a r a c t e r i z a t i o n

I t i s w e l l e s t a b l i s h e d t h a t c e r t a i n o r g a n i c compounds r e a c t r e a d i l y w i t h b o t h h y d r o c h l o r i c and h y d r o f l u o r i c a c i d s t o a l t e r chemical/physical properties. F o r example, e s t e r s , amides, olefins, quinones, and a l c o h o l s undergo v a r i o u s h y d r o l y s i s , a d d i t i o n , and a l k y l h a l i d e f o r m a t i o n r e a c t i o n s i n t h e presence o f HC1. ( 1 2 , 1 3 ) I n t h e c a s e o f HF, c o n d e n s a t i o n r e a c t i o n s i n v o l v i n g o l e f i n s a n d a r o m a t i c compounds o c c u r r e a d i l y . ( 1 3 ) T h e r e f o r e , t h e i n t e n s i t y o f s e v e r a l m a j o r I R bands c o r r e s p o n d i n g t o c h a r a c t e r i s t i c s t r e t c h i n g a n d b e n d i n g modes were m o n i t o r e d d u r i n g t h e c h e m i c a l e x t r a c t i o n p r o c e d u r e ( e . g . , OH a n d C^C s t r e t c h i n g v i b r a t i o n s ) . S i n c e no s u b s t a n t i a l d i f f e r e n c e s i n t h e s p e c t r a were o b s e r v e d , i t i s concluded t h a t i n s i g n i f i c a n t chemical rearrangement occurred during the p r e f e r e n t i a l d i s a s s o c i a t i o n procedure. Therefore, t h e r e s u l t s summarized i n T a b l e IV r e p r e s e n t o r g a n i c m a t t e r a s s o c i a t e d w i t h e i t h e r carbonate o r s i l i c a t e minerals as i t n a t u r a l l y occurs a t t h e i n t e r f a c e between k e r o g e n and t h e m i n e r a l m a t t e r m a t r i x . FTIR a n a l y s i s o f t h e v a r i o u s a c i d / e t h e r e x t r a c t e d f r a c t i o n s i n d i c a t e s c e r t a i n s t r u c t u r a l s i m i l a r i t i e s as w e l l as d i f f e r e n c e s between t h e o r g a n i c m a t t e r a s s o c i a t e d w i t h c a r b o n a t e m i n e r a l s a n d that associated with s i l i c a t e minerals (see Figure 2 ) . The c h a r a c t e r i z a t i o n o f o i l s h a l e by FTIR i s b a s e d o n t h e a s s i g n m e n t o f s e v e r a l I R bands ( 1 4 ) a n d t h e i r r e s p e c t i v e a b s o r b a n c e s ( 1 5 ) w h i c h a r e s u m m a r i z e d i n T a b l e V. Both t h e o i l s h a l e e t h e r e x t r a c t s a s s o c i a t e d w i t h carbonate and s i l i c a t e m i n e r a l s a r e found to contain insignificant concentrations of molecular water, a l c o h o l s , a n d a r o m a t i c compounds. The l a s t o b s e r v a t i o n i s a l s o c o n s i s t e n t w i t h NMR d a t a t o be d i s c u s s e d b e l o w . Although t h e a s s i g n m e n t o f t h e a r y l - a l k y l e t h e r bands i s somewhat u n c e r t a i n , a d e f i n i t e t r e n d among t h e s p e c t r a i s o b s e r v e d . ( 1 6 ) Since t h e bands a r e n o t p r e s e n t i n t h e HC1 f r a c t i o n s b u t do o c c u r i n t h e HF/HCI e x t r a c t s w i t h t h e l a r g e s t i n t e n s i t y f o r t h e pH 1 s a m p l e , a p r e f e r e n t i a l s i l i c a t e — a r y l - a l k y l ether a s s o c i a t i o n i s suggested.



Figure2. FTIR spectra ofether extracted (at ρ Η 6.5) HCl (a) and HFj H CI (b)fractions (184 L/t sample).


Ο

g

ι

I

I

a'

Ι

r

s

Ο

ο >

m Ο

ρο

504



I t i s determined t h a t both groups o f a c i d / e t h e r e x t r a c t e d o r g a n i c s a r e p r e d o m i n a n t l y p a r a f f i n ! c . The F T I R s p e c t r a i n d i c a t e t h a t the [CH^J/fCI^] r a t i o s i n the s e r i e s o f ether e x t r a c t s o f t h e organics associated with s i l i c a t e minerals increase with i n c r e a s i n g pH: 0.40, 0.44, a n d 0.54. T h i s seems t o i n d i c a t e t h e p r e s e n c e o f more h i g h l y b r a n c h e d compounds a n d / o r s m a l l m o l e c u l e s w i t h i n c r e a s i n g pH. B y c o m p a r i s o n , a r a t i o o f 0.48 i s d e t e r m i n e d f o r the n e u t r a l f r a c t i o n o f t h e H C l / e t h e r e x t r a c t e d sample. These relatively high r a t i o s a r e consistent: w i t h t h e high hydrogen c o n t e n t o f G r e e n R i v e r o i l s h a l e s ( a t o m i c H/C ^ 1 . 5 - 1 . 6 ) .

Table V

I R Band a s s i g n m e n t s

v (cm ^ 3430 3100-3000 2962 2930 2872 2860 1735 1712 1630 1620 1455 1185 1125, 1030 890 870, 820, 750 720

V i b r a t i o n a l Mode OH s t r e t c h CH s t r e t c h ( a r o m a t i c s ) A s y m m e t r i c CH3 s t r e t c h Asymmetric C H s t r e t c h S y m m e t r i c CH3 s t r e t c h S y m m e t r i c CH? s t r e t c h 0=0 s t r e t c h t e s t e r s ) C=0 s t r e t c h ( k e t o n e s , a l d e h y d e s ) C=0 s t r e t c h ( b r i d g e d q u i n o n e s ) C=C s t r e t c h A s y m m e t r i c C H a n d CH3 b e n d C-0 s t r e t c h C-0 v i b r a t i o n ( a r y l - a l k y l e t h e r s ) CH =C bend Out o f p l a n e d e f o r m a t i o n a r o m a t i c CH Skeletal vibration, s t r a i g h t chains > 9 CH 2

2

2

2

Both t h e organics a s s o c i a t e d w i t h carbonate minerals and those associated w i t h s i l i c a t e minerals contain long a l i p h a t i c c h a i n s a s e v i d e n c e d by t h e s i g n i f i c a n t a b s o r b a n c e i n t h e s e s p e c t r a a t 720 cm" . However, t h e d a t a i n d i c a t e t h a t r e l a t i v e l y more o f these chains a r e present w i t h t h e organics a s s o c i a t e d w i t h t h e s i l i c a t e m i n e r a l group. O b s e r v a t i o n o f t h i s s t r o n g band i s a l s o a t t r i b u t e d t o the r e l a t i v e l y h i g h hydrogen c o n t e n t o f the o r i g i n a l samples. The C=C s t r e t c h i n g v i b r a t i o n i s i d e n t i f i e d i n t h e HC1 e x t r a c t s , a l t h o u g h t h e i n t e n s i t y i s a p p r o x i m a t e l y a t e n t h o f t h e CH3 symmetric bending v i b r a t i o n . T h i s band d i s a p p e a r s e n t i r e l y i n t h e HF/HCI e x t r a c t s p e c t r a a t a l l t h r e e pH's i n v e s t i g a t e d . These r e s u l t s a r e i n c o n t r a s t t o t h e d a t a o b t a i n e d by S p i r o ( 2 ) f o r some I s r a e l i o i l shales using a s i m i l a r procedure as that described i n



28.

JEONG AND KOBYLINSKI

Organic-Mineral

Matter

Interactions

505

t h i s study. S p i r o ( 2 ) r e p o r t s r e l a t i v e l y high absorbance r a t i o s f o r O C / C H 3 , g e n e r a l l y b e t w e e n 0.1 a n d 0.5. The h i g h e r v a l u e s a r e predominantly i d e n t i f i e d with organics associated with s i l i c a t e s r a t h e r than w i t h carbonate minerals as t h e r e s u l t s o f t h i s study w o u l d seem t o i n d i c a t e . The band a s s i g n e d t o t h e CH2=C b e n d i n g mode i s o b s e r v e d i n b o t h t h e HC1 a n d HF/HCI s p e c t r a . The c a l c u l a t e d c o n c e n t r a t i o n r a t i o s C ^ K l / C ^ - K ^ a r e f a i r l y c o n s t a n t among t h e t h r e e HF pH s a m p l e s , 0.002,

Geochemistry and Chemistry of Oil Shales - American Chemical Society

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