Characterization by NMR of the fractions obtained by extrography on coal extracts

Journal of Molecular Structure, 143 (1986) 545-548 Elsevier Science Publishers B.V., Amsterdam -Printed

CHARACTERIZATION

545 in The Netherlands

BY NMR OF THE FRACTIONS

OBTAINED

BY EXTROGRAPHY

ON COAL EXTRACTS

S. R. MOINELO, Instituto

A. GARCIA,

National

J. BERMEJO

de1 CarbBn,

Apdo.

and R. MENENDEZ

73, 33080-Oviedo

(Spain)

ABSTRACT Extracts in pyridine of three coals of different rank are fractionated into seven class-compounds by Extrography. Proton NMR analysis of these fractions shows pronounced structural differences between fractions of a given coal, and between identical fractions of different coals. The aliphatic/aromatic hydrogen ratio decreases with the coal rank, as well in passing from I to IV fraction, remaining constant for the other three fractions. Proton NMR analysis in conjunction with Extrography is useful for the characterization of coal extracts because of its rapidity and simplicity.

INTRODUCTION The

liquid

liquefactions to

products

obtained

and extractions,

acquire

on their

a good

characterization,

it

fractions

in which

separation increase

and molecular

to

are gathered

according

is a novel

separation

size

analysis

the

which

to gather

and

time

separated

the different

species

be

a

(ref.

of hydrocarbons

of

which

refers

to

a

compounds a gradual

of increasing are

polarity

monitored

by thin

2). In addition,

information

the

about

fractionation

in individual

into

of

(ref.

valuable

separation

with

separations

because

For

solvents

of fractions

gives

interpreted

in order fuels.

extraction by

NMR spectroscopy

as

functionality.

name

elution

1). These

such

and

a previous

selective

Sequential

fractions

easily

out

chemicals

to their the

the separation

IR and

is more

carry

processes,

to be characterized into

technique, to

gel.

promotes

in a short

NMR

seems

silica

polarity

chromatography, of

which onto

layer

distribution

and need

transformations

is necessary

adsorbed in their

later

conversion

components

mechanism

previously

coal

are very complex

information

Extrography

from

makes

1H

hydrogen it possible

fractions.

EXPERIMENTAL Three of their tes,

coals

different

LP;

bituminous

a high coal

of

different

carbon volatile

rank

content.

were

Analyses

bituminous

from

Polio,HP

- are

in

pyridine

were

coal

utilized.

They

of these from

in Table

were

coals

Lieres,

selected

- a brown HL;

1, as well

and

on the

basis

from

Puen-

coal

a medium

volatile

as those of their

extracts

in pyridine. The ground

extracts

to 250 mesh,

0022-2860/86/$03.50

and later

obtained

fractionated

by

Soxhlet

by Extrography.

0 1986 Elsevier Science Publishers B.V.

extractions

of

the

coals

546 TABLE

1

Analysis

of coals

and their

extracts

(daf basis)

Coals LP HL HP

Extracts

cm

H(X)

65.5 83.3 86.1

5.9 5.7 5.5

The samples

OH(%)

Extrography dissolved

activated solvent

was

a glass

column.

chloroform;

obtaining

fractions

(IV), basic obtained

adsorbed

110s

C and

following

of aliphatics

of NMR spectra

under

was as follows:

Hn, CH3, CH2, and CH alpha

and the

Proton

from

The

packed

into

hexane/36% and

pyridine,

(III), monophenols

NMR spectra

VII was

were

obtained

or chloroform,

conditions.

ring: 2.0-3.4

4-5%.

(VI). Fraction

pyridine

instrumental

further

silica

ethanol;

compounds

previously

to

n-hexane;

(II), heteroaromatics

in deuterated

standard

or

dried

was utilized:

pyridine.

1). In short:

had been

adjusted

chloroform/7%

to an aromatic

CH beta

content

vacuum

(ref.

gel which

The

using

assignement

ppm.

an aromatic

ring

+ paraffinic

CH2

CH3: 0.5-1.0

ppm.

. 0 ppm .

,c,“dCIYH:b_, :.

I-$, CH3 gamma H ar, aromatic

water

ether;

dissolved

equipment

and

its

described

silica

sequence

with

fraction

80 MHz Varian

”

previously onto

(V) and high polar

extraction

of each

as

(I), aromatics

compounds

by Soxhlet

3.5 4.2 3.2

under

solvent

chloroform/5%

nitrogen

aliquots

out

were

by destillation

The

OH(%)

IO.7 6.1 6.0

carried

it at

removed

benzene;

from

was

in pyridine

by heating

H(%)

C(X) 78.4 83.2 86.4

6.5 4.6 3.9

or further

+ phenoiic:

from

an aromatic

6.0-10.0

ring

+ paraffinic

ppm.

RESULTS Figure fractions

in fractions contain

1 shows

obtained

percentage

also

HL, 79.7% from Figure

The signals

of the

definite The first as is deduced respectively.

the

sorts

of their

fraction

of the

Figure

that

most

extracts

in

the

seven

by oils; the products and

the

last

three

of the extracted

fractions compounds

83.8% of the material

extracted

LP. of the

fractions

of Ha1 belonging

higher

its Hal content:

coal

asphaltenes;

(IV-VII ) which contain

‘H NMR spectra

different

because from

of V are

HP, and 69.2% from

2 shows

of

I and II are formed

or asphaltoles.

in the same

are in the four last fractions from

part

polar compounds be seen

distribution

Fraction

III, IV, and a small

the highest

It can

the

by Extrography.

functional coals 95.2%;

obtained

to last

complexity

consists 98.2%;

are

and molecular

mainly and

from

fractions of aliphatic

each much

coal. less

magnitude. hydrocarbons,

100% for HP; HL; and LP,

541

@

q

Oils

30 -

Asphaltenes

0

LP

Asphaltoles

HL

HP

liI Fractions

Fig.

I. Distribution

of the extracts

a

in the fractions

obtained

b

6

6

L

2

by Extrography C

0

8

6

L

2

I

0

8

6

I

2

0

d ( p.p.m.1 Fig. 2. ‘H NMR spectra The values Hy reveal paraffins pattern

the

existence

decreases

(ref.

3). In the

fractions

a number

of

to Burke

2.0 ppm),

from

-CH2to

than

to the coal

HP only 5. The

and

HP.

The values

The multiplity

n > 5 according

4) in HB 1 (from

paraffinic

rank.

in such a way that at

LP and

higher

et al. (ref.

belonging

peak

LP; LJ, HL; and 5

hydrocarbons.

n increases

a single

3

ratio

of long chain

as the into

have to

fractions:

of Hal are in inverse

coalesces

according

of coal

the

of

-(CH ) - in 2n methylene multiplete

to Bartz

one signal signals

of H and B

appears,

of g protons

and

Chamberlain

therefore can

be

they divided

1.0 to 1.4 ppm) and HB2 (from

naphthenic

protons

respectively.

1.4

Fraction

I of HL has a higher

Ha2 and a lower

the existence

structures

The fraction, and,

of ciclic

values

increases

about

from

of Ha (from

with

In the

diminish,

evolution aliphatic

II) to 22.3% (fraction

the

decrease

27.2 to 31.2) might

condensation.

Ha

which

of

with

for

LP,

86.5

HP, however,

in which

H

structural the

most

In general

the

the nature

the

Har

number

fractions

but

reduction

increases ar features of

outstanding

from

HL

of the aromatic

to 77.7%);

the aromatic

of the

of the fractions,

of

to an anomalous

regular

of all its fractions.

with

IV). This increase

of Hal (from

be related

fractions

agrees

is observed nature

about

Thus,

shows

of this coal.

evolution

information coals.

of LP and HP, which

fraction

and their

respective

12.0 (fraction

agrees

and Ho,

structural

their

those

in the aliphatic

Ha,,

allow us to obtain

therefore,

character

of

of Hal,

I$ 1 than

the

increase

in the degree H

whereas coals.

fact

A

is the

character

and al similar

marked

increases

with

the rank of coals. The aliphatic are from the

Hal/Ha chains.

those

ratio The

expected,

6.5 for fraction

because

number,

aliphatic

the chains

a slight

than

those

with

the number

of

they HP.

which from

are

increase

poliaromatic

shows the average 1 H NMR spectra

in inverse

In regard

these

of

these

lignite

are

of the

fraction,

These

facts

suggest

larger

rank,

the coals

changing

of Hal/Ha

ratios

fraction

is found

of the

be clearly and

show

and the

the polarity,

that

coal

of

three

with for

trend. it can

character

as does

magnitude of the

to the

evolution

the number

parameters extracts

ratio

to the

with

of HL and HP. The aromatic

heteroatoms.

the

HL again shows an opposite

evolution of

measure obtained

LP to 2.0 for

LP and HP, whereas From

is a ratios

heteroatoms

deduced higher

molecular

and consequently, are

preferably

that

the

ramification size

increase

the number joined

to

structures.

REFERENCES 1 2 3 4

Moinelo, S.R., Menendez, R., Bermejo, J., and Garcia A.; Utilization of Extrography for the fractionation of coal extracts; 1985 International Conference on Coal Science, Sidney (australia); to be presented. Moinelo, S.R., Bermejo, J.,Garcia, A., and Menendez, R.; Utilizaci6n conjunta de CL, Extrografia, GPC, CC, IR y RNM en la caracterizaci6n de 10s lfquidos de1 carbon; Terceras Jornadas de an6lisis Intrumental. Barcelona, 1984. Bartz, K.W. and Chamberlain, N.F.;Determining Structure of naraffinic chains by NMR; Anal. Chem., a 2151, (1961). Burke, F.P., Winschel, R.A. and Pochaspsky, T.C.; Composition and performance of destillate recycle solvents from the SRC-I processes; Fuel, s 562, (1981.