Modern view at asphaltenes
Component analysis
High-molecular oil components
RAS classification
Separating crude oil into saturates, aromatics, resins and asphaltenes (SARA)
Molecular structure of proposed resin molecule
The main properties and hypothetical asphaltene molecule
Packing model of asphaltene structure (Yen, 1961)
The scheme of association asphaltenes in process of introduction sedimentator (lungs n-alkanes) in the PDS (T.Yen, 1961)
Organization level of ashaltens (1)
Organization level of ashaltens (2)
Dimers structure
The histogram of distribution of components in the ODS of a destructive origin (the rests of thermal processes of oil refining)
A way of looking at aggregation behavior of asphaltenes with increasing concentration
The fractal model of consecutive aggregation of asphaltenes
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Modern view at asphaltenes. (Lecture 4)

1. Modern view at asphaltenes

• The basic idea about the PDS dispersed phase resins, asphaltenes, carbenes and carboids
• Separating crude oil (SARA)
• Definition onset
• The various models of a structure asphaltenes :
packing (onion), continental (or island) and fractal
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2. Component analysis

• Paraffines [alkanes]:
n-/izostructure
Naphthenes: [cycloalkanes]
• Aromatic hydrocarbons [arenes]
• Hydrocarbons of mixed structure: in Diesel fraction and above
• Non-hydrocarbon oil components: S, N, O
• Mineral components: H2O, salts
• Macromolecular components
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3. High-molecular oil components

• Wax:
– С18-С35 (300-450 а.е.)
• Cerezines:
– С36-С55 (500-700 а.е.)
• Resins-asphaltenic substances (RAS):
– Resines:
– Asphaltenes:
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< 1000 а.е.
> 1000 а.е.
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4. RAS classification

• Resins:
• M <1000
• soluble in alkanes
• condensed systems related with aliphatic chains
• Asphaltenes:
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M > 1000
≈ 1 D and above
insoluble in alkanes
soluble in benzene,CS2, CCl4, etc.
tend to associations, define the structure of oil disperse systems
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5.

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6.

АFМ-image of asphaltenes at solid surface
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Energy&Fuels 2009

7.

Two approaches in development of
representations about structure RA
• Chemical
- structural formulas of molecules of resins and
asphaltenes СnH2n-z NpSqOr
(The calculated values z for resins 40-50,
for asphaltenes- 130-140)
• Physical
- packing model of asphaltene structure(Yen,1961);
- a scale sedimentators and solvents in relation to
asphaltene (Hotier, 1980);
- fractal model of a structure asphaltene(1994).
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8. Separating crude oil into saturates, aromatics, resins and asphaltenes (SARA)

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9.

The histogram of distribution of RAcomponents in oil and the oil rests
• The scheme of division of RA
• Oil + n-penthane (1:40)
100%
75%
• Asphaltenes (in a deposit) and
hydrocarbons + resines (in a
solution) ¯ method LAC
50%
25%
0%
Oil
Hydrocarbons
• Hydrocarbons (eluate - npenthane) and resins (eluate
pyridine)
Resins
Asphaltenes
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10. Molecular structure of proposed resin molecule

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11. The main properties and hypothetical asphaltene molecule

H/C = 0,8-1,4
molecular weight distribution
Monomers= 500-1000
Oligomers= 1000-5000
Heteroatoms, мас. %:
S = 0,5 - 10; N = 0,6 – 2,6; O = 0,3 - 4,8
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Metals: Ni, V, Fe
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12.

Asphaltenes extracted with two alkanes
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13.

Средние молекулярные массы асфальтенов,
определенные разными методами
Метод определения
Ультрацентрифугирование
Осмотическое давление
80
Ультрафильтрация
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Молекулярная масса,
тыс. у.е.
300
80 - 140
Эбулиоскопия
2,5- 4
Криоскопия
0,6 - 6
Осмометрия
1-8
Вязкость
0,9 - 2
Светорассеяние
1 -4
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14. Packing model of asphaltene structure (Yen, 1961)

• Packing structures in
diameter of 0,9-1,7 nm
from 4-5 layers, being at
0,36 nm each one from
other.
• By rectilinear pieces are
shown flat polyarenous,
and broken lines - the
saturated fragments of
molecules.
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15. The scheme of association asphaltenes in process of introduction sedimentator (lungs n-alkanes) in the PDS (T.Yen, 1961)

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I - molecular state
(up to 1 nm)
II – colloidal state
(1-100 nm)
III - disperse - stable state
(100 nm - 1 mc)
IY- disperse - unstable state
(> 1 mc)
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16. Organization level of ashaltens (1)


Monomers
Yen elementary particles (9 ÷ 17 Å)
Oligomers (25 ÷ 50 Å)
Polymers (> 150 Å)
+ Aggregation processes, including the
processes of gel / glass
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17. Organization level of ashaltens (2)

Monomers
Yen elementary particles
Oligomers (dimers, trimers, tetramers)
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18. Dimers structure

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19.

Molecular structures of proposed asphaltens molecules
(a) Maya crude oil (Mexico)
(b)Venezuelan crude oil
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20. The histogram of distribution of components in the ODS of a destructive origin (the rests of thermal processes of oil refining)

• The scheme of allocation
carbens and carboids
100%
hydrocarbons
+resins
asphaltenes
80%
60%
carbens
40%
20%
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asphaltenes (in solution CCl4) and
carbens + carboids
(in a deposit)
CS2
Carbens (in solution CS2) and
carboids (in a deposit)
0%
cracking
residues
Asphaltenes+carbens+ carboids
CCl4
pitches
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21. A way of looking at aggregation behavior of asphaltenes with increasing concentration

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22. The fractal model of consecutive aggregation of asphaltenes

Average density of a fractal
(r) = const / r D-d
• Weight of a fractal of M
(number of forming particles)
М ~ r d , where
r - radius particle,
d, D - topological and
fractal dimension
1 - paramagnetic skeleton of
asphaltenes
2- solvate layer formed by resins
3 - dispersive environment.
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