chapter02 - composition
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Chapter 2: The Composition of Petroleum and its products
Introduction
Petroleum is a mixture of compounds - HCs (C & H).
Range from CH4to C85H60.
Elemental Composition in rude oil1.
Table 2.1: Elemental Composition in crude oil.
Element % wt
HydrocarbonC
H
8487
1114
Non-hydrocarbon
S
N
O
03
00.6
Traces
V
Ni
Cu
Traces
Traces
Traces
Non-hydrocarbon elements (O, S, and N) are present as components of complex molecules
predominantly HC in character.
Non-hydrocarbon elements (V, Ni, and Cu) are present from filed production operations.
The boiling point of crude oil ranges from 90 to 1500 F.
Compounds in crude oil are classified as -
- Paraffins and isoparaffins
- Olefins- Naphthenes
- Aromatics
1Not to mention, water, salt, sand, sediments, etc.
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RSH R-S-R' R-S-S-R'
Thiols Sulfides Disulfides(Mercaptans)
Cyclic Sulfides Thiophene Benzothiophene Dibenzothiophene
Naphthobenzothiophene
Figure 2.1: Examples of simple organic sulfur compounds in crude oil and its products.
(source: Speight, 'the chemistry and technology of petroleum', 1999, p.229)
ROH R-COOH R-COO
Alkylalcohols Carboxylic acids Carboxylic acid anhydrides
R-O-R' R-COO-R' R-CO-R'
Ethers Carboxylic acid esters Ketones
Diphenylether Tetrahydropyran Furan Benzofuran
Figure 2.2: Examples of simple organic oxygen compounds in crude oil and its products.
(source: Speight, 'the chemistry and technology of petroleum', 1999, p.233)
SS
S S
S
S
O
O O
O
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Paraffins
General formula (CnH2n+2)
Carbon is capable of forming single, double multi-branched chains which give rise toisomers that have significantly different properties.
The number for possible isomers increases in geometric progression as the number of atom
increases (Table 2.2).
Crude oil contains molecules with up to 70-85 carbon atoms, & the number of possibleparaffinic HCs is very high.
propane n-butane isobutane n-pentane isopentane neopentane
Figure 2.3: Examples of simple paraffins in crude oil and its products
Table 2.2: Number of possible paraffinic hydrocarbon isomers.
Molecule Symbol # of paraffin isomers
Methane C1 1
Ethane C2 1
Propane C3 1
Butanes C4 2
Pentanes C5 3
Hexanes C6
Heptanes C7Octanes C8 17
Nonanes C9
Decanes C10
Undecane C11
Dodecanes C12 355
Tridecanes C13
Tetradecane C14
Pentadecanes C15
Hexadecanes C16
Heptadecanes C17
Octadecanes C18 60,533
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Olefins
Do not naturally occur in crude oils - but are formed during processing in the
thermal/catalytic cracking units like the delayed coker and the FCC.
They are very similar in structure to paraffins, but at least two of the C atoms are joined bydouble bonds.
The general formula is CnH2n.
In gasoline boiling range, olefins are desirablebecause they have a higher RON thanparaffins.
However, olefins are generally undesirablein finished products, because:
1.
Double bonds are reactive and the compounds are more easily oxidized andpolymerize to form gums and varnishes.
2. Some diolefins, formed during processing, react very rapidly with olefins to form
high MW polymers and form filter plugging compounds.
3. C5olefins have high reaction rates with compounds in the atmosphere that form
pollutants.
Naphthenes
Are cycloparaffins in which all the bonds are single.
The general formula is CnH2n.
Naphthenes can have paraffin side chains.
Many types of naphthenes exist in crude oil (Figure 2.4)
Except for the lower MW compounds, such as cyclopentane and cyclohexane, Naphthenesare generally not handled as individual compounds. They are classified according to boiling
range, and their properties are determined with the help of correlation factors such as Kw
factor, or CI.
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Cyclopentane Methylcyclopentane Dimethylcyclopentane
Cyclohexane Methylcyclohexane 1,2-dimethylcyclohexane
Decalin n-decylcyclopentane
(Decahydronaphthalene)
Figure 2.4: Examples of simple naphthenes in crude oil and its products
Aromatics
These are hydrocarbons that contain one or more benzene ring.
Aromatics can have paraffin side chains and can form a mixed structure with naphthenes.
These mixed types have many of the chemical & physical characteristics of both of theparent compounds (the aromatic and the paraffin), but generally are classified according to
the parent cyclic compound.
.
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Benzene Toluene o-xylene m-xylene p-xylene cumene
Naphthalene Indan Tertahydronaphthalene Diphenyl
Diphenylmethane Anthracene Phenanthrene
o-terphenyl m-terphenyl p-terphenyl
Pyrene Chrysene Flourene
Figure 2.5: Examples of simple aromatic hydrocarbons in crude oil and its products
.
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Composition of Petroleum Distillates
Figure 2.6:Principal petroleum products, their boiling range temperatures and their number of
carbon atoms.
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Boiling point and carbon number range for petroleum products
No. Petroleum product Boling Point (C) Carbon Number
1 LPG C3C4
2 Gasoline C4C133 Naphtha C5C11
4 WS C8C12
5 Jet Fuel C9C13
6 Lamp Oils C10C17
7 Diesel Fuel & Home Heating oil C11C23
8 Paraffins C22C33
9 Base Stocks 380610 C23C
10 Heavy Fuels C23C
11 Waxes C36C
12 Asphalts C45C
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Table 2.3: Compounds Completely Identifiable in Naphtha by a Detailed Hydrocarbon GC analyzer1.
No Model Compound No Model Compound
12345678910111213
141516171819202122232425
262728293031323334353637
38394041424344454647484950
PropaneIsobutanen-Butane2,2-Dimethylpropane (Neopentane)Isopentanen-Pentane2,2-Dimethylbutane (Neohexane)Cyclopentane2,3-Dimethylbutane2-Methylpentane3-Methylpentanen-Hexane2,2-Dimethylpentane
Methylcyclopentane2,4-Dimethylpentane2,2,3-TrimethylbutaneBenzene3,3-DimethylpentaneCyclohexane2-Methylhexane2,3-Dimethylpentane1,1Dimethylcyclohexane3-Methylhexane1-trans-3-Dimethylcyclopentane1-cis-3-Dimethylcyclopentane
3-Ethylpentane1-trans-2-Dimethylcyclopentane2,2,4-Trimethylpentane (Isooctane)n-HeptaneMethylcyclohexane2,2-DimethylhexaneEthylcyclopentane2,5-Dimethylhexane2,4-Dimethylhexane1-trans-2-cis-4-Trimethylcyclopentane2,3,4-Trimethylpentane1-trans-2-cis-3-Trimethylcyclopentane
2,3,3-TrimethylpentaneToluene2,3-Dimethylhexane2-methyl-3-Ethylpentane2-Methylheptane4-Methylheptane3,4-Dimethylhexane1-cis-2-cis-4-trans-Trimethylcyclopentane3-Methylheptane1-methyl-2-Ethylcyclopentane1-trans-4-Dimethylcyclohexane1,1-Dimethylcyclohexane1-cis-3-Dimethylcyclohexane
51525354555657585960616263
646566676869707172737475
767778798081828384858687
888990919293949596979899100
1-methyl-cis-2-Ethylcyclopentane1-methyl-trans-3-Ethylcyclopentane1-methyl-cis-3-Ethylcyclohexane1-ethyl-1-Methylcyclopentane1-trans-2-Dimethylcyclohexanen-OctaneIsopropylcyclopentaneC9 ParaffinC9 Paraffin2,2,5-Trimethylhexane2,2,4-Trimethylhexane2,4,4-Trimethylhexane2,3,5-Trimethylhexane
3,4-Dimethyheptane2,4-Dimethylheptane1-cis-2-Dimethylcyclohexanen-PropylcyclopentaneEthylcyclopentane1-cis-2-Dimenthylcyclohexane1,1,3-Trimethylcyclohexane2,5-Dimethylheptane3,3-Dimethylheptane3,5-Dimethylheptane2,4-Dimethylheptane2,3,3-Trimethylhexane
Ethylbenzene1-cis-3-cis-5-Trimethylpentane1,1,4-Trimethylcyclohexane2,3,4-Trimethylhexane3,3,4-Trimethylhexanem-Xylenep-Xylene2,3-Dimethylheptane1-cis-2-trans-4-Trimethylcyclohexane1-cis-2-trans-4-cis-Trimethylcyclohexane3,4-Dimethylheptane3-methyl-Ethylhexane
4-Ethylheptane4-Methyloctane2-MethyloctaneC9 Paraffin3-MethyloctaneC9 Paraffino-XyleneC9 Paraffin1-methyl-2-Propylcyclopentane1-methyl-trans-4-Ethylcyclohexane1-methyl-cis-4-EthylcyclohexaneC9 Paraffin3,3-Diethylpentane
1Source; Detailed Hydrocarbon Gas Chromatography Analyzer.
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Table 2.3: continued.No Model Compound No Model Compound
101102103104105106107108109110111112113
114115116117118119120121122123124125
126127128129130131132133134135136137
138139140141
2,2,6-Trimethylheptane1,1,2-Trimethylcyclohexanen-Nonane1-methyl-1-EthylcyclohexaneC10 ParaffinC10 ParaffinIsopropylbenzene (Cumene)tert-Butylcyclopentanetert-ButylbenzeneIsobutylcyclopentaneC10 ParaffinC10 Paraffin1-methyl-4-Isopropylcyclohexane
Sec-Butylcyclopentane1-cis-2-cis-3-cis-Trimethylcyclohexanen-Butylcyclopentane1-methyl-2-Ethylcyclohexane3-MethylnonaneC10 Paraffinn-Propylbenzenen-PropylcyclohexaneC9-AromaticC9Aromaticm-Ethyltoluenep-Ethyltoluene
1,3,5-TrimethylbenzeneC10 ParaffinC10 Paraffin2-Methylnonane0-Ethyltoluene2,2-Dimethyloctane3,6-DimethyloctaneC10 ParaffinC10 Paraffin1,2,4-Trimethylbenzene (Psuedocumene)1-cis-methyl-3-Ethylcyclohexane1-trans-methyl-2-Ethylcyclohexane
1-trans-2-methyl-PropylcyclohexaneC10 ParaffinC10 Paraffin1-methyl-Ethylbenzene
142143144145146147148149150151152153154
155156157158159160161162163164165166
167168169170171172173174175176177178
179180181182
1-ethyl-2,3-DimethylcyclohexaneIsobutylbenzenen-DecaneC11 ParaffinC11 Paraffin1,2,3-Trimethylbenzene (Hemimellitene)C11 ParaffinC11 ParaffinC11 ParaffinC11 Paraffin4-Methyldecane1-methyl-2-Isopropylbenzene (o-Cymene)C10 Naphthene
sec-ButylbenzeneC11 Paraffinn-ButylbenzeneC10 Aromatic1-methyl-4-Propylbenzene1-methyl-3-PropylbenzeneC10 AromaticIsobutylcyclohexaneC11 Paraffin5-Methyldecane1,4-DiethylbenzeneC10 Aromatic
C10 Aromatic1-methyl-2-PropylbenzeneC11 ParaffinC11 Paraffintrans-1-methyl-2-(4-methylpentyl)-CyclopentaneC11 ParaffinC11 Paraffin2-ethyl-1,4-DimethylbenzeneC10 Aromatic1,4-dimethyl-2-Ethylbenzenen- UndecaneC11 Paraffin
1,2,4,5-Tetramethylbenzene1,2-dimethyl-4-EthylbenzeneC11 ParaffinC11 Aromatic
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Table 2.4: Compounds Completely Identifiable in Naphtha by a Detailed Hydrocarbon GC analyzer1.
No Formula Model Compound No Formula Model Compound
12345678910111213
141516171819202122232425
262728293031323334
C3H8C4H10C4H10C5H10C5H12C5H12C6H12C6H12C6H14C6H14C6H14C6H14C6H14
C6H6C7H14C7H14C7H14C7H14C7H14C7H16C7H16C7H16C7H16C7H16C7H16
C7H16C7H16C7H16C7H8C8H10C8H10C8H10C8H10C8H16
Propaneisobutanen-butaneCyclopentane2-methyl butane (isopentane)n-pentaneCyclohexanemethylcyclopentane2,2-dimethyl butane (neohexane)2,3-dimethyl butane2-methyl pentane3-methyl pentaneN-hexane
Benzene1,1-dimethyl cyclopentane1,2-dimethyl cyclopentane-transcis-1,3-dimethylcyclopentaneEthylcyclopentanetrans-1,3-dimethylcyclopentane2,2,3-trimethylbutane (Triptane)2,2-dimethylpentane2,3-dimethylpentane2,4-dimethylpentane2-methylhexane3,3-dimethylpentane
3-ethylpentane3-methylhexaneN-heptaneTolueneEthylbenzeneM-xyleneo-xyleneP-xylenecis-1,2-ethylmethylcyclopentane
35363738394041424344454647
484950515253545556575859
606162636465666768
C8H16C8H16C8H16C8H18C8H18C8H18C8H18C8H18C8H18C8H18C8H18C8H18C8H18
C8H18C8H18C8H18C8H18C9H20C9H20C9H20C9H20C9H20C9H20C9H20C9H20
C9H20C9H20C9H20C9H20C9H20C9H20C9H20C9H20C9H20
cis-1,3-ethylmethylcyclopentanetrans-1,2-ethylmethylcyclopentanetrans-1,3-ethylmethylcyclopentane2,2,3-trimethylpentane2,2-dimethylhexane2,3-dimethylhexane2,4-dimethylhexane2,5-dimethylhexane2-methyl-3-ethylpentane2-methylheptane3,3-dimethylhexane3,4-dimethylhexane3-ethylhexane
3-methyl-3-ethylpentane3-methylheptane4-methylheptaneN-octane2,2,5-trimethylhexane2,2-dimethylheptane2,3,5-trimethylhexane2,3-dimethylheptane2,4-dimethylheptane2,5-dimethylheptane2,6-dimethylheptane2-methyl-4-ethylhexane
2-methyloctane3,3-dimethylheptane3,4-dimethylheptane3,5-dimethylheptane3-ethylheptane3-methyloctane4-ethylheptane4-methyloctanen-nonane
1Source; Detailed Hydrocarbon Gas Chromatography Analyzer.
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Table 2.5: Compounds Completely Identifiable in Naphtha by a PIONA GC analyzer2.
No Formula Model Compound No Formula Model Compound
1
23
4
5
6
7
8
9
10
11
1213
14
15
16
17
18
C5H10
C5H12C6H12
C6H14
C6H14
C7H14
C7H16
C7H16
C8H16
C8H18
C8H18
C9H20C9H20
C9H20
C10H20
C10H22
C10H22
C11H24
Cyclopentane
n-pentaneCyclohexane
2-methyl pentane
N-hexane
Methylcylohexane
2-methylhexane
N-heptane
Ethylcyclohexane
2-methylheptane
N-octane
isopropylcyclohexane2-methyloctane
n-nonane
tert-butylcylohexane
2-methylnonane
n-decane
n-undecane
19
2021
22
23
24
25
26
27
28
29
3031
32
33
34
35
36
C12H26
C6H6C8H10
C9H12
C10H14
C10H18
C8H10
C9H12
C11H16
C10H12
C5H10
C6H12C6H10
C7H14
C8H16
C9H18
C10H20
C7H8
n-dodecane
BenzeneEthylbenzene
isopropylbenzene
sec-butylbenzene
cis-decaline
o-xylene
1,2,3-trimethylbenzene
pentamethylbenzene
1,2,3,4-tetrahydronaphthalene
1-pentene
1-hexene1-methylcyclopentene-1
1-heptene
1-octene
1-nonene
1-decene
Toluene
2Source; PIONA Gas Chromatography Analyzer.
Table 2.6: Compounds Completely Identifiable in Naphtha by a PINA GC analyzer3.
No Formula Model Compound No Formula Model Compound
1
2
3
4
5
67
8
9
10
11
12
13
1415
C5H10
C5H12
C6H14
C6H14
C7H14
C7H16C7H16
C8H16
C8H18
C8H18
C9H20
C9H20
C9H20
C10H20C10H22
Cyclopentane
n-pentane
2-methyl pentane
N-hexane
Methylcylohexane
2-methylhexaneN-heptane
Ethylcyclohexane
2-methylheptane
N-octane
isopropylcyclohexane
2-methyloctane
n-nonane
tert-butylcylohexane2-methylnonane
16
17
18
19
20
2122
23
24
25
26
27
28
2930
C10H22
C11H24
C12H26
C6H6
C8H10
C9H12C10H14
C10H18
C8H10
C9H12
C11H16
C10H12
C7H8
C6H12C6H12
n-decane
n-undecane
n-dodecane
Benzene
Ethylbenzene
isopropylbenzenesec-butylbenzene
cis-decaline
o-xylene
1,2,3-trimethylbenzene
pentamethylbenzene
1,2,3,4-tetrahydronaphthalene
Toluene
Cyclohexanemethylcyclopentane
3Source; Detailed Hydrocarbon Gas Chromatography Analyzer.
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Composition of Vacuum Residue
Vacuum residue contains thousands of complex (high molecular weight, high boiling point)
hydrocarbons and organic compounds.
This is divided into three main fractions.1.
Oil fraction.
2. Resin fraction
3.
Asphaltene fraction.
Figure 2.7: Separation of vacuum residue.
1.
Oil fraction.
-
Highly paraffinic.
- Usually contains no metals.
-
Has lower S and N content than the vacuum residue.
2. Resin fraction
-
Contains certain condensed-ring aromatics
- Has substantial amount of paraffinic structure
-
Sulfur concentrations are approximately the same as the vacuum residue (from which they
are derived)-
Contain 10-20 %wt of the metals in the crude.
- Serves as a solvent for the asphaltenes
MW 600 5,000 (solution techniques)
MW 60 500 (mass spectrometer)
3. Asphaltene fraction.
- Very low H/C ratio.
- Contains 80-90% of the metals in crude (Ni, V).
- Consists of highly condensed aromatic ring compounds
MW 5,000 10,000 (solution techniques)MW 500 1000 (mass spectrometer)
C3EXTRACTIONVacuum Residue
C5/C6/C7EXTRACTION
Oil + C3
Resin + C5/C6/C7
Asphaltene
(insoluble in C3- C7)
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Figure 2.8:Hypothetical asphaltene molecule structure
S
S
Paraffinic side cha
Sheets of highly condensed ring structure (3-5)
Naphthenic rings
Valencebonds
hetro atom
(N, S, O, V, Ni)
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References
1. David R. Lide, CRC Handbook of Chemistry and Physics, 82nded, CRC Press, 2001. (QD
65 C7 2001-2002)
2. James Speight, The Chemistry and Technology of Petroleum, CRC Press, 1999.
3.
Klaus H. Altgelt and Boduszynski, Composition and analysis of heavy petroleum fractions,
CRC Press, 1993.
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