chapter02 - composition

7/24/2019 Chapter02 - Composition

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Petroleum RefiningChapter 2: Composition of Petroleum and its Products

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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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Copyrights 2001-2015, Dr. Tareq Albahri, Chem. Eng. Dept., Kuwait University

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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



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Table 2.5: Compounds Completely Identifiable in Naphtha by a PIONA GC analyzer2.


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.


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



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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.

chapter02 - composition

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