Characterization of Hydrocarbons in petroleum … · Characterization of Hydrocarbons in petroleum...

Characterization of Hydrocarbons in petroleum fractions using Comprehensive

Gas-Chromatography GCxGC coupledwith Fast Scan Quadrupole MSD

Marc Gibert - Ingenieria Anal´ñitica s.L.

Why GCxGC-MSD in petrochemistry

Which information is in this picture

• Fingerprint of crude oils (based on bidimensional distribution of more than1000 compounds)

Light crude oil A

Light crude oil C

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Light crude oil GC-MS chromatograms comparison

Which information is in this picture

• Fingerprint of crude oils (based on bidimensional distribution of more than1000 compounds)

• Chemical information (chemical structure, volatility, polarity, etc.)

Volatility vs. PolarityNr name RT1; RT2 (min) b.p.°C polarity index1 n-hexane 10.436; 0.715 69.0 0.12 benzene 12.536; 1.277 80.1 2.73 cyclohexane 12.536; 0.766 80.7 0.24 n-heptane 14.036; 0.817 98.4 0.05 cyclohexane, methyl 15.386; 0.868 101.0 n.d.6 toluene 18.086; 1.635 111.0 2.4

13

2 4 56

Volatility

Pola

rity

Which information is in this picture

• Fingerprint of crude oils (based on bidimensional distribution of more than1000 compounds)

• Chemical information (chemical structure, volatility, polarity, etc.)

• Information for application purposes(compound identification for geologicalexploration and process refinery uses)

• Goal: use the potentiality of the GCxGC to obtain as much as possible information and semplify instrument use for routine analysis

• One GCxGC method is here described:– to optimise the separation among classes;– to discrimine among information the more

interesting ones:–Hydrocarbons group type–S-containing compounds–N-containing compounds

GC x GC method approach

Hydrocarbons in light crude oil A

CH3

Single-ring aromatics

C30C28

C26C10 C20C6HC Saturated and Insaturated

Three ring-aromatics

(CH3)2

(CH3)3 (CH3)4 (CH3)5

CH3

CH3

(CH3)2 (CH3)3

CH3

CH3

(CH3)2

Double ring-aromatics

CH3

Single-ring aromatics

GCxGC analysis of light petroleum distillate

HC Saturated and Insaturated

Single-ring aromatics

Double ring-aromatics

Three ring-aromatics

• The increasing concern on the environmental conditions requires to limit the sulphur level in diesel fuel and gasoline (e.g. the specification in Europe for S content is lower than 10 ppm S).

• Very deep conversion of sulphur compounds is therefore required to produce extremely clean transportation fuel. Nature and amount of the sulphur compounds strongly influence the conditions of desulphurisation treatments.

• The understanding and mapping of these species is of vital importance for the further treatment of oil and oil derivatives.

Why to study sulphur compounds

S-containing compounds in light crude oil A

Thioles and sulfides in light crude oil A

1

1 – dimethyldisulfide2 – ethyl-methylethyldisulfide3 – 2-pentanthiol4 – 1-pentanthiol5 – 4-methyl, 2-pentanthiol6 – methyl ethyl disulfide7 – hexanethiol8 – tetrahydro thiopyran9 – hexanethiol10 – diethyl disulfide11 – methyl propyl disulfide12 – cyclohexanethiol13 – heptanethiol14 – dimethyl trisulfide15 – methyl cyclohexanthiol

2

3

6

4

5

7

8

9

1011

12

13

14

15

S-compounds in light crude oil A

Benzothiophenes in light crude oil A

1

2

3

4

5 6

S

S

CH3S

(CH3)2

S

(CH3)3

S

(CH3)4

1 – benzothiophene

2 – benzothiophene,2,3-dihydro

3 – benzothiophene, methyl

4 – benzothiophene, 2M5 – benzothiophene, 3M

6 – benzothiophene, 4M

CH3

(CH3)2

(CH3)3 (CH3)4

S

S-compounds in light crude oil A

Dibenzothiophenes in light crude oil A

1

23

4

CH3 (CH3)2

(CH3)3

1 – dibenzothiophene

2 – dibenzothiophene, methyl

3 – dibenzothiophene, 2M

4 - dibenzothiophene, 3M

S

S (CH3)2

S (CH3)3S CH3

64 identified compounds

S-compounds in light crude oil C

Thiophenes in light crude oil C

1 2

3

45

6

7

8

9

1011 12

13

1415 16

17 18 19

0 - thiophene1 – methyl-thiophene2 – tetrahydro-thiophene3 – dimethyl-thiophene4 – methyl-tetrahydrothiophene5 – dimethyl-thiophane6 – dimethyl-thiophene7 – tetra-hydro-thiopirane8 – dimethyl-tetrahydrothiophene9 – dimethyl-thiophene10 – dimethyl-thiophane11 – cis-2,3-dimethyl-thiophane 12 – trans-2,3-dimethyl-thiophane13 – dimethyl-thiophene14 – methyl-tetrahydrothiopirane15 – dimethyl-tetrahydrothiophene16 – dimethyl-thiophane17 – ethyl-tetrahydrothiophene18 – ethyl-methyl-thiophane19 – trimethyl-thiophene

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3D-VIEW

Benzene

3D-view: Thiophenes in light crude oil C

S CH3

S

S (CH3)2S

S CH3

S (CH3)2

thiophene

thiophene,methyl

tetrahydrothiophene

Tetrahydrotiophene,methyl

thiophene,dimethylthiophene,ethyl

thiophene,propyl

Thiophene,trimethyl

benzothiophene

Benzothiophene,2,3-dihydro

Benzothiophene,2,3-dihydro,3methyl

benzothiophene,methyl

benzothiophene,ethyl

Benzothiophene,dimethyl

Benzothiophene,dimethyl

benzenthiol

Thiophene,diethyl

Thiophene, methyl-ethyl

Thiophene, buthyl

Thiophene,diethyl

GCxGC S-compound map oflight petroleum distillate (527 ppm S )

36 identified S-compounds

Benzothiophenes 3D-view

Benzothiophene,dimethy

benzothiophene,methyl

benzothiophene,2,3-dihydro

benzothiophene

naphthalene

Naphthalene,methyl

Naphthalene,dimethyl

S

S

S

CH3

S

(CH3)2

S-compound identification: comparison with GC-AEDdata

36 S-compounds peaks

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GC-MS analysis

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Benzothiophene

Benzothiophene NIST MS spectrum

134 m/z 134 m/z

89 m/z

Benzothiophene GCxGC-MS spectrum

GC-MS spectrum

Benzothiophene GC-MS

• During desulphurisation, the presence of refractory and competitive species as nitrogen compounds is highly detrimental, due to their effect as inhibitors for HDS (hydrodesulphurisation) catalysts.

• Neutral (e.g. carbazole), slightly basic (e.g. quinoline) and basic (e.g. pyridine) nitrogen compounds are present in gas oil and cracked oil stream. The need to pre-remove these species is a function of their nature, the more stringent the removal the more basic are the species.

• The mapping of the nitrogen species is of vital importance for the further treatment of oil and oil derivatives.

Why to study nitrogen compounds

N-compounds in Naphtha

N-compounds in Naphtha

A9 A10 A11 A11A8

A7A6

pyrrole

NH

NH

CH3

pyrrole, methyl

NH

(CH3)2

NH

CH2CH3

pyrrole, dimethyl

pyrrole, ethyl

NH

(CH3)3

pyrrole, trimethyl

benzenamine

benzenamine, methyl

CH3

NH2

NH2

benzenamine, dimethyl

benzenamine, methyl ethyl

NH2 (CH3)2

NH2(CH3)

CH2CH3

pyridine

pyridine, methyl

pyridine, dimethylN

NH3C

pyridine, trimethyl

N(H3C)2

N(H3C)3

pyridine, methyl ethyl

NH3C

H2CH3C

hexanenitrile heptanenitrile

N-compounds in Petroleum fraction

N-compounds in Petroleum fraction

NH

quinoline, 1,2,3,4-tetrahydro

NH

CH3methyl-quinoline, 1,2,3,4-tetrahydro

CH3

NH

1H-indole, methyl

carbazole

NH

NH

CH3Carbazole, methyl

N-compounds in Petroleum fraction

57 identified compounds

GC-MS analysis

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Rt Carbazole 42.123 minCarbazole

Carbazole MS Spectra

GC-MS spectrum

Carbazole NIST MS spectrum167 m/z

CarbazoleGCxGC-MS

spectrum139 m/z

Development of one GCxGC methodfor petrochemical analysis

GCxGC-MSD System

GC 6890 Agilent

Technologies

MSD 5973 Fast ScanAgilent Technologies

ZOEX Dual Stage Thermal Modulator

LN2 ZoexAuto-Fill Unit

GC Agilent Technologies 6890N• Injector Split/Splittless with EPC• Split 1:100, carrier Helium• Primary column: HP-5 MS (25m x 0.25mm ID,

df=0.25μm)• Secondary column: HP-WAX (0.7m x 0.1mm ID,

df=0.1μm)• Oven: 40°C x 0.5min, 1.5°C/min to 260°C, 260°C

for 40 min (run time 187 min)• Ramp Pressure: 20psi, 0.1psi/min to 25psi,

0.55psi/min to 55psi

GCxGC-MSD System

GC 6890 Agilent

Technologies

MSD 5973 Fast ScanAgilent Technologies

ZOEX Dual Stage Thermal Modulator

LN2 ZoexAuto-Fill Unit

ZOEX dual stage thermal modulator• KT-2004 Zoex Dual Stage Thermal Modulator• LN2 Zoex Auto Fill Unit• Zoex GC-Image Software• Modulator Tube: uncoated fused silica tube 2mt X

0.1mmID• Modulation period: 9 seconds• Modulation duration: 450 msec• Hot Jet Temperature: 350°C

ZOEX modulatoroperation

GCxGC-MSD System

GC 6890 Agilent

Technologies

MSD 5973 Fast Scan AgilentTechnologies

ZOEX Dual Stage Thermal Modulator

LN2 ZoexAuto-Fill Unit

MSD 5973 Fast Scan AgilentTechnologies

• In order to maximize the spectral information, full-scan mass spectra acquisition mode (EI) was used

• MSD 5973 inert with Performance Electronics for Fast Scan Capabilities (10,000 amu/sec) and improved sensitivity

• Range 45-350 amu (19.80 scan/sec)• MS Transfer line: uncoated fused silica tube

(0.8m x 0.25mm ID, temperature 280°C)

Development of one GCxGC method forpetrochemical analysis

How many variables in setting up a GCxGC method?Columns choice (stationary phase and lenght)Main oven temperature and/or secondary oven temperatureColumn flowModulation period and durationCold and Hot jet flows

Simplify the user operation maintaining fixed the conditionsfor all type of compounds in oil-derivatives

• Column combination to maximize GCxGC potentiality: the most “bi-dimensional” stationary phases must be usedPrimary column: apolarSecondary column: polar

• Separate wide variety of hydrocarbon compounds (saturate/insaturate, light up to heavy aromatics and heteroatom compounds)

• Which stationary phase and column lenght?• Wax : polyethylene glycol• DB-1701: 14% cyanopropyl-phenyl, 86% dimethylpolysiloxane• HP-17: 50% phenyl, 50% dimethylpolysiloxane

Column choice

Secondary column 1 mt x 0.1 mmID x 0.1 um DB-1701Oven: 35°Cx0min, incr. 2°C/min to 300°C for 10 minNo secondary oven

Modulation period : 6 sec.

1 meter DB-1701Naphtalene

byphenyl

Three ring aromatics

Naphtalene

Three ring aromatics

byphenyl

Modulation period : 9 sec.

1 meter HP-17byphenyl

Three ring aromatics

Naphtalene

Secondary column 1 mt x 0.1 mmID x 0.1 um HP-17Oven: 40°Cx0.5min, incr. 2°C/min to 300°C for 10 minNo secondary oven

Secondary column 2 mt x 0.1 mmID x 0.1 um WAXOven: 40°Cx0.5min, incr. 0.5°C/min to 260°C for 40 minSecondary Oven: 30°C above main oven

Naphtalene

Three ring aromatics

Wrap-around

Modulation period : 9 sec.

2 meters WAX

byphenyl

Modulation period : 9 sec.

0.7 meter WAX Three ring aromatics

Secondary column 1 mt x 0.1 mmID x 0.1 um WAXOven: 40°Cx0.5min, incr. 0.5°C/min to 260°C for 40 minSecondary Oven: 30°C above main oven

Naphtalene

byphenyl

• Large enough to permit the elution of all the components from the secondary column (y- axis, separation by polarity)

• Should be tuned to collect at least three fraction of the elutingprimary column peaks (high modulation period values require wideprimary column peaks)

Modulation period

Naphtalene

byphenyl

Three ring aromatics

9 seconds mod. period

Modulation period

Modulation period

Nr name RT1; RT2 (min) b.p.°C

1 benzene 12.536; 1.277 80.12 ciclohexane 12.536; 0.766 80.7

1

2

Modulation period

BenzeneCiclohexane 1

1 st modulation

2 nd modulation

3 rd modulation

4 th modulation

Conclusions

• The GCxGC-qMSD showed to be a powerful tool in light petroleum fraction investigation. Its use allows the separation and identification of different polarity hydrocarbons (aromatic vs aliphatic) together with unique identification of heteroatom compounds, with a single sample run and without changing any analytical set up and parameters.

Thank you for your attention