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Selective Hydrogenation of PyGas over Palladium · PDF fileSelective Hydrogenation of PyGas...

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Centre for Catalysis Research, Dept of Chemistry, University of Glasgow, Glasgow, UK. Selective Hydrogenation of PyGas over Palladium Catalysts S David Jackson
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Centre for Catalysis Research, Dept of Chemistry, University of Glasgow, Glasgow, UK.

Selective Hydrogenation of PyGas over Palladium

CatalystsS David Jackson

Jean-Marc Bader and Gildas Rolland, (Axens), International Petroleum Refining, July 2013

by-product of high temperature naphtha cracking, highly unsaturated mixture

(carbon range ~C5-C12).

PyGas Components Weight percent (wt %)

Benzene, toluene and xylenesOlefins and dienesStyrene and other aromaticsParaffins and naphthenics

50251510

Typical composition of Pyrolysis Gasoline

Pyrolysis Gasoline

Jean-Marc Bader and Gildas Rolland, (Axens), International Petroleum Refining, July 2013

Pyrolysis Gasoline Composition

PyGas Components Weight percent (wt %)

TolueneStyrene1-penteneCyclopentene1-octeneHeptaneDecane

55101010102.52.5

Composition of our model Pyrolysis Gasoline

Reaction Conditions

Continuous flow fixed bed reactor

Catalysts:

16 wt.% Ni/Al2O3

1 wt.% Pd/Al2O3

Reaction Temperature:140C - 200C

Hydrogen Pressure :1 - 20 barg

WHSV: 4 h-1

Catalyst weight:0.5 g

Potential reactions of PyGas

Styrene Ethyl Benzene Ethylcyclohexane

Toluene Methycyclohexane

Cyclopentene Cyclopentane

1-Pentene 2-Pentene

Pentane

2-Octene

3-Octene

4-Octene

Octane

1-octene

0.0E+00

5.0E-07

1.0E-06

1.5E-06

2.0E-06

2.5E-06

0 5 10 15 20 25

Rat

e of

form

atio

n ( r

) M

oles

g-1

s-1

Hydrogen pressure ( PH2 ) barg

Praffins

Internal olefins

EB

Saturated compound from aromatics (MCH, ECH)

0

0.2

0.4

0.6

0.8

1

0

20

40

60

80

10 28 52 76

Yiel

d ( %

) [

MC

H ]

Con

v ( %

) [

Tolu

ene

]

Time of Reaction ( Hours )

Toluene(Conv) MCH

Carbon Balance

Reaction Temperature:140C - 200C

Hydrogen Pressure :20 bar

WHSV:4 h-1

Pd/Al2O3

Percent Carbon Balance of each species in synthetic PyGas hydrogenation

Reaction Temperature:140 C

Hydrogen Pressure :1 - 20 bar

WHSV:4 h-1

Percent Carbon Balance of each species in synthetic PyGas hydrogenation

Pd/Al2O3

Carbon Balance

FLOW

YIELD 100 % 100 % 90% 10%

Time

FLOW

GC/TPO

GC/TPO

0.0E+00

2.0E‐10

4.0E‐10

6.0E‐10

8.0E‐10

1.0E‐09

1.2E‐09

0

50

100

150

200

250

300

350

400

450

500

0 50 100 150 200 250 300

Ion curren

t

Tempe

rature (C)

Time (min)

Temp CO2 H2O

Pd/Al2O3, WHSV 4h-1, 140C, 5barg H2

Pd/Al2O3, WHSV 4h-1, 140C, 5barg H2

0

50

100

150

200

250

300

350

400

450

500

0.0E+00

5.0E‐12

1.0E‐11

1.5E‐11

2.0E‐11

2.5E‐11

3.0E‐11

3.5E‐11

0 20 40 60 80 100 120 140 160 180 200

Tem

pera

ture

(C

)

Ion Cu

rren

t ( n A)

Time ( mins)

92 104 78 106 Temp

78, benzene92, toluene104, styrene106, EB

-7.00E-04

-6.00E-04

-5.00E-04

-4.00E-04

-3.00E-04

-2.00E-04

-1.00E-04

0.00E+00

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0 100 200 300 400 500 600 700 800 900 1000

Ion

curr

ent (

a.u.

)

Der

ivat

ive

wei

ght (

%/C

)

Temperature [C]

Deriv weight m/e 44

Pd/alumina, cyclopentene

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

-6.0E-04

-5.0E-04

-4.0E-04

-3.0E-04

-2.0E-04

-1.0E-04

0.0E+00

0 100 200 300 400 500 600 700 800 900 1000

Der

ivai

tve

Wei

ght (

%/o

C)

Ion

Cur

rent

(mA)

Temperature (oC)

m/e 44 Deriv weight

Carbon laydown Toluene

3000

3100

3200

3300

3400

3500

3600

3700

3800

3900

4000

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Intensity (arb. units)

Raman Shift (cm‐1)

Raman Spectra for Pd/alumina after Toluene

Carbon laydown Toluene

0

0.2

0.4

0.6

0.8

1

0

20

40

60

80

10 28 52 76

Yiel

d ( %

) [ M

CH

]

Con

v ( %

) [ T

olue

ne ]

Time of Reaction ( Hours )

Toluene(Conv)

MCH

5 barg H2 WHSV 4 h-1

0

10

20

30

40

0

20

40

60

80

100

120

10 28 52 76

Yiel

d (%

) [ T

rans

/Cis

-oct

enes

]

Yiel

d (%

) [ O

ctan

e ],

Con

v (%

) [ 1

-oct

ene

]

Time of Reaction ( Hours )

1-octene(Conv) OctaneTrans-2-octene Cis-2-octeneTrans-4-octene Trans/Cis-3-octene & Cis-4-octene

5 barg H2 WHSV 4 h-1

0

7

14

21

28

35

0

20

40

60

80

100

10 29 53 76

Yiel

d ( %

) [ O

ctan

e, T

rans

/Cis

-oct

enes

]

Con

v ( %

) [ 1

-oct

ene

]

Time of Reaction ( Hours )

1-octene(Conv) Octane Trans-2-octene Cis-2-octene

Trans-3-octene Cis-3-octene Trans-4-octene Cis-4-octene

5 barg H2 WHSV 8 h-1

0

8

16

24

32

40

0

20

40

60

80

100

120

10 29 53 76

Yiel

d ( %

) [O

ctan

e, T

rans

/Cis

-oct

enes

]

Con

v ( %

) [

1-oc

tene

]

Time of Reaction ( Hours )

1-octene(Conv) Octane Trans-2-octene Cis-2-octene

Trans-3-octene Cis-3-octene Trans-4-octene Cis-4-octene

1 barg H2 WHSV 4 h-1

1-alkene reacts at edges/corners

2-alkene reacts on faces

For ring hydrogenation, the ring prefers a flat, parallel adsorption mode rather than an

edge-on adsorption

Reactions Orders of reactions wrt H2

Reactants Products PH2 (1-5 barg) PH2 (5-20 barg)

1-pentene Pentane 1.6 0.3

1-pentene Trans-2-pentene -1.1 -

1-pentene Cis-2-pentene -1.2 - 1-octene Octane 1.6 0.3

1-octene Trans-2-octene -0.7 -

1-octene Cis-2-octene -0.8 - Cyclopentene Cyclopentane 1.6 0.2

Reactions Orders of reactions wrt H2

Reactants Products

PH2 (1-20 barg)

Styrene Ethyl benzene 0.1

PH2 (1-5 barg) PH2 (5-20 barg)

Toluene Methylcyclohexane - 2.4

Ethylbenzene Ethylcyclohexane - 2.9

Reactions Orders of Reactions

wrt PyGas (WHSVPyGas 4-8 h-1)

Reactants Products PH2 = 5 barg, PT = 20 barg

(25% hydrogen gas)

PH2 = 10 barg, PT = 20 barg

(50% hydrogen gas) 1-pentene Pentane -0.3 0.7

1-pentene Trans-2-pentene 3.4 -

1-pentene Cis-2-pentene 3.6 - 1-octene Octane -0.7 0.3

1-octene Trans-2-octene 2.6 -

1-octene Cis-2-octene 2.9 - Cyclopentene Cyclopentane 0.0 0.8 Styrene Ethylbenzene 1.0 1.2

Ethylbenzene Ethylcyclohexane - - Toluene Methylcyclohexane - -

PyGas PyGas for aromatics extraction (aromatic + saturated paraffins)

PyGas for gasoline pool (aromatic + internal olefins)

Hydrogenated PyGas (saturated paraffins + saturated

compounds of aromatics)

Stream cracker plant

Aromatic

Gasoline pool

H-PyGas-III H-PyGas-II

H-PyGas-I

PyGas PyGas for aromatics extraction (aromatic + saturated paraffins)

PyGas for gasoline pool (aromatic + internal olefins)

Hydrogenated PyGas (saturated paraffins + saturated

compounds of aromatics)

Stream cracker plant

Aromatic

Gasoline pool

H-PyGas-III H-PyGas-II

H-PyGas-I

H-PyGas-I gives a high octane mixture which can be utilised as a gasoline

blending mixture

mild reaction parameters [T ≈ 140oC, PT ≈ 20 barg, PH2 ≈ 1-5 barg,

WHSVPyGas ≈ 4-8 h-1].

Reactive species like styrene and alkadienes are selectively hydrogenated.

High selectivity to internal olefins

No significant hydrogenation of the aromatic compounds.

H-PyGas-II gives a feed for aromatics extraction.

Uses moderate reaction conditions

[T ≈ 140oC, PT ≈ 20 barg, WHSVPyGas ≈ 4 h-1, PH2 ≈ 5-20 barg].

Selective hydrogenation of styrene and olefins

No hydrogenation of aromatics.

H-PyGas-III gives a low aromatic gasoline pool mix.

Uses more forcing hydrogenation reaction conditions [PH2 ≈ 20 barg, PT ≈ 20

barg, WHSVPyGas ≈ 4 h-1 T ≈ 140-200oC].

Can be coupled to acid catalyst to get ring opening and iso-alkanes for the

production of the high-octane components (iso-alkanes) for the gasoline pool

mixture.

1-alkene reacts at edges/corners

2-alkene reacts on faces

Acknowledgements

Kohat University of Science and Technology (KUST), Kohat, Pakistan

Javed AliMartin MacIntosh


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