hydrocarbon processingkkft.bme.hu/attachments/article/109/2020 hp_6 desulphuriation and... ·...

HYDROCARBON PROCESSINGDESULPHURISATION

AND

DIESEL QUALITY IMPROVEMENT

English version based on the presentation of

Prof. Dr. Jenő Hancsók, D.Sc.

held on 08.10.2014

[email protected]

Pannon UniversityMOL Crude Oil and Coal Technology Department

MOL Ásványolaj- és

Széntechnológiai Intézeti

Tanszék

Vegyészmérnöki- és

Folyamatmérnöki Intézet

8200 Veszprém, Egyetem u. 10. Pf. 158.

Tel.: +36 88/624217 Fax.:+36 88/624520

Jenő Hancsók: Hydrocarbon processing, BME, 08.10.2014., Copyright 2

Crude oil distillation fractions: carbon number

and atmospheric boiling point range

2

Desulphurisation of

hydrocarbon fractions

44

Desulphurisation of hydrocarbon fractions

Necessity, importance

◼ To meet product quality specifications (10 ppm)

◼ To prevent catalyst poisoning during later

processing (CCR, LNI)

◼ To prevent corrosion

◼ To protect car exhaust gas catalyst

◼ General and specific environment protection

Jenő Hancsók: Hydrocarbon processing, BME, 08.10.2014., Copyright

55

LPG Desulphurisation

Sulphur compounds in LPG

◼ carbonyl-sulphide (COS; bp.: -50°C)

◼ methyl-mercaptan (CH3SH; bp.: +6°C)

Processes

◼ Removal with caustic

Mercaptan-reformulation:

RSH + NaOH → RSNa + H2O

H2S + 2 NaOH → Na2S + 2 H2O

Caustic regeneration:

2 RSNa + ½ O2 + 2 H2O → RSSR + 2 NaOH + H2O

2 Na2S + 4 H2O + 2 O2 catalyst Na2S2O3 + 2 NaOH + 3 H2O

◼ Removal with molecular sieve


6

Molecular structure of cobalt-ftalocyanin

6Jenő Hancsók: Hydrocarbon processing, BME, 08.10.2014., Copyright

77

LPG Desulphurisation (MEROX)


88

Gasoline desulphurisation

Sulphur compounds in gasoline

Compound Formula Boiling Point, °C

Mercaptans

ethyl-mercaptan C2H5SH 35,0

n-nonyl-mercaptan C9H19SH 220

Sulphides

dimethyl-sulphide CH3-S-CH3 38

n-butyl-sulphide C4H9-S- C4H9 188

Disulphides

dimethyl-disulphide CH3-S-S-CH3 109

ethyl-disulphide C2H5-S-S- C2H5 153

Thiophenes

thiophene

S

80

dimethyl-thiophene S

135

benzothiophene

S

221


99

Light gasoline desulphurisation

Sulphur compounds removal by caustic (see LPG)

Reformulation to non-corrosive sulphur compounds („sweetening”)

During „sweetening” the mercaptan is reshaped to the less corrosive

disulphide form, which will remain in the product → the sulphur

concentration will be not changed!!!

2 RSH + 2 OH- → 2 RS- + 2 H2O

2 RS- + cat.0 → RSSR + cat.2-

cat.2- + 1/2O2 + H2O → cat.0 + 2 OH-

(cat.: catalyst, e.g. cobalt-ftalocyanin)


1010

Fixed bed MEROX sweetening process


1111

Desulphurisation of middle and heavy gasoline

fractions

Examples of hydrodesulphurisation reactions

◼ Mercaptans:

R - S - H + H2 → R - H + H2S

◼ Disulphides:

R1 - S -S - R2 + 3 H2 → R1 - H+ R2 - H + 2 H2S

◼ Thiophenes:


1212

Sulphur reduction possibilities of FCC and

pyrolisis gasoline

◼ Selective hydrogenation (industrial application)

◼ Catalytic distillation

◼ Hydrogenation + isomerisation

◼ Alkylation of sulphur compounds

◼ Adsorption

◼ Reactive adsorption

◼ Membrane separation

◼ Extractive distillation

◼ Oxidation of sulphur compounds

◼ Bio-catalytic desulphurisation


Typical sulphur and olefin compound

distribution in the FCC gasoline

13

0,7

0,6

0,5

0,4

0,3

0,2

0,1

050 100 150 200

70

60

50

40

30

20

10

0

Olefintartalom

Kéntartalom

Tiofének

Szulfidok, diszulfidok

Merkaptánok

S

CH3CH3

S

CH3

S

C2H5

S

C3H7

C2-S-C1 C2-S-C2 C3-S-C3

C2-S-S-C2

C4-S-C4

C2SH C3SH C4SH C5SH C6SH C7SH C8SH

Kén

tar t

alo

m,%

Forráspont, °C

Ole

fi nta

rtalo

m,%

S

Benzotiofének

S

SS

SS

CH3


Boiling point, ˙C

Ole

fin c

on

ten

t, %

Su

lph

ur

co

nte

nt,

%

Olefin content

Sulphur content

Typical composition of the FCC gasoline


Desulhurisation possibilities (processes)

of total and reduced FCC gasoline fractions


1616

Hydrodesulphurisation (heteroatom removal)

of petroleum fractions

Sulphur compounds example

220-230°C bp.

sulphur comp.

Nitrogen compounds example

Aniline

Oxygen compounds example

Carboxylic acids

R-COOH C5 ≤ R ≤ C7

R: alkyl-group

NH2

saturated hydrocarbon + H2S

cat., T, P, + H2saturated hydrocarbon + NH3

cat., T, P, + H2

cat., T, P, + H2 saturated hydrocarbon + H2O


1717

Desulphurisation of gasoil

Theoretical possibilities:

◼ Hydrodesulphurisation

◼ Adsorption/chemisorption processes

◼ Extraction/partly reactive extraction

◼ Oxidative desulphurisation

◼ Biocatalytic desulphurisation


1818


(heteroatom removal)

Basic reactions

◼ Mercaptans:

R - S - H + H2 → R - H + H2S R ≥ C10

◼ Sulphides:

Open chained:

◼ sulphides: R1 - S - R2 + 2H2 → R1 - H+ R2 - H + H2S

◼ disulphides: R1 - S -S - R2 + 3 H2 → R1 - H+ R2 - H + 2 H2S

Cyclic:

◼ thiophenes:


1919



◼ benzo-thiophenes:

◼ dibenzo-thiophenes:

+ 3 H2 + H2S

R

S

CH2-CH3

R

S

R R


2020



Reaction net of dibenzo-thiophene

(Numbers: reaction speed constants, dm3/gcat.s)

S

S S

4,2x10-8 2,8x10-5

1,1x10-44,7x10-5

lassú


Alternative desulphurisation reaction pathways

for sterically hindered diaklyl-dibenzo-thiophenes


2222

Relative reactivity of typical sulphur

compounds

Sulphur compound Formula Relative

reactivity

Thiophenes S

R

1

Benzothiophenes

S

R

0,6

Dibenzothiophenes

S

R R

0,04

4- and/or 6-methyl-

dibenzothiphene S

CH3

CH3

0,004


2323

Example reactions of heteroatom removal and

partial dearomatisation of gasoil

Nitrogen removal reactions:

◼ Amines: C18H37 - NH2 + H2 → C18H38 + NH3

◼ Nitriles: C18H37 - CN + 3H2 → C18H37 - CH3 + NH3

◼ Pyrrole-derivatives (pyrrole, indole, carbazole)

◼ Pyridine-derivatives (pyridine, kinoline, acridine)

NH

NH N

H

cat., T, P, + H2Saturated hydrocarbon + NH3

NN N

cat., T, P, + H2Saturated hydrocarbon + NH3


2424


partial dearomatisation of gasoil

Oxygen removal reactions:

◼ phenol-deriavatives (alkyl- and allyl-phenols, naphtaleneols)

◼ ketones (tetralones)

◼ furan-derivatives (alkyl-furans, benzofuran, dibenzofuran)

◼ carbonyles (carboxylic acids: R-COOH, aldehydes: R-COH, amides: R-CONH2)

OH

OHR R

O

R

O O O

R

R R

cat., T, P, + H2Hydrocarbon + H2O



cat., T, P, + H2 Hydrocarbon + H2O ( + NH3)



partial (20-40%) dearomatisation of gasoil

25

Mainly the multi ring aromatic partial saturation to mono ring compounds

From naphtalene to decaline:

2H izomerizáció 2H

H2H

R

6H

Three ring aromatic saturation :

R2

R1

+ H2

Katalizátor

R1

R2


catalyst

2626

Catalysts for desulphurisation

Catalysts with transition metals (Ni, Co, Mo)

On metal-oxide support (Al2O3, SiO2, TiO2), sometimes zeolite

(feed sulphur content ~250 mg/kg → 1-2%)

e.g.: CoMo/Al2O3; NiMo/Al2O3; CoNiMo/Al2O3

Catalysts with noble metals (Pd, Pt, Re, Ir)

◼ On metal-oxide support (Al2O3, SiO2, TiO2)

◼ On zeolite support (USY, MCM-41, MFI)

(feed sulphur content ≤ 250 mg/kg )

e.g.:Pt-Pd/Al2O3; Pt-Pd/USY

USY: ultra stable Y-type zeolite

MCM: Mesoporous Catalyst Materials


2727

Theoretical scheme of hydrodesulphurisation


2828

Typical parameters of desulphurisation of

different fractions

LAGO: light atmospheric gasoil; HAGO: heavy atmospheric gasoil; LVGO: light vacuum gasoil

Feed Gasoline Petroleum LAGO HAGO LVGO

Parameters: TBP cut points, °C Sulphur, % (mg/kg) Process parameters: Temperature, °C Pressure, bar LHSV, h

-1

H2/feed ratio, vol/vol Product sulphur, mg/kg Catalyst cycle life, month Relative catalyst cost, 1/t

70-200

(100-1000)

310-330 20-30

4,0-6,0 100-150

Sulphur removal and production

from hydrogen-sulphide

containing gases

Hydrogen-sulphide removal from high

hydrogen concentration gases

30

(H2, others)

Sweet gas

Sour gas


Absorber

Solvent

Stripper

(desorber)

End gas

The reaction (MDEA)

(HO-CH2-CH2)2-N-CH3+H2S

((HO-CH2-CH2)2-N-CH3)+(SH)−


Most frequently used absorbents

Absorbent MEA DEA MDEA

Molecular weight 61 105 119

Concentration (vol%) 15 30 50

Minimum H2S load (nH2S/namine) 0,05 0,02 0,01

Maximum H2S load (nH2S/namine) 0,6 0,6 0,5

Capacity (H2S/dm3) 1,77 2,18 2,77

32

MEA: mono-ethanol-amine

DEA: di-ethanol-amine

MDEA: methyl-di-ethanol-amine


Sulphur production from hydrogen-sulphide

(1) Partial oxidation in the burning chamber H2S + 1,5O2 → SO2 + H2O

or (including the unburnt H2S) 3H2S + 1,5O2 → 2H2S + SO2 + H2O ]

(2) Claus reaction in the burning chamber and in

the catalytic converter2H2S + SO2 → 3S + 2H2O

(1+2) Gross reaction 2H2S + O2 → S2 + 2H2O

COS production H2S + CO2 → COS + H2O

CS2 production CH4 + 2S2 → CS2 + 2H2S

COS hydrolisis COS + H2O → CO2 + H2S

CS2 hydrolisis CS2 + 2H2O → CO2 + 2H2S


Sulphur production from hydrogen-sulphide

by Claus process

Thermic step: H2S + 1,5 O2 → SO2 + H2O

Catalytic step: 2 H2S + SO2 ↔ 3S + 2 H2O

Véggáz-

tisztító

egységKémény

Termikus

utóégető

Katalitikus

konverter

Katalitikus

konverter

Kén leválasztó

kondenzátorKén leválasztó

kondenzátor

Kén leválasztó

kondenzátor

KénKénKén

Gőz

Hulladékhő

hasznosító

Égető kamra

H2S-ben

dús gázLevegő

H2S/SO2 = 2:1

Előmelegítő Előmelegítő

Víz

Vízgőz

Víz Víz

Vízgőz Vízgőz


35

Reduction the aromatic

compounds concentration in

gasoil


36

Saturation of aromatics in gasoil by

hydrogenation

Importance:

The lower the aromatic content, the better the working

behaviour: higher cetane number, lower exhaust emission

– specifically the particulate matters – middle distillate

production, raw material and energy efficient,

environmentally friendly and economic way.


37

Theoretical considerations


38

Reduction the aromatic compounds

concentration in gasoil

Non-catalytic processes

◼ Acidic refining

◼ Physical separation

adsorption

extractive distillation

Solvent extraction

Liquid membrane permeation

Catalytic processes

◼ Partial or total hydrogenation

(the goal is to convert the aromatics to naphtenes)

◼ hydrocracking (different severity)


39

Aromatic compounds in gasoil

Single ring aromatics Two ring aromatics Three ring aromatics

- alkyl-benzenes - Naphtalene and alkyl-

naphtalenes

- antracenes

- benzo-cycloparaffins - bifenyls - fenantrenes

-benzo-dicycloparaffins - naphteno-aromatics (indenes) - fluorenes


40

Saturation of aromatics

Highly exotherm reaction

alkyl-benzene to alkyl-cyclohexane

(reaction time increases with the alkyl chain size; exothermicity decreases)

Naphthalene to decaline: ∆H = -335 kJ/mol

2H izomerizáció 2H

H2H

R

6H

2H 2H 2H 2H

gyűrűfel-szakadás

szénhidrogén

R R R R

toluene → methyl-cyclohexane: ∆H = -205 kJ/mol

ethyl-benzene → ethyl-cyclohexane: ∆H = -202 kJ/mol

cumene → 2-cyclohexyl-propane: ∆H = -184 kJ/mol


hydrocarbonRing

rapture

41

Kinetic and thermodynamic factors determining

the hydrogenation of aromatic compounds

Tkinetika Tterm.

Aro

má

sta

rta

lom

, ft

f %

Hőmérséklet, °C

P = 50 bar


Transition metal/support

Noble metal/support

Temperature,

Aro

ma

tic c

on

ten

t, v

ol%

42

Catalysts for aromatic hydrogenation

Highly sulphur tolerant catalysts

(feed sulphur content ≥ 250 mg/kg)

◼ Mo, W (VI. group) and Co, Ni (VIII. group) in suphided form, on γ-Al2O3 support

Activity sequence: Mo > W >> Ni > Co

◼ NiMo/Al2O3, CoMo/Al2O3, NiW/Al2O3 in sulphided form

Activity sequence: NiW > NiMo > CoMo > CoW

◼ Partial aromatic saturation (up to ~50-80 %; at least 60 bar H2 partial pressure)

Low sulphur tolerant catalysts

(feed sulphur content 250 mg/kg, more typically 10-20 mg/kg)

◼ Pt or Pt, Pd amorphous Al2O3 – SiO2, or on acidic (USY) support

◼ High level aromatic saturation (up to ~95 %; Tmax: 300-310 °C, pH2: 25-40 bar)


43

Industrial applications

Differences in applications:

In the sequence of heteroatom removal and aromatic saturation (in teh same time or in sequence);

In the number of reactors applied;

In the catalyst(s) applied;

In the mode of catalyst distribution (e.g. divided bed);

In the mode of feed introduction to the catalyst bed;

In the mode of quench cooling;

In the used process parameters, etc.

The industrial applications may be classified into two main groups:

Single stage processes

Two stage processes


44

Sketch of the single stage aromatic reduction

of gasoil


45

Sketch of the two stage aromatic reduction of

gasoil


46

Catalytic reshaping of normal-

paraffins in gasoil

(„paraffin removal”)


4747

Catalytic reshaping of normal-paraffins in

gasoil

Importance

The goal is to convert the high freezing point normal paraffins to lower

freezing point ones (decrease of cold filtration point – CFPP)

Freezing point reduction possibilities

❑ Selective hydrocracking

❑ Selective isomerisation

❑ Combination of the two above


48

Theoretical considerations of freezing point vs

carbon number


-100

-80

-60

-40

-20

0

20

40

60

Fre

ezin

g p

oin

t, °

C

Carbon number

nincs

2-metil

5-metil

1312 16 18 20 22

Side chain

DT=60°C DT=64°C

DT=59°C

DT=48°C

DT=44°C

none

2-methyl

5-methyl

4949

Catalytic reshaping of normal-paraffins in

gasoil

Catalyst examples:

◼ Ni/ZSM-5 (mainly hydrocracking)

◼ Pt/SAPO-11, Pt/HZSM-22 (mainly isomerisation)

Process parameters

◼ Temperature: 330 – 370°C

◼ Pressure: 30 – 50 bar

◼ LHSV: 1,0 – 2,0 m3/m3h

◼ H2/hydrocarbon ratio: 250 – 300 Nm3/m3

Product yield: 80 – 95 %

Freezing point drop (ΔT): 15 – 25°C


Recommended literature

Hancsók, J., Baladincz, J., Magyar, J. (szerkesztők): „Mobilitás és környezet”, gyűjteményes kiadvány, 2008,

Pannon Egyetemi Kiadó, Veszprém (ISBN: 978-963-9696-50-1), 240 oldal

Srivastava, S. P., Hancsók, J.: „Fuels and Fuel-Additives”, 2014, John Wiley & Sons, Inc., Hoboken, New Jersey,

(ISBN: 978-0-470-90186-1), 376 oldal

Hancsók.Jenő.:Korszerű motor- és sugárhajtómű üzemanyagok II. Dízelgázolajok, tankönyv, Veszprémi Egyetemi

Kiadó 1999.

Hancsók Jenő, Kasza Tamás: „Katalitikus hidrogénező eljárások a kőolajiparban”, Oktatási segédlet, Veszprém,

2010.

Magyar Kémikusok Lapja következő számai: 2005/6-12, 2006/1-12, 2007/1-7

Gary, J.H.: Petroleum Refining Technology and Economics 3rd , Marcel Dekker, N.Y. 2004.

Speight,J.G.: The chemistry and technology of petroleum 3rd . Marcell Dekker, 1999.

Speight,J.G.: Petroleum Chemistry and Refining, Taylor and Francis 2006.

Weissermel, K., Arpe, H-J.: Ipari szerves kémia, Nemzeti Tankönyvkiadó, Budapest, 1993.

Mc Ketta, J.: Petroleum Processing Handbook, Marcell Dekker, 1992.

Hobson, G.D.: Modern Petroleum Technology, J. Wiley, 1986.

Meyers, R.A.: Handbook of petroleum Refining Processes, McGraw-Hill Inc., N.Y., Toronto, 2007.

Olah, G.A., Molnár, Á.: Hydrocarbon chemistry, John Wiley and Sons, Inc., 2003.


51

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