M. GUISNET

University of Poitiers

Instituto Superior Técnico(F. Gulbenkian)

Petrochemical ProcessesAromatics

Lisbon December 2005

Petrochemicals : a) Benzene, Paraxylene

Naphtha reforming Steam cracking Aromatization

BTX (+ EB)

Excess of toluene, meta and ortho xylenes

Selective Toluene disproportionation (modified MFI)

Isomerization (I) of the C8 aromatic cut and p xylene separation (S)

Aromatization of light naphtha (Pt(K, Ba) LTL)

+2

nC6 + 4 H2

pX

Aromatic loopEB, X

S ((K, Ba)X)

I (PtHMOR)

EB mX oX

Petrochemicals : b) Alkylaromatics

Ethylbenzene Styrene

Cumene Phenol

Linear Alkylbenzene (LAB) Biodegradable detergents

+ C C

+ C CC

+

MFI (gaz phase) MCM22, BEA (Liq phase)

MCM22, BEA

MOR MCM22

Selective toluene disproportionation (STDP)

+2

How to obtain selectively paraxylene (p : 5.5 Å/ o : 5.8 Å)

1) Choice of MFI (ZSM5)

10 5.1 x 5.5 10 5.3 x 5.6 Å

2) Large Crystal size

- Chemical treatment (B, P, Mg…)

- Coking at high temperature

Pore structure of MFI

[ 10 5.1 x 5.5 10 5.3 x 5.6]***

5.3 x 5.6 Å

5.1 x 5.7 Å

8.5 Å

Beneficial « coke »

Increase of the shape selective properties :

High selectivity to paraxylene with ZSM5 zeolite coked at high temperature

Sieving effect Elimination of non selective outer sites

Coke on surface

Internal pore volume

View of surface on molecular scale

+2e.g

Para xylene Manufacturing

Demand : 70% of xylenes films, fibers, resins

Production 25% (Reforming – Steam cracking)

Xylene isomerization

Th Eq 75% (ortho + meta) + 25% (para)

Separation + Recycle

Ethylbenzene produced with xylenes. (17% reforming, 50% steam cracking)

Too high cost of separation

Isomerization Dealkylation

Bifunctional Zeolite Catalysts

PtHMOR (Na), Others (IFP, UOP)

Xylene isomerization with ethylbenzene isomerization

Xylene isomerization Acid mechanism

Ethylbenzene isomerization Bifunctional mechanism

EB

ECHE DMCHE

X

+2 H2 -2 H2

H+

Pt/Al2O3 – HMOR mixtures under H2 pressure

Secondary reactions :

Disproportionation and transalkylation e.g. 2X T + TMB

Dealkylation e.g. EB B + C2

Hydrocracking

Pt Pt

H2

Ethylbenzene isomerization

Influence of the balance between hydrogenating and acid functions

on selectivity at 35% conversion

0

20

40

60

80

100

0 2 4 6 8 10 12nPt/nH+

Se

lec

tiv

ity

(%

)

0

10

20

30

40

50

60

0.00 0.50 1.00 1.50 2.00nPt/nH+

Se

lec

tiv

ity

(%

)

Disproportionation

Dealkylation

Cracking

Isomerization Disproportionation Dealkylation

Cracking

0

20

40

60

80

100

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5nPt/nH+

Sél

ecti

vity

%

Ethylbenzene isomerization

Influence of the Na exchange of the HMOR component on selectivity

at 35% conversion

Isomerization

NaHMOR

HMOR

Isomerization of the C8 aromatic cut

Recent advances

New processes based on zeolites more efficient than mordenite UOP (I 210), IFP (Oparis)

p Xylene yield of 93% instead of 88-89%

Most likely pore mouth catalysis

Separation of C8 aromatics

p-xylene

Crystallization (Chevron-Amoco) high cost of equipment, high

energy consumption

Adsorption : Parex (UOP), Aromax (Toray), Eluxyl (IFP)

m-xylene Complexation with HF/BF3

Mitsubishi

o-xylene Fractional distillation

Separation of p-xylene by selective adsorption

* adsorbent : X (K,Ba)

* 120 - 180°C ; 20 bar

* Desorbent : toluene or p-diethylbenzene (low adsorption capacity)

p-xylene (99.5%)

a : p-xylene; b : other C8; c desorbent

p-xylene

L N Aromatization

RC DH

Pt Pt

Confinement model (Derouane)

Aromax Catalyst Performance

Relative Feed Aromatization Rate Selectivity (%)

n-hexane 1.00 90n-heptane 0.80 90-94n-octane 0.70 86-94n-nonane 0.70 90-942-methylhexane - 97methylcyclopentane 0.75 892-methylpentane 0.60 833-methylpentane 0.60 83

LTL (Linde Type L): [001] 12 7.1x7.1*

Petrochemicals : b) Alkylaromatics

Ethylbenzene Styrene

Cumene Phenol

Linear Alkylbenzene (LAB) Biodegradable detergents

+ C C

+ C CC

+

MFI (gaz phase) MCM22, BEA (Liq phase)

MCM22, BEA

MOR MCM22

+ C C

Old catalyst (1950) AlCl3+HCl

AlCl3 corrosivity and problems associated with safe handling and disposal

For 1 tonne of EB, use of 2-4 kg catalyst, 1kg of HCl, 5 kg of caustic solution, production of salts

Zeolite catalysts

- 1980 Mobil Badger vapour phase process MFI (ZSM5) 370-420°C, 7-27 bar, B/C2

= 5-20, WHSV 300-400 h-1, recycling of DEB, yield > 99.5%, life time : 1 year

- 1995 EB Max liquid phase process MWW (MCM22) 200°C , B/C2

= 3.5, Yield > 99.9%, life time > 3 years, more energy efficient

Pore structure of MCM-22 (MWW)

Supercages(7.1 x 18.4 Å)

Sinusoidal Channels(4.0 x 5.0 Å)

(A)

(B)

External Cups(7.1 x 7.0 Å)

Sinusoidal channels openings

(C)

Channel(4.0 x 5.5 Å)

Alkylation over MCM-22. Location

N Effect of collidine ( )

A) Eb synthesis (B/C2= = 3.5, 220°C)

C2= conversion

•Undoped sample 95.6 %

•Collidine doped sample 1.4 %

B) No effect on ethylbenzene adsorption (no pore mouth blocking)

Benzene alkylation occurs in the external cupsH. Du and D.H. Olson, J. Phys. Chem. B 2002

Initial significant « coke » deposition within the supercages

Method for determining the catalytic role of the three MCM-22 pore systems

Deactivation by « coke »

Activity (A) of supercages and product distribution

Trap cages: large (7.1 x 18.2 Å h) with small apertures (4.0 x 5.5 Å)

Poisoning of the large external cups (7.1 x 7.0 Å) with a bulky

basic molecule: (2,4-DMQ)N

A of external cups and product distribution

A of sinusoidal channels = A Total – A supercages – A cups

Product distributions are those expected from the size and shape of pores and apertures.

S. Laforge et al, Micropor. Mesopor. Mater. 2004

0

5

10

15

0 5 10 15 20 25TOS (h)

Con

vers

ion

(%

) D = 10 %

D = 0.3 %

Method for determining the acid site distribution in the three MCM-22 pore systems

00 200 400

2,4-DMQ (µmol.g-1)

1

2

3

4

X (

%)

Q

CCup sites

1450 1500 1550

Wavenumber (cm-1)

0.1Fresh Coked 24 h

CPyH+ = CSupercage sites

CSinusoidal channel sites

=Ctotal – Csupercages - Ccups

Comparison of MCM-22 samples with different crystallite sizes

Supercages

Sinusoidal channels

Cups

Sext = 38 m².g-1 Sext = 114 m².g-1

0

20

40

60 48 %

%

18 %

0

20

40

60

25 %%

10 %

A B

A : m-Xylene conversion

B : Brönsted sites

A B

How to increase the external surface ?

Calcination

MCM-22

Swollen MCM-22

CTMA +

Pillaring

MCM-36

Delamination

ITQ-2

Corma et al, (1999)

Synthesis of cumene over HBEA zeolites

Eniricerche process

+ C C C

CCC

Bellussi 1995

Comparison of HBEA with the usual catalysts PA (H3PO4/kieselguhr)

HBEA PAT 150°C 200°C

C3= conversion 90 % 90 %Oligomers (wt %) 0.3 1.1

Cumene (wt %) 94.3 95.1n propylbenzene 175 400

(ppm)DIPB (wt%) 4.5 3.2

Selectivity C 9/C6 (%) 95.7 97IPBS/C3 98.3 96.4

HBEA a very particular zeolite Tridimensional channel system 12 6.6 x 6.7** 12 5.6 x 5.6*

Intergrowth hybrid of two distinct structures (polymorphs A and B)

many internal local defects (T atoms not fully coordinated to the framework Lewis acid sites)

Generally synthesized under the form of small crystallites ( 20-50 nm large external suface diffusion limitations)

Acid treatment of BEA (12) % dealumination (total, framework). Acidity (H+, Lewis)

EFAL species : monomeric (360), polymeric (290)

µmol.g-1 Structure defects (120)

Bridging OH (470)

Shape selectivity

Adaptability

Remarkable Acid Properties

CONCLUSIONS

Efficient adsorbents and catalysts

Refining Petrochemicals

Depollution Fine Chemicals

GREEN CHEMISTRYGREEN CHEMISTRY

CONCLUSIONS

Recent advances New industrial processes

Isodewaxing SAPO11, TON

Methanol to olefins SAPO 34

Ethylbenzene and cumene synthesis MWW, BEA etc.

Isomerisation of the C8 arom cut IFP OPARIS process

Aromatization KL, Ga/MFI

NEW CONCEPTS

New Concepts

Shape Selectivity of the external surface

External cups (MCM 22)

Pore mouth (SAPO 11, TON, FER …) and key lock catalysis

Coke molecules as active species

Synthesis of zeolites with large external surface (nanocrystalline, delaminated zeolites…)

Synthesis of zeolites with cups on the outer surface…