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M. GUISNET University of Poitiers Instituto Superior Técnico (F. Gulbenkian) Petrochemical Processes Aromatics Lisbon December 2005.

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Presentation on theme: "M. GUISNET University of Poitiers Instituto Superior Técnico (F. Gulbenkian) Petrochemical Processes Aromatics Lisbon December 2005."— Presentation transcript:

1 M. GUISNET University of Poitiers Instituto Superior Técnico (F. Gulbenkian) Petrochemical Processes Aromatics Lisbon December 2005

2 Petrochemicals : a) Benzene, Paraxylene Naphtha reformingSteam cracking Aromatization BTX (+ EB) Excess of toluene, meta and ortho xylenes Selective Toluene disproportionation (modified MFI) Isomerization (I) of the C 8 aromatic cut and p xylene separation (S) Aromatization of light naphtha (Pt(K, Ba) LTL) nC H 2 pX Aromatic loop EB, X S ((K, Ba)X) I (PtHMOR) EB mX oX

3 Petrochemicals : b) Alkylaromatics Ethylbenzene Styrene Cumene Phenol Linear Alkylbenzene (LAB)Biodegradable detergents MFI (gaz phase) MCM22, BEA (Liq phase) MCM22, BEA MOR MCM22

4 Selective toluene disproportionation (STDP) How to obtain selectively paraxylene (p : 5.5 Å/ o : 5.8 Å) 1)Choice of MFI (ZSM5) x x 5.6 Å 2)Large Crystal size - Chemical treatment (B, P, Mg…) - Coking at high temperature

5 Pore structure of MFI [ x 5.5  x 5.6]***

6 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 e.g

7 Para xylene Manufacturing Demand : 70% of xylenesfilms, 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 IsomerizationDealkylation Bifunctional Zeolite Catalysts PtHMOR (Na), Others (IFP, UOP)

8 Xylene isomerization with ethylbenzene isomerization Xylene isomerization Acid mechanism Ethylbenzene isomerizationBifunctional mechanism EB ECHE DMCHE X +2 H 2 -2 H 2 H+H+ Pt/Al 2 O 3 – HMOR mixtures under H 2 pressure Secondary reactions :  Disproportionation and transalkylation e.g. 2X T + TMB  Dealkylatione.g. EB B + C 2  Hydrocracking Pt H2H2

9 Ethylbenzene isomerization Influence of the balance between hydrogenating and acid functions on selectivity at 35% conversion Isomerization Disproportionatio n Dealkylation Cracking

10 Ethylbenzene isomerization Influence of the Na exchange of the HMOR component on selectivity at 35% conversion Isomerization NaHMOR HMOR

11 Isomerization of the C 8 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

12 Separation of C 8 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/BF 3 Mitsubishi o-xylene Fractional distillation

13 Separation of p-xylene by selective adsorption * adsorbent : X (K,Ba) * °C ; 20 bar * Desorbent : toluene or p-diethylbenzene (low adsorption capacity) p-xylene (99.5%) a : p-xylene; b : other C 8 ; c desorbent p-xylene

14 L N Aromatization Confinement model (Derouane) Aromax Catalyst Performance Relative Feed Aromatization Rate Selectivity (%) n-hexane n-heptane n-octane n-nonane methylhexane -97 methylcyclopentane methylpentane methylpentane LTL (Linde Type L): [001] x7.1*

15 Petrochemicals : b) Alkylaromatics Ethylbenzene Styrene Cumene Phenol Linear Alkylbenzene (LAB)Biodegradable detergents MFI (gaz phase) MCM22, BEA (Liq phase) MCM22, BEA MOR MCM22

16  Old catalyst (1950) AlCl 3 +HCl AlCl 3 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 Mobil Badger vapour phase process MFI (ZSM5) °C, 7-27 bar, B/C 2 = 5-20, WHSV h -1, recycling of DEB, yield > 99.5%, life time : 1 year EB Max liquid phase process MWW (MCM22) 200°C, B/C 2 = 3.5, Yield > 99.9%, life time > 3 years, more energy efficient

17 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)

18 Alkylation over MCM-22. Location N  Effect of collidine ( ) A) Eb synthesis (B/C 2 = = 3.5, 220°C) C 2 = conversion Undoped sample95.6 % Collidine doped sample1.4 % B) No effect on ethylbenzene adsorption (no pore mouth blocking) Benzene alkylation occurs in the external cups H. Du and D.H. Olson, J. Phys. Chem. B 2002  Initial significant « coke » deposition within the supercages

19 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 D = 10 % D = 0.3 %

20 Method for determining the acid site distribution in the three MCM-22 pore systems ,4-DMQ (µmol.g -1 )  X (%) Q C Cup sites Wavenumber (cm -1 ) 0.1 Fresh Coked 24 h  C PyH+ = C Supercage sites C Sinusoidal channel sites = C total – C supercages - C cups

21 Comparison of MCM-22 samples with different crystallite sizes Supercages Sinusoidal channels Cups S ext = 38 m².g -1 S ext = 114 m².g % % 18 % % % 10 % AB A : m-Xylene conversion B : Brönsted sites AB

22 How to increase the external surface ? Calcination MCM-22 Swollen MCM-22 CTMA + Pillaring MCM-36 Delamination ITQ-2 Corma et al, (1999)

23 Synthesis of cumene over HBEA zeolites Eniricerche process Bellussi 1995 Comparison of HBEA with the usual catalysts PA (H 3 PO 4 /kieselguhr) HBEAPA T150°C200°C C 3= conversion90 % Oligomers (wt %) Cumene (wt %) n propylbenzene (ppm) DIPB (wt%) Selectivity C 9 /C 6 (%) IPB S /C

24 HBEA a very particular zeolite  Tridimensional channel system x 6.7**  x 5.6*  Intergrowth hybrid of two distinct structures (polymorphs A and B) many internal local defects (T atoms not fully coordinated to the frameworkLewis acid sites)  Generally synthesized under the form of small crystallites (  nm large external sufacediffusion 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 )

25 Shape selectivity Adaptability Remarkable Acid Properties CONCLUSIONS Efficient adsorbents and catalysts Refining Petrochemicals Depollution Fine Chemicals GREEN CHEMISTRY

26 CONCLUSIONS Recent advances New industrial processes IsodewaxingSAPO11, TON Methanol to olefinsSAPO 34 Ethylbenzene and cumene synthesisMWW, BEA etc. Isomerisation of the C8 arom cutIFP OPARIS process AromatizationKL, Ga/MFI NEW CONCEPTS

27 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…


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