1 / 27

M. GUISNET University of Poitiers Instituto Superior Técnico (F. Gulbenkian)

Petrochemical Processes Aromatics. M. GUISNET University of Poitiers Instituto Superior Técnico (F. Gulbenkian). Lisbon December 2005. Petrochemicals : a) Benzene, Paraxylene. Naphtha reforming Steam cracking Aromatization. BTX (+ EB).

dionne
Download Presentation

M. GUISNET University of Poitiers Instituto Superior Técnico (F. Gulbenkian)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

  2. 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) pX S ((K, Ba)X) EB mX oX Aromatic loop EB, X I (PtHMOR) nC6 + 4 H2

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

  4. Selective toluene disproportionation (STDP) How to obtain selectively paraxylene (p : 5.5 Å/ o : 5.8 Å) • 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

  5. Pore structure of MFI [ 10 5.1 x 5.5  10 5.3 x 5.6]***

  6. Beneficial « coke » • Increase of the shape selective properties : e.g High selectivity to paraxylene with ZSM5 zeolite coked at high temperature Coke on surface Internal pore volume View of surface on molecular scale Sieving effect Elimination of non selective outer sites

  7. 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)

  8. Xylene isomerization with ethylbenzene isomerization Xylene isomerization Acid mechanism Ethylbenzene isomerization Bifunctional mechanism Pt Pt X EB +2 H2 -2 H2 H+ DMCHE ECHE • Secondary reactions : • Disproportionation and transalkylation e.g. 2X T + TMB • Dealkylation e.g. EB B + C2 • Hydrocracking Pt/Al2O3 – HMOR mixtures under H2 pressure H2

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

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

  11. 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

  12. Separation of C8 aromatics Crystallization (Chevron-Amoco) high cost of equipment, high energy consumption Adsorption : Parex (UOP), Aromax (Toray), Eluxyl (IFP) p-xylene m-xyleneComplexation with HF/BF3 Mitsubishi o-xylene Fractional distillation

  13. 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%) p-xylene a : p-xylene; b : other C8; c desorbent

  14. L N Aromatization LTL (Linde Type L): [001] 12 7.1x7.1* Aromax Catalyst Performance Relative Feed Aromatization Rate Selectivity (%) n-hexane 1.00 90 n-heptane 0.80 90-94 n-octane 0.70 86-94 n-nonane 0.70 90-94 2-methylhexane - 97 methylcyclopentane 0.75 89 2-methylpentane 0.60 83 3-methylpentane 0.60 83 Confinement model (Derouane)

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

  16. 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

  17. Pore structure of MCM-22 (MWW) (B) (A) Channel (4.0 x 5.5 Å) External Cups (7.1  x 7.0 Å) Sinusoidal Channels (4.0 x 5.0 Å) (C) Supercages (7.1  x 18.4 Å) Sinusoidal channels openings

  18. N Alkylation over MCM-22. Location  Effect of collidine ( ) A) Eb synthesis (B/C2= = 3.5, 220°C) 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 D = 10 %  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) D = 0.3 %  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 = ATotal – Asupercages – Acups Product distributions are those expected from the size and shape of pores and apertures. S. Laforge et al, Micropor. Mesopor. Mater. 2004

  20. Method for determining the acid site distribution in the three MCM-22 pore systems Fresh Coked 24 h Q 4 0.1 3 DX (%) CSinusoidal channel sites = Ctotal – Csupercages - Ccups 2 1 0 0 200 400 1550 1500 1450 2,4-DMQ (µmol.g-1) Wavenumber (cm-1) CCup sites DCPyH+ = CSupercage sites

  21. Comparison of MCM-22 samples with different crystallite sizes Supercages A : m-Xylene conversion Sinusoidal channels B : Brönsted sites Cups 48 % 60 60 40 40 25 % % % 18 % 20 20 10 % 0 0 A B A B Sext = 38 m².g-1 Sext = 114 m².g-1

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

  23. Synthesis of cumene over HBEA zeolites Eniricerche process Comparison of HBEA with the usual catalysts PA (H3PO4/kieselguhr) HBEA PA T 150°C 200°C C conversion 90 % 90 % 3= Oligomers (wt %) 0.3 1.1 Cumene (wt %) 94.3 95.1 n propylbenzene 175 400 (ppm) DIPB (wt%) 4.5 3.2 Selectivity C /C (%) 95.7 97 9 6 IPB /C 98.3 96.4 S 3 Bellussi 1995

  24. HBEA a very particular zeolite  Tridimensional channel system12 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)

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

  26. 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

  27. New Concepts • Shape Selectivity of the external surface  External cups (MCM 22)  Pore mouth (SAPO 11, TON, FER …) and key lock catalysis Synthesis of zeolites with large external surface (nanocrystalline, delaminated zeolites…) Synthesis of zeolites with cups on the outer surface… • Coke molecules as active species

More Related