Oleochemicals and Catalysts Used
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Oleochemicals - What are they? fatty acids fatty alcohols fatty methyl esters fatty amines glycerine Oleochemical pathways What are they used for? Where do they come from? Review of Organic Functional Groups Fatty Acids - Uses - Process - Splitting - Hydrogenation Ni Catalyst for FA hydrogenation Catalyst deactivation in fatty acids by corrosion Ni soap decomposition Nickel dissolution in the presence of hydrogen Comparison pore size & TG/FA molecules Effect of pore dimensions in fatty acid hardening Effect of premixing time on catalyst activity Effects of catalyst dissolution summarized: Reducing Ni soaps Issues Alternative catalyst for FA hydrogenation (i) Precious metal catalyst cycle Alternative catalyst for FA hydrogenation (ii) Fatty Alcohols - Uses - Process Fatty Ester Hydrogenolysis Fixed Bed Hydrogenolysis Slurry Phase Hydrogenolysis Fatty OH polishing Fatty Methyl Esters - Uses Advantages of ME vs FA as a feedstock FME - Biodiesel Fatty Amines Glycerin - Uses - The Future REFERENCE: Some graphs and photographs, in particular the photo of "The nickel deposits in the tube section", were extracted from Johnson Matthey contributions to International conferences.
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Oleochemicals and Catalysts Used
- 1. Gerard B. Hawkins Managing Director
- 2. Chemical intermediates and products derived from natural triglycerides 5 basic oleochemicals: ◦ fatty acids ◦ fatty alcohols ◦ fatty methyl esters ◦ fatty amines ◦ glycerine
- 3. Glycerine Fatty Acids Fatty Acid Methyl Esters Fatty Alcohol Oils & Fats splitting esterification trans-esterification Partial glycerides Triacetine Fatty Acid esters F.A. ethoxylates Soaps Fatty Amines Alkyl chlorides F. OH ethoxylates F.OH sulfates Esters F.A. Alkanolamides Fatty Alcohols esterification esterification ethoxylation neutralization amination hydrogenation amidation direct hydrogenation Adapted from: Zoeblein, INFORM, Vol 3. no.6 a b c d
- 4. Lubricants Detergents Plasticizer Cosmetics
- 5. • Palm Oil (PO)- Primarily derived from the palm oil plantations in Malaysia and Indonesia is the major feedstock in Asia. • Coconut - Major source Philippines. Declining in use. • Fish oil (FH) - Predominantly used in Chile/Peru. Was popular in UK, Norway, Japan. • Canola/Rapeseed - Predominantly grown in Canada and northern Europe. Typically has higher poisons than soya. • Soyabean Oil (SO)- Primarily derived from the major soya states in the US, Brazil and Argentina. • Tallow - animal fat, usually a by-product of rendering. Lard from pigs also used. Where do they come from? • Whales - major source of oleochemicals for many years - oils, waxes, ester, spermaceti, squaleen. No longer available due to over- hunting
- 6. Alcohols ◦ OH OH O CR OH H CR H H H NR O O CR H R1 • Amines – NH2 • Esters – COOR1 • Carboxylic Acids – COOH
- 8. Splitting Hydrogenation Distillation
- 9. Different Process ◦ Twitchell used catalyst ◦ Continuos Colgate-Emery higher T & P than Twitchell ◦ Enzymatic lipases limited interest to date
- 10. Usually to full saturatiuon ◦ i.e. break all double bonds Catalysts used ◦ Ni on silica powder; slurry phase ◦ Pd on C powder; slurry phase ◦ Pd on C; fixed bed Reactor systems ◦ Batch Dead End reactors ◦ Continuous Plug flow continuous reactors ◦ Loop reactors ◦ typical conditions 200°C & 20bar
- 11. Typically a 22-25% Ni on silica or kieselguhr support Used by the majority of the market Particle diameter 6-14 microns Narrow pores to prevent Ni dissolution Used once and then must be discarded Dissolved Ni soaps end up in distillate residues
- 12. Equilibrium is determined by hydrogen concentration ! Ni(fa)2 + H2 low pressure/ hydrogen shortage high pressure/ abundance of hydrogen Ni + 2 ffa
- 13. Fate of nickel crystallites: Nickel dissolution is chemically reversible, but catalytic surface vanishes drastically thereby (loss of Nickel dispersion): + ffa - ffa + Ni-soaps fresh catalyst 100 m²/g Ni used catalyst 10-20 m²/g Ni
- 15. 0 5 10 15 20 25 0 0.1 0.2 0.3 0.4 0.5 0.6 1/H2 pressure (bar-1) DissolvedNi(ppm) 2 bar10 bar30 bar Ni2+ = K.(H+)2/H2 Ni + 2H+ = Ni2+ + H2 Note Ni dissolution decreases by factor 100 for every pH unit rise! (data based on fatty acid hydrogenation 180 C)
- 16. Smaller pore sizes impede diffusion of larger molecules, i.e. triglycerides (Gly(fa)3) or nickel soaps (Ni(fa)2)
- 17. Soybean soap stock fatty acids, 15 bar, 200°C 1 10 100 1 10 pore size diameter (nm) final iodine value presumable course
- 18. tallow olein fatty acids vacuum 140°C fast stirring catalyst dosage 450 ppm Nickel 50 55 60 65 70 75 80 85 90 95 100 0 50 100 time (min) relativeactivity(%)
- 19. Loss of Nickel dispersion Nickel soap formation Residual Nickel in final product
- 20. Minimize contact time in absence of hydrogen ◦ Dose Ni to reactor just before addition of H2 or when it is already under H2 pressure ◦ Filter catalyst from FA as quickly as possible If melting of catalyst pellets required, melt in triglyceride
- 21. Ni residues Environment
- 22. Pd/C slurry phase Typical 5% Pd on a carbon support Can be re-used Must have very efficient recovery Current Pd price - $737/ounce Financial management as important as operational management
- 24. Pd/C fixed bed Extrudates / Gauze High working capital use Efficient, continuous production Ni fixed bed has proved difficult (basic supports, posion resistance) IV < 1 unsat FA
- 25. Fatty Alcohols Surfactants 80% Shampoo Powders Bath gels etc Cosmetics Lubricants in polymer processing Emulsifying agents OH O CR
- 26. “Natural” fatty alcohols ◦ Hydrogenation (hydrogenolysis) of fatty methyl esters ◦ direct hydrogenation of fatty acids Synthetic fatty alcohols ◦ Oxo-Alcohols ◦ Ziegler process
- 27. Catalysts used: ◦ CuCr ◦ CuZn ◦ CuSi ◦ Raney Cu Fixed bed and slurry phase units in operation Move to eliminate Cr
- 28. Feed: methyl esters Gas phase FB ◦ 2900-3600psi; 230-250°C Trickle-bed ◦ 2900-4350psi; 250 °C
- 29. Higher cat consumption than FB Greater flexibility Vertical plug-flow reactor ◦ 3600psi; 250-300°C Direct hydrogenolysis of fatty acids (Lurgi) ◦ Acid-resistant catalyst required ◦ Excess of fatty OH and loop employed ◦ 4350psi; 300°C
- 30. Carbonyls in fatty OH can give unwanted color, odor, etc Can be removed by hydrogenation with Ni ◦ e.g. fixed bed process with PRICAT HTC Ni impregnated alumina trilobe extrudate ◦ 100-150°C; 20-50bar
- 32. Usually manufactured directly from oils via methanolysis with alkaline catalysts (e.g. sodium methylate) CH2OH CHOH CH2OH 3CHOH 3RCOOCH3 RCOOCH2 RCOOCH RCOOCH2 NaOCH3 + + methyl ester
- 33. Lower energy consumption Less corrosive -> less expensive equipment More concentrated glycerine Easier to distill Superiority in some reactions However the use of MeOH can have its downsides
- 34. 3-armed high viscosity molecule broken down to single chain low viscous fuel Similar to cetane (C16) • Growth industry due to: – green movement and agricultural incentives in Europe – agricultural lobby and aim for domestic fuel production in USA cetane (C16) biodiesel
- 35. Most uses depend on the cationic nature of the amine Fatty Amines Corrosion Inhibitors Fabric Softeners Lubricant Additive Organoclays Sanitizing Agents H H NR
- 36. Primary amine Secondary amine Tertiary amine R-NH2 R2NH R3N
- 37. Which amines are produced depends on: reaction conditions ◦ NH3 pressure ◦ temperature Catalyst choice ◦ Raney Ni ◦ Supported Ni powders
- 38. Fatty nitriles Fatty acidsAl2O3 NH3 Unsaturated primary amine Saturated primary amine Saturated and unsaturated secondary amines Dialkyl monomethyl tertiary amine Ni(P) Raney Ni(D) Ni(D) Formaldehyde
- 39. Batch slurry phase most common Fixed bed or continuous slurry phase also used Product Temp (C) Pressure (bar) Catalysts Special Conditions Primary 80-150 10-550 nickel, raney nickel, cobalt Ammonia added to feed to suppress secondary and tertiary amine formation Secondary 150-200 50-200 nickel, cobalt Ammonia removed by purging with hydrogen Tertiary 160-230 7 - 14 nickel, cobalt Secondary Amine used as feed; hydrogen purge necessary to remove ammonia Unsaturated copper chromite, nickel powder similar to abovesimilar to above
- 40. R-COOH + NH3 R-COONH4 R-COONH4 R-CONH2 + H2O ammonium salt amide R-CONH2 R-CN + H2O nitrile R-CN + 2H2 FATTY AMINES
- 41. R-C≡N + H2 R-CH=NH imine First reaction step
- 42. R-CH=NH + H2 imine Primary amine formation R-CH2NH2
- 43. Secondary amine formation R-CH=NH + R-CH2NH2imine R-CH-NH-CH2-R NH2 1-aminodialkylamine
- 45. Secondary amine formation R-CH2-NH-CH2-R secondary amine R-CH=N-CH2-R imine +H2
- 46. Secondary amine formation via hydrogenolysis R-CH-NH-CH2-R NH2 1-aminodialkylamine R-CH2-NH-CH2-R - NH3 secondary amine +H2
- 47. Tertiary amine formation proceeds via the same route as with the secondary amine formation. However, secondary amine condenses with imine to yield tertiary intermediates.
- 48. By-product during manufacture of ◦ fatty acid ◦ methyl esters & bio-diesel ◦ fatty alcohols Also synthetic manufacturing Supply-Demand balance always difficult What to do with it all?
- 50. Supply will increase ◦ increasing production of biodiesel and use of oils and fats as industrial feedstock New demands must be found/created ◦ some of these may involve catalytic processes ◦ e.g. glycerine to glyceric acid over gold catalyst