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Chemicals based on ethylene


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Chemicals based on ethylene

  1. 1. COMSATS Institute of Information Technology Defence Road, Off Raiwind Road, Lahore, Pakistan
  2. 2. Chemistry of Petrochemical Processes Chemicals based on Ethylene
  3. 3. Presented by Group #7 • Hafiz Annus Mahmood CIIT/SP10-BEC-015/LHR • Mohammad Abubakar CIIT/SP10-BEC-022/LHR • Noaman Ahmed CIIT/SP10-BEC-037/LHR • Saim Khan CIIT/SP10-BEC-044/LHR
  4. 4. Outline • Brief introduction of ethylene • Properties of ethylene • List of major products of ethylene • Discussion of products obtained from ethylene ▫ Ethylene Glycol ▫ Acetaldehyde • Conclusion • References
  5. 5. Ethylene – An Introduction • Ethylene is a hydrocarbon with a chemical formula C2H4
  6. 6. Ethylene – Properties • Colorless, flammable gas with a sweet and musky odor in its pure form • Simple structure • High reactivity • Relatively inexpensive • Produces less by-products, during reactions with other compounds, as compared to other olefins
  7. 7. Ethylene – Properties (contd.) • Raw material for various chemicals and polymers e.g., ethanol and polyethylene • Easily produced from any hydrocarbon source through steam-cracking • Molecular weight – 28.05 g/mol • Density - 1.178 kg/m3 at 15 °C, gas • At standard conditions, ▫ Melting point is −169.2 °C or 104.0 K ▫ Boiling point is −103.7 °C or 169.5 K
  8. 8. Major Chemicals & Polymers produced form Ethylene
  9. 9. Products of Ethylene ETHYLENE OXIDE
  10. 10. Ethylene Oxide • A precursor for many important commercial chemicals such as, ▫ Ethylene glycol ▫ Ethanolamines ▫ Polyesters
  11. 11. Ethylene Oxide - Production • Main reaction is controlled oxidation (either using oxygen or air) of ethylene over a silver catalyst • Reaction is exothermic and heat content should be controlled • Excessive temperature increase and over-oxidation causes complete combustion of ethylene liberating water and carbon dioxide • Catalyst deteriorates at high temperature
  12. 12. Ethylene Oxide - Production (contd.) Ethylene Oxide
  13. 13. Ethylene Oxide - Production (contd.) • Why use oxygen instead of air ? • Oxygen (> 95% purity) is preferred for several reasons such as, ▫ Higher molar yield of ethylene oxide (75–82% for oxygen vs. 63–75% for air) ▫ Higher reaction rate (no gas dilution) ▫ No need of separating nitrogen in the reaction products
  14. 14. Ethylene Oxide - Production (contd.)
  15. 15. Ethylene Oxide - Production (contd.) • Compressed oxygen, ethylene, and recycled gas are fed to a multi-tubular reactor • The temperature of oxidation is controlled by boiling water in the shell side of the reactor • Effluent gases are cooled and passed to the scrubber where ethylene oxide is absorbed as a dilute aqueous solution • Un-reacted gases are recycled • Epoxidation reaction occurs at approximately 200–300°C with a short residence time of one second
  16. 16. Ethylene Oxide - Production (contd.) • A selectivity of 70–75% can be reached for the oxygen based process • Ethylene oxide selectivity can be improved when the reaction temperature is lowered and the conversion of ethylene is decreased (higher recycle of un- reacted gases)
  17. 17. Products of Ethylene ACETALDEHYDE
  18. 18. Acetaldehyde • A colorless liquid with a pungent odor • A reactive compound with no direct use except for the synthesis of other compounds e.g., raw material for production of acetic acid
  19. 19. Acetaldehyde - Production • Old Technique: Silver-catalyzed oxidation or chromium activated copper- catalyzed dehydrogenation of ethanol (reaction temperature for oxidation is approximately 500 °C whereas for dehydrogenation is approximately 250 °C ) • New Technique: Oxidation of ethylene using a homogeneous catalyst (Wacker catalyst and reaction temperature of 130 °C )
  20. 20. Acetaldehyde – Production (contd.) • Ethylene oxidation is carried out through redox reactions • The overall reaction is exothermic Acetaldehyde
  21. 21. Acetaldehyde – Production (contd.) The Wacker Process • The process employs an aqueous solution of palladium(II) chloride, copper(II) chloride catalyst system • Pd2+ ions are reduced to Pd metal, and ethylene is oxidized to acetaldehyde
  22. 22. Acetaldehyde – Production (contd.) The Wacker Process (contd.) • Pd° is re-oxidized by action of Cu(II) ions, which are reduced to Cu(I) ions • The reduced Cu(I) ions are re-oxidized to Cu(II) ions by reaction with oxygen and HCl
  23. 23. Acetaldehyde – Production (contd.) • The oxidation reaction may be carried out in a single- stage or a two stage process ▫ In the single-stage, ethylene, oxygen, and recycled gas are fed into a vertical reactor containing the catalyst solution. Heat is controlled by boiling off some of the water. The reaction conditions are approximately 130°C and 3 atmospheres ▫ In the two-stage process, the reaction occurs under relatively higher pressure (approximately 8 atmospheres) to ensure higher ethylene conversion. The reaction temperature is approximately 130°C
  24. 24. Acetaldehyde – Production (contd.) • The yield of acetaldehyde from either process is about 95% • By-products from this reaction include acetic acid, ethyl chloride, chloroacetaldehyde, and carbon dioxide
  25. 25. Conclusion
  26. 26. Conclusion • Ethylene is indeed one of the most important raw materials for manufacturing of various chemicals and polymers • It is sometimes referred to as the “king of petrochemicals” • It has great commercial importance and thus improvements should be continuously made in its manufacturing, in order to increase production of various other petrochemicals
  27. 27. References 1. S. Matar, Ph.D., Chemistry of Petrochemical Processes, 2nd Ed., Gulf Publishing Company, Houston, Texas 2. 3.
  28. 28. HAVE A NICE DAY ! 