Group #7 from COMSATS Institute of Information Technology presented on the chemistry of petrochemical processes related to ethylene. They discussed ethylene properties, major products including ethylene oxide and acetaldehyde. For ethylene oxide, they described its production through the controlled oxidation of ethylene over a silver catalyst. For acetaldehyde, they explained its production through both older ethanol oxidation methods and newer ethylene oxidation using a homogeneous Wacker catalyst at 130°C. They concluded that ethylene is a very important raw material for chemicals and polymers.

1. COMSATS Institute of Information Technology
Defence Road, Off Raiwind Road, Lahore,
Pakistan

2. Chemistry of Petrochemical Processes
Chemicals based on Ethylene

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. 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. Ethylene – An Introduction
• Ethylene is a hydrocarbon with a chemical formula
C2H4

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. 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. Major Chemicals & Polymers produced form Ethylene

9. Products of Ethylene
ETHYLENE OXIDE

10. Ethylene Oxide
• A precursor for many important commercial
chemicals such as,
▫ Ethylene glycol
▫ Ethanolamines
▫ Polyesters

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. Ethylene Oxide - Production (contd.)
Ethylene Oxide

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. Ethylene Oxide - Production (contd.)

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. 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. Products of Ethylene
ACETALDEHYDE

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. 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. Acetaldehyde – Production (contd.)
• Ethylene oxidation is carried out through redox
reactions
• The overall reaction is exothermic
Acetaldehyde

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. 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. 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. 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. Conclusion

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. References
1. S. Matar, Ph.D., Chemistry of Petrochemical
Processes, 2nd Ed., Gulf Publishing Company,
Houston, Texas
2. http://en.wikipedia.org/wiki/Ethylene_oxide
3. http://en.wikipedia.org/wiki/Acetaldehyde

28. HAVE A NICE DAY ! 