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
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
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
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)
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
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
