Ethylene Oxide Production via Silver-Catalyzed Oxidation

A key intermediate for surfactants and antifreeze

Petrochemical & Refining Global Industrial Scale $45 billion

Overview

Ethylene oxide (EO) is produced by the direct catalytic oxidation of ethylene over silver catalysts, making it one of the largest-scale selective oxidation processes in the chemical industry. EO is a critical intermediate for ethylene glycol (antifreeze and PET polyester), ethoxylated surfactants, and ethanolamines. The process requires extremely precise reaction control, as the desired partial oxidation competes with complete combustion to CO₂ and water.

Chemical Process

Ethylene and oxygen (or air) are passed over promoted silver catalyst (Ag/α-Al₂O₃ with Cs and Re promoters) at 220-280 degrees C and 10-30 bar in multitubular fixed-bed reactors. The EO is absorbed in water from the reactor effluent and recovered by steam stripping. Selectivity is 80-90% with oxygen-based processes.

C₂H₄ + ½O₂ →[Ag catalyst] C₂H₄O (desired, ΔH = −105 kJ/mol)
C₂H₄ + 3O₂ → 2CO₂ + 2H₂O (undesired total combustion)

Raw Materials

  • Ethylene (C₂H₄) — Steam cracking (Reactant)
  • Oxygen (O₂) — Air separation unit (cryogenic) (Oxidant)
  • Silver catalyst (Ag/α-Al₂O₃) — Specialty catalyst manufacturers (Selective oxidation catalyst)

End Products

  • Ethylene oxide (C₂H₄O) — Ethylene glycol, surfactants, ethanolamines (>99.5% purity)
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Environmental Impact

EO is a known human carcinogen and potent greenhouse gas. Fugitive emissions from EO plants are tightly regulated. The combustion side reaction wastes feedstock and generates CO₂. Scrubber systems capture EO from vent streams.

Safety Considerations

Recent Innovations

High-selectivity catalysts with rhenium and cesium promoters have pushed selectivity above 90%.
Microchannel reactor designs offer improved heat removal and safety.
Electrocatalytic ethylene epoxidation is being explored as a low-temperature alternative.

Production Scale

35000000

tons/year

$45 billion

market value

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Frequently Asked Questions

What industry uses Ethylene Oxide Production via Silver-Catalyzed Oxidation?
Ethylene Oxide Production via Silver-Catalyzed Oxidation is used in the petrochemical & refining sector at global industrial scale scale.
What process is involved in Ethylene Oxide Production via Silver-Catalyzed Oxidation?
Ethylene and oxygen (or air) are passed over promoted silver catalyst (Ag/α-Al₂O₃ with Cs and Re promoters) at 220-280 degrees C and 10-30 bar in multitubular fixed-bed reactors. The EO is absorbed in water from the reactor effluent and recovered by steam stripping. Selectivity is 80-90% with oxygen
What is the economic significance of Ethylene Oxide Production via Silver-Catalyzed Oxidation?
Ethylene Oxide Production via Silver-Catalyzed Oxidation has a market value of $45 billion and annual production of 35,000,000 tons.
What is the environmental impact of Ethylene Oxide Production via Silver-Catalyzed Oxidation?
EO is a known human carcinogen and potent greenhouse gas. Fugitive emissions from EO plants are tightly regulated. The combustion side reaction wastes feedstock and generates CO₂. Scrubber systems capture EO from vent streams.
What raw materials are used in Ethylene Oxide Production via Silver-Catalyzed Oxidation?
The main raw materials include: Ethylene (C₂H₄), Oxygen (O₂), Silver catalyst (Ag/α-Al₂O₃).