What Is Ethylene Gas?
Ethylene gas is a hydrocarbon consisting of two carbons linked by a double bond and is the simplest alkene structure.
It is stable as a gas at room temperature, but can also be produced industrially by thermal cracking of substances such as ethane, propane, and butane, or by cracking petroleum naphtha.
Uses of Ethylene Gas
Ethylene gas has two types of uses: used solely as is, and as a synthetic material for organic compounds.
1. Applications in Which Ethylene Gas Is Used As-Is
Ethylene gas is known to have various physiologically active effects as a plant hormone. Specifically, ethylene gas is used to suppress the ripening of bananas and kiwifruit as well as inhibit the sprouting of potato plants.
The main component of ethephon solution used as a plant growth regulator for fruit trees and tomatoes is an aqueous solution of 2-chloroethyl phosphonic acid, which decomposes to produce ethylene gas after being sprayed on plants.
2. Uses of Ethylene Gas as a Synthetic Material
Ethylene gas, with its simple structure and highly reactive double bonds, is used as a material for various low-molecular-weight and high-molecular-weight compounds.
Ethanol, ethylene oxide, and acetaldehyde are typical examples of low molecular weight compounds synthesized from ethylene gas.
- Ethanol: raw material for cosmetics and paints
- Ethylene oxide: Raw material for sterilization of medical instruments and ethylene glycol
- Acetaldehyde: Raw material for fish preservatives and acetic acid
In addition, vinyl chloride and styrene, monomers synthesized from ethylene gas, are polymerized into polyvinyl chloride and polystyrene, respectively.
- Polyvinyl chloride: Daily necessities, clothing, water pipes
- Polystyrene: Parts for home appliances, building boards, tableware
Polymer Compounds
When ethylene gas is polymerized directly as a monomer, polyethylene is obtained. Polyethylene has a wide range of applications and is used in various packaging materials and plastic bags.
For example, copolymerization with vinyl acetate yields ethylene vinyl acetate (EVA), which is used as an adhesive, etc. When EVA is saponified, ethylene vinyl alcohol (EVOH) is used as an oxygen barrier food packaging material.
Properties of Ethylene Gas
With a melting point of -169°C and a boiling point of -104°C, ethylene exists as a gas at room temperature. The specific gravity of ethylene is 0.975, which is close to that of air (specific gravity 1), and its color is colorless, making it difficult to distinguish it from air.
However, it is flammable and combustible, and fires can produce irritating or toxic gases, so it should be handled with care.
Ethylene gas is also found in nature and is known to be produced by vegetables and fruits.
How Ethylene Gas Is Produced
Ethylene gas is manufactured industrially. The most mainstream method involves the reaction of petroleum naphtha, which contains a variety of hydrocarbons, with steam at temperatures above 800°C. Ethylene gas is then separated from the hydrogen, ethylene, propylene, and aromatic compounds that are produced. Other methods include pyrolysis of ethane contained in shale gas.