What are the production process of ethylene glycol?
Ethylene oxide production
In this initial stage, ethylene and oxides are injected together into a multi-tube reactor, which forms ethylene oxides (EO). This reaction is exothermic, carried out in fixed beds in reactor tubes, usually in the gas phase (using a silver catalyst supported on alumina).
Recovery of ethylene oxide
The product obtained from the reactor is transferred to the EO absorber by water to remove excess material. Part of the gas vapor is recycled in the reactor and the rest is sent to a carbon dioxide removal unit consisting of an absorber and a holder. In this phase, carbon dioxide is separated to be used more in the production of ethylene carbonate. In the next step of the process, the diluted ethylene oxide vapor leaves the absorber to feed into the EO stripper. Additional costs are reduced by gathering in this place. The crude form of EO is finally concentrated, which is directed to the next part of the process
Production and purification of ethylene glycol
Finally, ethylene oxide reacts with carbon dioxide to form ethylene carbonate. It then undergoes further hydrolysis to form MEG and carbon dioxide. Both processes are carried out using a homogeneous catalyst in the liquid phase.
The price of monoethylene glycol and its buying and selling market
This compound acts as a versatile medium that is perfectly miscible with water as well as with organic solvents. These features increase its applications in various industries and this proves to be the growth drivers for the monoethylene glycol market. MEG also serves as a key ingredient in the production of paints, paper, textiles and adhesives. As a result, increasing demand for these applications is driving the growth of the MEG market globally
Complications and dangers of monoethylene glycol
Monoethylene glycol is relatively toxic to humans (LDLo = 786 mg/kg) and its sweet smell attracts children and animals. After consumption, ethylene glycol is oxidized to glycolic acid, which in turn is oxidized to oxalic acid, which is toxic. Due to its sweet taste, this compound is often consumed accidentally or intentionally and decomposes into toxic compounds in the body. Its toxic by-products first affect the central nervous system (CNS), then the heart, and finally the kidneys, consuming high amounts of this substance can be fatal. Monoethylene glycol is odorless, so there is no warning against inhalation exposure in dangerous concentrations. For this reason, recently antifreeze products for car use contain propylene glycol instead of this compound, which is considered safer because it turns into lactic acid in the body, which is a natural product of metabolism and exercise. While low doses of this chemical show no toxic effects in humans, lethal doses (about 1,000 mg/kg daily) act as teratogens.
Environmental impact of ethylene glycol
Monoethylene glycol is a high production volume chemical that decomposes in the air for about 10 days and in water or soil within a few weeks. Products containing this substance enter the environment especially through airports because it is used as an antifreeze to clear the runway.