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Ethylene Glycol Production

Monoethylene glycol (MEG), also known as ethylene glycol, is conventionally produced through the hydrolysis of ethylene oxide, which is obtained by oxidizing ethylene. The document describes a process similar to Shell's OMEGA catalytic process for producing MEG via ethylene oxide in an integrated plant. Key features include negligible byproduct production and ethylene and oxygen being fed to a multi-tubular reactor to form ethylene oxide over a silver catalyst. Ethylene oxide is then reacted and purified to form MEG, which is purified through distillation. An economic analysis estimates $630 million in capital costs and $620/ton operating costs for a 750,000 ton/year

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588 views3 pages

Ethylene Glycol Production

Monoethylene glycol (MEG), also known as ethylene glycol, is conventionally produced through the hydrolysis of ethylene oxide, which is obtained by oxidizing ethylene. The document describes a process similar to Shell's OMEGA catalytic process for producing MEG via ethylene oxide in an integrated plant. Key features include negligible byproduct production and ethylene and oxygen being fed to a multi-tubular reactor to form ethylene oxide over a silver catalyst. Ethylene oxide is then reacted and purified to form MEG, which is purified through distillation. An economic analysis estimates $630 million in capital costs and $620/ton operating costs for a 750,000 ton/year

Uploaded by

Quang Nguyễn
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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ETHYLENE GLYCOL PRODUCTION

By Chemical Engineering | October 1, 2015

Monoethylene glycol (MEG), also known as ethylene glycol (EG) or simply glycol, is a diol
mostly used for the production of polyester fibers and polyethylene terephthalate (PET) resins. It
is also used in antifreeze applications and in pharmaceuticals and cosmetics. MEG is
conventionally produced through the hydrolysis of ethylene oxide (EO), which itself is obtained
via ethylene oxidation.

THE PROCESS

Figure 1 depicts MEG production from ethylene via a process similar to the OMEGA catalytic
process from Shell Global Solutions (The Hague, the Netherlands; www.shell.com). In the
described process, MEG is produced via EO, which is manufactured in an integrated plant
utilizing Shell EO technology. An important feature of the process is the negligible production of
diethylene glycol (DEG) and triethylene glycol (TEG), which occur as byproducts in other
ethylene glycol production processes.

Figure 1. Monoethylene glycol (MEG) production, according to a process similiar to the Shell
OMEGA process
Ethylene oxide production. Ethylene and oxygen are fed to a multi-tubular reactor, forming EO.
This exothermic reaction, conducted in fixed beds in the reactor tubes, occurs in the gaseous
phase with the use of a silver catalyst supported on alumina. Steam is generated by the heat of
reaction.

Ethylene oxide recovery. The reactor product stream is fed to the EO absorber for lights removal
by water quenching. Part of this gaseous overhead stream is recycled to the reactor, while the
other part is sent to a carbon-dioxide-removal unit composed of an absorber and a stripper. In
this unit, CO2 is separated to be used in ethylene carbonate production.

A diluted EO stream removed from the absorber is fed to the EO stripper, where it is
concentrated and recovered in the overheads. The crude EO stream is condensed. Residual light
gases are recovered from it and recycled to the reactor. The resulting EO stream is directed to the
next section.

Ethylene glycol production and purification. Ethylene oxide is reacted with CO2, forming
ethylene carbonate, which is then hydrolyzed to form MEG and CO2. Both reactions are carried
out in the liquid phase using homogeneous catalysts.

CO2 streams from the reaction steps are recycled to the ethylene carbonate reactor. MEG is
purified in two distillation columns where water is removed, leading to the final MEG product.
The catalyst is separated and recycled to the ethylene carbonate reactors.

ECONOMIC PERFORMANCE

An economic evaluation of the process was conducted based on data from the first quarter of
2015, assuming a facility with a nominal capacity of 750,000 ton/yr of MEG constructed on the
U.S. Gulf Coast.

Estimated capital expenses (total fixed investment, working capital and initial expenses) to
construct the plant are about $630 million, while the operating expenses are estimated at about
$620/ton of MEG.

GLOBAL PERSPECTIVE

Shell OMEGA is the first process to enable ethylene glycol production via a fully catalytic
process. According to the licenser, the process is able to achieve EO-to-EG converstion and
selectivity near 100%, leading to production of MEG only.
However, although 40% of worldwide ethylene glycol production is derived from processes
using Shell technologies, only three plants in the world use the new Shell OMEGA technology
(Figure 2). As can be seen, two of these plants are located in Asia, which is the region of the
world responsible by the major share of MEG global consumption. China alone accounts for
about 45% of global demand for MEG.

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