HaNoi University of Mining and Geology
Advanced program




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Name: LêĐứcHuy
ID student: CTTT 13210134


Self study #1






Ethylene glycol
Ethylene glycol is produced from ethylene (ethene), via the intermediate ethylene oxide. Ethylene oxide reacts with water to produce ethylene glycol according to the chemical equation:
C2H4O + H2O → HO–CH2CH2–OH
This reaction can be catalyzed by either acids or bases, or can occur at neutral pH under elevated temperatures. The highest yields of ethylene glycol occur at acidic or neutral pH with a large excess of water. Under these conditions, ethylene glycol yields of 90% can be achieved. The major byproducts are the oligomers diethylene glycol, triethylene glycol, and tetraethylene glycol. The separation of these oligomers and water is energy intensive. About 6.7 million tonnes are produced annually.
A higher selectivity is achieved by use of Shell`s OMEGA process. In the OMEGA process, the ethylene oxide is first converted with carbon dioxide (CO2) to ethylene carbonate. This ring is then hydrolyzed with a base catalyst in a second step to produce mono-ethylene glycol in 98% selectivity.  The carbon dioxide is released in this step again and can be fed back into the process circuit. The carbon dioxide comes in part from the ethylene oxide production, where a part of the ethylene is completely oxidized.
The following two newly commercialized EG technologies are evaluated:
Shell OMEGA® (Only MEG Advanced) technology
Dow METEOR® (Most Effective Technology for Ethylene Oxide Reactions) technology
Shell OMEGA® technology is a two-step process in which EG is produced from ethylene oxide (EO) via ethylene carbonate (EC), the latter being produced as an intermediate product. EO, for this process, is produced through the conventional EO technology of Shell, using a proprietary Ag-based, promoted catalyst. Ethylene conversion is 10 to 15% and EO selectivity is 90%. EC is produced from EO using a phosphonium halide catalyst The overall result of the two step process is that the MEG yield in ethylene glycols product is extremely high (99–99.5%). This is the main advantage of this new technology that it selectively produces MEG and minimizes the production of diethylene and triethylene glycols. According to Shell, the higher growth rate in MEG demand than for DEG was a major factor for the commercialization of this technology.
Our evaluation indicates that the Shell technology may give a 15% savings in the total capital investment cost for a 400 thousand metric ton/annum MEG plant.
Dow METEOR® technology is a single-step process in which EG is directly produced from EO by a thermal hydrolysis process. EO, for this process, is produced through the conventional EO technology, using a proprietary Ag-based, promoted catalyst. Ethylene conversion is 8 to 13% and EO selectivity is 89%. The overall MEG yield in the ethylene glycols product is about 90 to 93%. The hallmark of the METEOR® technology is that is principally based on a simplified process structure involving fewer process steps, less major equipment, and smaller plot plan as compared to a conventional EG plant of the same capacity.
Our evaluation indicates that the Dow technology may give an 11% savings in the total capital investment cost for a 400 thousand metric ton/annum EG plant.

Block diagram of EG production from ethylene by hydration of ethylene oxide
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Where:
Ethylene oxide reactor
Ethylene oxide absorber
Ethylene oxide stripper
Lights removal unit

𝐶𝑂
2 absorber

𝐶𝑂
2 stripper
Ethylene carbonate reactor
Hydrolysis reactor
Water removal column
MEG purification column
Cooling tower (CL)
Steam boiler (ST)

Draw block diagram of EG based on Shell OMEGA technology by ethylene carbonation using CO2.