To produce mono-ethylene glycol (MEG) from ethylene oxide (EO).
EO in an aqueous solution is reacted with CO2 in the presence of a homogeneous catalyst to form ethylene carbonate (1). The ethylene carbonate subsequently is reacted with water to form MEG and CO2 (3). The net consumption of CO2 in the process is nil since all of the CO2 converted to ethylene carbonate is released again in the ethylene carbonate hydrolysis reaction. Unconverted CO2 from the ethylene carbonate reaction is recovered (2) and recycled, together with CO2 released in the ethylene carbonate hydrolysis reaction.
The product from the hydrolysis reaction is distilled to remove residual water (4). In subsequent distillation columns high-purity MEG is recovered (5) and small amounts of co-produced di-ethylene glycol are removed (6). The homogeneous catalyst used in the process concentrates in the bottom of column 5 and is recycled back to the reaction section.
The process has a MEG yield of 99%+. Compared to the thermal glycol process, steam consumption and wastewater production are relatively low, the latter because no contaminated process steam is generated.
MEG quality and the performance of the MEG product in derivatives (polyesters) manufacturing have been demonstrated to be at least as good as, and fully compatible with, MEG produced via the thermal process.
