A method and plant for purifying ethylene carbonate

A method for purifying ethylene carbonate from a crude ethylene carbonate composition comprising:

• subjecting a crude composition containing ethylene carbonate to at least one distillation step so as to obtain a pre-purified composition containing at least 99.5% by weight of ethylene carbonate;
• subjecting the pre-purified composition to at least one melt crystallization step so as to obtain a purified ethylene carbonate composition;
• and
• performing the method in a plant comprising at least one distillation column, one vessel, at least one crystallizer and a feed line for the crude composition containing ethylene carbonate, the at least one distillation column, if when the plant comprises one distillation column, or the first distillation column, if when the plant comprises two or more distillation columns, comprises an overhead outlet line, a bottom outlet line and a side outlet line, the at least one crystallizer comprises an inlet line for the pre-purified composition and an outlet line for the purified ethylene carbonate composition, the side outlet line of the at least one distillation column is directly or indirectly connected with the inlet line for the pre-purified composition of the at least one crystallizer,
• either the vessel is connected with the feed line for the crude composition containing ethylene carbonate and with an inlet line, the inlet line is connected with a gas outlet of a first reboiler, the first reboiler is further connected with the bottom outlet line of the distillation column, the vessel further comprises an outlet line leading via a second reboiler to an inlet line of the at least one distillation column, a bottom fraction of the at least one distillation column being withdrawn from the at least one distillation column via the bottom outlet line is partially evaporated in the first reboiler so as to obtain a gaseous fraction and a liquid fraction, or
• the feed line for the crude composition containing ethylene carbonate leads into the at least one distillation column, the bottom outlet line of the at least one distillation column leads via the first reboiler to the vessel, wherein the vessel comprises a gas outlet connected with the inlet line of the at least one distillation column and the vessel comprises a liquid outlet connected with a line leading into the second reboiler, the second reboiler comprises an outlet for gas connected with an the inlet line of the at least one distillation column, the bottom fraction of the at least one distillation column being withdrawn from the at least one distillation column via the bottom outlet line is partially evaporated in the first reboiler, and at least a portion of the gaseous fraction obtained in the first reboiler is recycled into the at least one distillation column via the inlet line