| abstract |
An alkylene carbonate is produced by reacting an alkylene oxide with carbon dioxide in the presence of a phosphonium catalyst in a process in which (a) the alkylene oxide, carbon dioxide and the phosphonium catalyst are continuously introduced in a reaction zone from which a product stream containing alkylene carbonate and phosphonium catalyst used is extracted, (b) alkylene carbonate and a stream containing phosphonium catalyst used are separated from the product stream, (c ) the alkylene carbonate, separated in step (b), is recovered as a product, (d) at least a portion of the stream containing phosphonium catalyst used is subjected to purification, to obtain a purified phosphonium catalyst, and the (e) purified phosphonium catalyst is recycled to the reaction zone, optionally in combination with another part of the stream containing phosphonium catalyst used. |