Epichlorohydrin Production from Glycerol and Hydrogen Chloride

The process under analysis comprises three major sections: (1) Glycerol Treatment; (2) Chlorohydrination; and (3) Dehydrochlorination.

Glycerol Purification. Glycerol is mixed with a surfactant to precipitate soaps dissolved in the glycerol and routed to an oil-water separator to remove contaminating oils. The recovered glycerol stream is sent to a decanter centrifuge to remove precipitated and dispersed solids. It is then directed to Vacuum Distillation to separate dissolved lighter and heavier contaminants from glycerol, which is obtained as a side product and sent to chlorohydrination.

Chlorohydrination. The purified glycerol is heated and fed to two reactors operating in series, along with gaseous hydrogen chloride. In the first one, these components react at low pressures producing monochlorohydrins. The reaction products are partially vaporized for the removal of water and unreacted HCl, which are sent to the dehydrochlorination column. The liquid effluent, containing the monochlorohydrins, is routed to the second reactor, operating at mild pressures, further reacting with hydrogen chloride, yielding dichlorohydrins (DCH). This stream is also partially vaporized, and the vapor is sent to Dehydrochlorination column, while the DCH is directed to a fractionation step.

Dehydrochlorination. The DCH stream is fed to a distillation column to recover DCH as an overhead product, sent to dehydrochlorination downstream, while residual monochlorohydrins are withdrawn from the bottom and recycled to the LP reactor. The DCHs are fed, along with caustic soda, to a distillation column where they are converted to Epichlorohydrin (ECH). This product is recovered in a decanter, and sent to further purification in two distillation columns, which remove light and heavy impurities, respectively. The high-purity ECH is then routed to storage.