Propylene Oxide Production from Propylene and Cumene

The process under analysis comprises three major sections: (1) Product Formation; (2) Product Purification; and (3) Cumene Recovery.

Product Formation. Fresh and recovered cumene is fed, along with air, to column reactors, where an oxidation reaction takes place. A sodium carbonate solution is also fed to the reaction media to control pH. The cumene hydroperoxide (CHP) effluent is routed to a separator vessel, where the carbonate solution is removed, and dissolved air is flashed off. The CHP is concentrated in an evaporator, and directed to the Epoxidation reactor, where it reacts with fresh and recovered polymer grade (PG) propylene, yielding propylene oxide (PO) and dimethyl benzyl alcohol (DMBA). The epoxidation effluent is separated in a liquid and a gaseous stream in a flash vessel, which are sent to the Depropenizer columns.

Product Purification. The liquid and gaseous epoxidation effluents are fed to low-pressure and high-pressure distillation columns, respectively. Propylene, propane and light ends are removed as overheads products from these columns. The C3’s stream from the high-pressure column is routed to the Propane Splitter, which separates propylene from propane, which is burned as fuel. The propylene is mixed with the overhead stream from the low-pressure column and returned to the Epoxidation reactor. The bottom products of the columns are mixed and routed to Crude PO Separation, where PO is separated from unreacted cumene and DMBA, which are directed to cumene recovery. The PO is further purified in PO purification and PO product column, obtaining a 99.9 wt% PO.

Cumene Recovery. The bottom of PO crude separation is fed to cumene recycle column, which separates cumene, recycled to Peroxidation, from DMBA, which is sent to purification, yielding high purity DMBA, that is then is directed to a hydrogenolysis reactor. In this step, DMBA reacts with hydrogen, generating cumene, which is sent to purification and then recycled to Epoxidation.