| 摘要 |
A process for working up a reaction mixture which is formed during the alkylation of benzene with propene to give isopropylbenzene (cumene) on phosphoric acid-containing catalysts in the presence of propane. The reaction mixture is reduced in pressure from about 35 bar to 20 bar in a pressure reduction step with the dissipation of heat, so that phase equilibrium is assured at the entry site of the subsequent rectification column. Flashing is largely avoided. The reaction mixture is worked up in a first rectification column, less than 1% by weight of the benzene present being separated at the top of the column. The vapours are worked up in a second rectification column into propane as the top product and into purge product as the bottom product. The bottom effluent of the first rectification column is worked up in three rectifications arranged successively into, firstly, circulation product recycle II as the top product and into the constituents boiling in the boiling range after benzene, as the bottom product, secondly purge product boiling in the boiling range before cumene, as the top product and into cumene with constituents boiling higher than cumene, as the bottom product, and thirdly into cumene and residue. <IMAGE>
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