Chemistry, 01.02.2019 21:50
Cumene is made by alkylation of benzene with propylene over zeolitic catalyst. to maximize selectivity to desired products, several beds of catalyst are used inside the same reactor. a mixture of feed and recycle benzene enters the top of the reactor and the feed propylene is split so that a portion of the propylene is fed to each catalyst bed. a large excess of benzene is used, to minimize propylene oligomerization and ensure complete reaction of propylene. the reactor product is cooled and sent to a stabilizer column that removes any light hydrocarbons. the bottoms from this column is sent to a benzene column that recovers benzene overhead for recycle to the alkylation and transalkylation reactors. the bottoms from the benzene column is distilled to give cumene product and a heavy stream. the heavy stream is further distilled in a heavies column to give a mixture of dipropyl- and tripropyl-benzene overhead and a heavy waste stream as bottoms. the distillate from the heavies column is sent to a transalkylation reactor and reacted with excess benzene. the product from the transalkylation reactor is returned to the benzene column. sketch a block flow diagram of the process.