The Q-Max process produces high-quality cumene (isopropylbenzene) by alkylating benzene with propylene (typically refinery, chemical or polymer grade) using zeolitic catalyst technology.
Benzene is alkylated to cumene over a zeolite catalyst in a fixed-bed, liquid-phase reactor. Fresh benzene is combined with recycle benzene and fed to the alkylation reactor (1). The benzene feed flows in series through the beds, while fresh propylene feed is distributed equally between the beds. This reaction is highly exothermic, and heat is removed by recycling a portion of reactor effluent to the reactor inlet and injecting cooled reactor effluent between the beds.
In the fractionation section, unreacted benzene is recovered from the overhead of the benzene column (3) and cumene product is taken as overhead from the cumene column (4). Poly-isopropylbenzene (PIPB) is recovered in the overhead of the PIPB column (5) and recycled to the transalkylation reactor (2) where it is transalkylated with benzene over a second zeolite catalyst to produce additional cumene. A small quantity of heavy byproduct is recovered from the bottom of the PIPB column (5) and is typically blended to fuel oil. A depropanizer column is required to recover propane when refinery or chemical-grade propylene feed is used. The cumene product has a high purity (99.96 – 99.97 wt%), and cumene yields of 99.7 wt% and higher are achieved.
The zeolite catalyst is noncorrosive and operates at mild conditions; thus, carbon-steel construction is possible. Catalyst cycle lengths are five years and longer. The catalyst is fully regenerable for an ultimate catalyst life of 10 years and longer. Existing plants that use SPA or AlCl3 catalyst can be revamped to gain the advantages of Q-Max cumene technology while increasing plant capacity.
Licensor: UOP LLC, A Honeywell Company
