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CUMENE MANUFACTURING ROUTES

 REACTION :

By-Product : DIPB & TIPB

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1990 gas phase alkylation process dominated but today liquid phase process with acid based catalyst.

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Catalyst are : 1) Solid Phosphoric acid based 2) Aluminum chloride based 3) Zeolite based process

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In now a days zeolite based catalyst are environment friendly, offering high productivity & Selectivity. Technologies for cumene production based on zeolite : MobileBerger

CD-Tech

UOP Q-max

EniChem

Zeolite

MCM-22

Y

Beta

Beta

Reactor

Fixed Bed

Catalytic distillation

Fixed Bed

Fixed Bed

1) UOP Cumene Process :

PFD for UOP Cumene PROCESS

Propylene feed fresh benzene feed and recycle benzene are charged to the upflow reactor, which operates at 3-4 Mpa and at 200-260°C. The solid phosphoric acid catalyst provides an essentially complete conversion of propylene on a one-pass basis. The typical reactor effluent yield contains 94.8 Wt. % cumene and 3.1 Wt.% of diiso propylbenzene. The remaining 2.1 % is primarily heavy aromatics. This high yield of cumene is achieved without transalkylation of diiso propylbenzene and is unique to the solid phosphoric acid catalyst process. The cumene product is 99.9 Wt. % pure and the heavy aromatics, which have an octane number of 109, can either be used as high octane gasoline blending components or combined with additional benzene and sent to a transalkylation section of the plant where diiso propylbenzene is converted to cumene. The overall yields of cumene for this process are typically 97-98 Wt. % with transalkylation and 94-96 Wt. % without transalkylation.

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Application : To produce high-quality cumene (isopropylbenzene) by alkylating benzene with propylene (typically refinery or chemical Grade) using liquid-phase Q-Max process based on zeolitic catalyst Technology.

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Description : 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, propane that accompanies the propylene feedstock is recovered as LPG product from the overhead of the depropanizer column (2), unreacted benzene is recovered from the overhead of the benzene column (4) and cumene product is taken as overhead from the cumene column (5). Diisopropylbenzene (DIPB) is recovered in the overhead of the DIPB column (6) and recycled to the transalkylation reactor (3) 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 DIPB column (6) and is typically blended to fuel oil. 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 two years and longer. The catalyst is fully regenerable for an ultimate catalyst life of six 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.

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Commercial Plants : The first Q-Max unit went on-stream in 1996. Since that time, UOP has licensed a total of nine Q-Max units throughout the world having a total plant capacity of 2.3 million MTA of cumene. Six Q-Max units have been commissioned and three more are in various stages of design or construction. Capacities range from 35,000 to 700,000 MTA of cumene produced. Several of these units have been on-stream for more than 5 years without performing a single catalyst regeneration.

2) Badger Cumene Process :

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Description : The process includes: a fixed-bed alkylation reactor, a fixed-bed transalkylation reactor and a distillation section. Liquid propylene and benzene are premixed and fed to the alkylation reactor (1) where propylene is completely reacted. Separately, recycled polyisopropylbenzene (PIPB) is premixed with benzene and fed to the transalkylation reactor (2) where PIPB reacts to form additional cumene. The transalkylation and alkylation effluents are fed to the distillation section. The distillation section consists of as many as four columns in series. The depropanizer (3) recovers propane overhead as LPG. The benzene column (4) recovers excess benzene for recycle to the reactors. The cumene column (5) recovers cumene product overhead. The PIPB column (6) recovers PIPB overhead for recycle to the transalkylation reactor.

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Application : To produce cumene from benzene and any grade of Propylene—including lowerquality refinery propylene-propane mixtures—using the badger process and a new generation of zeolite catalysts from Exxonmobil.

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Process Feature : The process allows a substantial increase in capacity for existing SPA, ALCL3, or other zeolite cumene plants while improving product purity, feedstock consumption, and utility consumption. The new catalyst is environmentally inert, does not produce byproduct oligomers or coke and can operate at the lowest benzene to propylene ratios of any available technology with proven commercial cycle lengths of over seven years. Expected catalyst life is well over five years.

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Commercial Plants : The first commercial application of this process came onstream in 1996. At present, there are 12 plants operating with a combined capacity exceeding 5.2 million mtpy. In addition, four grassroots plants and an ALCL3 revamp are in the design phase. Fifty percent of the worldwide and 75% of zeolite cumene production are from plants using the badger process.

3) CDTECH & ABB Lummus Global :

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Description : The cd column (1) combines reaction and fractionation in a single-unit operation. Alkylation takes place isothermally and at low temprature. Cd also promotes the continuous removal of reaction products from reaction zones. These factors limit byproduct impurities and enhance product purity and yield. Low operating temperatures and pressures also decrease capital investment, improve operational safety and minimize fugitive emissions. In the mixed-phase CD reaction system, propylene concentration in the liquid phase is kept extremely low (