Transalkylation reactor effluent

Description The process include 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. The alkylation reactor effluent is fed to the distillation section. Separately, recycled polyisopropylbenzene (PIPB) is premixed with benzene and fed to the transalkylation reactor (2), where PIPB reacts to form additional cumene. The transalkylation reactor effluent is fed to the distillation... 

EB enter the transalkylation reactor. Effluents from the alkylation and transalkylation reactors are fed to the benzene column (3), where unreacted benzene is recovered from crude EB. The fresh benzene feedstock and a fraction of the benzene distillate are fed to the lights column (4) to reject light impurities. The lights column bottoms is returned to the benzene column. The bottoms from the benzene column is fed to the EB column (5) to recover EB product. The bottoms from the EB column is fed to the PEB column (6) where recyclable alkylbenzenes are recovered as a distillate and diphenyl compounds are rejected in a bottoms stream that can be used as fuel. 

The alkylation and transalkylation reactor effluent streams are sent to the distillation section, which consists primarily of three fractionation columns. The first column is the benzene column. It separates unconverted benzene into the overhead stream for recycle to the reactors. The benzene column bottom stream is the feed to the EB column. The EB column recovers the EB product in an overhead stream at purities as high... 

The solvent is 28 CC-olefins recycled from the fractionation section. Effluent from the reactors includes product a-olefins, unreacted ethylene, aluminum alkyls of the same carbon number distribution as the product olefins, and polymer. The effluent is flashed to remove ethylene, filtered to remove polyethylene, and treated to reduce the aluminum alkyls in the stream. In the original plant operation, these aluminum alkyls were not removed, resulting in the formation of paraffins (- 1.4%) when the reactor effluent was treated with caustic to kill the catalyst. In the new plant, however, it is likely that these aluminum alkyls are transalkylated with ethylene by adding a catalyst such as 60 ppm of a nickel compound, eg, nickel octanoate (6). The new plant contains a caustic wash section and the product olefins still contain some paraffins ( 0.5%). After treatment with caustic, cmde olefins are sent to a water wash to remove sodium and aluminum salts. 

Propylene feed, fresh benzene feed, and recycle benzene are charged to the upflow reactor, which operates at 3—4 MPa (400—600 psig) and at 200—260°C. The SPA catalyst provides an essentially complete conversion of propylene [115-07-1] on a one-pass basis. A typical reactor effluent yield contains 94.8 wt % cumene and 3.1 wt % diisopropylbenzene [25321-09-9] (DIPB). The remaining 2.1% is primarily heavy aromatics. This high yield of cumene is achieved without transalkylation of DIPB and is unique to the SPA catalyst process. 

Ethyltoluene is manufactured by aluminum chloride-cataly2ed alkylation similar to that used for ethylbenzene production. All three isomers are formed. A typical analysis of the reactor effluent is shown in Table 9. After the unconverted toluene and light by-products are removed, the mixture of ethyltoluene isomers and polyethyltoluenes is fractionated to recover the meta and para isomers (bp 161.3 and 162.0°C, respectively) as the overhead product, which typically contains 0.2% or less ortho isomer (bp 165.1°C). This isomer separation is difficult but essential because (9-ethyltoluene undergoes ring closure to form indan and indene in the subsequent dehydrogenation process. These compounds are even more difficult to remove from vinyltoluene, and their presence in the monomer results in inferior polymers. The o-ethyltoluene and polyethyltoluenes are recovered and recycled to the reactor for isomerization and transalkylation to produce more ethyltoluenes. Fina uses a zeoHte-catalyzed vapor-phase alkylation process to produce ethyltoluenes. 

The catalytic performances obtained during transalkylation of toluene and 1,2,4-trimethylbenzene at 50 50 wt/wt composition over a single catalyst Pt/Z12 and a dualbed catalyst Pt/Z 121 HB are shown in Table 1. As expected, the presence of Pt tends to catalyze hydrogenation of coke precursors and aromatic species to yield undesirable naphthenes (N6 and N7) side products, such as cyclohexane (CH), methylcyclopentane (MCP), methylcyclohexane (MCH), and dimethylcyclopentane (DMCP), which deteriorates the benzene product purity. The product purity of benzene separated in typical benzene distillation towers, commonly termed as simulated benzene purity , can be estimated from the compositions of reactor effluent, such that [3] ... 

In the Mohil-Badger vapor-phase process, fresh and recycled benzene are vaporized and preheated to the desired temperature and fed to a multistage fixed-bed reactor. Ethylene is distributed to the individual stages. Alkylation takes place in tile vapor phase. Separately, file polyethylbenzene stream from the distillation section is mixed with benzene, vaporized and heated, and fed to the transalkylator, where polyethylbenzenes react with benzene to form additional ethylbenzene. The combined reactor effluent is distilled in the benzene column. Benzene is condensed in the overhead for recycle to the reactors. The bottoms from the benzene column are distilled in the ethylbenzene column to recover the ethylbenzene product in the overhead. The bottoms stream from the ethylbenzene column is further distilled in the polyefitylbenzene column to remove a small quantity of residue. The overhead polyethylbenzene stream is recycled to the reactor section for transalkylation to ethylbenzene. 

The sidedraw from the DIPB column containing mainly DIPB combines with a portion of the recycle benzene and is charged downflow into the transalkylation reactor. In the transalkylation reactor, DIPB and benzene are converted to additional cumene. The effluent from the transalkylation reactor is then sent to the benzene column. 

In the latest version of aluminum chloride plant designs, the alkylation reactions occur in a homogenous liquid phase at 160-180" C. The conditions of the alkylation reactor prohibit the recycle of PEB to the reactor. As a result, these plants have a separate transalkylation reaction zone. The recycle PEB stream is mixed with the alkylation reactor effluent and fed to the transalkylation reaction zone. The aluminum chloride present in the alkylation reactor effluent catalyzes the transalkylation reactions. 

In the UOP process (Figure 10-5), fresh propylene feed is combined with fresh and recycled benzene, then passed through heat exchangers and a steam preheater before being charged to the reactor.The effluent is separated, and excess benzene recycled. Cumene is finally clay treated and fractionated. The bottom product is mainly diisopropyl benzene, which is reacted with benzene in a transalkylation section ... 

Monsanto s reactor layout, in simplified form, is shown in Figure 2. Dry benzene, ethylene, catalyst, and promoter are fed continuously to the reactor. The alkylator effluent is mixed with polyethylbenzenes, mainly diethyl benzene recycled from the subsequent recovery system. The transalkylator allows enough residence time for the product to approach equilibrium. The aluminum... 

Description Alkylation and transalkylation reactions take place in the liquid phase in fixed-bed reactors. Propylene is completely reacted with benzene in the alkylator (1), producing an effluent of unconverted benzene, cumene and PIPB (diisopropylbenzene and small amounts of polyisopropylbenzenes). The specially formulated zeolite catalyst allows production of high-purity cumene while operating at reactor temperatures high enough for the reaction heat to be recovered as useful steam. PIPB is converted to cumene by reaction with benzene in the transalkylator (2). The process operates with relatively small amounts of excess benzene in the reactors. 

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