JPH0491039A - Transalkylation method - Google Patents

Abstract

PURPOSE: To produce a monoalkylated benzene, by reacting benzene with an alkylating agent in the presence of a molecular sieve catalyst, separating the resultant mono- and polyalkylated benzene products and transalkylating the polyalkylated benzene products.

CONSTITUTION: Ethylene and benzene are supplied respectively through pipes 51 and 52, and reacted in an alkylation zone 56 in the presence of a molecular sieve catalyst at 220°C under ≥600 psig. The effluent flow is passed to a pre- fractionation column 58 to fractionate a column-top fraction containing benzene and a heavier fraction containing benzene, ethylbenzene and polyethylbenzene, the latter fraction being passed to a benzene separation zone 61. A benzene- containing fraction is taken from the top of the column and the heavier fraction is passed to an ethylbenzene separation zone 65 to collect ethylbenzene from the top of the column. The fraction at the bottom of the column is passed through a polyethylbenzene separation zone 68, and the fraction from the top of the column is passed to a transalkylation zone 72. The obtained ethylbenzene- rich fraction is passed to the separation zone 61 via a second separation zone 71.

COPYRIGHT: (C)1992,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the transalkylation of polyalkylated aromatic compounds, and more particularly to alkylation of benzene feedstocks with 02-C4 alkylating agents, liquid phase transalkylation of the resulting polyalkylbenzenes, The present invention relates to an alkylation-transalkylation process comprising treating an alkylated product in a separation zone and recycling at least a portion of the transalkylation product to the separation zone.

In summary, according to the present invention, the present alkylation-transalkylation process comprises the alkylation of aromatics with a C7-C, alkylating agent, separation and polyalkylation to recover monoalkylated aromatic products. [liquid phase of reaction product] - Contains in combination with lance alkylation. Both alkylation and transalkylation are carried out in the liquid phase over molecular sieve aromatic alkylation and transalkylation catalysts.

The reactants from the alkylation reaction zone are separated to provide a low boiling fraction comprising aromatics and a high boiling fraction comprising a mixture of monoalkylated and polyalkylated aromatics, the latter comprising: is separated into a monoalkylated fraction and a high-boiling polyalkylated fraction.

At least 7 portions of the polyalkylated fraction containing substantially all dialkylated and trialkylated aromatics are
Disproportionation products, together with aromatics, are fed to the first separation zone, with a reduced polyalkylated aromatics content and an increased monoalkylated aromatics content due to the disproportionation of the polyalkylated fraction. is fed to a transalkylation reaction zone operated under liquid phase conditions such that .

A benzene feedstock and a C2-C4 alkalizing agent are fed to an alkylation reaction zone containing a molecular sieve alkylation catalyst and operated to provide an alkylation product comprising a mixture of monoalkyl and polyalkylbenzenes. Ru. The alkylation zone can be operated under liquid phase or gas phase conditions and the reactants from the alkylation zone are subjected to a separation step. The transalkylation reaction zone is operated at an average temperature that is less than or equal to the average temperature of the alkylation reaction zone and under conditions that maintain the benzene in the liquid phase.

In the production of ethylbenzene, where the alkylation reaction takes place over an aromatic alkylation catalyst selected from the group consisting of zeolite beta and zeolite omega, the reactants from the alkylation reaction zone are fed to a benzene separation zone. A high boiling fraction comprising an ethylbenzene polyethylbenzene mixture is fed from the benzene separation zone to the ethylbenzene separation zone.

This separation zone is operated to obtain a low-boiling product fraction comprising ethylbenzene and a high-boiling fraction comprising polyethylbenzene containing at most 5% by weight of ethylbenzene. The polyethylbenzene fraction is fed with benzene to a transalkylation reaction zone containing a transalkylation catalyst preferably selected from the group consisting of Zeolide Y and Zeolite Omega.

Processes for the alkylation of aromatic feedstocks and the use of zeolite molecular sieve catalysts in aromatic alkylation processes are well known in the art. Such alkylation processes can be carried out in the gas phase, in the liquid phase, or under conditions where both liquid and gas phases are present.

An example of vapor phase alkylation is found in Dwyer US Pat. No. 4,107,224. Here,
Gas phase ethylation of benzene over a zeolite catalyst is accomplished in a downflow reactor. The reactants from this reactor are sent to a separation system that recovers the ethylbenzene product and the polyethylbenzene is recycled to the alkylation reactor where it undergoes a transalkylation reaction with benzene.

An example of an alkylation-transalkylation process in which the reactants from the alkylation reaction zone are sent directly to the transalkylation zone is disclosed in US Pat. No. 3,551.510 to Pollitzer et al. In the Paulitzer process, alkylation is carried out using an alkylating agent characterized as an olefinic compound over a solid phosphoric acid alkylation catalyst. Olefinic compounds may be selected from materials such as monoolefins, diolefins, polyolefins, acetylenic hydrocarbons, alkyl halides, alcohols, ethers and esters. The product from the alkylation reaction zone containing polyethylbenzene is fed to the transalkylation reaction zone along with an aromatic material such as benzene. In the transalkylation zone, an acid-extracted crystalline aluminosilicate catalyst,
In particular, it is loaded with mordenite and used in an upflow method. Transalkylation conditions are exemplified including a liquid hourly space velocity of 1.0, a pressure of 500 psig, and a temperature of 250°C. The reactants from the transalkylation zone are fed to a separation zone from which polyalkyl aromatics, such as polyethylbenzene, are removed and recycled to the alkalization reaction zone.

Other alkylation transalkylation methods include War
d) in US Pat. No. 4.008.290. Ward, like the Boritzer patent, discloses the use of a solid phosphoric acid catalyst in the alkalization zone. In Ward's method, benzene is reacted with propylene to produce cumene. The reactants from Ward's alkylation reactor are separated such that the portion containing primarily benzene and cumene is recycled to the alkylation reactor. Other portions containing primarily benzene, cumene, propane and di- and triisopropylbenzene are fed to the separation zone. In this separation zone, a stream rich in di- and triisopropylbenzene is separated and fed together with benzene to the transalkylation zone. The transalkylation zone also incorporates a solid phosphoric acid catalyst. A cumene-rich stream is removed from the transalkylation zone and recycled to the separation zone.

White U.S. Patent No. 4,169,111
No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, 2003, 2007, 2003, discloses an alkylation-transalkylation process for the production of ethylbenzene using crystalline aluminosilicate in the alkylation and transalkylation reactors. The catalysts in the alkylation and transalkylation reactors may be the same or different and have a silica/alumina molar ratio between 2 and 80, preferably between 4 and 12, with a low sodium content, preferably 0.5% by weight of Na, O. Contains gelaoite. Examples of this gelaoite are XSY, L%B1ZSM-
Contains molecular sieves of E and omega crystal type, approximately 0
．． Steam-stabilized Y gelaoite containing 2% Na□O is preferred. The alkylation reactor is operated in downflow mode and under temperature and pressure conditions where some liquid is present. Transalkylation reactors, which are generally described as requiring higher than optimal alkylation temperatures to achieve maximum transalkylation efficiency, are also operated in downflow mode. In Wide's process, the reactants from the alkylation reactor are cooled and fed to a benzene column from which benzene is recovered as overhead and recycled to the alkylation reactor. The bottoms of the benzene tower are fed to the ethylbenzene tower, from which ethylbenzene is recovered as a product. The bottom product from the ethylbenzene column is fed to a third column. The column is operated to provide a substantially pure diethylbenzene overhead fraction comprising 10-90%, preferably 20-60%, of the total diethylbenzene feed to the column. This diethylbenzene overhead fraction is recycled to the alkylation reactor, while the remaining diethylbenzene and fractions containing triethylbenzene and high molecular weight compounds are fed together with benzene to the transalkylation reactor. The effluent from the transalkylation reactor is recycled to the benzene column.

U.S. Pat. No. 4,774 to Barger et al.
No. 377 is an alkylation/transalkylation process that, like the Wide process described above, uses separate alkylation and transalkylation reaction zones and involves recycling the transalkylated product to an intermediate separation zone. is disclosed. In the Burger process, temperature and pressure conditions are adjusted so that the alkylation and transalkylation reactions occur essentially in the liquid phase. The transalkylation catalyst is of type X, Y
aluminosilicate molecular sieves, including ultra-stable Y, L-type, omega-type and mordenite-type zeolites, the latter being preferred. The catalyst used in the alkylation reaction zone is a solid phosphoric acid containing material.

Aluminosilicate alkylation catalysts can also be used, with O, O
Water varying from 1 to 6% by volume is fed to the alkylation reaction zone. Reactants from the alkylation reaction zone are fed to first and second separation zones. In the second reaction zone, intermediate aromatic products and trialkylaromatics and heavier products are separated, leaving only the dialkylaromatic components or diethylbenzene in the case of the ethylbenzene production process or diethylbenzene in the case of the cumene production. provides the feed to the transalkylation reaction zone with diisopropylbenzene. Benzene material is also fed to the transalkylation zone for the transalkylation reaction, and the reactants from the transalkylation zone are recycled to the first separation zone. The alkylation and transalkylation zones can be operated in downflow, upflow or horizontal flow mode.

According to the present invention, alkylation of aromatics with a C2-C, alkylating agent is combined with separation of a tank to recover monoalkylated aromatic products and liquid phase transalkylation of polyalkylated products. Provided are alkylation-transalkylation methods comprising:

In one aspect of the invention, both the alkylation and transalkylation are carried out over a molecular sieve aromatic alkylation and transalkylation catalyst in the liquid phase. The reactants from the alkylation reaction zone include a low boiling fraction comprising aromatics and a high boiling fraction comprising a mixture of monoalkylated and polyalkylated aromatics which can be recycled to the alkylation reaction zone. is fed to a separation zone which is operated to give This high-boiling fraction is fed to a second separation zone to provide a second low-boiling fraction comprising the desired monoalkylated product and a high-boiling fraction comprising the polyalkylated product. .

At least a portion of the polyalkylated fraction containing substantially all dialkylated and trialkylated aromatics,
Along with the aromatics, the molecular sieve is fed to a transalkylation reaction zone containing a transalkylation agent. This transalkylation zone is operated under liquid phase conditions in which the polyalkylated fraction is disproportionated to reach a disproportionated product of reduced polyalkylated aromatic content and increased monoalkylated aromatic content. become At least a portion of this disproportionated product is fed to the first separation zone.

In a particular application of the invention for the production of ethylbenzene or cumene, the reactants from the transalkylation zone are fed to a third separation zone where the benzene and monoalkylbenzene (ethylbenzene or cumene) fractions are recovered and circulates.

In another embodiment of the invention, the benzene feedstock and the alkylating agent contain a molecular-sieve alkylation catalyst and are configured to provide an alkylated product comprising a mixture of monoalkyl and polyalkylbenzenes. is fed to an alkylation reaction zone operated at In this embodiment of the invention, the alkylation zone can be operated under liquid phase or gas phase conditions and the reactants from the alkylation zone are subjected to a separation step as described above. The transalkylation reaction zone is operated at an average temperature that is less than or equal to the average temperature of the alkylation reaction zone and under conditions that maintain the benzene in the liquid phase. In a particular application of this embodiment of the invention to processes employing gas phase ethylation of benzene, leading to liquid phase transalkylation, the average temperature of the transalkylation reaction zone is less than the average temperature of the alkylation reaction zone. Both are 100 degrees Celsius lower.

However, in a further aspect of the invention involving alkylation of a benzene feedstock with a C2-C4 alkylating agent, the alkylation catalyst is selected from the group consisting of Zeolite Beta, Zeolite Omega and Zeolite Y, and the alkylation reactor is It is operated under conditions that maintain the benzene feedstock in the liquid phase as described above.

The effluent from the alkylation reactor is subjected to a separation step of the system described above, followed by a separation to recover at least a portion of the polyalkylbenzene fraction containing substantially all of the desired monoalkylbenzene, such as ethylbenzene or cumene, dialkylbenzene content. and the main portion of the trialkylbenzene containing t is fed to a transalkylation zone containing a transalkylation catalyst selected from the group consisting of zeolite Y and zeolite omega. Preferably the alkylation catalyst comprises zeolite beta. It is also preferred that the transalkylation catalyst comprises omega zeolite.

In a further embodiment of the invention, namely the production of ethylbenzene in which the alkylation reaction takes place over an aromatic alkylation catalyst selected from the group consisting of zeolite beta and zeolite omega, the reactants from the alkylation reaction zone are benzene separated. supplied to the area.

A high boiling fraction comprising an ethylbenzene polyethylbenzene mixture is fed from the benzene separation zone to the ethylbenzene separation zone. This separation zone is operated to obtain a low-boiling product fraction comprising ethylbenzene and a high-boiling point fraction comprising polyethylbenzene containing at most 5% by weight of ethylbenzene. The polyethylene benzene fraction is fed with benzene to a transalkylation reaction zone containing a transalkylation catalyst preferably selected from the group consisting of zeolite I-Y and zeolite omega.

Figures 1a-1c and 2a-20 are graphs illustrating the results of transalkylation experiments conducted with two different zeolite l-Y catalysts.

Figures 3a-30 are graphs showing the results of experimental studies conducted using zeolite omega in the transalkylation of diethylbenzene.

Figures 4a-4c are a series of graphs illustrating experimental studies performed using rare earth zeolites.

Figures 5a, 5b and 6 are graphs showing another experimental study using a zeolite Y catalyst.

FIG. 7 is a simplified system flow diagram illustrating one embodiment of the present invention in which the polyethylene benzene fraction is subjected to a residue extraction step prior to transalkylation.

Figure 8 schematically illustrates a modification of the process of Figure 7 in which the reactants from the transalkylation reactor are subjected to a separation step before recycling.

FIG. 9 is a simplified schematic diagram of another embodiment of the present invention in which the bottoms fraction from the ethylbenzene column is fed directly to the transalkylation reactor and the effluent of the transalkylation reactor is provided to a downstream separation zone. exemplify.

FIG. 10 is a system 7 row diagram showing a modification of the specific example shown in FIG.

A preferred application of the invention is the liquid phase alkylation of molecular sieves selected from the group consisting of zeolite beta and zeolite omega over an alkylation catalyst of molecular sieves selected from the group consisting of zeolite Y and zeolite omega. In combination with liquid phase transalkylation over a transalkylation catalyst. A particularly preferred embodiment of the invention involves the use of zeolite beta as the alkylation catalyst and zeolite omega as the transalkylation catalyst. However, as will become apparent, other molecular sieve catalysts may also be used in carrying out the present invention. Further, although a preferred application of the present invention is to use liquid phase transalkylation in combination with liquid phase alkylation, the present invention combines gas phase alkylation with liquid phase as disclosed, for example, in Dwyer's above-mentioned patents. It can also be carried out by use in combination with transalkylation and appropriate recycling of the transalkylated product to the separation zone.

In a more general aspect, the present invention broadly describes alkylating agents of the type disclosed in the above-mentioned patents of Paulitzer et al. Includes transalkylation in combination with aromatic alkylation using alkylating agents. The most widely used alkylating agents are ethylene and propylene, which are applied in the production of ethylbenzene and cumene, respectively. The present invention is particularly applicable to the ethylation of benzene under conditions such that the yield of by-product xylene is reduced;
The invention will therefore be described with particular reference to the production of ethylbenzene, including the concomitant transalkylation of polyethylbenzene.

As previously mentioned, a conventional method for producing ethylbenzene involves recycling the polyethylbenzene separated from the ethylbenzene product to an alkylation reactor where it is transalkylated to produce ethylbenzene. A byproduct of this process is increased xylene yield in the effluent from the alkylation reactor. The presence of xylene complicates downstream processing and separation steps. The special impact of the significant xylene content in the product stream is that it often removes ethylbenzene from the top in such a way that it gives a substantial ethylbenzene content, sometimes 15-20% or more, in the bottom polyethylbenzene fraction. It is necessary to operate the distillation column to obtain For example, ethylbenzene produced according to the invention can be used in the production of styrene by catalytic dehydrogenation. The boiling points of ortho-xylene and styrene are very close, within 1° C. of each other. As a practical matter, the quality of ethylbenzene will require a very low xylene content, usually less than 2000 ppm. To meet this quality, it is usually necessary to operate the ethylbenzene column under moderate distillation conditions to achieve a high ethylbenzene content in the bottom fraction, as described above. The present invention involves carrying out the transalkylation of polyethylbenzene in a separate reactor under relatively mild liquid phase conditions.
Minimize the production of xylene during the manufacturing process.

This limits the ethylbenzene content in the polyethylbenzene fraction to 511% by weight or less, and to about 2% by weight or less when using suitable catalysts to further minimize the formation of xylene. This can reduce the circulation of ethylbenzene.

A preferred aspect of the present invention is to separate a polyethylbenzene fraction containing diethylbenzene and triethylbenzene and high molecular weight compounds in order to recycle a substantial portion of the diethylbenzene to the alkylation zone as disclosed in Wide's above-referenced patents. or feeding the transalkylation reactor as opposed to separating the trialkyl aromatic for transalkylation with dialkylbenzenes alone, as disclosed in Berger's above-mentioned patents. include. In this regard, depending on the configuration of the transalkylation reactor and the polyethylbenzene or other separation zone, substantially all of the diethylbenzene and substantially all or most of the triethylbenzene content is transferred to the transalkylation reactor. will be supplied. In either case, the practical effect of embodiments of the invention is that circulation to the alkylation reactor is limited to benzene and lighter components such as ethylene, while most, if not all, triethylene is retained in the system together with diethylbenzene for ultimate conversion to benzene and ethylbenzene.

This not only reduces the production of xylene as mentioned above, but also provides significant advantages over conventional methods in terms of final product yield.

In the experimental work for this invention, a number of catalysts were used in transalkylation tests conducted in an upflow overflow unreactor. That is, only the liquid phase was brought into contact with the catalyst. The feed used in this experimental study was approximately 1:1 of benzene and polyethylbenzene overhead fraction from a commercial operation used for the production of ethylbenzene by gas phase alkylation of benzene.
It was a mixture of A typical feed used in the experimental study had a composition as shown in Table 1 below.

Table 1 component non-aromatic benzene toluene ethylbenzene p+m-xylene styrene 0-xylene Kumen n-propylbenzene H1+p-ethylbenzene 1.3.5-Trimethylbenzene 0-ethyltoluene 12.44 Limethylbenzene 12.34 Limethylbenzene m-diethylbenzene o+p-diethylbenzene butylbenzene heavy material weight% 0.032 50.24i o, oo.

6.117 o, oo.

O,063 0,066 3,973 7,816 2,053 0,356 0,536 0,401 14,808 7,328 1,653 4,429 In experimental studies, the average pressure was approximately 300 psig;
The pressure drop across the reactor was approximately 5-15 psi. The temperature distribution across the reactor was relatively constant, with an endotherm of less than 10°C from inlet to outlet, typically less than 5°C. Experiments were started at relatively low temperatures, typically below 100°C, and were gradually increased as described below. The space velocity was kept at a relatively constant value of 6 hours-' (LH3V) based on the total hydrocarbon feed.

The conversion of diethylbenzene and selectivity to ethylbenzene was measured as a function of catalyst age (duration of experiment) along with the production of various other components, including xylene.

In the first test experiment, the catalyst used was commercially available Zeolite Y (here designated as Catalyst A), the inlet temperature was gradually increased to about 235°C, and only 1 or 2°C was passed through the reactor. The temperature was stabilized to give an average temperature rise.

The results of this experiment are illustrated in Figures 1a-IC. In the diagram,
Dietyno L benzene conversion rate % C1 Selectivity to ethylbenzene % 5 So-xylene production ppm ○ and temperature °C T are plotted against the catalyst time A (time) on the horizontal axis as curves +1, 2, 14 and 16, respectively. It is. As can be seen from the experiment of the data shown in Figure 1, the conversion of diethylbenzene is about 32°C for a reactor temperature of about 237°C.
Stabilized in the range of ~37%, the catalyst deactivated very little over the duration of the experiment. The selectivity to ethylbenzene was essentially 100%. During the experiment, 0-
The production of xylene stabilized at about 400-500 ppm.

Other test runs were conducted using experimental zeolite Y, shown here as Catalyst B. The results of this experiment are shown in Sections 2a-2.
Shown in Figure 0. Curves 18, 19, 21 and 22 are graphs of diethylbenzene conversion C1 selectivity S to ethylbenzene, o-quinolene ppmo, and temperature T plotted as a function of catalyst age A, respectively. In this experiment,
After starting, gradually increase the temperature over time to a final temperature of about 240°C.
The catalyst was used for almost 400 hours. As can be seen, the conversion of diethylbenzene was relatively good, mostly in the range of 30-40% at relatively moderate temperatures.

Selectivity to ethylbenzene was greater than 90% and virtually 100% during most of the experiment.

The 0-xylene content of the product stream stabilized at about 900 ppm.

Additionally, other test experiments were conducted using a zeolite omega catalyst, designated herein as Catalyst C.

The results for diethylbenzene conversion, selectivity and as a function of time and temperature are shown in Figures 3a-30. In FIG. 3, curves 24, 25, 27 and 28 represent diethylbenzene conversion, selectivity to ethylbenzene, and 0-xylene content (ppm) O.

and temperature (°C) T as a function of the catalyst temperature on the horizontal axis. As shown in Figure 3, diethylbenzene conversion was ultimately slightly better than that for Catalysts A and B, generally falling within 40-50% at reactor temperatures ranging from about 210 to about 236°C. . Selectivity to ethylbenzene was greater than 90% and virtually 100% in many of the experiments. 0-xylene content is approximately 800-90
It was stabilized at 0 ppm. The catalyst deactivated very little over the period of the experiment.

Rare earth zeolite y, shown here as catalyst, was used in other tests. The results for the catalyst are shown in Section 4a.
- Shown in Figure 40. Curves 30, 32, 33, and 35 are graphs of diethylbenzene conversion, selectivity to ethylbenzene, 0-xylene ppm, and temperature, respectively, as a function of catalyst age.

The catalyst shows relatively good results, including divinylbenzene conversions in the range of 40-50%. The initial selection rate is approximately 1
00%, and the selectivity decreased slightly to about 90% towards the end of the experiment. Although good conversion and selectivity were achieved, the reaction temperature was substantially higher than for zeolites t-Y and Omega, rising to about 27,000 at the end of the about 210 hour run.

The feeds for the experiments shown in Examples 1-4 generally corresponded to the compositions shown in Table 1. However, the feed for the first test run (catalyst A) contained no orthoquinolene, and the feed for the second run (catalyst B) contained approximately 0.02
% p- and m-xylene.

Further experimental studies under duplicate conditions were carried out using three additional catalysts: Catalyst E10- from Rohm & Haas to Amberlyst (A
cation exchange resin commercially available as Catalyst F1 Varshaw-Filtrol (
superacid alumina, commercially available as 3998 from Harshaw-F 1lttrol, and nickel-modified mordenite, commercially available as Ni-Cn9040 from Catalyst G1 Union Carbide. Catalyst E showed very little diethylbenzene conversion and no total heat ethylbenzene production until the end of the experiment for about 50 hours and at a temperature of 155°C due to experimental difficulties.

Catalyst F provides diethylbenzene conversion in the range of about 10-20% at temperatures in the range of about 300-450°C;
Selectivity to ethylbenzene is 50 at most points.
% or less. Catalyst G was tested at temperatures ranging up to 100°C for 100 hours and showed little/v and no total diethylbenzene conversion! two.

Zeolite Y catalysts, designated above as Catalysts A and B,
It was also used in a downflow trickle bed reactor in which a substantial gas phase was present. Fresh and regenerated catalysts were used. This experimental study was conducted at a pressure of about 330 ps ig, an apparent space velocity (L HS) of about 10 h and a temperature of about 300 °C for fresh catalyst A and about 300-400 ° for fresh catalyst B.
C and an average reactor temperature of about 200'C for regenerated catalyst. For new Catalyst A, the initial diethylbenzene conversion was about 24%, but this dropped rapidly after a few hours. The catalyst was then regenerated and experiments were conducted under less severe temperature conditions of about 200'C. The initial conversion rate of divinylbenzene was as high as about 60%, but in this case as well, this decreased to a few percent after about 24 hours.

When new catalyst B was used, the initial diethylbenzene conversion was about 50% or more, but after about 5 hours it was about 20%.
It then further decreased to several percent. Regenerated Catalyst B showed an initial divinylbenzene conversion of about 58% when reacted at a low temperature of about 200° C., which decreased to about 27% 29 hours after the experiment ended.

Further experimental studies were carried out using zeolite Y, designated as catalyst B. The feed in this case was a mixture of relatively pure diethylbenzene and approximately equal parts benzene. Unlike the raw materials used in the experimental studies shown in Figures 1 to 4,
The pure diethylbenzene feed contained very little xylene-forming materials that were sensitive to graphing or other conversion reactions such as deethylation, and also contained no xylenes. The components of the raw materials used in this experiment are shown in Table 2.

Table ■ Ingredients Weight% Non-aromatic
0.01 benzene
56.58 toluene
0.09 ethylbenzene
0.01 xylene
o, ooo.

n-PR-BZ O,0
2m + p-ethyltoluene 0.
030-Ethyltoluene 0.0
112.4-Trimethylbenzene 5ec-Bll-BZ
O,471,2,3-trimethylbenzene m-diethylbenzene 27.62o
, p-diethylbenzene 14.27n
-BIJ-BZ O,
35 Heavy 0.54 In this test experiment, the inlet and outlet pressures were set to 310
and maintained at 305 psig. The average temperature of the reactor was increased approximately linearly over time from an initial value of about 198°C to a final value of about 298°C.

The space velocity is generally about 5.8-6.0 hours-' (LH3V)
kept within the range. However, if the speed drops to about 5.1 before recovering to a higher speed, the opening speed of the test should be changed to about 2.
/3.

The results of this test are shown in Figures 5 and 6. In factor 5a, a curve 38 is a graph of temperature T versus catalyst age A (hours) on the horizontal axis. In Figure 5b, curves 40 and 41 are graphs of ethylbenzene selectivity and % ethylbenzene conversion, respectively. Curve 22 is the total xylene production X in ppm based on the amount of ethylbenzene produced.
This is a graph of FIG. 6 shows the relationship between the conversion rate of ethylbenzene and temperature. Curve 43 is a graph of the ethylbenzene conversion rate C on the vertical axis and the temperature T on the horizontal axis.

As the data in Figure 5 shows, xylene production remained low throughout the test run. Xylene has a temperature of about 260°C
(which generally corresponded to a decrease in space velocity to about 5.1 h−1 as reported in the past). The % conversion remained good until the temperature was increased above 280°C. As shown in Figure 6, ethylbenzene conversion appeared to remain at about 50% over a temperature range of about 200-290°C, with the optimum range being about 210-280°C.

Still referring to the drawings, FIGS. 7-10 are systematic flow diagrams supporting different embodiments of the present invention.

The present invention is applied to the production of ethylbenzene by the reaction of ethylene with benzene and the alkylation reaction is carried out in a fluidized bed liquid phase alkylation reactor by using zeolite beta, zeolite Y or zeolite omega as alkylation catalyst. This is for discussion purposes only. However, as previously mentioned and discussed in more detail below, the alkylation step may also be carried out as a gas phase reaction using a catalyst such as noricalide or ZSM-5.

Referring first to FIG. 7, a feed stream 5 containing ethylene and benzene is fed through conduits 51 and 52, respectively.
0 is first fed to a dehydrator 54 which reduces the water content to about loop per million or less and then to an alkylation reaction zone 56. An alkylation reactor comprising a plurality of series adiabatic reactors with an ethylene injection intermediate stage and a cooling intermediate stage typically maintains the benzene in the liquid phase and the ethylene at an average temperature of about 220°C. Sufficient pressure to dissolve 2 mole % in benzene, i.e. approximately 600 ps.
ig or higher. An alternative method using an adiabatic reactor includes suitable cooling means used to maintain a substantially constant temperature (little or no variation in thermal temperature) from the inlet to the outlet of the reactor. One or more isothermal reactors can be used. The effluent from the alkylation reactor is sent to prefractionator 58. This is operated to provide a light overhead fraction containing benzene and a heavy liquid fraction containing benzene, ethylbenzene and polyethylbenzene which are fed to the inlet of the alkylation reactor through conduit 59.

Effluent from prefractionation zone 58 is fed through conduit 60 to benzene separation zone 61. The overhead fraction from column 61 contains residual benzene which is recycled to the alkylation reactor inlet via conduit 62. The heavy bottom fraction from column 61 is transferred to conduit 64
ethylbenzene separation zone 65. The overhead fraction from group 65, of course, comprises ethylbenzene which is fed to storage or to appropriate product purposes. To illustrate, ethylbenzene may be used as a feed stream to a styrene plant where styrene is produced by dehydrogenation of ethylbenzene. The bottom fraction containing polyethylbenzene, heavy aromatics and preferably only a small amount of ethylbenzene, as mentioned above, at most 5%, is passed to the polyethylbenzene separation zone 6.
Supply to 8. The bottoms fraction of column 68 comprises residue.

Column 68 containing polyethylbenzene, triethylbenzene (usually in relatively small amounts) and a small amount of ethylbenzene.
The overhead fraction from is fed to transalkylation reaction zone 72. Minimizing the amount of ethylbenzene recovered from the bottom of column 65 keeps the ethylbenzene content of the transalkylation feed stream low and directs the transalkylation reaction toward the production of ethylbenzene. conduit 7
The polyethylbenzene fraction, which is also taken overhead through 0, is mixed with benzene fed through conduit 73 and then fed to 1-lance alkylation reactor 72. The molar ratio of benzene to polyethylbenzene is at least 1
:1, preferably within the range of 1:1 to 4:6. The effluent from the transalkylation reactor containing benzene, ethylbenzene and a reduced amount of polyethylbenzene is fed to benzene column 61 through conduit 75.

In the process shown in Figure 7, the alkylation reaction is carried out in the liquid phase with dehydration of the feed to the alkylation reactor. As previously mentioned, the present invention can be carried out using liquid phase transalkylation in conjunction with gas phase alkylation, and in such reactions, depending on the catalyst used, in the feed to the alkylation reactor. may contain significant amounts of water.

In this case, it may be necessary to separately dehydrate the feed to the transalkylation reactor.

Such dehydration can take place at any point upstream of the transalkylation, and if necessary dehydration can be accomplished with respect to the fresh benzene fed through conduit 73 as well as with respect to the polyethylbenzene component formed during the alkylation reaction. Should.

Figure 8 discloses a modification of the process disclosed in Figure 7 in which the transalkylation reactor effluent is subjected to further processing before being recycled to the separation system. The embodiment of FIG. 8 is particularly useful when relatively high conversion rates are achieved in the transalkylation reactor. In the embodiment of FIG. 8, the alkylation reactor and separation system are equivalent to those of FIG. 7, and like components are designated by the same reference characteristics. However, the effluent from the transalkylation reactor is fed to a second separation zone 77. This may be in the form of a distillation column,
Bottom barge stream removed through conduit 78 and conduit 8
The benzene column is operated to provide a recycle stream which is taken through 0 and fed to the benzene column.

A purge stream containing heavy hydrocarbons is removed from the system to provide a partially single flow system in which high molecular weight hydrocarbons are not recycled.

FIG. 9 illustrates another embodiment of the present invention in which the polyethylbenzene fraction recovered from the ethylbenzene column is passed directly to the transalkylation reactor. In Figure 9,
Components of the same system as shown in FIGS. 7 and 8 are designated with like reference numbers. As shown in FIG. 9, the effluent from ethylbenzene column 65 is mixed with benzene fed through conduit 82 to transalkylation reactor 8.
Supply to 4. Here, the entire polyethylbenzene fraction is subjected to transalkylation. The conditions used in reactor 84 may be the same as described above, with a benzene to polyethylbenzene ratio of about 1:1 to 4:1.

The process shown in Figure 9 is similar to that of Figure 8 except that the entire bottom fraction from the ethylbenzene column is subjected to the transalkylation reaction. Limiting the ethylbenzene content of the input to the transalkylation reactor to no more than 5%, preferably 2% or less is particularly important in establishing conditions that promote the transalkylation reaction. The effluent from the transalkylation reactor is removed from the circulation via conduit 85, consisting primarily of benzene and ethylbenzene, and C9 and C1° hydrocarbons such as ethyltoluene, cumene, etc., which are removed from the circulation via discharge conduit 88. to a post-transalkylation separation zone 86 which may be in the form of a distillation column operated to provide a bottoms fraction consisting of , butylbenzene, or the like. The overhead fraction is recycled to the benzene column via conduit 89 in the same manner as described above.

The embodiment of FIG. 10 splits the transalkylation reactor effluent, feeds a portion directly to benzene column 61 through conduit 92, and the remainder to a separation zone 8 operated as described above.
It is the same as in FIG. 9 except that it is supplied to 6. The arrangement of FIG. 1O provides a means to keep the concentration of C9 and C1o hydrocarbons in the system low and reduces the energy cost of operating column 86. Typically about 60% of the transalkylation reactor effluent
0% or more is recycled directly to benzene column 61 and the remainder is sent to separation zone 86.

Having described particular embodiments of the invention, it will be understood that modifications thereof will occur to those skilled in the art, and all such modifications are intended to fall within the scope of the following claims. Ru.

Features and aspects of the invention are as follows: 1.8) Aromatic substances
b) feeding a C, to C, alkylating agent to the reaction zone; C) connecting the reaction zone to the aromatic material; is operated at a temperature and pressure that maintains the aromatic material in the liquid phase, and the aromatic material is alkylated with the alkylating agent in the presence of the catalyst to produce a mixture of monoalkylated and polyalkylated aromatic products. d) collecting the alkylated product into the reaction zone and feeding the product from the reaction zone to a separation zone for the separation of aromatics; e ) operating said separation zone to obtain a low boiling fraction comprising said aromatics and a high boiling fraction comprising a mixture of monoalkylated aromatics-polyalkylated aromatics; f) said separation; g) feeding the high boiling fraction from the zone to a second separation zone; g) connecting the second separation zone to a second low boiling fraction comprising a monoalkylated aromatic product and a heavier operating to obtain a high boiling fraction comprising an alkylated aromatic product; h) said polyalkylated aromatic comprising substantially all dialkylated and trialkylated aromatics in said polyalkylated product; supplying at least a portion of the group product to a transalkylation reaction zone comprising a molecular sieve transalkylation catalyst: l) supplying the aromatic material to the transalkylation zone; j) the transalkylation reaction maintain the aromatics in the liquid phase and disproportionate the polyalkylated aromatic fraction (
k) operating under temperature and pressure conditions effective to achieve a disproportionation product with reduced polyalkylated aromatic content and increased monoalkylated aromatic content; and k) An alkylation-transalkylation process comprising: feeding at least a portion of the disproportionated product to the first detailed separation zone.

2. The aromatic material comprises benzene, and the alkylating agent is an ethylating or propylating agent, wherein the polyalkylated aromatic content of the disproportionated product comprises dialkyl and trialkylbenzenes. Method 1.

3. Prior to step k) of 1 above, feeding the effluent from the transalkylation zone to a third separation zone, and supplying the third separation zone with a benzene-monoargylbenzene component. and said benzene-monoalkylbenzene component to said first detailed separation zone according to step k) of 1 above. 2. The method of 2 above, further comprising: supplying.

4. The method of 3 above, wherein the alkylating agent is an olefin.

5. The method of 4 above, wherein the alkylating agent is ethylene.

6. a) feeding a benzene feed into an alkylation reaction zone containing a molecular di-aromatic alkylation catalyst; b) feeding a 02-C4 alkylating agent to the reaction zone; C) feeding the reaction zone. d) operating under temperature and pressure conditions to alkylate the benzene with the alkylating agent in the presence of the catalyst to obtain an alkylated product comprising a mixture of monoalkyl and polyalkylbenzenes; d) the reaction zone; e) collecting the alkylated product from the reaction zone and feeding the product from the reaction zone to a benzene separation zone; operating to obtain a high boiling fraction comprising a mixture; f) feeding the high boiling fraction from the separation zone to a second separation zone; g) connecting the second separation zone to a monoalkylbenzene production h) operating at least a portion of the polyalkylbenzene fraction in a molecular sieve; 1) supplying benzene to the transalkylation zone containing a transalkylation catalyst, and 1) supplying benzene to the transalkylation zone, the temperature of the transalkylation reaction zone being at least 50'C below the average temperature of the alkylation reaction zone; effective at low average temperatures and to maintain the benzene in liquid phase and disproportionate the polyalkylbenzene fraction to reach a disproportionated product with reduced polyalkylbenzene content and increased monoalkylbenzene content. and k) feeding at least a portion of said disproportionated product to said first detailed separation zone.

7. The method of 6 above, wherein the alkylating agent is an ethylating agent or a propylating agent.

9. The method of 8 above, wherein the alkylating agent is an olefin.

10. The method of 9 above, wherein the alkylating agent is ethylene.

ll, operating the alkylation reaction zone at a temperature and pressure that causes gas phase ethylation of the benzene; and operating the transalkylation reaction zone at least 100° below the average temperature of the alkylation reaction zone. C. The above method of operating at a low average temperature.

12. a) feeding a benzene feedstock to a reaction zone comprising an aromatic alkylation catalyst comprising a molecular sieve selected from the group consisting of zeolite beta, zeolite omega, and zeolite Y; b) C, to C4 alkylation; C) operating the reaction zone at a temperature and pressure that maintains the benzene in a liquid phase; and alkylating the benzene with the alkylating agent in the presence of the catalyst. d) recovering the alkylated product from the reaction zone and transferring the product from the reaction zone to a benzene separation zone. e) operating the separation zone to obtain a low boiling fraction comprising benzene and a high boiling fraction comprising a monoalkylbenzene-polyalkylbenzene mixture; f) supplying the high boiling fraction from the separation zone; g) supplying the boiling point fraction to a second separation zone; operating to obtain a boiling point fraction; h) at least a portion of the polyalkylbenzene fraction comprising substantially all of the dialkylbenzene content and a major portion of the trialkylbenzene content from the group consisting of zeolite Y and zeolite omega; supplying a selected molecular sieve to a transalkylation reaction zone comprising a transalkylation catalyst comprising: I) supplying benzene to the transalkylation zone; maintaining the benzene and the alkylbenzene and trialkylbenzene in a liquid phase flooding the transalkylation catalyst;
and operating under temperature and pressure conditions effective to disproportionate the polyalkylbenzene fraction to arrive at a disproportionated product with a reduced polyalkylbenzene content and an increased monoalkylbenzene content; and k) feeding at least a portion of said disproportionated product to said first detailed separation zone.

13. The method of 12 above, wherein the alkylation catalyst is zeolite beta.

If the alkylating agent is an ethylating agent or a propylating agent, the method of 13 above.

15. The method of 14 above, wherein the alkylating agent is ethylene.

16. The method of 15 above, wherein the transalkylation catalyst is zeolite omega.

17. a) feeding a benzene feedstock to a primary reaction zone containing an aromatic alkylation catalyst comprising zeolite beta; b) feeding a C, to C, alkylating agent to the reaction zone; The reaction zone is operated at a temperature and pressure that maintains the aromatic in the liquid phase, and the benzene is alkylated with the alkylating agent in the presence of the catalyst to form a mixture of monoalkylated and polyalkylbenzenes. d) recovering an effluent containing benzene and the alkylated product from the primary reaction zone; and producing an alkylated product comprising:
feeding a benzene component, a monoalkylbenzene component and a polyalkylbenzene component in full to a separation system operated to obtain them; e) recovering a high-boiling fraction comprising the polyalkylbenzene component from the separation system; f) recovering the polyalkylbenzene component; supplying a high boiling fraction to a transalkylation reaction zone comprising a transalkylation catalyst selected from the group consisting of Zeolite Y and Zeolite Omega; g) supplying benzene to the transalkylation zone; The alkylation reaction zone is subjected to liquid phase disproportionation of the polyalkylbenzene component in the presence of the transalkylation catalyst to arrive at a disproportionated product with a reduced polyalkylbenzene content and an increased monoalkylbenzene content. Operate at temperature and pressure conditions that are effective to:
and ]) feeding at least a portion of said disproportionated product to said first detailed separation zone.

18. The method of 17 above, wherein the alkylating agent is an ethylating agent or a propylating agent.

19. The method of 18 above, wherein the alkylating agent is ethylene and the high boiling fraction of step d) of 17 above comprises a mixture of diethylbenzene and triethylbenzene.

20. Prior to step f), the boiling fraction is treated to separate the polyethylbenzene fraction from the residual fraction with a higher boiling point than triethylbenzene, and the polyethylbenzene fraction is subjected to step [) above in 17. 17. The method of 17 above, further comprising feeding the transalkylation reaction zone.

21,8) supplying a benzene feedstock and an ethylating agent to a primary reaction zone containing an aromatic alkylation catalyst; b) supplying the primary reaction zone with a benzene feedstock containing a mixture of ethylbenzene and polyethylbenzene; C) recovering the alkylated product from the reaction zone and feeding the product to a benzene separation zone; d) operating the benzene separation zone under temperature and pressure conditions to obtain an alkylated product; operating to obtain a low boiling fraction comprising benzene and a high boiling fraction comprising an ethylbenzene-polyethylbenzene mixture; e) feeding the high boiling fraction from the benzene separation zone to an ethylbenzene separation zone; f) operating the ethylbenzene separation zone to obtain a second low boiling fraction comprising ethylbenzene and a second high boiling fraction comprising a heavy polyethylbenzene fraction; g) the ethylbenzene column; h) feeding benzene to the transalkylation reaction zone; operating under temperature and pressure conditions to disproportionate the fraction to arrive at a disproportionated product having a reduced content of polyethylbenzene and an increased content of ethylbenzene; k) converting the polyethylbenzene zone into a third low-boiling fraction comprising a mixture of benzene and ethylbenzene and a third high-boiling fraction of C3+ hydrogenated hydrogen; and 1) recycling said third low-boiling fraction of benzene and ethylbenzene to said first detailed benzene separation zone.

22. Separate the disproportionation product and process a portion of the product.
) and feeding another portion of the product to the benzene separation zone.

23. The method of 21 above, wherein the transalkylation catalyst comprises a molecular sieve selected from the group consisting of Zeolite Y and Zeolite Omega.

24. The method of 23 above, wherein the primary reaction zone is operated under temperature and pressure conditions that effect gas phase alkylation of the benzene feedstock.

25. The aromatic alkylation catalyst in the primary reaction zone comprises a molecular sieve selected from the group consisting of zeolite beta and zeolite omega, and the primary reaction zone maintains the benzene feedstock in a liquid phase. 23. The method of 23 above, which operates under pressure conditions.

26.8) feeding a benzene feedstock and an ethylating agent into a primary reaction zone containing an aromatic alkylation catalyst selected from the group consisting of zeolite beta and zeolite omega; operating at a temperature and pressure to effect the ethylation of the benzene feedstock while maintaining it in the liquid phase to obtain an alkylated product comprising an ethylbenzene polyethylbenzene mixture; C) recovering the product from the reaction zone; and feeding said product to a benzene separation zone; d) operating said benzene separation zone to obtain a low boiling fraction comprising benzene and a high boiling fraction comprising an ethylbenzene-polyethylbenzene mixture; e) feeding the high-boiling fraction from the benzene separation zone to an ethylbenzene separation zone; f) supplying the ethylbenzene separation zone to a second low-boiling fraction comprising ethylbenzene and comprising not more than 5% by weight of ethylbenzene; g) feeding the ethylbenzene fraction from the ethylbenzene column to a transalkylation reaction zone containing a transalkylation catalyst; h) supplying benzene to the transalkylation reaction zone; i) disproportionating the polyethylbenzene fraction to reduce the polyethylbenzene content and increase the ethylbenzene content; J) supplying at least a portion of the disproportionated product to the first-mentioned separation zone; Manufacturing method.

27. feeding the disproportionated product to a separation zone, operating the zone to provide a low boiling fraction comprising benzene and ethylbenzene and a high boiling polyethylbenzene fraction; 27. The method of 26 above, further comprising feeding the benzene separation zone according to step 1).

28. The method of 26 above, wherein the transalkylation catalyst comprises a molecular sieve selected from the group consisting of Zeolite Y and Zeolite Omega.

29, the transalkylation zone has a benzene and alkylbenzene based space velocity (L HS V) lower than the benzene based space velocity (L HS V) in the primary reaction zone.
28. The method of 28 above.

30, the space velocity in the transalkylation zone is 1
29 above, within the range of LH3V of ~10.

31. The method of 29 above, wherein the space velocity of the transalkylation zone is less than % of the space velocity of the sub-alkylation zone.

32. The method of 28 above, wherein the transalkylation zone is operated at a temperature within the range of 50 to 300°C.

[Brief explanation of drawings]

Figures 3a-30 and 2a-20 are graphs illustrating the results of transalkylation experiments conducted using two different Zeolite Y catalysts; Figures 4a-4c are a series of graphs illustrating experimental studies conducted with rare earth zeolites. Figures 5a, 5b and 6 are graphs illustrating another experimental study using Zeolite Y catalyst: Figure 7 is one of the present invention in which the polyethylenebenzene fraction is subjected to a residue extraction step before transalkylation. Figure 8 schematically illustrates a modification of the process of Figure 7 in which the reactants from the transalkylation reactor are subjected to a separation step before recycling; Figure 9 shows a simplified schematic diagram of another embodiment of the present invention in which the base fraction from the ethylbenzene column is fed directly to the transalkylation reactor and the effluent of the transalkylation reactor is provided to a downstream separation zone. By way of example, FIG. 10 is a system flow diagram illustrating a modification of the embodiment of FIG.

Claims (1)

[Claims] 1. a) feeding a feedstock containing an aromatic substance to a reaction zone containing a molecular sieve aromatic alkylation catalyst; b) feeding a C_2 to C_4 alkylating agent to the reaction zone c) operating the reaction zone at a temperature and pressure that maintains the aromatic in the liquid phase, and alkylating the aromatic with the alkylating agent in the presence of the catalyst to form a monoalkyl d) collecting the alkylated product into the reaction zone and converting the product from the reaction zone to the aromatic product; d) collecting the alkylated product into the reaction zone; e) supplying said separation zone to a separation zone for the separation of aromatics; e) said separation zone comprising a low boiling fraction comprising said aromatics and a mixture of monoalkylated aromatics-polyalkylated aromatics f) feeding the high boiling fraction from the separation zone to a second separation zone; g) connecting the second separation zone to a monoalkylated aromatic product; operating to obtain a second low-boiling fraction comprising a second low-boiling fraction and a high-boiling fraction comprising a heavier polyalkylated aromatic product; h) substantially all dialkyl in the polyalkylated product; i) supplying at least a portion of the polyalkylated aromatic product, including the polyalkylated and trialkylated aromatics, to a transalkylation reaction zone comprising a molecular sieve transalkylation catalyst; j) supplying the transalkylation reaction zone with a polyalkylated aromatic content by maintaining the aromatics in the liquid phase and averaging the polyalkylated aromatic fraction; operating under temperature and pressure conditions effective to arrive at a disproportionated product with reduced and increased monoalkylated aromatic content; and k) at least a portion of said disproportionated product is feeding one detailed separation zone. 2. a) feeding a benzene feed into an alkylation reaction zone containing a molecular sieve aromatic alkylation catalyst; b) feeding a C_2-C_4 alkylating agent to the reaction zone; c) feeding the reaction zone. d) operating under temperature and pressure conditions to alkylate the benzene with the alkylating agent in the presence of the catalyst to obtain an alkylated product comprising a mixture of monoalkyl and polyalkylbenzenes; d) the reaction zone; e) recovering the alkylated product from the reaction zone and feeding the product from the reaction zone to a benzene separation zone; operating to obtain a high boiling fraction comprising a mixture; f) feeding the high boiling fraction from the separation zone to a second separation zone; g) connecting the second separation zone to a monoalkylbenzene production h) operating at least a portion of the polyalkylbenzene fraction to obtain a second low-boiling fraction comprising polyalkylbenzene and a higher boiling fraction comprising a heavier polyalkylbenzene fraction; supplying a transalkylation reaction zone containing a transalkylation catalyst of a sieve; i) supplying benzene to the transalkylation zone; j) lowering the transalkylation reaction zone to a temperature less than the average temperature of the alkylation reaction zone; both at an average temperature of 50° C. lower and maintaining the benzene in the liquid phase and disproportionating the polyalkylbenzene fraction to reach a disproportionated product with a reduced polyalkylbenzene content and an increased monoalkylbenzene content. and k) feeding at least a portion of said disproportionated product to said first detailed separation zone. cation law. 3. a) feeding a benzene feedstock to a reaction zone comprising an aromatic alkylation catalyst comprising a molecular sieve selected from the group consisting of zeolite beta, zeolite omega and zeolite Y; b) C_2-C_4 alkyl c) operating the reaction zone at a temperature and pressure that maintains the benzene in the liquid phase, and alkylating the benzene with the alkylating agent in the presence of the catalyst; d) recovering the alkylated product from the reaction zone and subjecting the product from the reaction zone to benzene separation. e) operating said separation zone to obtain a low-boiling fraction comprising benzene and a high-boiling fraction comprising a monoalkylbenzene-polyalkylbenzene mixture; f) supplying said separation zone from said separation zone; feeding a high boiling fraction to a second separation zone; g) said second separation zone comprising a second low boiling fraction comprising a monoalkylbenzene product and a heavier polyalkylbenzene fraction; h) at least a portion of the polyalkylbenzene fraction comprising substantially all of the dialkylbenzene content and a major portion of the trialkylbenzene content from the group consisting of zeolite Y and zeolite omega; supplying a transalkylation reaction zone comprising a transalkylation catalyst comprising a selected molecular sieve; i) supplying benzene to the transalkylation zone; The pentene and the alkylbenzene and trialkylbenzene remain in the liquid phase bathing the transalkylation catalyst and disproportionate the polyalkylbenzene fraction to reduce the polyalkylbenzene content and increase the monoalkylbenzene content. and k) supplying at least a portion of said disproportionated product to said first detailed separation zone. This is an alkylation-transalkylation method. 4. a) feeding a benzene feedstock to a primary reaction zone containing an aromatic alkylation catalyst comprising zeolite beta; b) feeding a C_2-C_4 alkylating agent to said reaction zone; c) said primary reaction zone. is operated at a temperature and pressure that maintains the aromatic in the liquid phase, and the benzene is alkylated with the alkylating agent in the presence of the catalyst to form a mixture of monoalkylated and polyalkylbenzenes. d) recovering an effluent containing benzene and the alkylated product from the primary reaction zone; and producing an alkylated product of
feeding a benzene component, a monoalkylbenzene component and a polyalkylbenzene component to a separation system operated to obtain them separately; e) recovering from the separation system a high-boiling fraction comprising the polyalkylbenzene component; f) recovering the high-boiling fraction from the separation system; supplying the boiling point fraction to a transalkylation reaction zone comprising a transalkylation catalyst selected from the group consisting of Zeolite Y and Zeolite Omega; g) supplying benzene to the transalkylation zone; h) the transalkyl the polyalkylbenzene component in the presence of the transalkylation catalyst to reach a disproportionated product with a reduced polyalkylbenzene content and an increased monoalkylbenzene content. operating at temperature and pressure conditions that are effective; and i) feeding at least a portion of the disproportionated product to the first detailed separation zone. . 5. a) supplying a benzene feedstock and an ethylating agent to a primary reaction zone containing an aromatic alkylation catalyst; b) supplying the primary reaction zone with an ethylated benzene feedstock containing a mixture of ethylbenzene and polyethylbenzene; c) recovering the alkylated product from the reaction zone and feeding the product to a benzene separation zone; d) operating the benzene separation zone under temperature and pressure conditions to obtain an alkylated product; operating to obtain a low boiling fraction comprising benzene and a high boiling fraction comprising an ethylbenzene-polyethylbenzene mixture; e) feeding the high boiling fraction from the benzene separation zone to an ethylbenzene separation zone; f) operating the ethylbenzene separation zone to obtain a second low boiling fraction comprising ethylbenzene and a second high boiling fraction comprising a heavy polyethylbenzene fraction; g) the ethylbenzene column; h) feeding benzene to the transalkylation reaction zone; i) connecting the transalkylation reaction zone to the transalkylation reaction zone containing the operating under temperature and pressure conditions that cause the ethylbenzene fraction to be disproportionated to reach a disproportionated product having a reduced content of polyethylbenzene and an increased content of ethylbenzene; (j) reducing the amount of the disproportionated product; k) the polyethylbenzene zone is divided into a third low-boiling fraction comprising a mixture of benzene and ethylbenzene and a third high-boiling fraction of C_3+ hydrogen; and l) recycling said third low-boiling fraction of benzene and ethylbenzene to said first detailed benzene separation zone. 6. a) feeding a benzene feedstock and an ethylating agent into a primary reaction zone containing an aromatic alkylation catalyst selected from the group consisting of zeolite beta and zeolite omega; operating at a temperature and pressure to effect the ethylation of the benzene feedstock while maintaining it in the liquid phase to obtain an alkylated product comprising an ethylbenzene polyethylbenzene mixture; c) recovering the product from the reaction zone; and feeding said product to a benzene separation zone; d) operating said benzene separation zone to obtain a low boiling fraction comprising benzene and a high boiling fraction comprising an ethylbenzene-polyethylbenzene mixture; e) feeding the high boiling fraction from the benzene separation zone to an ethylbenzene separation zone; f) supplying the ethylbenzene separation zone to a second low boiling fraction comprising ethylbenzene and at most 5% by weight of ethylbenzene. g) feeding the ethylbenzene fraction from the ethylbenzene column to a transalkylation reaction zone containing a transalkylation catalyst; h) supplying benzene to the transalkylation reaction zone; i) disproportionating the polyethylbenzene fraction to reduce the polyethylbenzene content and increase the ethylbenzene content; operating under temperature and pressure conditions to reach a disproportionated product; j) feeding at least a portion of said disproportionated product to said first-mentioned separation zone; Law.