Applicants' invention is an improvement in a process wherein a feed o benzene is alkylated with an olefin in an alkylation reactor in the presence of a alkylation catalyst. The alkylation reactor, or alkylator, has at least one stage In accordance with the present invention, a portion of the catalyst bed is replace on a continuous or periodic basis. In accordance with an aspect of the present invention, alkylation of benzene with olefin is effected in the presence of a moving bed of alkylation catalyst, i.e., a portion of the catalyst is continuously replaced. In a preferred embodiment, the alkylation catalyst bed is caused to move countercurrently with respect to the olefin and benzene feed. The alkylation catalyst may be a zeolite catalyst. The olefin is preferably selected from the class consisting of ethylene and propylene, which, when used to alkylate benzene, produce ethylbenzene or cumene product, respectively.

If there is more than one catalyst bed (two or more stages) the catalyst is preferably replaced in each stage or bed separately.

In accordance with another aspect of the present invention, a portion of th catalyst in the bed is periodically replaced by removing a layer of catalyst fro the bed and adding a layer of catalyst to the bed. The catalyst layer which i removed is preferably comprised of deactivated catalyst and the added layer i active catalyst. In accordance with a preferred embodiment, catalyst is remove from the bottom of the bed, and catalyst is added to the top of the bed. As a alternative process, removal of a portion of the catalyst on the top of the be may take place and new, regenerated or fresh catalyst may be added to th bottom of the bed.

In the al ylator, olefin and benzene are introduced into the bottom of th bed and it is preferred to remove a portion of the catalyst from the bottom of th stage or bed and replace it with new catalyst at the top of the stage or be because during alkylation, the catalyst becomes inactivated in layers from th bottom up to the top, thus forming strata of inactive catalyst.

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The effluent from the alkylator may be flashed and/or distilled to recov products such as paraffins, benzene, polyalkylbenzene, and diphenylalkanes, well as the desired alkylbenzenes. Benzene and distilled polyalkylbenzenes ma be sent to a transalkylator in order to be reacted in the presence of an alkylatio catalyst to form alkylbenzenes. The alkylation catalyst in the transalkylator ma be a moving bed of catalyst as described above. Diphenylalkanes can be sent to diphenylalkane converter where they are converted to alkylbenzenes in th presence of an alkylation catalyst, which may be a moving bed of alkylatio catalyst as described above. In both the transalkylator and the diphenylalkan converter, the bed of catalyst need not move in a direction countercurrent to th direction of the feed to the transalkylator or diphenylalkane converter becaus there are no strata of inactivation of the alkylation catalyst in the transalkylat or diphenylalkane converter. In addition, in both the transalkylator a diphenylalkane converter, a portion of the catalyst bed may be periodical replaced by removing a layer of catalyst from the bed and adding a layer catalyst to the bed as described above.

When a portion of inactivated catalyst is removed from a bed or stage of th alkylator, it is then passed to a catalyst regeneration zone. The catalys regeneration zone may be "off site", i.e., separate from the alkylation apparatus or it may be part of a closed loop system with an alkylator, a transalkylator, or diphenylalkane converter. In the catalyst regeneration zone, carbonanceou materials such as tar, coke, and other hydrocarbons are burned off in a controlle O2 atmosphere. This process preferably results in a slow combustion of th materials in the regeneration zone without the creation of "hot spots". Preferre temperatures for the catalyst regeneration zone are from about 400 ^β C to abou 500 ^β C. In the catalyst regeneration zone, the O content may initially be at about 0.5%, followed by an increase in the O2 content to about 2%. The inactivate catalyst is preferably heated for a period from about 8 hours to about 24 hours.

The regeneration of the catalyst can be a batch regeneration wherei inactivated catalyst is removed from the alkylator, passed to a first holding tank and held until the holding tank is filled with catalyst. The catalyst is then passed to the regeneration zone, regenerated, and then passed to a second holding tank. When new, regenerated, catalyst is needed, the regenerated catalyst can be passed from the second holding tank to the alkylator, where the regenerated catalyst again becomes part of the catalyst bed.

In an embodiment where a catalyst portion is periodically replaced, the amount of inactivated catalyst which is periodically removed preferably may be from about 1/4 to about 1/3 of the total amount of catalyst in the bed. There is usually from about 6 feet to about 10 feet of catalyst in the bed. Thus, the period of time between replacements of portions of catalyst is determined by how long it takes to inactivate the portion of catalyst.

The temperature of the catalyst bed may be monitored in order to determine where temperature increases occur in the catalyst bed. In a portion of the catalyst bed that is deactivated, no sharp increases in temperature of this portion of the catalyst bed will be detected during alkylation.

The use of a moving catalyst bed, or a bed where a layer of catalyst is periodically replaced, decreases the amount of coking in the alkylation reactor, which helps to prevent catalyst deactivation. A replacement of catalyst (periodically or continuously) allows for a decrease in the volume of catalyst necessary for the alkylation of benzene and, therefore, a smaller alkylation reactor may be used. In addition, replacement of catalyst (periodically or continuously) permits the use of a ratio of benzene to olefin lower than that used that used in prior art, fixed bed alkylators. The use of a catalyst regeneration zone enables one to regenerate deactivated catalyst and recycle the catalyst to the alkylation reactor, which lessens the need for replacement of spent catalyst.

The invention will be described with reference to the accompanying drawings, wherein:

The drawing is a simplified schematic representation of an embodiment of the alkylation process of the present invention.

Referring now to the drawing, benzene is introduced into alkylator 10 through line 11 and is passed to stage 14 of alkylator 10. In the embodiment shown, alkylator 10 contains two reaction stages 14 and 16. In accordance with the invention, however, any number of reaction stages may be contained within alkylator 10. Although the embodiment shown depicts benzene as being introduced into only one stage of alkylator 10, benene may be introduced directly into each stage of alkylator 10 as well.

Olefin may be passed through lines 12 and 11 for introduction into stage 14 of alkylator 10, as well as being passed through lines 13 and 15 for introduction into stage 16 of alkylator 10. Any olefin may be used in accordance with this invention, although ethylene and propylene are preferred. Overall benzene to olefin mole ratios may be from about 2:1 to about 10:1, preferably at about 3:1.

Contained within each of stages 14 and 16 of alkylator 10 is a bed o alkylation catalyst. The bed may be a continuously moving bed of catalys

wherein a portion of catalyst is continuously replaced, or a layer of catalyst be periodically replaced by removing a layer of catalyst from the bed and addin layer of catalyst to the bed. In a preferred embodiment, the alkylation catalys a zeolite catalyst. Preferred zeolite catalysts are zeolite X, zeolite Y, zeolite zeolite Beta, ZSM-5, Omega crystal zeolites, mordenite, and chabazite. benzene and olefin introduced into stage 14 of alkylator 10 is then converted alkylbenzene under the following catalytic conversion conditions:

Broad range Preferred range outlet temp (°F) 150-900 200-500

Pressure (psig) 150-2,000 250-1,000 Space Velocity

(LHSV) 2-1,000 4-100

The feed from stage 14 of alkylator 10 is then passed to stage 16 of alkyla 10, into which olefin from line 15 is also introduced. Unreacted benzene and ole from stage 14 and olefin from line 15 are then reacted in stage 16.

Preferably, each reaction stage is adiabatic and the outlet temperature stage 16 does not exceed the outlet temperature of stage 14. In reactors hav more than two stages, the outlet temperature of each reactor stage prefera does not exceed the outlet temperature of the preceding stage. In anot embodiment, the increase in temperature in each stage of the alkylator 10 d not exceed 100 ^® F, preferably not exceeding 75"]?. In addition, cooling of t effluent may occur between the stages of alkylator 10.

In a preferred embodiment the beds contained within stages 14 and 16 alkylator 10 are continuously moving beds which are caused to move in a directi countercurrent to the movement or flow of benzene and olefin in stages 14 and This countercurrent movement is an aid in the prevention of early deactivation the catalyst by preventing undesired coking in the alkylator reaction stages.

The temperature of each bed or stage of catalyst is monitored in order determine where temperature increases occur in order to determine catal activity. If a portion of the catalyst has become deactivated, no sh temperature increases will occur in that portion. A deactivated portion

catalyst can then be removed from stage 14 through line 21 and/or from stage 1 through line 22, and passed to holding tank 24. Catalyst can be removed fro stages 14 and/or 16 continuously. Preferably, it is a bottom portion of th catalyst that is continuously removed. Periodically, inactivated catalyst is passe from holding tank 24 through line 23 to kiln 20. In another embodiment, a layer o catalyst, e.g., a bottom layer of the catalyst bed, in stages 14 and/or 16 i periodically withdrawn and passed to the holding tank 24, and subsequently passe to the kiln 20. The period of time between withdrawals of a layer of catalys from stages 14 and/or 16 is determined by how long it takes for the layer t become deactivated.

During regeneration of the catalyst in kiln 20, carbonaceous materials suc as tar, coke, and other hydrocarbons are burned off in a controlled oxyge atmosphere. The catalyst is oxidized with molecular oxygen generally provided i admixture with an inert gas introduced through line 19 into kiln 20. The inert ga has a low concetration of O2, e.g., about 0.5% O2, which can be increased t about 2%. The catalyst is heated in the kiln 20 at a temperature of preferabl from about 400 ^β C to about 500°C and for a period of from about 8 hours to abo

24 hours.

After the catalyst has been regenerated in kiln 20, it is passed through lin

25 to holding tank 26. The regenerated catalyst remains in holding tank 26 unt new, regenerated catalyst is needed in stage 14 or stage 16 of alkylator 10. Whe regenerated catalyst is needed in alkylator 10, it can be passed from holding tan

26 through line 27 to stage 14, and/or from holding tank 26 through line 28 t stage 16. Preferably, the catalyst is passed from holding tank 26 through line 2 to stage 14, and/or from holding tank 26 through line 28 to stage 16 continousl Alternatively, the regenerated catalyst is passed to stages 14 and/or 1 periodically. As shown, it is seen that the regenerated catalyst, in a preferr embodiment, is added to the top of stages 14 and/or 16. The catalyst, in t preferred embodiment, is withdrawn from the bottom of the stages 14 and 16

alkylator 10 because the catalyst, in the embodiment shown, becomes inactivate in strata from the bottom to the top of each stage. In alternative embodiments the catalyst may be withdrawn from the top of stages 14 and/or 16 of alkylato 10, and new, regenerated catalyst may be added to the bottom of stages 14 and/o 16 of alkylator 10.

The regeneration zone comprising holding tank 24, line 23, kiln 20, line 25 and holding tank 26, may be part of a closed loop system which includes alkylato 10, or the regeneration of the catalyst may be done off-site, wherein th regeneration zone is not part of a closed loop system. When a continously movin bed is used, holding tank 24, line 23, kiln 20, line 25, and holding tank 26 must b part of a closed loop system. When the regeneration zone is not part of a close loop system, holding tank 24 is taken off-site upon being filled with inactivate catalyst. This inactivated catalyst is then passed to an off-site kiln wher regeneration of the catalyst takes place as described above. The regenerate catalyst is then passed from the kiln to another holding tank, which may b connected with line 27 to stage 14 and with line 28 to stage 16 when new regenerated catalyst is needed in stages 14 and/or 16 of alkylator 10.

Effluent from stage 16 of alkylator 10 is passed through lines 17 and 18 fo further processing. The effluent may be flashed and/or distilled to recove products such as paraffins, benzene, alkylbenzene, polyalkylbenzene, an diphenylalkanes. Benzene may be recycled to alkylator 10, or may be passed to transalkylator (not shown), whereby benzene and distilled polyalkylbenzenes ar reacted under catalytic conversion conditions to form alkylbenzenes Polyalkylbenzenes may also be recycled to alkylator 10 in some instances Transalkylation may take place in the presence of at least one continuousl moving bed of transalkylation catalyst, or in the presence of at least one catalys bed wherein a layer of catalyst is periodically removed and a replacement layer i added. Transalkylation may take place at a temperature from about 150°F t about 900°F, at a pressure from about 150 psig to about 2,000 psig, at a tota

LHSV from about 1 to about 1,000, and wherein the feed to the transalkylator has a phenyl to alkyl group ratio from about 2 to about 50. Diphenylalkanes may be passed to a diphenylalkane converter (not shown). Diphenylalkane conversion may take place at a temperature from about 350°F to about 800°F, and the residence time may be from about 5 minutes to about 80 minutes. This converter may contain one or more moving catalyst beds as well, or one or more catalyst beds wherein a layer of catalyst is periodically removed and a replacement layer is added. Preferred alkylbenzenes formed in alkylator 10 and in the transalkylator are ethylbenzene and cumene.

When a moving bed is used in a transalkylator or in a diphenylalkane converter, the moving bed need not move in a direction countercurrent to the direction of movement of the feed to the transalkylator or diphenylalkan converter. This is because there are no strata of deactivation of the catalyst i the transalkylator or in the diphenylalkane converter. In other respects, however portions of catalyst may be withdrawn from and replaced in the transalkylator o in the diphenylalkane converter as described above for the continuous withdrawa from stages 14 and/or 16, regeneration in kiln 20, and continuous replacement o catalyst in stages 14 and/or 16 of alkylator 10.

As an alternative to a moving bed wherein a portion of catalyst is remove continuously, a bed of catalyst may be used wherein periodically a layer o deactivated catalyst is being removed from a stage of alkylator 10, or transalkylator or diphenylalkane converter, and a new layer of regenerate catalyst is added to the stage or bed. Preferably, the deactivated catalyst laye is withdrawn from the bottom of each stage, and the new regenerated layer o catalyst is added to the top of each stage, although a layer of catalyst can b withdrawn from the top of each stage and a new, regenerated catalyst layer ca be added at the bottom of each stage or bed.

Advantages of the present invention include the reduction of coking in th reactor and the prevention of catalyst deactivation. When the catalyst eventuall

does become deactivated, it may be passed to the kiln wherein the catalyst regenerated by passing a heated mixture of inert gas and molecular oxygen ov the catalyst, and then the catalyst may be recycled to the alkylator. The movi catalyst bed also enables one to use a feed to the alkylator having a low benzene to olefin ratio and also decreases the volume and amount of cataly necessary for the alkylation reactions. This, in turn, enables one to use a small reactor for carrying out the alkylation reactions.

It is to be understood, however, that the scope of the invention is not to b limited to the specific embodiments described above. For example, alkylatio catalysts other than zeolites may be employed, and the reactor may contain an number of stages. A regeneration apparatus other than a kiln may also be use The invention may be practiced other than as particularly described and still b within the scope of the accompanying claims.