JPS6354421B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for treating alkylation or transalkylation catalysts. In particular, the present invention relates to a method for treating a catalyst used in an alkylation or transalkylation reaction in order to prevent the catalyst from deteriorating its catalytic activity. The use of aluminum trichloride as a catalyst for alkylation reactions of aromatic hydrocarbons with olefins is well known. At this time, even if aluminum trichloride is charged into the reaction system in a solid state, it forms a complex and exists in a liquid state in the coexistence of hydrogen halide used as a promoter and water. This complex is called red oil, slurry, contact oil, etc., and is thought to be mainly composed of aluminum trichloride, aromatic compounds, hydrogen halides, and the like. The catalyst aluminum chloride complex used in the alkylation reaction not only rapidly decreases its catalytic activity as it is used, but even if it is not used in the reaction, it is left (stored) under very mild conditions at room temperature. ), the drawback is that the catalytic activity decreases. Storage of such catalyst complexes is unavoidable, for example, when producing cumene by the alkylation reaction of benzene with propylene, or during interruptions in operation due to periodic equipment inspections.
If the catalytic ability of the catalyst complex decreases during the period of suspension, it will be necessary to prepare a new catalyst when restarting the operation, resulting in an economic disadvantage. JP-A-49-52195 describes a method of washing an aluminum chloride complex as an alkylation catalyst to be reused with a paraffinic hydrocarbon to remove substances that reduce the catalytic activity contained in the catalyst complex. There is. In this cleaning process, the paraffinic hydrocarbon may contain up to about 20% by weight of aromatic hydrocarbons, and prior to cleaning with the paraffinic hydrocarbon, cleaning with the aromatic hydrocarbon is necessary. However, in either case, cleaning with paraffinic hydrocarbon is a necessary condition. This seems to be related to the fact that, looking at the examples in the same patent publication, the aim is to produce higher alkyl-substituted benzenes using lauryl chloride or dodecene-1 as an alkylating agent. However, in the case of the catalytic aluminum chloride complex used in the alkylation reaction for the production of lower alkyl-substituted benzene with olefin, the treatment can be carried out by contact with benzene that is unsubstituted or substituted with an alkyl group having 1 to 4 carbon atoms. Not only immediately after,
Even if it is left (stored) at room temperature for a relatively long period of time,
The present inventors have found that no decrease in catalytic activity is observed, and the effect of preventing a decrease in catalytic activity due to such catalyst treatment is demonstrated when lower alkyl-substituted benzene is used as one of the reactants. A similar phenomenon is observed in the case of the catalytic aluminum chloride complex used in the transalkylation reaction. Therefore, the present invention relates to a method for treating an alkylation catalyst, and this treatment is carried out by converting the produced aluminum chloride complex used in the alkylation reaction of aromatic hydrocarbons with an olefin having 2 to 4 carbon atoms into unsubstituted or unsubstituted aluminum chloride complexes. This is carried out by contacting with benzene substituted with ~4 alkyl groups. The present invention also relates to a method for treating a transalkylation catalyst, which comprises treating (a) an aromatic hydrocarbon substituted with at least one C2-C4 alkyl group and (b) an unsubstituted or Bringing the catalyst aluminum chloride complex used in the transalkylation reaction with an aromatic hydrocarbon substituted with an alkyl group having 1 to 4 carbon atoms into contact with benzene that is unsubstituted or substituted with an alkyl group having 1 to 4 carbon atoms. This is done by In these processing methods, the alkylation or transalkylation catalyst can be left in contact with the unsubstituted or alkyl-substituted benzene until reuse, or it can be left in contact with the unsubstituted or alkyl-substituted benzene for a short time. After separating it, it can be left until reuse. In the alkylation reaction, olefins having 2 to 4 carbon atoms include ethylene, propylene, 1-butene, 2-butene, and isobutene, and aromatic hydrocarbons alkylated with these include benzene, toluene, and xylene. , cumene, diisopropylbenzene, ethylbenzene, ethyltoluene, etc. are used. For example, the alkylation reaction of benzene with propylene is shown by the following formula. In addition, in the transalkylation reaction that is carried out to convert the polyalkyl-substituted benzene by-produced by such alkylation reaction into the target product such as monoalkyl-substituted benzene, (a) at least 1 Examples of aromatic compounds substituted with alkyl groups having 2 to 4 carbon atoms include ethylbenzene, diethylbenzene, ethyltoluene, cumene, cymene, ethylcumene, diisobutylbenzene, triisopropylbenzene, butylbenzene, butyltoluene, etc. ) In addition to the alkyl-substituted compounds of (a), toluene, xylene, trimethylbenzene, etc. are used as the aromatic compound substituted with an alkyl group having 1 to 4 carbon atoms, which is used in the same way as unsubstituted benzene. The transalkylation reaction between diisopropylbenzene and benzene is shown by the following formula. The catalytic aluminum chloride complex used in such alkylation or transalkylation reactions is unsubstituted benzene or benzene substituted with an alkyl group having 1 to 4 carbon atoms, such as toluene,
Contact with xylene, cumene, cymene, diisopropylbenzene, ethylbenzene, ethyltoluene, butylbenzene, etc., preferably benzene or toluene. These benzenes are generally brought into contact with each part of the catalyst complex at a rate of about 0.1 part by volume or more, preferably about 1 to 10 parts by volume, at a temperature of about 0 to 50°C, generally at room temperature. For the contact method, it is sufficient to simply mix the catalyst complex and benzenes in a container, preferably with stirring, and then the benzenes can be left in contact without being separated until reuse. Alternatively, after separating the benzenes, it can be left as is until reuse. Storing is carried out at about 0 to 50°C, generally at room temperature; if stored at too high a temperature, the catalyst activity will be reduced, and conversely, if stored at too low a temperature, it will solidify and become difficult to handle. For example, even if the catalytic aluminum chloride complex treated with benzenes is stored at room temperature for about 60 days,
No decrease in catalytic activity was observed, and in some cases even an increase in catalytic activity was observed. The present inventors reason that such an effect is brought about as follows. For example, when hydrogen chloride gas is blown into a mixture of cumene and solid aluminum trichloride with stirring, a pale yellow liquid aluminum chloride complex phase with a specific gravity (d ²⁰ ₄ ) of about 1.06 is formed. This aluminum chloride complex has an Al content of approximately 6.4% by weight,
The composition of the oily phase component obtained by decomposing this with ice water is:
As shown in the table below, it has a composition in which approximately 2 moles of aromatic hydrocarbons are bonded to 1 mole of aluminum trichloride. When this newly prepared aluminum chloride complex is left at room temperature, the composition (wt%) of components other than Al changes over time as follows.

[Table] Materials As shown above, a rapid increase in isopropyltrimethylindene and high-boiling materials was observed over time, and the apparent hue of the aluminum chloride complex changed from pale yellow to red, then reddish-black; shows a change corresponding to a decrease in the catalytic activity of this complex. The present inventors discovered that isopropyltrimethylindene and high-boiling substances are catalytic activity inhibitors, and that these catalytic activity inhibitors are very basic, and therefore they bind strongly to aluminum trichloride. Alkylation reactions or trans-alkyl-substituted benzenes, such as cumene, diisopropylbenzene, and triisopropylbenzene, have been found to reduce the catalytic activity of the complex and that these inhibitors are formed from alkyl-substituted benzenes such as cumene, diisopropylbenzene, and triisopropylbenzene forming aluminum chloride complexes. By contacting the catalyst complex used in the reaction with benzenes,
The inhibitory substances are extracted by benzenes to restore the catalytic activity, and a considerable amount of alkyl-substituted benzene is extracted from the complex by the benzenes, so even if left for a long period of time, the amount of inhibitory substances produced will be small. It is estimated that the catalytic activity is reduced and the catalytic activity is maintained. It should be noted that benzene and toluene are preferred as the benzenes used in such treatment, and those treated with benzene and toluene do not reduce their catalytic activity even after long-term storage.
On the other hand, those treated with lower alkyl-substituted benzenes other than toluene retain sufficient catalytic activity immediately after treatment, but the catalytic activity decreases over time. However, as shown in Example 3 below, those treated with cumene and stored in contact with benzene or toluene retain their catalytic activity both immediately after the cumene treatment and after the storage period. Next, the present invention will be explained with reference to examples. Reference Example The alkylation reaction of benzene with propylene and the transalkylation reaction of the reaction product were carried out as shown in the flow sheet of the drawings. 170 parts of fresh benzene from line 6 (wt.
330 parts of benzene distilled and dehydrated in the distillation column 5 and circulated through the line 15,
It is supplied to the alkylation reaction tank 1. To this alkylation reactor 1, 106 parts of propylene containing 6 parts of propane are supplied via line 7, 23 parts of catalytic aluminum chloride complex recycled from the catalyst separator 3 are supplied via lines 10 and 21, and substantially 0.1 part of water-free hydrogen chloride gas is supplied via lines 9 and 28, respectively. The reaction between benzene and propylene in the alkylation reaction tank 1 is carried out at 80° C., and propane not involved in the reaction is discharged from the system through a line 25.
The reaction products are m-diisopropylbenzene, p-diisopropylbenzene, which are fed to the transalkylation reactor 2 via line 26 and recycled from distillation columns 5'' and 5'' via lines 16 and 19, respectively. 175 parts of polyisopropylbenzene, such as triisopropylbenzene, 219 parts of catalytic aluminum chloride complex recycled from catalyst separator 3 via lines 10 and 22, line 9
0.45 parts of hydrogen chloride gas which does not contain substantially water via lines 8 and 24, and 0.6 parts of aluminum trichloride which is intermittently supplied from lines 8 and 23 are respectively supplied to the transalkylation reaction tank 2. In this transalkylation reaction tank 2, a transalkylation reaction between unreacted benzene from the alkylation reaction tank 1 and recycled polyisopropylbenzene is carried out at 74°C, and the reaction product is passed through a line 27 to a catalyst separator 3. the higher specific gravity catalyst phase is circulated as described above by line 10;
A portion (0.3 parts) is discharged from the system through line 11. The oil-liquid phase of the reaction product is sent via line 12 to water washing neutralization tank 4 to completely remove the catalyst component, and then 775 parts is fed to distillation column 5 via line 13. Note that the washing neutralization liquid is extracted from the bottom of the washing neutralization tank 4 through a line 14. Distillation is carried out in distillation columns 5, 5', 5'', 5 and 5
``'''', but without installing a distillation column to remove ethylbenzene.
240 parts of cumene with a purity of 99.9% by weight or more containing 0.06% by weight was also supplied from line 17 of the distillation column 5' and p-
26 parts of diisopropylbenzene were each obtained as a product from line 18 of distillation column 5, while a total of 330 parts of benzene fraction was obtained from distillation column 5 through line 15.
A total of 175 parts of the remaining p-diisopropylbenzene fraction, m-diisopropylbenzene and triisopropylbenzene fractions are circulated to the alkylation reactor 1 via line 16 of distillation column 5'' and distillation column 5'''' is circulated to the transalkylation reaction tank 2 via line 19.
3.2 parts were discharged through line 20. In such a double reaction, the catalyst separator 3
When the catalytic activity coefficient M value of the catalyst complex inside was determined according to the following method, a value of 90×10 ⁻⁴ /min was obtained. Here, the catalytic activity coefficient M value is defined as a value obtained by the following measuring method. First, p-diisopropylbenzene and benzene are mixed so that the molar ratio of isopropyl groups to benzene nuclei is exactly 0.6. This mixture 200
ml into a 500 ml reactor equipped with a stirrer, and while maintaining the temperature at 50°C, dry hydrogen chloride gas was blown in at a rate of about 300 ml/min under normal pressure for 30 minutes with stirring, and the mixture was heated with hydrogen chloride. Bring it to a saturated state.
In this operation, a reflux cooling device is provided in the hydrogen chloride gas outlet line so that benzene and p-diisopropylbenzene are not volatilized outside the system. Then 10ml of the catalyst aluminum chloride complex to be measured
was added dropwise at once, and while maintaining this temperature, hydrogen chloride gas was continued to be blown in at a rate of about 10 ml/min.
After dropping the complex, samples are taken out from the reactor about 5 to 10 times every 1/2 to 1 minute, and each sample is subjected to the following treatment to remove the catalyst. That is, each sample is washed with a 2% aqueous sodium hydroxide solution, then washed with water, and dehydrated with anhydrous sodium sulfate. The above processing is
This is done carefully to prevent volatile components such as benzene from evaporating and scattering. For the sample treated in this manner, cumene is quantified by gas chromatography to determine the cumene concentration [CU]i. here,
The suffix i means the value for the sample at time ti. Next, the value of Yi is measured according to the following formula (). Yi=[CU]e/2[DIPB]o×ln([CU]e/[CU]e
−[CU]i) ...() Here, [CU]e: Equilibrium cumene concentration (mol/) (Note 1) [DIPB]o: Mixture of benzene and p-diisopropylbenzene before dropping the catalyst complex The concentration of the latter (mol/) (Note 2) in Find the M value. Y=Mt+C (constant) ... () The catalyst activity constant M value obtained in this way shows a positive correlation with the reaction rate constant K of the transalkylation reaction shown by the following reaction formula, and the M value is A large value means that the catalytic activity of the catalyst complex is large. (Note 1) In the presence of Friedel-Crafts catalyst,
When benzene, cumene, diisopropylbenzene, etc. are mixed, a transalkylation reaction occurs, and the final composition ratio of each component of benzene, cumene, o-diisopropylbenzene, m-diisopropylbenzene, p-diisopropylbenzene, and triisopropylbenzene changes. A thermodynamic equilibrium is reached, and the cumene concentration at this time is defined as the equilibrium cumene concentration. This equilibrium cumene concentration varies depending on the molar ratio of isopropyl groups to benzene nuclei in the reactants or depending on the temperature, but in the present invention, [CU]e = 3.62 mol/ is the value applied to the above formula (). Applicable. (Note 2) In the present invention, [DIPE] o = 2.5 mol/
The value is . Example 1 30 ml of the catalytic aluminum chloride complex having steady-state activity obtained in Reference Example was placed in a 300 ml flask, 200 ml of benzene was added thereto, and the mixture was stirred at room temperature for 1 hour. Thereafter, the catalyst phase and the oily phase (benzene phase) were separated, and the catalyst phase had a volume of 38 ml. When the catalytic activity coefficient M value of this catalyst was measured, it was 130 immediately after separation from the oily phase.
*10 ^-4 /min, and for those left at room temperature for 40 days after treatment, values of 120x10 ^-4 /min were obtained. Comparative example When the catalyst complex obtained in the reference example is left as it is at room temperature for 40 days, its catalytic activity coefficient M value is
It decreased to 60×10 ^-4 /min. Example 2 In Example 1, after stirring with benzene for 1 hour,
For the catalyst complex that was allowed to stand at room temperature for 50 days without being separated from the oily phase, and then separated from the oily phase, a catalytic activity coefficient M value of 110×10 ⁻⁴ /min was obtained. Example 3 When 30 ml of the catalyst complex obtained in the reference example was treated with 200 ml of cumene in the same manner as in Example 1, the catalyst phase became 28 ml.
It became. When the catalytic activity number M value of this catalyst was measured, it was found that immediately after cumene treatment,
A value of 120×10 ^-4 /min was obtained, and a value of 110×10 ^-4 /min was obtained when 100 ml of benzene was added to this and the oily phase was separated after standing for 40 days. Example 4 When 30 ml of the catalyst complex obtained in the reference example was treated with 200 ml of toluene in the same manner as in Example 1, the catalyst phase was 33
It became ml. When 50 ml of fresh toluene was added to this and left for 40 days, the oily phase was separated and the catalytic activity coefficient M value was measured.
A value of 100×10 ^-4 /min was obtained.

[Brief explanation of the drawing]

The drawing is a flow sheet of the alkylation reaction of benzene with propylene. In this drawing, reference numeral 1 indicates an alkylation reactor, 2 indicates a transalkylation reactor, 3 indicates a catalyst separator, 4 indicates a water washing neutralization tank, and 5 indicates a distillation column.

Claims (1)

[Scope of Claims] 1. Contacting a catalytic aluminum chloride complex used in the alkylation reaction of an aromatic hydrocarbon with an olefin having 2 to 4 carbon atoms with benzene that is unsubstituted or substituted with an alkyl group having 1 to 4 carbon atoms. 1. A method for treating an alkylation catalyst, which is characterized in that the alkylation catalyst is left in a contact state or in a separated state after being in contact for a short time until it is reused. 2 (a) an aromatic hydrocarbon substituted with at least one alkyl group having 2 to 4 carbon atoms; and (b) an aromatic hydrocarbon unsubstituted or substituted with an alkyl group having 1 to 4 carbon atoms. The catalyst aluminum chloride complex used in the transalkylation reaction is unsubstituted or has 1 carbon number.
A method for treating a transalkylation catalyst, which comprises bringing it into contact with benzene substituted with an alkyl group of -4, and leaving it in a contact state or in a separated state after a short contact period until reuse.