DE2259500A1 - Continuous alkylation of benzene with olefins - using aluminium chloride catalyst activated by treatment with benzene - Google Patents

Abstract

In prepn. of alkyl benzenes by AlCl3 catalysed alkylation of benzene with olefins, alkylated catalyst complexes are continuously treated with benzene outside the alkylation vessel, in alkyl:phenyl ratio 0.2-0.6 at 60-100 degrees 1-3 atmos. for 15-60 mins. The catalyst, which becomes deactivated by contamination with polyalkylates and resins, may be continuously reactivated without increasing temp. and press. Treatment can be effected in a normal liq-liq. continuous transalkylation unit, and does not decrease productivity.

Description

Process and apparatus for the production of alkylbenzenes The invention relates to a process for the preparation of alkylbenzenes from benzene and concentrated lower olefins in the presence of aluminum chloride as a catalyst and a device for performing this method.

The economics of the alkylation process of benzene with lower Olefins (ethylene, propylene) depends on the formation of monoalkylbenzene with maximum Yield off.

From "Publications of the Institute for Chemistry and Technology" Mendeleew ", Volume XXIII, 1956, Lebendeew N., Koltschin I. and Markovitsch ", as well as" Nefthimia ", Volume X, No. 2, 1970, pages 189-194 "is known to achieve high yields of nonoalkylbenzene for one predetermined ratio olefin / benzene on maintaining an optimal ratio between the reaction rates the alkylation and the transalkylation is dependent.

Alkylation is a much faster reaction than transalkylation. This causes an increase in the content of heavy alkylates, those with aluminum chloride Form stable complexes and thus deactivate the catalytic complex to lead. It is therefore used in the ratio between alkyl and phenyl groups in the reaction mass If the value 2 is exceeded, the complex loses the capacity to produce further lower olefins to absorb.

From "Inst. Petrochim, 1967, benzene alkylation with dilute ethylene" and "Nefthimia, No. 1, 1967, p. 26, Lebedeew N.N., Oreschin M.M." is furthermore known that at. the distribution of the alkyl aromatic hydrocarbons between the catalytic complex and the hydrocarbon layer are the mono- and dialkylbenzenes predominantly pass into the hydrocarbon layer, while the trialkylbenzene remains practically completely in the complex where it accumulates.

The relatively low transalkylation rate of trialkylbenzene, as well as the high value of the distribution ratio of this hydrocarbon point out that in the alkylation process a slow steady enrichment takes place on trialkylbenzenes in the catalytic complex.

This build-up is the main cause of the reaction to proceed in the direction of polyalkylate and resin formation, the rate of formation of which is that of the Trialkylbenzenes in the complex is proportional. The formation of these polyalkylates and the side reactions taking place among them are the main cause of the Deactivation of the complex and the additional consumption of aluminum chloride, Benzene and olefin.

After it is deactivated by enrichment in polyalkylates of the catalyst comes through the formation of stable complexes, deactivation occurs the alkylation process by blocking hydrochloric acid and aluminum chloride.

It has already been suggested the rate of reaction of the transalkylation due to higher reaction temperature or

increase higher reaction pressure. However, these methods have the The disadvantage that a temperature increase of over 80-90 ° C for rapid deactivation of the aluminum chloride complex leads, with temperatures of over 130 ° C anyway are not possible and that, to the temperature of the reaction mixture, which is at normal pressure boiling between 80 and qOOC, to be able to increase an increase in the operating pressure necessary which is, in turn, a more complicated and costly one requires more equipment. Furthermore, the transalkylation reactions also have a relatively lower thermal coefficient of about 1.6 for the rate constant, corresponding to an activation energy of 13 kgcal / mol, so that under kinetic How every temperature increase of 10 ° C works, an increase in the reaction rate corresponds to the transalkylation of about 60%.

Another known method is the reaction rate the transalkylation is increased by placing the catalytic complex in an activated one State is maintained.

However, this method using an excess of benzene works no benzene treatment of the complex in terms of its reactivation before.

It is known that the blocking of the catalyst to be stable and inactive complexes is reversible, with the transalkylation reaction of the polyalkylate products and especially the trialkylbenzenes by changing the equilibrium concentration or by changing the ratio of the alkyl and phenyl radicals is possible.

Under the conditions of a large-scale alkylation reactor, in which the ratio of the ethyl groups to the Phenyl groups is about 0.6, however, is the reactivation of the catalytic complex not possible. Therefore, the complex only partially takes part in the transitional reactions part of the alkyl groups, with the other part as a stable complex in the plant is recycled, in which slow irreversible deactivation reactions of the Catalyst take place, which is of significant viscosity increase and deterioration are accompanied in the behavior of the entire complex mass.

In the processes currently in use, the consumed Complex continuously replaced with fresh complex.

This way of working leads to a high consumption of catalyst, Benzene and olefins without optimal activity results being achieved thereby.

As can be seen from "Inst. Petrochim 1967, benzene alkylation with dilute Ethylene11, the addition of fresh complex only partially solves the problem maintaining optimal activity and composition of the returned Complex, since the solubility of the fresh complex in the reaction mass is greater than that of the returned complex.

There is therefore a permanent loss of fresh complex, -which is discharged in dissolved form with the alkylation product or is in the accumulated inactive complex is located.

It is therefore an object of the present invention to overcome these disadvantages to avoid, especially the inactive part of the catalyst without increasing it reactivate by temperature and pressure and thus the productivity of the alkylator to increase.

This object is achieved according to the invention in that the catalytic Complex mass outside the alkylator with an alkyl / phenyl ratio of 0.2 - 0.6, a temperature of 65 - 100 ° C and a pressure of 1 - 3 atmospheres for 15 - 60 min. is treated continuously with benzene for a long time.

The catalytic complex mass can with fresh, circulating or Condensate treated.

The alkyl / phenyl ratio should preferably be 0.2, the temperature 75 ° C, the pressure 1 atm and the treatment time 30 min.

be.

According to the invention, the benzene treatment takes place outside the reactor instead, so as not to affect its productivity and, above all, about suitable operating conditions to be able to maintain. In a special continuous transalkylation plant The benzene treatment to be carried out can be inserted into the normal flow chart, where they are separated with the one in the first and possibly in the second separator complex and with fresh, recycled or condensation recovered benzene is charged.

Further advantages and features of the method according to the invention result from the following exemplary embodiments with reference to the drawing.

In all experiments, the alkylation of benzene was concentrated with Olefins in a corrosion-protected alkylation column (diameter = 25 mm, Height = 2,500 mm). The benzene treatment of the complex was in one metallic, corrosion-protected stirred tank equipped with a stirrer (180 rpm) of 4 1 content or in a contact system for benzene and complex, consisting of Reservoir and circulation pump carried out.

A high-speed centrifugal pump was used as the circulation pump (6), the perfect mixing of the benzene-plex-circulation mixture and a high / speed in the pipelines and tanks as well as a high degree of turbulence. An acid-proof pump was used as there was a risk of the complex Contained hydrochloric acid. Above the suction side of the circulation pump were fresh and reversed Benzene, benzene from the condenser 4, in which escaping benzene vapors from the upper one Part of the alkylation reactor 1 were condensed, and circulation complex from the Separator 2 possibly from the separator 3, which is connected downstream of the alkylator are fed. The benzene complex mixture was via the circulation pump 6 in the Transalkylation tank 7 is pumped.

The container 7 is lined acid-proof and dimensioned so that a Eontaktzeit necessary Eontaktiverung the catalytic complex is guaranteed. During the alkylation of benzene in the alkylation reactor in gas-liquid phase takes place, the benzene treatment of the complex mass in the particular is continuous Trans alkylated plant carried out in liquid liquid phase.

The process was carried out under the following conditions: Process conditions for the alkylation: - pressure 1 atü - temperature 800C - reaction time (absorption of the olefin) 60 min.

- Weight ratio of benzene to complex 3: 1.

Reaction conditions for reactivation of the complex: - temperature 75 ° C - reaction time (contact time of the used complex with benzene) 60 min. or 30 min. (see Examples 3 and 4).

- AlkyS / phenyl group ratio 0.5 or 0.2 (see. Examples 3 and 4).

In all cases the ratio of the alkyl groups to the phenyl groups was in the fresh complex 2 and 3. During the alkylation process this decreases in value Ratio due to the presence of benzene keeps decreasing until it is repeated Use becomes less than 1. Nevertheless, the complex deactivates itself through enrichment on heavy polyalkylates and resins. After treatment with benzene, the value decreases of the ratio further from (up to 0.2), the transalkylation reactions being favored will.

Example 1: A complex was used whose initial ratio Ethyl / phenyl groups was 2. The reaction time was 60 minutes.

Table 1 Time Ethylene absorbed mole Min. Initial complex treated with C6H6 Alkylation alkylation alkylation complex 1 2 3 alkylation alkylation 1 2 5 0.187 0.179 0.135 0.313 0.190 O 0.166 0.140 0.108 0.182 0.176 5 0.143 0.121 0.108 0.162 0.168 0 0.128 0.095 0.108 0.132 0.149 5 0.104 0.095 0.094 0.114 0.131 30 0.104 0.095 0.094 0.102 # 0.131 5 0.093 0.090 0.081 0.085 0.122 0 0.083 0.088 0.081 0.090 0.108 5 0.073 0.078 0.081 0.090 0.095 0 0.065 0.068 0.067 0.077 0.084 55 0.065 0.068 o, c67 0.075 0.054 o 0.065 0.060 0.054 0.075 0.054 Total- value 1.276 1.177 1.078 1.497 1.462 Example 2: A complex was used whose initial ethyl / phenyl group ratio was 3. The reaction time was 60 minutes. In the first two examples, the benzene treatment was carried out with an ethyl / phenyl group ratio equal to 0.5 and with a reaction time of 60 minutes, while in Examples 3 and 4 the reaction time was 30 minutes.

fraud.

Table 2 Time Ethylene absorbed mole Min. Initial complex treated with C6H6 Alkylation alkylation alkylation complex 1 2 3 alkylation alkylation 1 2 5 0.174 0.135 0.097 0.24 0.27 10 0.183 0.168 0.077 0.19 0.20 15 0.163 0.135 0.058 0.17 0.20 20 0.102 0.101 0.058 0.14 0.134 25 0.081 0.054 0.038 0.14 0.134 30 0.06 0.054 0.058 0.12 0.134 35 0.051 0.034 0.058 0.12 0.068 40 0.051 0.034 0.058 0.095 0.068 45 0.041 0.027 0.038 0.095 0.068 50 0.041 0.013 0.038 0.071 0.068 55 0.041 0.007 0.019 0.047 0.068 60 0.041 0.007 0.019 0.024 0.034 Total- value 1.035 0.769 0.596 1.468 1.446 Example 3: A complex was used whose initial ethyl / phenyl group ratio was 2. The ethyl / phenyl group ratio in the benzene treatment was 0.2. The reaction time was 30 minutes.

Table 3: Time Ethylene absorbed mole Min. Initial complex treated with C6H6 Alkylation alkylation alkylation complex 1 2 3 alkylation alkylation 1 2 5 0.358 0.322 0.240 0.496 0.373 10 0.288 0.218 0.202 0.298 0.296 15 0.213 0.192 0.178 0.217 0.224 20 0.177 0.180 1.166 1.189 0.220 25 0.141 0.146 0.144 0.170 0.167 30 0.132 0.124 0.111 0.148 0.150 Total- value 1.304 1.182 1.045 1.518 1.430 Example 4: Benzene was alkylated with propylene, the initial propyl / phenyl group ratio being 2. The propyl / phenyl group ratio in the benzene treatment was 0.2.

The reaction time was 30 minutes.

Table 4: Eit absorbed ethylene mole in. Initial complex treated with C6H6 Alkylation alkylation alkylation complex 1 2 3 alkylation alkylation 1 2 0.685 0.652 0.552 0.726 0.718 0 0.410 0.405 0.340 0.511 0.507 15 0.392 0.372 0.312 0.423 0.411 20 0.375 0.370 0.265 0.412 0.404 25 0.341 0.315 0.251 0.362 0.352 30 0.282 0.220 0.215 0.315 0.302 Continuation of table 4: Total- value 2.485 2.304 1.933 2.749 2.694 As can also be seen from Tables 1-4, the process according to the invention has the following advantages: 1. Due to the separate benzene treatment of the complex outside the alkylator, the transalkylation process can be carried out under optimal operating conditions, which achieve a maximum rate of transalkylation by reducing the alkyl / phenyl ratio enable without an increase in temperature or pressure is necessary.

2. From the complex become continuous by disproportionation Trialkylbenzenes removed, the presence of which is the main cause of irreversible deactivation of the complex and the deterioration in its flowability.

3. 3. After the benzene treatment, the catalytic complex receives at least the same, but generally a higher activity than the fresh complex, thereby increasing the rate of the alkylation reaction.

4. A substantial saving of the catalytic complex is achieved. The loss of complex is limited on the compensation of mechanical and losses caused by the solubility of the complex.

5. Allow the reactivation of the complex by the benzene treatment the operation of the alkylation reactor at higher alkyl / phenyl group ratios (up to 0.6) with higher yields of alkylbenzene without reducing the selectivity with a simultaneous increase in the production of the alkylator per unit volume.

Literature: 1. Lebedeew N., Koltschin I. and Markovitsch, - publications of the Institute for Chemistry and Eechnology "Mendeleew" Vol XXIII 1956.

2. Mamedow A.A., Pinscher "Nefthimia" vol. X no. 2 1970 pp 189-194.

3. "Benzene alkylation with dilute ethylene" Inst. Petrochim 1967.

4. Lebedeew N.N., Oreschin M.M., "Nefthimia" No. 1 1967 p.26.

5. Braun H., Smoot C.H., JACS Vol 78 May 20 1956 5.2176-2181.

6. Lien A.P. and EcCaulay D.A., JACS, May 20, 1953, pp.2407-2410.

7. Lebedeew N.N. and Oreschin M.M. "Nefthimia" Vol VII, No. 2, 1967 Pp.199-207.

8. Kiperman S.L. "Introduction to the Kinetics of Heterogeneous Catalytic Reactions "Verlag für Wissenschaft Moscow 1964 p. 12 9. B.P. 646.941 / 29.XI.1950.

Claims (8)

Claims 1) Process for the preparation of alkylbenzels from benzene and concentrated low olefins in the presence of aluminum chloride as a catalyst, characterized in that that the catalytic complex mass outside the alkylator at an alkyl / phenyl ratio of 0.2 - 0.6, a temperature of 65 - 100 ° C and a pressure of 1 - 3 atmospheres 15 - Is continuously treated with benzene for 60 minutes. 2) Method according to claim 1, characterized in that the catalytic Complex mass is treated with fresh, circulating or condensed benzene. 3) Method according to claim 1 or 2, characterized in that the Alkyl / phenyl ratio is 0.2. 4) Method according to one of claims 1 - 3, characterized in that that the temperature is 75 ° C. 5) Method according to one of claims 1 - 4, characterized in that that the pressure is 1 atm. 6) Method according to one of claims 1 - 5, characterized in that that the treatment duration is 30 min. amounts to. 7) Method according to one of claims 1 - 6, characterized in that that the alkylation of benzene in an alkylation reactor in gas-liquid phase and the benzene treatment of the complex mass in a special continuous transalkylation plant is carried out in liquid-liquid phase. 8) Device for performing the method according to one of the claims 1 - 7, characterized by an alkylation reactor (1), separator (2), possibly Separator (3) and condenser (5) and a special transalkylation tank (7), condenser (4) and a circulation pump (6).