CS260350B1 - Method of ethylbenzene preparation - Google Patents

Abstract

The solution relates to the preparation of ethylbenzene continuous or discontinuous transalkylation di- and / or polyethylbenzene v liquid phase in the presence of a catalyst. Its essence is that the mixture di- and / or polyethylbenzene and benzene by weight a ratio of 1: 1 to 1: 8 in the presence of 5 to 15 wt. a catalyst-based complex aluminum chloride is added to ethylene, which is continuously fed to the reaction mixture in an amount of 1 to 8 wt. parts on 100 wt. parts of aromatic hydrocarbons at such a rate that the temperature of the reaction mixture was between 90 and 120 ° C.

Description

The present invention provides the preparation of ethylbenzene by liquid phase transalkylation of polyethylene benzenes.

Ethylbenzene is industrially produced by alkylation of benzene with ethylene. The alkylation reaction is catalyzed by a complex catalyst prepared from AlCl ₃ , an aromatic hydrocarbon, or more often a mixture thereof and an activator. The preparation of alkylation catalysts is described in numerous patents and technical publications [German Patent No. 2 325 325; fr. pat.

342 788; US Pat. 3,848,012; US Pat. 3,766,290; jap. pat. 76 16 680; US Pat. 3,448,161; Olah C.A., Friedel Crafts Chemistry, John Wiley, New York 1973; Mc Farlane, A. C., Oil Gas J., 74, 99 (1976); Kudryasheva I.A, Ž. Ex. Chim., 50, 311 (1977); Basov, V. P., Thought 708 (1977)].

The usual process is to add powdered or granular anhydrous aluminum chloride to the aromatic hydrocarbon mixture with stirring and then to add the activator. The hydrocarbon component used in the preparation of the benzene alkylation complex is a mixture comprising benzene, ethylbenzene, diethylbenzenes, and optionally a certain amount of polyethylene benzenes. In special cases, toluene or the xylene fraction may also be used.

Benzene alone does not form a complex with aluminum chloride, but its presence positively affects the activity of the catalyst. The presence of an activator is necessary in order to form an active catalyst complex from a mixture of aluminum chloride and an aromatic hydrocarbon. Ethyl chloride (Japanese Pat. 77 106 392), water, resp. hydrogen chloride [Efendieva L. A., Neftepererabotka i Neftechimija 37 (1976) no. 8], chlorobenzene (US Pat.

123 650), dichloroethane [Binaeva, Bockova. Chim. Thought 1, 20 (1957)] and many other chlorinated, oxygenated or nitro compounds.

The water used in the preparation of the catalyst complex releases hydrogen chloride, which is actually an activator, from the aluminum chloride by hydrolysis. The activity of the catalyst is dependent on the amount of water added. By studying various aluminum chloride complexes for the alkylation of benzene with ethylene prepared at temperatures of 30 to 70 ° C from different aromatic hydrocarbons and using different activators, the analysis of the composition of the active complexes concluded that qualitatively the hydrocarbon portion of the catalytic complexes prepared using the same aromas but different. activators is the same and qualitatively the composition of the hydrocarbon portion of complexes prepared from different aromatic hydrocarbons but the same activators does not depend on the composition of the aromatic hydrocarbons used to prepare the catalyst.

Benzene is alkylated with ethylene in bubbling tower reactors. The liquid reaction mixture drives the reactor to the height of the side overflow. It consists of a catalytic aluminum chloride complex of 20 to 40% vol. and a mixture of aromatic hydrocarbons which do not mix with the liquid catalyst. Dry benzene and ethylene are fed to the bottom of the reactor, which is bubbled through the liquid and thereby vigorously stirring it. The liquid reaction mixture flows through the side overflow into the separator, where the heavier catalyst complex is stripped off, which is returned to the bottom of the alkylation reactor and the alkylate proceeds for further processing. The reaction temperature is maintained in the range of 100-120 ° C, a pressure of 0.01 to 0.04 MPa.

In some newer processes for the alkylation of benzene by liquid-phase ethylene [Mac Farlane AC, Oil Gas J. 74, 99 (1.978) (higher reaction temperatures of 130 to 180 ° C and pressures of 0.5 to 0.8 MPa are used. This reduces the amount of catalyst, thereby also corrosion, while utilizing the heat of reaction.

The hydrocarbon layer leaving the separator contains 35 to 65 wt.% Benzene, 35 to 45 wt. % ethylbenzene, 7 to 15 wt. % diethylbenzenes and up to 3 wt. of higher alkylated aromatic hydrocarbons. This mixture is cooled in a heat exchanger and freed of catalyst and hydrogen chloride residues by washing with water, base and again with water. The neutralized hydrocarbon mixture is finally separated by distillation into the appropriate fractions.

Alkylation of benzene with ethylene does not stop at the ethylbenzene formation stage, but proceeds further. Di-, tri- to hexaethylbenzene is formed, but also various polyalkylbenzenes are formed. To increase the yield of ethylbenzene, these higher alkylated benzenes are transalkylated in the presence of benzene and the catalyst. Usually, the diethylbenzene fraction is partially returned to the alkylator, but is mostly used to prepare the catalyst complex. The higher polyalkylbenzenes are transalkylated separately in a transalkylation reactor. Since the transalkylation of polyalkylbenzenes with berizene is a reaction in which the reaction heat is very low, only about 4 µmol, there are no particular problems of chemical engineering nature.

However, the problem is to ensure a low energy consumption of the transalkylation process, especially when the cold feedstock is transalkylated, which needs to be heated to reaction temperatures that are usually 100 ° C or more.

We have found that the above drawbacks of the transalkylation process can be overcome by the method according to the invention, wherein the transalkylation of di- and / or polybenzenes with benzene catalyzed by aluminum chloride complexes is carried out in the presence of an amount of ethylene which reacts with alkylaromatic hydrocarbons. it produces the heat of reaction required for heating and maintaining the temperature of the reaction mixture at 90 to 120 ° C. Transalkylation is carried out in a con260350 tin or discontinuously operating reactor or multiple reactors. Reactors are typically tower-type, made of acid-resistant material. Benzene together with di- and / or polyethylene benzenes and a liquid catalytic aluminum chloride complex are fed into the reactor from below. The weight ratio of benzene to di- and / or polyethylene benzenes is 1: 1 to 8: 1. The catalyst complex is used in an amount of 5 to 15 washes. % by weight, calculated on the amount of aromatic hydrocarbons. This is prepared from diethylbenzene anhydrous aluminum chloride or a mixture of benzene with diethylbenzene and an activator which is water, aqueous hydrochloric acid or alkyl chloride. In order for the polyethylene benzenes to be transalkylated with benzene to ethyl benzene at a sufficient rate, the reaction must be carried out at an elevated temperature. In practice, temperatures in the range of 90 to 120 ° C, usually 100 to 110 ° C, are suitable. Since the reaction heat of the transalkylation is very low, these temperatures can only be achieved in the reactor by external heat input, but this increases the demands and costs of the reactor design.

However, we have found that the desired heat of transalkylation can be advantageously provided by utilizing an exothermic alkylation reaction of ethylene with benzene and / or alkylbenzenes in the presence of an aluminum chloride complex catalyst. This is accomplished by admitting a certain amount of ethylene to the transalkylation reactor. The amount of ethylene added depends mainly on the temperature of the aromatic hydrocarbons injected into the reactor. In addition, the addition of ethylene helps to better mix the reaction mixture consisting of two non-mixing liquids, a catalyst complex and a mixture of aromatic hydrocarbons. Typically, ethylene is added in an amount of 1 to 8 parts by weight per 100% by weight. parts of the reacting aromatic hydrocarbons. Such amounts of ethylene ensure that the temperature in the transalkylation reactor is maintained at 90 to 120 ° C continuously.

The quality of the ethylbenzene produced by the described process is comparable to the quality of ethylbenzene obtained only by alkylation, both in the content of the desired substance and in the content of undesirable chlorinated compounds.

The advantages of the transalkylation method of the invention can be seen from the following examples.

Example 1

Transalkylation was performed in a 20 m < 3 > reactor ^. into which 3.3 m ³ · h- ^{t of} benzene, 0.7 m ^{3 of} polyethylene benzene was continuously fed. ^h-1 and a liquid catalyst complex of A1C1 ₃ 400 kg. . ^h-1 is used a polyetylbenzény containing 2.8% by weight. diethylbenzenes, 46.8% w / w. the triethylbenzenes and the remainder were various polyalkylbenzenes. The catalyst complex was prepared by dissolving 15.0 parts by weight of anhydrous AlCl ₃ powder in 320 parts by weight of diethylbenzene. Deionized water in an amount of 0.75 wt. parts. By injecting ethylene into the bottom of the reactor at a rate of 100 kg.h ^-1 , the temperature at the bottom of the reactor was maintained at 90-92 ° C and at a head of 93 ^° C. The reactor overpressure was 7 kPa. From the reaction mixture leaving the reactor, a catalyst complex was separated in a separator and recycled back to the reactor. After removal of the catalyst residue by washing with water, alkali and again with water, a reaction mixture was obtained which contained 51.6 wt. % benzene, 0.5 wt. % toluene, 36.1 wt. % ethylbenzene, 0.3 wt. of cumene, 7.6 wt. % diethylbenzene and 2.1 wt. polyetylbenzénov. The rest consisted of other alkylaromatic hydrocarbons.

Example 1 and d 2

Procedure as in Example 1, but 3.3 m ³ were fed into the reactor. h ¹ benzene, 0,7 ju ³ .

. h ^{1 of a} diethylbenzene fraction containing

74.3% wt. diethylbenzenes, 0.7 in ³ . IV ^{1 of} polyethylene benzenes of the same composition as in Example 1, 400 kg.h ^{-1 of the} catalyst complex prepared as in Example 1 and 115 kg. h ^-1 ethylene. The temperature of the lower part of the transcalation reactor was 90 ° C and at the head 93 ° C. The overpressure in the reactor was 7 kPa. Under steady state, the reaction mixture contained

48.4% wt. benzene, 0.6 wt.%, toluene, 30.2 wt. % ethylbenzene, 0.4 wt. of cumene, 13.1 wt. diethylbenzenes and 4.9 pere. wt. polyetylbenzénov. The rest consisted of other hydrocarbons. After distillation of the reaction mixture, ethylbenzene containing 2.9 ppm of chlorinated substances was obtained.

Example 3

Procedure as in Example 1, but 2.0 m ³ were injected into the transalkylation reactor.

. h ^-1 benzene and 1.0 m ³ .h ^{-1 of the} distillation residue after separation of ethylbenzene, which contained 0.1 wt. % toluene, 3.9 wt. % ethylbenzene, 1.3 wt. of cumene, 73.7 wt. % diethylbenzenes, 14.2 wt. polyethylene benzenes and the remainder up to 100% of other aromatic hydrocarbons. To this mixture was added 370 kg.h ^{-1 of the} catalytic complex composition as in Example 1 and 100 kg.h ^{-1 of} ethylene. The temperature at the bottom of the reactor rose to 102 ° C during the reaction and the temperature at the top of the reactor to 106 ° C. The overpressure in the reactor was 6 kPa. At steady state, the reaction mixture contained 37.6 wt. benzene, 0.6 pere. wt. % toluene, 44.4 wt. % ethylbenzene, 0.4 wt. of cumene, 13.1 wt. % diethylbenzenes, 1.9 wt. polyethylene benzenes and the remainder to 100% were other hydrocarbons. After distillation of the reaction mixture, ethylbenzene containing 2.1 ppm of chlorinated compounds was obtained.

Example 4

Procedure as in Example 1, to the reactor were charged 2.5 m ³ h ^-1 of benzene, 0.6 m ^"first . h ^{-1 of the} distillation residue after separation of ethylbenzene of the same composition as in Example 3, 200 kg.h ^{-1 of} ethylene and 200 kg.h ^{-1 of the} catalytic complex composition as in Example 1. The bottom temperature of the reactor was 95 ° C and head 98 ° C, overpressure in a 5 kPa reactor. The reaction mixture contained 38.2 wt. % benzene, 0.7 wt. % toluene, 42.1 wt. % ethylbenzene, 0.4 wt. of cumene, 15.3 wt. % diethylbenzenes and 3.1 wt. polyetylbenzénov. The remainder to 100% was other hydrocarbons.

Example 5

Procedure as in Example 1, but 2.5 m ³ · h ^-1 benzene, 1.0 m ^3, were fed into the reactor. . h ^{-1 of the} distillation residue from the ethylbenzene separation column having the same composition as in Example 3, 150 kg. ^h-1 kg-hr of ethylene and 300 ^-1 complex catalyst composition as in Example 1. In the steady state temperature of the transalkylation reactor bottom was 111 C ^Q and head 116 ° O. The reaction mixture contained 30.7 wt. % benzene, 45.2 wt. % ethylbenzene, 17.1 wt. % diethylbenzenes and 3.8 wt. polyetylbenzénov. The remainder to 100% were other hydrocarbons. After distillation of this reaction mixture, ethylbenzene containing 2.3 ppm of chlorinated compounds was obtained.

Ethylbenzene finds use mainly as a solvent and as a raw material for the production of ethylbenzene hydroperoxide and styrene.

Claims (2)

SUBJECT Process for the preparation of ethylbenzene by continuous or discontinuous liquid-phase transalkylation of di- and / or polyethylbenzene, characterized in that for a mixture of di- and / or polyethylene-benzene and benzene in a ratio of 1: 1 to 1: 8 in the presence of 5 to 15% by weight . The aluminum chloride-based catalyst complex is treated with ethylene, which is continuously fed to the reaction mixture in an amount of 1 to 8 wt. parts per 100 wt. parts of the aromatic hydrocarbons at a rate such that the temperature of the reaction mixture is in the range of 90 to 120 ° C.