CS212929B1 - A method for producing an activated aluminum chloride catalyst complex for catalysis in organic synthesis - Google Patents

Abstract

The invention relates to a method for producing an activated catalytic complex based on aluminium chloride, aromatic hydrocarbons and water as a promoter and its use in the alkylation of benzene with ethylene or propylene in the process of producing ethylbenzene or cumene. The starting materials are, in addition to aluminium chloride and water, benzene or alkylaromatic hydrocarbons or their mixtures in a mass ratio of benzene to alkylaromatic hydrocarbons of 0.5 to 2.0. During the reaction, a cushion of gas, which is inert with respect to the formation of the catalytic complex, is maintained above the level of the suspension of aluminium chloride in aromatic hydrocarbons at a temperature of 10 to 90 °C, and a spring is introduced into it in an amount of not more than 3.5 kg per 100 kg of AlCl-3.

Description

The invention relates to a method for producing an activated catalytic complex based on aluminum chloride, aromatic hydrocarbons and water as a promoter and its use in the alkylation of benzene with ethylene or propylene in the process of producing ethylbenzene or cumene.

Anhydrous aluminum halides, especially aluminum trichloride, are important catalysts for the so-called Friedel-Grafte and analogous reactions, such as alkylation, transalkylation, isometation, acylation, etc.

Aluminum chloride, a strongly acidic catalyst, does not react with benzene or ethylene on its own, but it can form complexes with a number of compounds. In the presence of promoters, aluminum chloride forms active liquid complexes with alkylaromatic hydrocarbons. This ability is used in the preparation of liquid catalytic complexes of aluminum chloride, the use of which has eliminated a number of disadvantages associated with the use of solid aluminum chloride as an alkylation catalyst (difficulties with dosing and handling, different particle sizes, coating of aluminum chloride particles with an inactive coating, long induction times, etc.)

Currently, in industrial alkylation processes, aluminum chloride-based catalysts are almost exclusively used in liquid complexes instead of solid AlCl^.

As aromatic components for the preparation of these complexes, ethylbenzene, alkylbenzenes and polyalkylbenzenes, or mixtures of these hydrocarbons with benzene, are usually used.

Anhydrous hydrogen chloride, chlorinated hydrocarbons and water are most commonly used as promoters for the preparation of the catalytic complex of aluminum chloride with the mentioned aromatic components on an industrial scale.

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When using water as a promoter, when in the usual procedure liquid water is fed into a suspension of aluminum chloride in an aromatic hydrocarbon, it is not possible to ensure its sufficient homogenization even by intensive mixing and therefore hydrolysis of aluminum chloride is strongly applied in this system, as a result of which local overheating of the reaction mixture occurs, leakage of hydrogen chloride and losses of aluminum chloride, which is adversely reflected in increased consumption of AlCl^ in the alkylation process itself. In order to suppress these undesirable phenomena, which adversely affect the activity of the complex being prepared, to a minimum, it is necessary to work with a significant excess of the aromatic component in the aluminum chloride suspension compared to the minimum required amount and therefore it is not possible to prepare a homogeneous catalytic complex by this procedure.

Since the solubility of water in the aromatic input component of the complex is very low, it is not realistic to add the promoter as water dissolved in this component.

Catalytic complexes prepared with water as a promoter, as described by the commonly used procedure, show lower activity compared to, for example, a catalytic complex prepared using ethyl chloride as a promoter.

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One of the other factors adversely affecting the activity of the catalytic complex prepared on the basis of AlCl^ with an alkylaromatic component is the presence of higher alkylated aromatic hydrocarbons, which bind dissolved AlCl^ due to its stronger binding to these higher alkylated compounds into more stable complexes and thus reduce its catalytic efficiency. Removing these undesirable higher alkylated compounds by converting them to lower alkylated compounds activates the catalytic complex.

and

A new method for preparing an activated catalytic complex of aluminum chloride is based on the elimination of adverse effects associated with the dosing of water as a promoter and the simultaneous activation consisting in the disproportionation reaction of higher alkylated compounds with benzene during the actual preparation of the complex.

The method for producing an activated catalytic complex of aluminum chloride for catalysis in organic syntheses, in particular for alkylation of benzene with low molecular weight olefins, from a suspension of aluminum chloride, water and benzene in a mixture with alkylaromatic hydrocarbons, in particular ethylbenzene, alkylbenzene, polyethylbenzenes or a fraction of polyalkylaromatic hydrocarbons remaining in the production of ethylbenzene with a boiling point above 136 °C, consists, according to the invention, in that benzene in a mixture with alkylaromatic hydrocarbons is introduced into the reaction in a mass ratio of benzene 2 alkylaromatic hydrocarbons of 0.5 to 2.0, preferably 1.0 to 1.75, and above the level of the suspension of aluminum chloride in aromatic hydrocarbons, at a suspension temperature of 10 to 90 °C, preferably 20 to 75 °C, a layer of gas inert in terms of the reaction of formation of the catalytic complex, such as air or nitrogen, is maintained and water vapor is introduced into this gas in an amount of not more than 3.5 kg HgO per 100 kg AlCl2. HgO as a promoter is gradually sorbed with constant stirring into a suspension of AlCl2 in a mixed aromatic component formed by benzene and alkylaromatic hydrocarbons or their fractions in a mass ratio of benzene:alkylaromatic hydrocarbons of 0.5 to 2.0, preferably 1.0 to 1.5, by introducing water vapor into a closed space above the suspension with a cushion of gas inert in terms of the formation of the catalytic complex, such as air or nitrogen, in an amount of not more than 3.5 kg HgO per 100 kg AlCl2, while the excess pressure corresponding to the partial pressure of water vapor at the dew point given by the temperature of the system is maintained in the device. As alkylaromatic hydrocarbons for the preparation of the catalytic complex, some of the following hydrocarbons can be used separately in a mixture with benzene or mixtures thereof in combination with benzene:

- ethylbenzene, alkylbenzenes

- polyethylbenzenes

- fraction of polyaromatic hydrocarbons remaining during the production of ethylbenzene and with a boiling point above 136 °C.

The production of the catalytic complex according to the invention can be carried out as follows: benzene is introduced into the vessel ae in a mixture with an alkylaromatic hydrocarbon, the stirrer is started and, with constant stirring, the required amount of aluminum chloride is poured into the autoclave, the vessel is hermetically sealed, into the gas space above the level of the aluminum chloride suspension ae

212 929, water vapor is introduced with constant stirring, after the addition of water vapor is completed, the contents of the container are stirred until all the aluminum chloride is converted into a homogeneous liquid complex.

The obtained aluminum chloride complex is a brownish-red clear homogeneous liquid with a lower density and viscosity compared to complexes prepared without a mixed aromatic component, which has a positive effect on the actual technological process of alkylation by its easier and more perfect dispersion in the alkylation reactor.

In the described method of preparing the catalytic complex, water is uniformly transferred from the gas space to the AlCl- suspension across the interphase interface, i.e. without a local increase in water concentration, and the catalytic complex is characterized by high initial catalytic activity due to activation by disproportionation reactions during the preparation itself.

This high initial activity of the complex thus prepared can be effectively used in the technological process of alkylation of benzene with ethylene or propylene. The use consists in the fact that the alkylation is carried out in comparison with less active catalytic complexes with a lower content of 5 - 70% vol., preferably 10 - 50% vol. of the catalytic complex in the alkylator, i.e. with a shorter residence time of the complex in the alkylation reactor, which allows the use of its high initial activity and leads to a significant reduction in the specific consumption of aluminum chloride per 1 t of ethylbenzene or cumene produced by 10 - 50% at the same productivity of the alkylation reactor and to a reduction in the specific consumption of benzene and ethylene by 1 - 2%.

The method of producing the catalytic complex of aluminum chloride and utilizing its high initial activity according to the invention is illustrated by the following examples:

Example 1

A specified amount of diethylbenzene fraction from the production of ethylbenzene or a mixed aromatic component consisting of benzene and diethylbenzene fraction is introduced into a steel enamelled vessel, equipped with a stirrer, temperature measurement and pressure measurement. The stirrer is started and the corresponding amount of aluminium chloride is poured into the vessel. The vessel is hermetically sealed and the required amount of effluent is gradually dosed from the steam generator into the gas space above the surface of the AlCl-j suspension over the course of 1 h with continuous stirring. The temperature in the vessel rises from the original 42 °C to 66 °C, the excess reaction heat of complex formation is transferred to the surroundings in the form of heat losses. The pressure in the vessel increases during the dosing of water to a maximum of 50 torr. After the dosing of water foam is completed, the contents of the vessel are stirred for another 4 h.

The catalytic complex is obtained as a homogeneous clear reddish-brown liquid.

The basic properties of the complex depending on the aromatic input component used are given in Table 1.

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Table 1

All the components of the complex:

A1C1 ₃ (kg) 100 100 100 100 100 delethylbenzene fraction (kg) 136 80 80 80 80 benzene (kg) - 60 80 120 140 water spring (kg) 2.55 2.55 2.55 2.55 2.55 Quantity of complex obtained (kg) 238.55 242.55 268.55 302.55 322.55 Basic features of the complex: obssh Aid-} (mg/g) 420 412 372 330 310 density at 30 °C (g/cm ³ ) 1.12 1.11 1,102 1,080 1,055 viscosity at 30 °G (cst) 12.1 8.2 3.6 2.53 2.3 +/activity (mol 0^/60 min.) 5.36 9.68 11.26 11.29 11.35 .io- ² ,10 ² .10 ² .10" ² .10" ²

+/ Initial activity of the complex expressed in moles of reacted ethylene during alkylation under the catalytic effect of the complex per unit time.

Example 2

The alkylation of benzene with ethylene was carried out on an experimental continuous alkylation unit at a molar ratio of benzene:ethylene of 2.5 and a temperature of 97 °C with continuous dosing of catalyst.

lytic complex prepared according to example 1 with the ratio of input components: mark K - 1 mark K - 2 A1C1 ₃ (kg) 100 100 distilbenzene fraction waste from ethylbenzene production. (kg) 136 80 benzene (kg) - 140 water spring (kg) 2.55 * 2.55

Depending on the content of the catalytic complex in the alkylation reactor, the results shown in Table 2 were achieved with the same alkylator productivity. ^x

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Table 2

Catalytic complex K - 1 K - 2 +/ complex content

in alkylator (% vol.) 10 20 50 70 90 10 20 50 70 90 specific consumption (kg per 1 t of ethylbenzene obtained): benzene - 785 785 786 770.3 770.4 770.4 773 775 ethylene - 277 277 278 271.5 271.5 272.5 247 275 aici ₃ - 11.6/11.6/12.9 +/ Amount of catalytic complex in alkylator in % order on filled volume of alkylation

reactor at operating temperature.

Claims (1)

SUBJECT OF THE INVENTION Process for the production of an activated catalytic aluminum chloride complex for catalysis in organic syntheses, in particular for the alkylation of benzene with low molecular weight olefins, with a suspension of aluminum chloride, water and benzene in admixture with alkylaromatic hydrocarbons, especially ethylbenzene, alkylbenzenes, boiling above 136 ° C, characterized in that the benzene in admixture with the alkylaromatic hydrocarbons is reacted in a weight ratio of benzene: alkylaromatic hydrocarbons of 0.5 to 2.0, preferably 1.0 to 1.75, and above the level of the aluminum chloride slurry in aromatic hydrocarbons at a suspension temperature of from 10 to 90 ° C, preferably from 20 to 75 ° C, maintains a pad of gas inert to the catalytic complex formation reaction such as air or nitrogen and water vapor is introduced into the gas at a rate of not more than 3.5 kg Ή; , Ο per 100 kg AlCl-j.