SU899517A1 - Process for preparing higher alkylaromatic hydrocarbons - Google Patents

Description

(54) METHOD FOR OBTAINING HIGHER ALKYLROMATIC

one

The invention relates to a method for producing alkyl aromatic compounds.

In addition to traditional applications as surfactants, alkyl aromatic compounds with a long substitute length, and a significant molecular weight of 300 for use as additives to oils, components of synthetic silk, are of increasing interest.

Despite the importance of these products, their production is hindered by the lack of high molecular weight olefinic feedstock (other alkylating agents such as higher alcohols, halide alkyls are even more scarce).

Various methods have been developed to produce higher olefins: thermal and thermal catalytic cracking of petroleum hydrocarbons, catalytic dehydrogenation of paraffinic hydrocarbons, controlled polymerization of low molecular weight olefins.

Despite the simplicity and accessibility of methods for the synthesis of olefins by thermal and catalytic cracking of paraffins, the resulting mixtures of oC-olefins have OPERATED HYDROCARBONS

limited use due to difficulties associated with the release of pure components 1.

A much more selective method for the formation of linear olefins 1c is the method of shallow dehydrogenation of paraffins. The olefins obtained by this method are the most suitable (by

10 quality and cost) raw material for the synthesis of alkylaromatic ss cineg

SRI.

Synthesis of C-olefins by controlled polymerization of ethylene, propylene, butene, and isobutylene in the presence of a sour Lew15 isa, followed by alkylation of aromatic compounds, is much more expensive, but the products are of better quality.

20

As for the aromatic feedstock, benzene is commonly used, however, due to the deficiency, toluene and xylene are used.

25 The closest to the invention according to the technical essence and the achieved result is the method of obtaining higher alkyl aromatic hydrocarbons by catalysis; 30 tic interaction of aromatic hydrocarbon with olefin-containing raw materials.

According to a known method, benzoalkirovanie polybutene with a molecular weight of 300-600 at a molar ratio of 1: 1-5: 1 in mild temperature conditions (T 10s) in the presence of 0.511 weight,% AlClj to the polybutene, when it is formed exclusively heavy alkylate with conversion up to 99.5%.

The polybutene used is obtained by catalytic polymerization of C hydrocarbons containing up to 20% isobutylene and more than 20% butenes, in the presence of AlClj 3.

The disadvantage of this method for the synthesis of alkyl aromatic hydrocarbons is the use of specially prepared high molecular weight olefinic feedstock (polybutene), the production of which is self-contained production. It includes, in addition to the polyolefin synthesis itself, the steps of product introduction (washing of the catalyst, distillation), removal of unreacted raw materials, and decontamination of wastewater. Particularly important is the complete removal of unbroken butenes and isobutylene, since they lead to the formation of an undesirable light alkylate at the alkylation stage.

All of these operations are repeated in the synthesis of alkyl benzenes.

The second significant disadvantage of this method for the preparation of alkyl aromatic compounds is the strict requirements on the content of isobutylene in the raw material for the synthesis of polybutene (20%). In most industrial fractions of Sc, the content of isobutylene is 20-50%.

The polymers obtained from such fractions, in the process of alkylation, tend to decompose with the formation of significant amounts of light alkylate (36% or more).

Conversion to alkylate is also reduced to 59.9%. The use of pure isobutylene under these conditions is excluded altogether. Thus, the provision of raw materials for the synthesis of polyolefins and further alkylaromatic compounds is not completely satisfactory.

This method is also characterized by the use of an extremely hygroscopic catalyst (AlClj) in an inconvenient form (solid powder) in the synthesis process of alkylaromatic compounds. This circumstance complicates the work with it and leads to a high consumption of the catalyst both at the stage of production of higher olefins and at the stage of alkylation.

The purpose of the invention is to control the process technology, which consists in combining the synthesis of isobutylene oligomers and alkylation of toluene.

The goal is achieved by the described method of obtaining higher alkyl aromatic hydrocarbons by reacting toluene at a temperature of (-30) - (-78) ° C with a mixture of olefins C (or with isobutylene in the presence of catalysts of the general formula

.x "-"

:

AS.-nsg-kae

fvi

with.

where r

hydrogen, methyl,, 6

"G methyl, butyl, And tolyl,

C1, ethyl, taken in the amount of (2.1-6.3) 10 mol / l. The distinctive features are the use of toluene as a lower alkylaromatic hydrocarbon, a mixture of olefins Sc or isobutylene is used as an olefin-containing raw material and the process is carried out at a temperature ( -30) - (- 78) C in the presence of a catalyst as indicated above.

The technology of this method is as follows.

The isobutylene or hydrocarbon fraction Cx is oligomerized during bubbling in a flow reactor through a catalyst bed and an aromatic solvent or in a reactor with simultaneous loading of isobutylene to toluene at temperatures of (-30) - (- 76) C. If isobutylene in a non-aromatic solvent in the presence of AlClj is smoothly converted to higher olefin, then in aromatic solvent at T oc occurs, with complete inhibition of oligomerization of olefin, alkylation of aromatic hydrocarbon with isobutylene with the formation of a light alkylate (Scheme).

(C4Hi) ir-nonu yMeti

McCan

(dymaH)

ьао-с and, tert С, Н,

It has been established that at T (-30) C the aromatic solvent can simultaneously act in the environment of oligomerization of isobutylene and the object of alkylation by growing higher olefins.

 catalyst X (SHO t OJ arenTb (-eooGS

-

Thus, the use of an aromatic solvent under conditions of low-temperature oligomerization 65 of erbutylene in the presence of soluble

complexes of aluminum chlorides allowed to obtain higher alkylaromatics directly in one stage on iobutylene.

In spite of the combination of two operations of different nature in one synthesis, quite high yields of final products (90-96%) with a molecular weight of 300-9000 are obtained, characterized by a low pour point, high gas absorption capacity and low unsaturation. ;

The catalysts used are liquid complexes based on industrial aluminum chlorides (AlClj, alkyl aluminum chlorides), toluene, and -hydrogen chloride. It should be particularly emphasized that the catalyst solvent — an aromatic hydrocarbon — is an alkylation object, i.e. he does not make any complications in the process. The complexes are mobile, easily dispensed. In comparison with powdered 1 AlCl, liquid complexes are more active. It follows from the calculation that the total consumption of AlClj for the formation of an alklaromatic product is 7.5–19% and includes the consumption of the catalyst at the stage of producing polybutene and the alkylation of benzene with polybutene (0.5–11%, according to the known). The use of liquid complex catalysts reduces the overall consumption of AlClj, which is 5-8%. The advantages and distinctive features of this method are illustrated by the examples below.

Example. 40 ml of toluene, 0.5 ml of the liquid AlCly complex (2.540 mol / l) of the composition: SC HjCHj НЯС-2-2А1С1з, where К 2; are loaded into the bubbling type reactor equipped with a thermostatic jacket, a thermometer and a reflux condenser. (obtained by reacting dry HC1 with a suspension of A1Cl in toluene, mol. weight. 579, l5 kg / cmM and at (-45) C, dried isobutylene is passed through for 10 min at a molar ratio of toluene: isobutylene 6: 1. As the reaction proceeds (rare bubbling; the temperature inside the reaction increases by. Alkylate is neutralized by washing with water for three times, followed by drying with CaCl. After distilling off the toluene, 3.2 g of product is obtained. The catalyst consumption is 8.1% per product. Light alkylate with Bp-S 250C / 7bO a torus is not formed.

According to the physicochemical analysis data, the product has the following characteristics: mol. Weight. 750. Exit, 0.55J-C 85.97; H 14.04. The presence of aromatic fragments in oligomeric products characterized by a low content of double bonds is confirmed by the data of the PMR spectra (signals with chemical shifts at 6.90 ppm, 4H; 2.15 ppm GH), IR spectra (bands at 1900, 820, 725) and UV spectra. (poles at 257, 265, 272 nm, 420 l / mol, cm). - The yield of alkyl aromatic compound of general formula CHjC (, H ,, () is 82.8%.

Example 2. The experiment was carried out in a bubble mode under the same conditions.

..and in the same sequence as

  and in example 1. The difference is that the temperature in the reactor is equal to (-30) C and the concentration of catalyst is 510 mol / l. 6 g of light alkylate and 8.1 g of product were obtained. Eakhod

5 AlClj to the product of 6.6% mol. Weight.380. Yield,%: 0.8; C 85.3; H 13.9. Exit of the aromatic compound of the general formula CHJC, H, (C H H) 5: equal to 87%.

0 Example. The experiment was carried out in a bubbling mode, as in Example 2. The difference is that the initial temperature in the reactor is (-20) ° C. Received 9.6 g

5 light alkylate and 6.9 g of product. Consumption A1S1z to the product of 7.7%. Mol. Weight .370, yield,%: 0.63) C 86.0; H 13.4. The output of alkylaromatic compounds of General formula

- СНзСбНц (Cv, Hg) 5- equal to 90%.

Example4. The experiment was carried out in a bubbling mode as in Example 2. The difference is that a complex is used as a catalyst, consisting of 3 C HjCHj-HCx

CjHfAlCli, where, R - ethyl,

It was obtained by mixing 0.004 mol of C HfAlClj with a solution of HC1 (0.004 mol) in toluene (40 ml). The temperature in the reactor is (-30) ° C. 0.5 g of light alkylate and 10.5 g of product were obtained at a CjHfAlClj consumption of 5.1%. The yield of the alkylaromatic compound of the general formula CHj Cj is Hz (Cr Hj) |, mol. weight. 300 is equal to 90%.

Example 5. In a reactor equipped with a stirrer, a thermometer, a dropping funnel and a thermostatically controlled jacket, at (-30) C with simultaneous loading, 150 ml of liquid isobutylene are introduced

 and 800 ml of toluene (molar ratio 1: 5). Catalyst (15 ml) of composition 3 CHjCtHf. HC1 2 AlClj, where, (3.2-10) mol / l) is added dropwise at a rate at which the rise

5 the temperature in the reactor does not exceed. Received. 106 g of the product at the consumption of AlClj - 7.6%, mol. Weight 500. is 0.3%. Easy alcclate is not formed. The yield of alkyl aromatic compound of the general formula

CH C (, N c (CrN3)), spectrally identical to the product of example 1, is equal to 94%. EXAMPLE 6 The experiment was carried out as in example 5, i.e. with a single monomer loading and

Claims (1)

Claim A method for producing higher alkyl aromatic hydrocarbons by catalytic interaction of an aromatic hydrocarbon with an olefin-containing feed, characterized in that, in order to simplify the process technology, toluene is used as an aromatic hydrocarbon, and a mixture of C <, or olefin-containing raw materials, or isobutylene and the process is carried out at a temperature of (-30) - (-78) ^with C in the presence of a catalyst of the general formula: o ft P ^h s _and where. And ,, - hydrogen, methyl, w = 3_; 5 | R _a - methyl, butyl, K = 1; 2 50 A - tolyl, R ₃ is Cl, ethyl taken in an amount of (.2.1 - 6.3) -10 - ² mol / L.