RU2734985C1 - Method of preparing catalyst and method of producing isopropylbenzene (versions) - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to methods of alkylating benzene with isopropyl alcohol. Alkylation is carried out in a flow reactor having two reaction zones, in the first of which the catalyst used is γ-Al₂O₃ and maintaining temperature not lower than 450 °C, and in second zone there used is catalyst prepared by method described below, and temperature is maintained at least 200 °C. In another version of alkylation method two series-connected flow reactors are used, in the first of which catalyst is used γ-Al₂O₃ and maintaining temperature not lower than 450 °C, and in second reactor there used is catalyst prepared by described method, and maintaining temperature not lower than 200 °C. Manual preparation of the catalyst based on ZSM-12 decationized zeolite comprises granulating with a binder, drying and calcining the pellets. Decationized zeolite ZSM-12 for imparting hydrophobic properties before granulation with binder is first treated with a solution of a chelating agent, and then treated with superheated steam at temperature not higher than 550 °C for at least 2 hours. Chelating agent used is sulphosalicylic acid, ethylenediaminetetraacetic acid EDTA, sulphobenzoic acid, 3-hydroxynaphthalene-1,4-disulphonic acid.

EFFECT: increased duration of inter-regeneration range of catalyst.

2 cl, 10 ex

Description

The invention relates to a method for preparing a catalyst for the process of highly selective synthesis of isopropylbenzene (cumene) by alkylation of benzene with isopropyl alcohol.

It is now known that isopropylbenzene can be prepared by alkylating benzene with isopropyl alcohol (IPA) as an alkylating agent or mixtures of isopropyl alcohol and propylene in a method that provides the best results in terms of productivity, catalyst life, even in the presence of significant amounts of water.

The most commonly used method for the alkylation of benzene with isopropyl alcohol or a mixture of IPA and propylene, which involves carrying out the reaction entirely in the gas phase and in the presence of a catalytic system containing a zeolite belonging to the MTW family. The reaction conditions correspond completely to gas-phase reagents, i.e. the method is carried out under such pressure and temperature conditions so as to ensure the presence of the reactants and reaction products exclusively in the gas phase.

Zeolites with MTW type structure that can be used in this process are: ZSM-12, CZH-15, Nu-13, Theta-3 and TPZ-12 (GB 2079735, B01J29 / 00, 27.01.1982; EP 162719, B01J29 / 7034, 27.11.1985; US 4557919, B01J29 / 70, 10.12.1985). Preferably, a zeolite with a MTW type structure is used, which is a silicate with a SiO ₂ / Al ₂ O ₃ molar ratio greater than or equal to 20 (A. Katovic and G. Giordano // Synth. Porous Mater. - Zeolites, Clays and Nanostructures. 1997. V .69, P. 127-137). Aluminum can be completely or partially replaced by In, Ga, Fe or mixtures thereof (Toktarev AV lone KG et al. // Stud. Surface Sci. & Cat. 1997. V. 105. P. 333-340).

Zeolite MTW-type, and in particular zeolite ZSM-12, is preferably used in a form in which the cationic centers present in its structure are at least 50% occupied by hydrogen ions. Preferably, there are 90% cationic sites for hydrogen ions.

In the case of catalysts based on zeolite, the negative effects due to the presence of water are well known, which manifests itself in a decrease in the total yield of isopropylbenzene along with a more or less rapid deactivation of the catalyst as such. Adverse effects are known and occur even with very low water levels present in the reaction, relative to the amount generated by using isopropyl alcohol as the alkylating agent for benzene in the production of isopropyl benzene. Therefore, the stage of dehydration of IPA to propylene is necessary for specific industrial applications due to the extreme complexity of the alkylation of benzene directly using isopropyl alcohol as an alkylating agent when using traditional acid catalysts, since the water released by IPA during the reaction has a negative effect on the characteristics of the catalyst - on selectivity, but above all on the life of the catalyst itself.

In fact, in the alkylation of benzene with isopropyl alcohol, the benzene / IPA molar ratio when fed to the reaction section is 4 to 8, with a corresponding water concentration in the reaction of approximately 48,000 and 26,000 ppm, assuming complete conversion of the IPA. Even when carrying out the alkylation of benzene with an alkylating agent consisting of a mixture of IPA and propylene, in any case, a significant reduction in the amount of isopropyl alcohol used is required to provide a water content that does not limit the use of the catalyst system.

Also describe the possibility of alkylation of benzene with isopropyl alcohol using beta-zeolite as catalyst in the gas phase, preferably at atmospheric pressure (KSN Reddy et al. // Appl.Cat .: A. 1993. V. 95. P. 53-63) and in this case, problems with the catalyst life are observed during the tests.

A method for the synthesis of phenol from isopropylbenzene obtained by alkylation of benzene, also carried out using IPA, is described. The alkylation phase of benzene with isopropyl alcohol is carried out in the presence of an acidic catalyst selected from various materials; zeolites are indicated as preferred catalysts (US 5015786, B01J29 / 08, May 14, 1991), however, there is no information on the catalyst life and on the consistency of characteristics, given that the test duration is 200 hours.

To overcome the above problems, it is proposed to use some zeolites with pronounced hydrophobic characteristics, such as ZSM-5 zeolite with a high silica / alumina ratio, or H-mordenite and dealuminated zeolite Y with a SiO ₂ / A ₂ O ₃ molar ratio from 8 to 70 ( US 5160497, B01J29 / 08, 03.11.1992).

The catalysts used for the alkylation of benzene with propylene are not always easy to adapt for the alkylation reaction of benzene with isopropyl alcohol or mixtures of IPA and propylene as the alkylating agent, since these catalysts are generally very sensitive to water and, therefore, their lifetime in the presence of water formed during dehydration of IPA is significantly reduced. Under the conditions of the alkylation reaction, water is chemisorbed at active sites and reduces the activity of the catalyst as a whole.

To reduce coke formation, as well as to impart hydrophobic properties to MTW-type zeolite, the latter is modified with phosphorus. The modification can be carried out by treating the zeolite, preferably in its ammonium form, with a phosphorus compound using any of the known methods such as mechanical mixing, impregnation or vapor deposition. The phosphorus compounds can be selected from the corresponding salts, acids and organic compounds such as, for example, alcoholates. The impregnation technology is preferably used, i. E. the zeolite is treated with an ammonium form from an aqueous solution of a phosphorus compound. The resulting suspension, after being kept with stirring, is dried under vacuum at a temperature sufficient to remove the solvent. The modes and conditions for carrying out the impregnation are known in the art. Then the solid phase obtained after drying is calcined at a temperature of 400 to 600 ° C for 1-10 hours. Phosphorus is usually present in an amount of less than 3% based on the total weight of the catalyst composition, preferably greater than or equal to 0.05 wt. %, but less than or equal to 2 wt.% with respect to the total weight of the catalyst composition.

Zeolite is used as such in powder or with a binder: for example, in the form of granules (extrudates), or in the form of spray dried microspheres. The binder is aluminum oxide, silicon dioxide, aluminum silicate, titanium dioxide, zirconium dioxide or clay, preferably aluminum oxide. In the finished catalyst, the zeolite and binder may be present in a weight ratio of 5/95 to 95/5, preferably 20/80 to 80/20.

Closest to the proposed invention is a catalyst and a method for alkylation of benzene with isopropyl alcohol or a mixture of IPA and propylene (RU 2525122, C07C2 / 86, 08/10/2014), in which the operating temperature range is from 150 ° C to 230 ° C, the reaction pressure is from 0 , 1 to 2 MPa (1 to 20 bar), preferably 0.5 to 0.9 MPa (5 to 9 bar). The process is carried out under conditions such as to ensure that the reactants are completely in the gas phase, regardless of whether the alkylating agent is IPA or a mixture of IPA and propylene. According to the invention, the benzene / IPA molar ratio is from 2 to 10, preferably from 2 to 4. In the case of using propylene additionally as an alkylating agent together with IPA, the molar ratio between benzene and alkylating agent (IPA + propylene) is from 2 to 10, preferably 2 to 4. The IPA / propylene molar ratio is 10 to 0.01, preferably 5 to 0.1.

The method is carried out in the presence of a catalytic system containing a zeolite belonging to the MTW family, the most preferred structure is ZSM-12. To reduce the negative effects caused by the presence of water, which are manifested in a decrease in the total yield of isopropylbenzene, along with a more or less rapid deactivation of the catalyst, it is necessary to impart hydrophobic properties to the zeolite. For this purpose, MTW-type zeolite is modified with phosphorus. The modification can be carried out by treating the zeolite, preferably in its ammonium form, with a phosphorus compound using any of the known methods such as mechanical mixing, impregnation or vapor deposition. The phosphorus compounds can be selected from the corresponding salts, acids and organic compounds such as, for example, alcoholates. Preferably, an impregnation technique is used when the zeolite is treated with an aqueous solution of a phosphorus compound in the ammonium form.

The disadvantage of this catalyst is the duration of the interregeneration run no more than 200 hours.

The invention solves the problem of developing a method for preparing an effective catalyst for highly selective synthesis of isopropylbenzene in the process of alkylation of benzene with isopropyl alcohol.

The technical result is an increase in the duration of the regeneration run of the catalyst during the synthesis of isopropylbenzene by alkylation of benzene with isopropyl alcohol.

The problem is solved by the proposed method for preparing a catalyst intended for the production of isopropylbenzene by alkylation of benzene with IPA, based on decationized zeolite ZSM-12, which includes granulation with a binder, drying and calcining of granules, while zeolite ZSM-12 to impart hydrophobic properties and dealumination of the outer surface of the zeolite before granulating with a binder previously treated with a solution of a chelating agent, and then treated with superheated steam at a temperature not higher than 550 ^{° C} for at least 2 hours. as a chelating agent used sulfosalicylic acid, ethylenediamine tetraacetic acid (EDTA), sulfobenzoic acid, 3-hydroxynaphthalene -1,4-disulfonic acid.

The problem is also solved by the method of producing isopropylbenzene in the process of alkylation of benzene with isopropyl alcohol in a flow reactor having two reaction zones (option 1), in the first of which γ-Al ₂ O _{3 is} used as a catalyst and the temperature is maintained at least 450 ^o C, and the second zone uses a catalyst prepared by the method described above, and maintains a temperature not lower than 200 ^o C, or in two series-connected flow reactors (option 2), in the first of which γ-Al ₂ O _{3 is} used as a catalyst and the temperature is maintained not lower than 450 ^about C, and in the second reactor, a catalyst prepared as described above is used, and the temperature is maintained at not lower than 200 ^about C.

Zeolite MTW-type ZSM-12, pretreated with solutions of organic or inorganic acids, granulated with aluminum oxide as a binder, is used as the acidic component of the catalyst. An essential distinguishing feature of the proposed method from the prototype is that the specified acid component used for the production of a porous catalyst, before the granulation stage to create hydrophobic properties, is pretreated with a solution of a chelating agent selected from the series: sulfosalicylic acid, EDTA, sulfobenzoic acid, 3-hydroxynaphthalene -1,4-disulfonic acid, and then treated with superheated steam at a temperature of 550 ^{° C} for at least 2 hours.

Pretreatment with a solution of a chelating agent and then with superheated steam at a temperature not higher than 550 ^{° C} for at least 2 hours results:

firstly, to a decrease in the number of catalyst acid sites located mainly on the outer surface of the ZSM-12 zeolite crystals, which are responsible for the secondary cracking reactions and the formation of polyalkyl derivatives, practically does not affect the acid sites in the volume of the zeolite crystals (selective dealumination), and as a consequence - to improve selectivity;

Secondly, the removal of active sites, including lattice aluminum atoms from the outer surface of the porous catalyst, leads to an increase in the hydrophobicity of the ZSM-12 zeolite, and, as a consequence, to an increase in the duration of the catalyst's regeneration run.

These distinctive features give the catalyst new properties, as a result of which the technical result is achieved - an increase in the duration of the continuous run of the catalyst during the synthesis of isopropylbenzene by alkylation of benzene with isopropyl alcohol by the method described in the prototype, up to 2500 h versus 200 h in the prototype (RU 2525122, C07C2 / 86, 08/10/2014) while maintaining a high level of both the conversion of benzene and the selectivity for the target product (isopropylbenzene).

In addition, carrying out the process of alkylation of benzene with isopropyl alcohol by a two-stage method significantly increases the duration of the catalyst's continuous run. At the first stage, IPA is dehydrated on a γ-Al ₂ O ₃ catalyst to obtain propylene and water, and then the resulting mixture is fed with benzene to the second stage of alkylation on the proposed catalyst based on zeolite ZSM-12. Due to this, the technical result is achieved - an increase in the duration of the continuous run of the catalyst during the synthesis of isopropylbenzene by alkylation of benzene with isopropyl alcohol by the proposed method (1 or 2 options) up to 3200 h versus 200 h in the prototype (RU 2525122, C07C2 / 86, 08/10/2014) while maintaining at a high level and conversion of benzene, and conversion of propylene, and selectivity for the target product (isopropylbenzene).

The essence of the invention is illustrated by the following examples.

Example 1 (prototype).

The decationized form of zeolite ZSM-12, dried at 105-110 ^o C, is loaded into a mixer for preparing pastes. Then, with continuous stirring, load in a certain ratio and in the specified sequence pseudoboehmite, water and nitric acid for plasticization. After homogenization for 1 hour, a paste is obtained, which is passed with an extruder or a syringe through a die and a wet granular zeolite is obtained in the form of cylindrical cuttings with a diameter of up to 3 mm, a length of 3-5 mm, which is dried at 105-110 ^o C and calcined at 500 -550 ^o C. Granules have the following composition, wt%: zeolite ZSM-12 - 80, alumina - 20.

Then the granular zeolite is treated with an equal volume aqueous solution of diammonium phosphate having a density in the range of 1.06-1.18 (20 ^o C). The treatment is carried out without stirring at a temperature of 20-30 ^o C for 10-12 hours. At the end of the impregnation, the excess solution is drained from the granules; the wet catalyst is dried at 105-110 ^° C and calcined at 500-550 ^° C.

Testing the catalyst in the alkylation of benzene with isopropyl alcohol is carried out in a flow reactor, which is charged with 10 g of catalyst. The reaction is carried out at atmospheric pressure, a temperature of 200 ^about C, a benzene / IPA molar ratio of 4, with a weight feed rate of the mixture equal to 0.3 h ^-1 . The catalyst is activated with air at 500 ^o C for about 1 hour, the operating temperature is set in the frontal catalyst bed, displacing the air with an inert gas. After turning off the inert gas supply, a mixture of benzene with IPA is fed into the reactor through the evaporator. The reaction products are collected in a separator and analyzed by gas-liquid chromatography. The conversion rates of benzene and IPA, as well as the selectivity (mol) for all reaction products, are calculated as characteristics of the catalyst activity.

The change in these characteristics determines the duration of the catalyst run between regeneration, which in this example is 200 h.

Example 2.

The decationized form of zeolite ZSM-12, dried at 105-110 ^o C, is subjected to selective dealumination with a 10% sulfosalicylic acid solution under stirring and at a temperature of 90-95 ^o C for 2 hours. After extraction treatment, the product is washed with distilled water until the purified wash water will not have a pH in the range from 5 to 8. The resulting decationized powder of zeolite ZSM-12 is granulated with 20 wt.% pseudoboehmite as a binder similar to example 1 (prototype).

After drying the granulation produces pellets for 12 hours at ¹²⁰ ° C and treatment with superheated steam for 2 hours at a temperature of 550 ° ^C.

Testing the catalyst in the alkylation reaction of benzene with isopropyl alcohol is carried out in a flow reactor analogously to example 1 (prototype).

The duration of the regeneration run of the obtained catalyst is 2500 h.

Example 3.

The decationized form of zeolite ZSM-12, dried at 105-110 ^o C, is subjected to selective dealumination with a 10% solution of EDTA with stirring at a temperature of 90-95 ^o C for 2 hours. After extraction treatment, the product is washed with distilled water until purified the wash water will not have a pH in the range from 5 to 8. The rest of the catalyst preparation and testing procedures are similar to example 2.

The duration of the regeneration run of the obtained catalyst is 1150 h.

Example 4.

The decationized form of zeolite ZSM-12, dried at 105-110 ^o C, is subjected to selective dealumination with a 10% solution of sulfobenzoic acid with stirring at a temperature of 90-95 ^o C for 2 hours. After extraction, the product is washed with distilled water until the purified wash water will not have a pH in the range from 5 to 8. The rest of the catalyst preparation and testing procedures are similar to example 2.

The duration of the regeneration run of the obtained catalyst is 1650 h.

Example 5.

The decationized form of zeolite ZSM-12, dried at 105-110 ^o C, is subjected to selective dealumination with a 10% solution of d3-hydroxynaphthalene-1,4-disulfonic acid with stirring at a temperature of 90-95 ^o C for 2 hours. After extraction treatment, the product is washed distilled water until the purified wash water has a pH in the range from 5 to 8. The rest of the preparation and testing procedures for the catalyst are similar to example 2.

The duration of the regeneration run of the obtained catalyst is 2400 h.

Example 6.

The flow reactor was charged with two catalysts: loaded γ-Al ₂ O ₃ in a high-temperature upper zone in an amount of 10 g and it is maintained in a temperature of 450 ^{° C,} the lower low temperature zone was charged with 10 g of the catalyst prepared in accordance with Example 2. The remaining test conditions catalyst in the reaction of alkylation of benzene with isopropyl alcohol are similar to example 1 (prototype).

The duration of the regeneration run of the obtained catalyst is 3000 h.

Example 7.

Two flow reactors connected in series are used. The first reactor is charged with γ-Al ₂ O ₃ in an amount of 10 g and the temperature is maintained at 450 ^about C, the second reactor is charged with 10 g of the catalyst prepared in accordance with example 2. The rest of the test conditions for the catalyst in the alkylation reaction of benzene with isopropyl alcohol are similar to example 1 (prototype).

The duration of the regeneration run of the obtained catalyst is 3200 h.

Example 8.

Two flow reactors connected in series are used. The first reactor is charged with γ-Al ₂ O ₃ in an amount of 10 g and the temperature is maintained at 450 ^about C, the second reactor is charged with 10 g of a catalyst prepared in accordance with example 3. The remaining conditions for testing the catalyst in the alkylation reaction of benzene with isopropyl alcohol are similar to example 1 (prototype).

The duration of the regeneration run of the obtained catalyst is 1550 h.

Example 9.

Two flow reactors connected in series are used. The first reactor is charged with γ-Al ₂ O ₃ in an amount of 10 g and the temperature is maintained at 450 ^about C, the second reactor is charged with 10 g of a catalyst prepared in accordance with example 4. The remaining conditions for testing the catalyst in the alkylation reaction of benzene with isopropyl alcohol are similar to example 1 (prototype).

The duration of the regeneration run of the obtained catalyst is 2150 h.

Example 10.

Two flow reactors connected in series are used. The first reactor is charged with γ-Al ₂ O ₃ in an amount of 10 g and the temperature is maintained at 450 ^about C, the second reactor is charged with 10 g of a catalyst prepared in accordance with example 5. The remaining conditions for testing the catalyst in the reaction of benzene alkylation with isopropyl alcohol are similar to example 1 (prototype).

The duration of the regeneration run of the obtained catalyst is 2950 h.

Claims (2)

1. A method of producing isopropylbenzene in the process of alkylation of benzene with isopropyl alcohol in a flow reactor having two reaction zones, in the first of which γ-Al ₂ O _{3 is} used as a catalyst and the temperature is maintained at not lower than 450 ° C, and in the second zone the temperature is not maintained below 200 ° C, and the catalyst used is a catalyst prepared by granulation of decationized zeolite ZSM-12 with a binder, followed by stages of drying and calcining the granules, and the zeolite ZSM-12 before granulation with a binder is preliminarily treated with a solution of a chelating agent, and then treated with superheated water vapor at a temperature not exceeding 550 ° C for at least 2 hours, sulfosalicylic acid, ethylenediaminetetraacetic acid EDTA, sulfobenzoic acid, 3-hydroxynaphthalene-1,4-disulfonic acid are used as a chelating agent. 2. A method for producing isopropyl benzene in the process of alkylation of benzene with isopropyl alcohol in two series-connected flow reactors, in the first of which γ-Al ₂ O _{3 is} used as a catalyst and the temperature is maintained at not lower than 450 ° C, and in the second reactor the temperature is maintained at not lower than 200 ° C and use a catalyst prepared by granulation of decationized zeolite ZSM-12 with a binder, followed by stages of drying and calcining the granules, and the zeolite ZSM-12 before granulation with a binder is preliminarily treated with a solution of a chelating agent, and then treated with superheated steam at a temperature not higher than 550 ° C for at least 2 hours, sulfosalicylic acid, ethylenediaminetetraacetic acid EDTA, sulfobenzoic acid, 3-hydroxynaphthalene-1,4-disulfonic acid are used as a chelating agent.