RU2289477C1 - Alkylation catalyst preparation method - Google Patents

Abstract

FIELD: organic synthesis catalysts.

SUBSTANCE: invention relates to petrochemical processes, in particular production of ethylbenzene via alkylation of benzene with ethylene catalyzed by solid acid catalyst, and provides elevated-strength (cleavage strength above 2 kg/mm diameter) catalyst showing high characteristics regarding activity (theoretical yield of ethylbenzene 65.83-70.7%) and selectivity (yield of ethylbenzene based on converted benzene 68,18-71.4%). This is achieved by way of mixing Pentasil-type zeolite with binder, said zeolite having been preliminarily subjected to exchange of cations: consecutively ammonium and calcium or magnesium. As binder, pseudoboehemite-structure aluminum hydroxide, to which inorganic acid was add to pH 2-4, is utilized. Molding mass is characterized by calcination loss 35-45 wt %. Heat treatment is effected in one to three steps.

EFFECT: improved strength, activity and selectivity of catalyst.

2 tbl, 5 ex

Description

The invention relates to petrochemistry, in particular to methods for producing ethylbenzene by alkylating benzene with ethylene on a solid acid catalyst.

At present, the process of alkylation of benzene with olefins on a solid catalyst is increasingly replacing the alkylation process in the presence of liquid acids such as sulfuric, hydrofluoric, etc. (N.A. Plate, E.V. Slivinsky "Fundamentals of chemistry and technology of monomers", M., " Science ”, 2002). Anhydrous aluminum chloride was used as a solid catalyst in the preparation of ethylbenzene by alkylation of benzene with ethylene, and zeolites of various structures were used in the development of science and technology of zeolites (Copyright certificate SU No. 1245337; A.S. SU No. 1576194; A.S. SU No. 1625519; A.S. SU # 1694202; A.S. SU # 1715396; A.S. SU # 1803189). The well-known scientific school of the Institute of Organic Chemistry of the Russian Academy of Sciences for the study and application of zeolites of the faujasite and mordenite type in alkylation processes (“Kinetics and Catalysis”, authors E.S. Mortikov, H.I. Minachev et al., Publications 1970-1980 )

However, catalysts based on zeolites of the type faujasite and mordenite have a low selectivity for the yield of the target product.

Known methods for the preparation of a catalyst for the alkylation of benzene with olefins in ball form by molding a zeolite-containing suspension in an oil layer (A.S. SU No. 1625519, A.S. SU No. 1694202, and A.S. SU No. 1803179). The disadvantage of these methods is that with the introduction of a zeolite of more than 20 wt.%, The mechanical strength of the balls sharply decreases and the yield of rejects increases to 40%, which leads to an unreasonably high price of the catalyst.

A known method of preparing a catalyst for the alkylation of benzene with olefins based on a faujasite type zeolite, in which sodium cations are exchanged for calcium. The disadvantage of this method is that the exchange for calcium is carried out in a sealed apparatus under pressure, which dramatically reduces the possibility of using this method (A.S. No. 936991, 1982).

The sensitivity of alkylation catalysts to the presence of moisture is known, which causes their poisoning and accelerated coking.

In this regard, it is advisable to use catalysts with hydrophobic properties, including silicalite and high-modulus zeolites of the ZSM-5 type, which determines their practical application (catalysts from Siide Chemie Ebemax-1 and Ebemax-2). However, the binder of these catalysts and the method for their preparation do not provide them with high strength.

The closest in technical essence and the achieved effect to the proposed technical solution method of preparing a catalyst for the alkylation of benzene and its monoalkyl compounds with ethylene by mixing 70 ÷ 80 wt.% Silicalite or zeolite like pentasil with an alumina binder and molding by extrusion into granules of the “trefoil” type, this catalyst contains 0.007 ÷ 0.02% Na ₂ O and 0.02 ÷ 0.05% Fe ₂ O ₃ (Pat. EP No. 1188734, 2002, Fina Technology Inc.).

The disadvantages of this method are

firstly, increased requirements for the content of impurities of sodium and iron oxides in the catalyst, which leads to the need for very deep washing of the carrier from these impurities with two to three times the overrun of the wash water, compared with the industrial method;

secondly, the low mechanical strength of the extrudates.

The aim of the proposed technical solution is to develop a method for producing a benzene alkylation catalyst with ethylene with high activity and selectivity and high strength using industrial binder without additional washing.

This goal is achieved by using the method of producing a catalyst for the alkylation of benzene with ethylene by mixing a pentasil-type zeolite with a binder, molding and heat treatment, while the zeolite is preliminarily exchanged for sodium cations sequentially for ammonium and calcium or magnesium cations, aluminum hydroxide of a pseudoboehmite structure with the addition of inorganic acid to pH 2 ÷ 4, the molded mass is characterized by the magnitude of the loss during calcination of the SPP = 35 ÷ 45 wt.%, and thermal processing is carried out in one to three stages. Distinctive features of the proposed technical solution are the use of a pentasil-type zeolite with preliminary exchange of sodium cations for ammonium and calcium or magnesium cations, the use of a pseudoboehmite structure with an inorganic acid as an aluminum hydroxide binder to a pH of 2 ÷ 4, molding of the mass by extrusion with an amount of loss on ignition 35 ÷ 45 wt.%, Carrying out heat treatments in one to three steps.

The proposed method for producing a catalyst for the alkylation of benzene with ethylene is implemented as follows.

A pentasil zeolite, preferably obtained with an organic template, having a silicate module (molar ratio SiO ₂ : Al ₂ O ₃ ) of 50 to 250, is treated sequentially with solutions of ammonium chloride and calcium or magnesium nitrate with or without intermediate calcination, with final calcination or without him.

Aluminum hydroxide of a pseudoboehmite structure obtained by reprecipitation of hydrargillite or by hydrothermal treatment of the product of thermal dispersion of hydrargillite is treated with inorganic acid or acids from the number of nitric, hydrochloric, orthophosphoric to pH 2 ÷ 4. A pentasil-type zeolite, treated as described above with solutions of ammonium chloride and calcium or magnesium nitrate, is introduced into the resulting mass, the mixture is stirred until a uniform state is achieved and the loss value during calcination is 35–45 wt.%. The mass is formed by extrusion, the extrudates are dried and calcined.

The activity of the catalyst in the process of alkylation of benzene with ethylene is 65 ÷ 70% of the theoretical level, the mechanical cracking strength is 2.0 ÷ 2.5 kg / mm diameter.

The use of a pentasil-type zeolite with preliminary exchange of sodium cations sequentially for ammonium and calcium or magnesium cations results in a catalyst with high activity and selectivity in the process of benzene alkylation with ethylene.

The use of a pseudoboehmite structure as an aluminum hydroxide binder with the addition of an inorganic acid to a pH of 2–4 makes it possible to obtain a catalyst with high strength with the introduction of zeolite in an amount of 70–80 wt.%, Which ensures a longer catalyst life without decreasing activity. The selected nature of the binder and the method of processing it with inorganic acids make it possible to form a mass with a loss on ignition of 35 ÷ 45 wt.%, Which also contributes to the formation of strong granules.

Conducting heat treatments from one to three allows you to adjust the selectivity of the process of alkylation of benzene with ethylene in relation to the yield of by-products - toluene and diethylbenzene.

The implementation of the entire set of techniques in combination with the selected raw materials indicated in the formula of the invention leads to the production of a benzene alkylation catalyst with ethylene with high activity and stability.

In the known methods for producing a catalyst for the alkylation of benzene with ethylene, the above complex of methods is unknown.

Thus, this technical solution meets the criteria of "novelty" and "significant difference".

The following are specific examples of the implementation of the proposed method, which he illustrates, but is not limited to.

Example 1. Preparation of zeolite.

1.1. Exchange of Na ⁺ for NH ₄ ⁺ (H ⁺ )

Zeolite type ZSM-5, obtained using an organic template, characterized by silicate module 99 (molar ratio of SiO ₂ : Al ₂ O ₃ ), in an amount of 300 g, filled with 1N solution of ammonium chloride NH ₄ Cl in a volume of 1.2 l and with stirring

- kept at a temperature of 50 ° C for 2 hours;

- filtered and again filled with 1.2 l of IN solution of NH ₄ Cl at 50 ° C, kept for 2 hours;

- filtered and again filled with 1.2 l of IN solution of NH ₄ Cl at 50 ° C, kept for 2 hours (threefold pouring);

- filtered and washed on the filter with distilled water to the absence of chlorine ions;

- dried "cake" on the filter;

- dried in the air to a state where the "cake" falls to pieces;

- dried at a temperature of 120 ° C for 4 hours;

- calcined at a temperature of 550 ° C for 5 hours to the value of the losses during calcination of the SPP = 1 wt.%.

The last calcination operation may not be carried out (as a variant of the technical solution).

1.2. Exchange of NH ₄ ⁺ (or H ⁺ ) for Ca ²⁺ or Mg ²⁺ .

Zeolite according to claim 1.1. filled with a 0.1 M solution of calcium nitrate Ca (NO ₃ ) ₂ in a volume of 0.9 l, brought to a boil with stirring and

- boiled for 1 hour,

- cooled to 40 ° C, filtered, the precipitate was transferred to a glass,

- again filled with 0.9 l of 0.1 M calcium nitrate solution and left for 24 hours without heating,

- filtered, washed with hot water, filtered again and washed (only 3 ÷ 4 times) until there are no NO ^- ₃ ions in diphenylamine;

- dried "cake" in the air to a state where it falls apart into pieces;

- dried at a temperature of 120 ° C for 6 hours to SPP = 3.05 wt.%;

- calcined at a temperature of 550 ° C for 5 hours to SPP = 1 wt.%.

The last calcination operation may not be carried out (as a variant of the technical solution).

Similarly, operations are carried out with the introduction of Mg ²⁺ .

Example 2. Preparation of a binder.

2.1. Aluminum hydroxide pseudoboehmite structure obtained by reprecipitation of hydrargillite (GOA).

120 g of GOA (PPP = 75% wt.) Was mixed with 3.85 ml of 28% nitric acid, the mixture had a pH of 2.55, was heated to a temperature of 55 ° C and kept under stirring for 0.5 hour.

The introduction of hydrochloric, phosphoric or mixtures thereof with nitric acid to a pH of 2-4 was accompanied by heating with stirring to a temperature of 55 ° C for 0.5 hour.

2.2. Aluminum hydroxide pseudoboehmite structure obtained by hydrothermal treatment of the product of thermal dispersion of hydrargillite (AO-TA).

1 option. - 120 g of AO-TA (PPP = 79.2%), pH 3.5 was heated with stirring to a temperature of 55 ° C for 0.5 hour.

Option 2: 120 g of AO-TA was mixed with 1.5 ml of 28% nitric acid, and a mixture was obtained with a pH of 2.3; heated with stirring to a temperature of 55 ° C for 0.5 hour.

3 option. - 120 g of AO-TA was mixed with 1.8 ml of 30% hydrochloric acid, a mixture was obtained with a pH of 2.0; heated with stirring to a temperature of 55 ° C for 0.5 hour.

4 option. - 120 g of AO-TA was mixed with 4.0 ml of phosphoric acid, a mixture was obtained with a pH of 3.1; heated with stirring to a temperature of 55 ° C for 0.5 hour.

Example 3. The synthesis of the catalyst.

72 g of the zeolite prepared according to the conditions of Example 1 were added to a binder prepared according to the conditions of Example 2, mixed thoroughly and the mixture was processed by passing through a die of a molding device 3–4 times, a homogeneous mixture with good rheological properties was obtained and the SPP = 41.8 wt. .%, molded extrudates on a die with a hole diameter of 3 mm The extrudates were air-dried, dried at 120 ° C for 4 hours, calcined at 550 ° C for 10 hours.

Table 1 shows the conditions for the synthesis of catalysts and their physicochemical characteristics.

Example 4. Determination of activity.

The catalyst was ground to a size of 0.5 ÷ 1.0 mm. The catalyst loading into the reactor is 3 cm ³ .

Testing of the catalysts was carried out at atmospheric pressure in the reactor in the form of a quartz tube 12 cm long, with an inner diameter of 7.5 mm, placed in an electric furnace. A filter made of quartz wool is located at the bottom of the catalyst bed, and a sample filled with ground quartz with a height of 20 mm is placed on top (fraction 1.0–2.0 mm).

The temperature in the catalyst bed (length 68 mm) was maintained constant using a temperature controller 375 ° C ± 1 ° C, connected to a chromel-alumel thermocouple placed on top of the catalyst layer to a depth of 25 mm.

The supply of benzene was carried out by a syringe dispenser (3.75 cm ³ / h or 3.3 g / h or 0.042 mol / h).

Ethylene was supplied from the cylinder through a fine flow control unit (468 cm ³ / h or 7.8 ml / min or 0.021 mol / h). Ethylene was supplied 0.5 hours after starting benzene in the reactor.

The molar ratio of benzene / ethylene = 2/1.

The reaction temperature is 375 ° C.

A sample of the reaction product was collected in a 10 ml trap, cooled to 5 ° C with ice for 1 hour.

Samples were analyzed using chromatography. The figure shows the chromatogram of the sample from catalyst No. 1.

Calculation Methodology.

In a mixture with a molar ratio of benzene / ethylene = 2/1, the maximum possible content (theoretical) of ethylbenzene in the sample is

106 / (2 × 78 + 28) × 100 = 57.6 wt.%.

The yield of ethylbenzene (in% of theoretical) is equal to the value of Sab.x 100/5 7.6; and the selectivity of its formation in% is Sab.x100 / (100-Sbens.)

Table 2 shows data on the activity and selectivity of benzene alkylation catalysts with ethylene according to the proposed production method.

Example 5. Determination of mechanical strength.

To determine the strength index, a semi-automatic device of the VNIINeftekhim design was used to determine the strength of the catalyst (PIK-1 device) with a knife having a blade width (0.8 ± 0.013) mm.

For testing, the catalyst sample was dried at 200-250 ° C for 2 hours in an oven and cooled in a desiccator. 30 catalyst pellets were taken from the prepared sample and their diameter was measured.

Granules (extrudates) are placed in the grooves of the stand, placed smoothly under the knife and immediately turn on the motor. After crushing the granule (the carriage with the indicator stops at the moment of crushing), the motor is stopped, the reading (Z) is recorded on the scale.

The mechanical strength of the catalyst (P) in kg / granule is determined by the formula:

P = m / e * Z,

where m is the mass of the weight, kg,

e is the distance from the axis of swing of the lever of the device to the knife (equal to 10 cm),

Z - reading on a scale at which the granule is crushed (distance from the swing axis of the lever to the middle of the weight), see

The average strength of the granules is determined by the formula

Rsred = (m / e) * ((Z ₁ + Z ₂ + ... + Z ₃₀ ) / 30),

where Z ₁ , Z ₂ , Z ₃₀ - readings on a scale when crushing the first, second, etc. granules

30 - the number of crushed granules. The strength index in kg / mm of the diameter of the granules is determined by the formula

Coll. = Del. / Del.,

where is rsred. - average mechanical strength of the catalyst, kg / granule,

Dsred. - the average diameter of the granules, mm

Table 1 The synthesis conditions and characteristics of the catalysts. No. p / p Zeolite Binder Number of calcinations Catalyst Formable mass, SPP,% mass Silicate module SiO ₂ / Al ₂ O ₃ Exchange of Na ⁺ for NH ₄ ⁺ (H ⁺ ) Exchange for Ca ²⁺ or Mg ²⁺ Acid treatment pH one 99 Exchange, calcination Exchange for Ca ²⁺ GOA, HNO ₃ 2,55 41.8 2 99 Exchange Exchange for Ca ²⁺ calcination GOA, HCl, HNO ₃ 2.0 38.1 3 99 Exchange, calcination Exchange for Ca ²⁺ , calcination AO-TA, HCl, H ₃ PO ₄ 2.8 41.3 four 60 Exchange Exchange for Mg ²⁺ AO-TA 3,5 37,4 5 123 Exchange, calcination Exchange for Ca ²⁺ GOA, HNO ₃ , H ₃ PO ₄ 1.9 40.9 6 123 Exchange, calcination Exchange for Mg ²⁺ AO-TA, HNO ₃ 3.0 39.5 7 123 Exchange Exchange for Ca ²⁺ calcination GOA, HNO ₃ 4.0 35.3 8 240 No sharing Exchange for Mg ²⁺ , calcination AO-TA, N ₃ PO ₄ 3.2 47.6 9 60 No sharing No sharing GOA, N ₃ PO ₄ 4.2 49.8 10 180 Exchange Exchange for Ca ²⁺ AO-TA, HCl 2.3 45.0 eleven Prototype 1,5 54.7 table 2 The test results of the catalysts synthesized according to the conditions of table 1. Catalyst No. according to Table 1 The composition of the sample,% of the mass The yield of Et-benzene from theor.,% The selectivity of Et-benzene,% benzene toluene xylene Et benzene Di- Et-benzene Others one 41.80 0.50 0.80 40.70 15.00 1.20 70.70 70.00 2 48.80 2.00 1.40 36.60 8.40 2.80 63.50 71.40 3 43.72 3.09 0.32 39.50 8.49 4.88 68.58 70.18 four 29.70 6.74 2.09 40.04 11.79 9.64 69.51 56.95 5 52,20 9.40 1.33 26.62 5.02 4.71 46.21 56.54 6 45.28 3.24 0.29 37.92 7.90 5.37 65.83 69.30 7 43.68 2.95 0.36 38.40 8.31 5.07 66.70 68.18 8 58.95 10.97 1.43 22.94 3.19 2,52 39.83 55.88 9 68.18 0.23 next 17.25 6.04 8.30 29.95 54.21 10 42.30 1.90 1,6 40.00 10,4 3.80 69.44 69.30 11 Prototype 46.22 4.18 0.91 33.73 6.78 8.28 58.56 62.60

A review of the materials of Tables 1 and 2 shows that the proposed method allows to obtain benzene alkylation catalysts with ethylene with high strength (cracking coefficient above 2.0 kg / mm diameter) and high activity rates (ethylbenzene yield is 65.83 - 70, 7% of theoretical) and selectivity (the yield of ethylbenzene to converted benzene is 68.18-71.4%). Moreover, going beyond the declared limits of the characteristics of the moldable mass, pH> 4.0 and SPP> 45%, leads to the fact that the strength of the catalyst is reduced to 1.3-1.4 kg / mm of diameter, which is not acceptable for industrial operation; at pH <2.0 (example 5), a very strong catalyst is obtained, but its activity is low, at SPP <35 wt.% it is not formed by extrusion.

Calcination after one or two exchanges (2-3 calcinations in total) leads, as a rule, to a high selectivity of the catalyst during the alkylation of benzene with ethylene.

The use of zeolite such as pentasil in sodium form (without exchanges) does not allow to obtain an active catalyst (example 9).

Thus, the experimental material in terms of the synthesis of the catalyst in comparison with the strength and activity indicators demonstrated the advantages of the proposed method for raw materials while increasing strength and activity.

Claims (1)

A method of producing a benzene alkylation catalyst with ethylene by mixing a pentasil type zeolite with a binder, molding and heat treatment, characterized in that the zeolite is preliminarily exchanged for sodium cations sequentially for ammonium and calcium or magnesium cations, aluminum hydroxide of a pseudoboehmite structure with the addition of inorganic is used as a binder acid to pH 2 ÷ 4, the moldable mass is characterized by the value of losses during calcination of PPP = 35 ÷ 45 wt.%, and heat treatment is carried out in one to three Yeni.