CS276808B6 - Process for preparing high-effective zeolite adsorbents of a type - Google Patents

Abstract

The invention solves the method of preparation high effective zeolite adsorbents type A by contacting the starting zeolite adsorbent 4a formed with with an aqueous aluminosilicate binder sodium hydroxide solution and high-potency preparation formed zeolite adsorbent 5a exchange of Na + ions in the high efficiency formed zeolite adsorbent 4a divalent metal cations of the other groups of the periodic system of elements.

Description

The present invention relates to a process for preparing high performance molded type A zeolite adsorbents by contacting a starting aluminosilicate binder formed with the addition of an aluminosilicate binder with an aqueous sodium hydroxide solution and to preparing a high performance molded zeolite adsorbent 5A by exchanging Na ^{+ ion ions} groups of the periodic table.

Zeolites have significant uses as adsorbents in adsorption separation processes due to their selective adsorption properties, which allow components or certain groups of components to be separated from a mixture of substances on the basis of different molecular diameters of the separated components or on different affinity of the active surface of the zeolite. components.

Adsorption processes based on zeolite adsorbents are currently economically important technologies, which on the one hand purify barbecue industrial media and produce important intermediates in the chemical industry. Typical intermediates in the chemical industry produced by high-capacity adsorption technologies using type 5A zeolites include liquid n-alkanes, which are an essential component in the production of biodegradable detergents. Equally important is the adsorption purification of industrial exhausts and process streams from oxides of carbon, sulfur, hydrogen sulfide and water. Zeolite type 4A adsorbents, such as NaA, are preferred for drying hydrocarbon streams to a particularly low residual water content. '

From the point of view of adsorbent efficiency, their most important properties are adsorption capacity, selectivity, kinetic characteristics and particle strength, which determine the size of the charge, dimensions of the adsorber for the required performance, product quality from the adsorption process and adsorbent charge life.

Developments in the preparation of adsorbents based on synthetic zeolites are therefore constantly focused on improving the above-mentioned characteristics.

It is known that zeolite adsorbents are prepared for practical application by molding into particles of different shape and spit size. Prior to forming the particles, for example by pelletization, extrusion or tableting, the base zeolite is mixed with a binder, which on the one hand facilitates the formation of the particles and also increases the mechanical strength of the adsorbent particles. From the point of view of the specific adsorption properties of the zeolite adsorbent, the binder is practically inert.

As binders for the production of zeolite adsorbents, natural aluminosilicate, for example halloysite, kaolin, bentonite, is mostly used. The addition of these binders, in addition to the advantages already mentioned, also has disadvantages, as they are characterized by a minimal, yet non-specific adsorption capacity, therefore their share in the formed adsorbent is reduced by the adsorption capacity of zeolite adsorbent compared to pure zeolite and can adversely affect kinetic particle characteristics or dynamics of the adsorption process.

It is also known that binders of the natural aluminosilicate type can be converted in fine powder form to zeolite type 4A and further to 5A zeolite, thus acquiring similar adsorption capabilities but at the same time losing binding properties and not being used as binders in this state. The molded binders themselves can also be converted to the zeolite 4A form, but only after prior activation at extremely high temperatures of 700 to 850 ° C, thereby converting the non-reactive binder form to a reactive one capable of recrystallization to zeolite.

According to the present invention, it has been found that from zeolite adsorbent 4A formed with the addition of an aluminosilicate binder, high performance molded zeolite adsorbents of type 4A and 5A with increased adsorption capacity, improved kinetic characteristics and increased strength are prepared without the above drawbacks. zeolite 4A is formed with the addition of an aluminosilicate binder, after molding it is dried at a temperature up to 200 ° C and / or calcined at 450 to 600 ° C and the thus prepared calcined molded zeolite adsorbent 4A or directly finished commercial molded zeolite adsorbent 4A is contacted with aqueous sodium hydroxide solution with a NaOH concentration of 0.1 to 10% by weight, at a temperature of 20 to

130 ° C, at a pressure of 0.1 to 0.5 MPa, for 1 to 10 hours, then the excess sodium hydroxide is separated from the adsorbent by washing with water and the washed adsorbent is dried at a temperature of up to 200 ° C and / or dehydrated at 350 to 600 ° C to obtain a highly effective formed zeolite adsorbent 4A or, after contacting with aqueous sodium hydroxide solution and subsequent washing with water, the zeolite adsorbent 4A is exchanged for Na * flood cations for divalent metal cations from the second group of periodic elements by further contact with aqueous with a hydroxide solution or a salt of this divalent cation with a cation concentration of 0,05 to 1 mol / l solution, at a temperature of 20 to 130 ° C, at a pressure of 0,1 to 0,5 MPa for 1 to 10 hours, after ion exchange it is separated from the adsorbent, the excess ion exchange solution is washed with water, and the washed adsorbent is dried at a temperature of up to 200 ° C or further dehydrated at a temperature of 300 to 600 ° C to obtain a high performance zeolite adsorbent 5A.

The present invention is based on the novelty that pure zeolite 4A present in a molded and calcined mixture with an aluminosilicate binder initiates the conversion of the binder to zeolite 4A upon contact with aqueous sodium hydroxide solution. This eliminated the material and energy-intensive high-temperature reactivation of the binder and revealed a new efficient process for the preparation of type A zeolite adsorbents with improved quality indicators.

The high performance adsorbent prepared according to the present invention. is characterized not only by an increased adsorption capacity, but also by an improved kinetic characteristic, which has a favorable effect on the dynamic capacity of the adsorbent in the adsorption process and also on the increased strength of the adsorbent particles.

According to the invention, conventional commercially formed type 4A adsorbents, i.e. NaA, which generally contain about 20% by weight of adsorption-inert aluminosilicate binder, can also be easily converted to high-performance adsorbents 4A or 5A with an adsorption capacity increased by about 20%, increased strength and improved kinetic characteristic.

The preparation of the high-performance adsorbents according to the invention has a positive effect on both manufacturers and consumers. tel'a.

. In the production of the adsorbent, it is possible to increase the binder content, which is cheaper than pure zeolite 4A, for example to 30 to 40 or up to 80% by weight, depending on the type and quality, and the adsorption process can reduce its adsorption capacity. even the dimensions of the adsorber or in a given device can increase production and save energy. The increased strength of the particles also contributes to improving the life of the charge and prevents increased pressure loss in the adsorbent layer.

Another advantage of the high performance adsorbents prepared in accordance with the present invention is their reduced catalytic activity against polymerization and alkylation reactions. The effect of reduced catalytic activity can be particularly favorable when drying or adsorbing mixtures containing reactively unsaturated hydrocarbons.

The method of preparation of the high-performance adsorbent 4A is not adversely affected by the addition of special additives to the mixture of zeolite and binder before the formation of the zeolite adsorbent according to the usual manufacturer's formulation. However, it is possible to reduce the amount or completely eliminate additives which had the function of flooding to improve the kinetic characteristics of the formed adsorbent.

The formed adsorbent must be calcined at temperatures of 350 to 650 ° C before contact with the aqueous sodium hydroxide solution to prevent the adsorbent particles from disintegrating on contact with the aqueous solution. Prior to calcination, it is preferable to dry the adsorbent at a temperature of 100 to 200 ° C. .

In case the starting molded adsorbent 4A is a commercial product, it is not necessary to calcine it before contact with aqueous sodium hydroxide solution, because this operation has already been performed by the manufacturer. \

Both the low-moisture adsorbent is preferably moistened or saturated with water before contact with the aqueous sodium hydroxide solution to prevent excessive and rapid overheating of the adsorbent and solution particles released by the adsorption heat as the solution flows through the adsorbent layer. The adsorbent can be moistened by free contact with ammonia air; humidified air, scientifically or directly when filling it into the container in which the contact takes place.

The contact of the adsorbent with the aqueous sodium hydroxide solution can be carried out in a batch manner in a stirred vessel or, more preferably, in a column apparatus in which a solution of sodium hydroxide flows through a solid layer of adsorbent particles. In order to maximize the utilization of sodium hydroxide in CS 276808 B6, a known two- or multi-stage countercurrent system for contacting the solution with the adsorbent can be used by means of two or more solution reservoirs.

The starting solution may have a sodium hydroxide concentration of up to 10% by weight, preferably 1.5 to 5% by weight. The amount of solution at a given concentration depends on the amount and composition of the aluminosilicate bond in the adsorbent. Per 1 kg of binder, the starting aqueous solution should contain at least 0.4 to 0.6 kg of NaOH, which at an initial concentration of, for example, 2.5% by weight. NaOH represents at least 16 to 24 kg of sodium hydroxide solution per 1 kg of binder.

The temperature when contacting the adsorbent with the solution may be 20 to 130 ° C, preferably 65 to 100 ° C. The pressure is chosen with respect to the operating temperature so that the aqueous solution is kept reliably in the liquid phase.

The contact time of the adsorbent with the solution is in the range of 1 to 10 hours, but 4 hours of intensive contact are sufficient at 65 to 100 ° C to reach a stable final concentration of the solution and thus the degree of conversion of the binder to zeolite 4A.

After completion of the contact with the sodium hydroxide solution, the adsorbent is washed with water at a temperature of 20 to 60 ° C until excess, unreacted hydroxide is removed. The washing phase is terminated when the pH of the washing water drops to 7.5 to 9.

If the final product is high performance adsorbent 4A, washing and high temperature dehydration of the adsorbent at 350 to 600 ° C follow. If a high performance adsorbent 5A is to be prepared, the exchange of Na ⁺ ions for divalent cations, e.g. Ca ^'1' '·., The ion exchange adsorbent washed again with water and then drying and high-temperature dehydratěcia adsorbent. The ion exchange and the washing with water can be carried out in the same device as the contact with the sodium hydroxide solution.

Aqueous exchange solutions of the hydroxide and especially salts of the cation with an inorganic or organic acid are used as ion exchange solutions of divalent cations for the preparation of the high-performance molded adsorbent 5A from 4A. For example, in the preparation of calcium adsorbent 5A, i.e. CaA, ion exchange aqueous solutions of acetate, formate, nitrate, or calcium chloride may be advantageously used. The initial concentrations of the solutions are in the range from 0.05 to 2 mol / l. The ratio of divalent metal equivalents in the starting solution to the original Na ⁺ cations is generally less than 2 = 1, preferably 1 to 1.5: 1 due to efficient use of the ion exchange solution.

From the point of view of ion exchange, the high-performance NaA adsorbent can be evaluated as pure zeolite 4A and therefore the theoretical number of exchangeable metal equivalents is 7.04 gram eq / kg of anhydrous high-performance adsorbent, assuming an average SiO: AL2O3 molar ratio of 2 = 1 in the adsorbent. Preferred temperatures for this ion exchange are 70 to 100 ° C. The high performance adsorbent 4A or 5A, after washing with water, can be dried at temperatures up to 200 ° C directly in the apparatus in which the solutions were contacted or wet washed out of the apparatus.

After drying, it is subjected to dehydration at temperatures of 300 to 600 DEG C., for example in a suitably arranged oven with removal of the adsorbed water vapor.

The high-performance molded adsorbents 4A and 5A prepared by the process of the present invention are, in addition to the advantages already mentioned, demonstrably free of dust that has been washed from their surface during solution contacting and water washing operations.

The following examples illustrate the effectiveness of the invention but do not limit its scope.

Example 1

A mixture containing 20% by weight of binder, expressed as anhydrous zeolite and binder, was prepared from pure powdered zeolite 4A and natural powdered aluminosilicate binder with a molar ratio of SiCl 2 and AlaO of 2.26. After homogenization of the mixture of zeolite and binder and after addition of water, an extrusion-formed adsorbent 4A, in the shape of rollers with a diameter of 1.5 mm, was prepared. The adsorbent was dried at 120 ° C and calcined in an oven by gradually raising the temperature to 50 ° C per hour up to 550 ° C. It was then heated at this temperature for 2 hours. Thus, the starting adsorbent 4A was prepared. A 100 g sample of cooled starting adsorbent 4A was moistened with air humidity for 24 hours and then contacted with 1300 cm ^{3 of} aqueous sodium hydroxide solution at a concentration of 2.5 wt. NaOH.

The one-step contact of the adsorbent with the sodium hydroxide solution was carried out in a glass tempering flask equipped with a thermometer and a bad condenser at a temperature of 100 ° C, i.e. boiling the solution, thus at the same time achieving good stirring without an external source. After contacting at 100 ° C for 4 hours, the residual sodium hydroxide solution was decanted. The adsorbent was washed 3 times in the flask with 300 cm ^{3 of} water. It was then dried at 120 ° C and dehydrated in an oven at 450 ° C. Thus, a high performance adsorbent 4A - V was prepared.

The starting and high-efficiency adsorbent 4A was evaluated by the test of equilibrium adsorption capacity (RAK) for gas in the gas phase at a temperature of 25 ° C, partial pressure of water 0.61 kPa, kinetic characteristic - time of half equilibrium saturation /to.5/. by determining the mechanical strength of the cylindrical particle and the fraction of the crumb particles 0.8 to 1 mm prepared from the cylindrical particles of the extrudate.

Table 1

Absorbent

4A default

4A - High efficiency

RAK - H2O, 25 ° C, g / 100 g to. 5 - Ha 0, with strength, N / particle rollers $ 1.5 mm crumb 0.8 to 1 mm

21.0

138

13.2

3.7

25.3 96

15.2

4.4

From the results of the tests given in tab. 1 it can be seen that the high-performance adsorbent 4A-V has a significantly increased equilibrium adsorption capacity (RAK) on water compared to the initial adsorbent 4A, relative by 20.5%, improved kinetic characteristics, half-saturation time to.5 shortened by 42 s, i.e. by 30.4% and at the same time increased strength.

Example 2

The starting commercial adsorbent 4A, a cylindrical extrudate 1.6 mm in diameter, was contacted without further treatment with a 2.5% strength by weight aqueous sodium hydroxide solution. NaOH and by the same procedure as in Example 1, a high performance adsorbent 4A - KV was prepared.

Table 2

Absorbent

4A - K; 4A - HF starting high efficiency

RAK - HzO, 25 ° C, g / 100 g to. 5 - H2 0, with strength, N / particle rollers 1.6 mm crumb 0.8 to 1 mm

21.0 145

10.1 5.4

24.8

102

14.5

6.8

In tab. 2 are test results showing that a high performance 4A-KV adsorbent 4A with KV with increased particle capacity and strength and improved kinetic characteristics was prepared from a commercial 4A-K adsorbent.

Example 3

Adsorbents 4A and 4A-V prepared according to the procedure of Example 1 were contacted with an ion exchange aqueous solution of calcium salt to modify adsorbent 4A to 5A and high performance adsorbent 4A-V to 5A-V.

100 g of adsorbent 4A and 4A-V were contacted separately in glass teniper flasks with a bad condenser, twice, i.e. in two stages, for 150 minutes with the addition of fresh ion exchange solution of calcium formate at a concentration of 0.2 mol / l in an amount of 1760 cm ³ to each degree. The contact was made by boiling the solution at 100 ° C.

After completion of the ion exchange, the residual ion exchange solution was decanted, the adsorbent was washed 3 times with 300 cm ^{3 of} water, dried at 120 ° C and dehydrated in an oven at 450 ° C.

The calcium adsorbent 5A and high-performance 5A-V thus prepared, in addition to the tests described in Examples 1 and 2, were also evaluated for the equilibrium adsorption capacity on n-heptane at 25 ° C and steam, n-heptane vapor pressure 1.5 KPa.

From the test results given in tab. It can be seen from this that the high-performance adsorbent 5A-V has a significantly increased capacity for both water and n-heptane in comparison with the adsorbent 5A, with excellent kinetic characteristics, in particular for the adsorption rate of n-alkanes and the increased particle strength.

Table 3

Calcium adsorbent 5A 5A-V RAK - H ₂ 0, 25 ° C, g / 100 g 20.1 24.8 RAK - nCy, 25 ° C, g / 100 g 12.9 15.7 t _o . 5 - H2 0, p 204 131 to. 5 - nCv, p 42 10 strength, N / particle rollers 1.6 mm 13.8 15.9 drt 0.8 to 1 mm 3.9 5.8

Example 4

From pure powdered zeolite 4A and natural powdered aluminosilicate binder with a molar ratio of SiCl 2 ^: Al 2 O 3 of 2.26 ', starting and sodium zeolite adsorbents 4A contacted with a binder content of 40% by weight, 50% by weight were prepared according to the procedure described in Example 1. , and 100 wt. clean joint ivo.

In tab. 4 compares their equilibrium water adsorption capacities, including the pair of adsorbents of Example 1 containing 20% by weight of binder. From the changes in the equilibrium adsorption capacities (RAK) on water, it can be seen that up to 40% by weight of the binder in the molded adsorbent 4A, a high-performance adsorbent 4ft was prepared by contacting with an aqueous solution of calcium hydroxide. From the point of view of production, a contacted adsorbent with 50% by weight of binder is also effective, since its capacity is at the level of the starting adsorbent with 20% by weight of binder and at the same time contains 30% by weight, less pure zeolite.

The molded binder itself is not converted into a practically usable adsorbent by contact with aqueous sodium hydroxide solution, as already mentioned in the description of the invention, because the error-initiating component - pure zeolite.

Table 4

Binder content RAK - H ₂ 0, g / 100 g in the adsorbent Adsorbent Adsorbent % wt. default contacted with NaOH . 20 21.0. 25.3 40 16.2 24.8 50 14.5 21.2 100 1.8 2.7

PATENT CLAIMS

Claims (4)

PATENT CLAIMS Process for the preparation of high-performance type A zeolite adsorbents, characterized in that the crystalline powder zeolite 4A is formed with the addition of an aluminosilicate binder, dried after drying at a temperature of up to 200 ° C and / or calcined at 450 to 600 ° C and thus prepared the formed zeolite adsorbent 4A is contacted with an aqueous solution of sodium hydroxide having a concentration of 0.1 to 10% by weight, at a temperature of 20 to 130 ° C, a pressure of 0.1 to 0.5 MPa, for 1 to 10 hours, then excess sodium hydroxide is separated from the adsorbent by washing with water and the washed adsorbent is dried at up to 200 ° C and / or dehydrated at 350-600 ° C to obtain a high performance molded zeolite adsorbent 4A or zeolite adsorbent 4A after contact with aqueous sodium hydroxide solution and washing us in January with water to exchange the Na ⁺ cation for divalent metal cations from the second group of the Periodic Table of the Elements, by further contacting with an aqueous solution of a hydroxide or a salt of this divalent cation at a concentration of 0.05 to 1 mol / liter of solution, at a temperature of 20 to 130 ° C, a pressure of 0.1 to 0.5 MPa for 1 to 10 hours, after the exchange of ions, the excess ion exchange solution is separated from the adsorbent by washing with water and washed the adsorbent is dried at a temperature of up to 200 ° C or further dehydrated at a temperature of 300 to 600 ° C to obtain a high performance molded zeolite adsorbent 5ft. 2. The process according to item 1, characterized in that the molding comprises a minimum of 20 zeolite 4A and a maximum of 80% binder. provided that the mixture is prepared in% by weight of crystalline powder. aluminosilicate 3. The process according to item 1, characterized in that halloysite or kaolin or bentonlt is used as the main silicate bond Ivo. 4. The process according to item 1, characterized in that a molded commercial adsorbent 4A is used as the starting zeolite adsorbent, which is directly contacted with a sodium hydroxide solution without prior calcination to obtain a highly effective adsorbent.