CS276808B6 - A method for preparing high-performance type A zeolite absorbents - Google Patents

Abstract

The invention solves a method of preparing highly effective molded zeolite adsorbent type A by contacting the starting zeolite adsorbent 4a formed with the addition of an alumino-silicon binder with an aqueous solution of sodium hydroxide and preparing a highly efficient molded zeolite adsorbent 5a- by exchanging the original Na+ ions in the highly efficient molded zeolite adsorbent 4a with divalent metal cations from the second group of the periodic table systems of elements.

Description

1 EN 276808 86

The invention relates to a process for the preparation of high-efficiency formulated zeolite adsorbents of type A by contacting the starting zeolite adsorbent 4A formed with the addition of a hI1 nitro-chemical bonding agent with an aqueous solution of sodium hydroxide and preparing a high-purity molded zeolite adsorbent 5A by exchange of Na + ions in the high performance molded zeolite adsorbent4A. for divalent metal cations from the second group of periodic components.

Zeolites have significant utility as adsorbents in adsorption separation processes for their selective adsorption properties, which make it possible to separate individual components of the constituent constituents individually from the compound mixtures based on the different diameters of the molten components or the different affinity of the active zeolite to the separated components. components.

Adsorption Processes Based on Zeolite Adsorbents Imagine It! currently economically important technologies that purify barbecue industrial media and produce important intermediate products of the chemical industry. Typical intermediates of the chemical industry produced by high capacity adsorption technologies using type 5A zeolites are liquid n-alkanes, which are the essential component of the production of biodegradable detergents. Equally important is the adsorption purification of industrial exlates and process streams from carbon oxides, sulfur, sulfur dioxide and water. For the drying of hydrocarbon streams to a particularly low residual water content, zeolite adsorbents of type 4A, such as NaA, are preferred. Adsorbent capacity, selectivity, kinetic characteristics and strength of particles, which determine the size of the filling, the dimensions of the adsorber for the required performance, the quality of the product from the adsorption process and the lifetime of the adsorbent filling, are adsorbent capacity, selectivity, kinetic characteristics. The development in the preparation of adsorbents based on synthetic zeolites is therefore permanently oriented towards the improvement of the above-mentioned characteristics.

It is known that zeolite adsorbents are prepared for practical application by molding to different shape and spit particles. Prior to forming the particles, for example by pelletizing, extruding or tabletting, the base zeolite is mixed with a binder which in turn facilitates particle formation, and also increases the mechanical strength of the adsorbent particles. In view of the specific adsorption properties of the zeolite adsorbent, the binder is virtually inert.

Natural aluminosilicate, for example halloysite, kaolin, bentonite, is used as binders for the production of zeolite adsorbents. The addition of these binders, in addition to the advantages already mentioned, also has the disadvantages of having a minimum, yet non-specific adsorption capacity, therefore the adsorption capacity of the zeolite adsorbent is reduced in proportion to its proportion in the adsorbent form, compared to pure zeolite and the kinetic characteristics of the particles or the dynamics of the adsorption CS 276808 B6 2 process may adversely affect.

It is also known that natural aluminosilicate binders can be converted into zeolite type 4Aa further to 5A in a powdery powder form, thereby obtaining similar adsorption capability but at the same time losing binding properties and not being used as binders in this state. The formed binders themselves can also be transferred to the zeolite 4A form, but only after prior activation at extremely high temperatures of 700 to 850 ° C, whereby the non-reactive form of the binder is converted to a reactive which is capable of re-crystallization to zeolite.

It has been found that the subject of the present invention is made of zeolite adsorbent 4A formed with the addition of aluminosilicate binder without the above drawbacks of high-performance formulated zeolite adsorbents of type 4A and 5A with increased adsorption capacity, improved kinetic characteristics and improved strength, characterized in that the crystalline zeolite 4A powder is formed with the addition of an aluminosilicate binder, after molding it is heated to 200 ° C and / or calcined at 450 to 600 ° C and the calcined formed zeolite adsorbent 4A or the ready-made commercially formed zeolite adsorbent 4A is formed contacting the 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 a period of 1 to 10 hours, then 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 tar drilling at 350 to 600 ° C to obtain high-performance formulated zeolite adsorbent 4A or contacting the zeolite adsorbent 4A with an aqueous solution of sodium hydroxide followed by water washing followed by a Na + exchange of the divalent metal cations of the second group of the periodic system by contacting the aqueous hydroxide or salt solution of the divalent cation with a cation concentration of 0.05 to 1 mol / l of 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, an excess of ion-mercury solution is separated from the adsorbent by washing with water and the washed adsorbent is dried to 200 ° C or dehydrated further at 300 to 600 ° C, m high zeolite adsorbent 5A is obtained.

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

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

According to the present invention, conventional commercially formed type 4A adsorbents, i.e. NaA, which typically contain about 20 wt. adsorption-inert aluminosilicate binder to high-performance adsorbents 4A or 5A with adsorption capacity increased by about 20%, enhanced by strength and improved kinetic characteristics. The preparation of the high-performance adsorbents according to the invention presents a positive effect on both manufacturers and consumers. . In the production of the adsorbent, it is possible to increase the binder content, which is cheaper than pure zeolite 4A, for example 30 to 40%, or up to 80% by weight. According to the type and quality, and in the adsorption process itself, in proportion to the increased capacity of the adsorbent, to reduce its filling and the dimensions of the adsorber or in the apparatus, production and energy savings can be achieved. The increased particle strength also contributes to improving the life of the cartridge and prevents the pressure buildup in the adsorbent layer. Another advantage of the high-performance adsorbents prepared by the present invention is their reduced catalytic activity against polymerization and alkylation reactions. The effect of reduced catalytic activity may be particularly favorable in the drying or adsorption of mixtures containing their reactively unsaturated hydrocarbons.

The process for the preparation of the high-performance adsorbent 4A is not adversely affected by the addition of special additives to the zeolite-binder mixture prior to forming the zeolite adsorbent according to the established manufacturers' formula. However, it is possible to reduce or completely eliminate additives that have the function of improving the kinetics of the formed adsorbent.

The formed adsorbent must be calcined at temperatures of 350 to 650 ° C prior to contacting the aqueous sodium hydroxide solution to avoid disintegration of the adsorbent particles upon contact with the aqueous solution. Before calcination, it is preferable to dry the adsorbent at a temperature of 100 to 200 ° C. If the starting molded adsorbent 4A is a commercial product, it is not necessary to calculate it prior to contact with the aqueous sodium hydroxide solution, since this has already been carried out by the manufacturer.

It is preferable to calculate the calcined low moisture adsorbent to moisten and hydrate the water prior to contacting the aqueous sodium hydroxide solution so that, when the solution flows through the adsorbent layer, the adsorbent particles and the solution are not overheated rapidly by the adsorption heat. The adsorbent can be wetted by free contact with the amphospheric air; damp air, water or directly when filling it into a container in which contact is made.

The contact of the adsorbent with the aqueous sodium hydroxide solution can be carried out in a batch process in a solution mixing vessel or more preferably in a column apparatus in which a sodium hydroxide solution flows through the solid adsorbent particle layer. In order to maximize the use of sodium hydroxide, a two-stage or countercurrent solution-to-adsorbent system can be used by using two or more containers of solution. The starting solution may have a sodium hydroxide concentration of 10% by weight, preferably 1.5 to 5% by weight. The amount of solution at a given concentration is dependent on the amount and composition of the aluminosilicate binder in the adsorbent. For 1 kg of binder, the starting aqueous solution should contain at least 0.4 to 0.6 kg of NaOH at an initial concentration of, for example, 2.5% by weight. NaOH represents at least 16-24 kg of sodium hydroxide solution per kg of binder.

The temperature of contacting the adsorbent with the solution is 20 to 130 ° C, preferably 65 to 100 ° C. The pressure is selected with respect to the working temperature so as to maintain the aqueous solution 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 intense contact is sufficient for 65 hours to reach a steady-state final concentration of solution and hence the degree of conversion of the binder to zeolite 4A.

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

If the final product of the high performance adsorbent 4A is followed by drying, drying and high temperature dehydration of the adsorbent at 350 to 600 ° C. If a high-performance adsorbent 5A is to be prepared, immediately after washing with water, the Na + ion exchange of double-stranded cations, e.g., Ca @ + +, is observed. After ion exchange, washing of the adsorbent with water and then drying and high temperature dehydration of the adsorbent exchange. The ions and washing with water can be carried out in the same apparatus as contacting with the sodium hydroxide solution.

As ion exchange solutions of divalent cations for the preparation of the high-efficiency formulated adsorbent 5A of 4A, aqueous solutions of hydroxide and mainly salts of the cation with the inorganic or organic acid are used. For example, ionic aqueous solutions of acetate, formate, nitrate, or calcium chloride may be used in the preparation of calcium adorbent 5A, that is, CaA, and the base concentrations of the solutions are in the range of 0.05-2.

The ratio of equivalents of divalent metal in the starting solution to the Na + cation is, in particular, less than 2 = 1, preferably 1 to 1.5 = 1 due to the efficient use of the ion exchange solution.

The high-performance NaA adsorbent can be evaluated as pure 4A zeolite for ion exchange, hence the theoretical number of exchangeable metal equivalents is 7.04 gram / kg anhydrous high-performance adsorbent, assuming an average molar SiO ratio in the adsorbent. AL2O3 2 = 1. Preferred temperatures in this ionic exchange are 70 to 100 ° C.

The high-performance adsorbent 4A or 5A is washed with water at a temperature of up to 200 ° C directly in the apparatus where contact with the solutions has been completed or wetted from the equipment.

After drying, it is subjected to dehydration at temperatures of 300 to 600 ° C, for example in a suitable arranged furnace with a pair of water removed.

The high-performance molded adsorbents 4A and 5A prepared according to the invention are, in addition to the advantages already mentioned, remarkably free of dust which has been washed away from their surface during the contacting operations with the solutions and washing with water.

The following examples illustrate the effectiveness of the invention but do not limit its scope. Example 1 From pure powdered zeolite 4A and a natural powdered aluminosilicate binder with a SiO 2 molar ratio of Al 2 O 3 2.26 prepared a zraes containing 20 wt. binder, expressed as a solid state of zeolite and binder. After the homogenization of the zeolite / composite mixture and after the addition of water, an extruded adsorbent 4A was prepared, in the form of rollers having a diameter of 1.5 mm. The adsorbent was dried at 120 ° C and calcined in the furnace by gradually increasing the temperature by 50 ° C per hour to 550 ° C. At this temperature, it was then heated for 2 hours. Thus, the starting adsorbent 4A was prepared. A sample of cooled 4A adsorbent at 100 g 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% by weight. NaQH.

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 poor condenser at a temperature of 100 ° C, i.e. with a varor solution, thereby achieving a substantial mixing without an external source. After 4 hours of contacting at 100 ° C, the residual sodium hydroxide solution was decanted. The adsorbent in the flask was 3 times with 300 cm 3 of water. It was then dried at 120 ° C and dehydrated in an oven at 450 ° C. The high-performance adsorbent 4A-V was prepared in this way. The 4A adsorbent starting and high-performance adsorbents were evaluated by comparing the adsorption capacity (RAK) to water in a gaseous phase of 25 ° C, water pressure 0.61 kPa, kinetic characteristics - half equilibrium time. saturating (.times.5), determining the mechanical strength of the cylindrical particle and the particle size fraction of 0.8 to 1 mm, prepared from cylindrical extrudate particles. CS 276808 B6 6

Table 1

Absorbent

4A default

4A - V High Performance RAK - H2O, 25 ° C, g / 100 g 21.0 25.3 to. 5 - H2O, with 138 96 strength, N / roller particle $ 1.5 rounds 13.2 15.2 drb 0.8 to 1 mm 3.7 4.4 2 test results shown in Tab. 1 shows that the high-performance adsorbent 4A-V has a markedly increased equilibrium adsorption capacity (RAK / water) relative to the starting adsorbent 4A, relative to the 20.5 improved kinetic characteristic, half-saturation time to 5 s reduced by 42 sec, thus a 30.4% increase in strength. EXAMPLE 2 The starting commercial adsorbent 4A, a 1.6 mm diameter cylindrical extrudate, was contacted with an aqueous solution of sodium hydroxide at a concentration of even 2.5% by weight without further treatment. NaOH and the same procedure as in Example 1, a 4A-KV high performance adsorbent was prepared.

Table 2

Absorbent

4A - K 4A - KV high performance RAK - H2O, 25 ° C, g / 100 g 21.0 to. 5 - H2 0, with 145 strength, N / particle rollers 1.6 mm 10.1 crush 0.8 to 1 mm 5.4 24.8 102 14.5 6.8 In tab. 2 are test results showing that a high performance adsorbent 4A-KV with increased capacity and strength of particle improved kinetic characteristics from commercial adsorbent 4A, labeled 4A-K. Example 3

The adsorbents 4A and 4A-V prepared according to the procedure of Example 1 were contacted with an ion exchange aqueous solution of calcium salts with the targetification of adsorbent 4A to 5A and high performance adsorbent 4A-V 7 CS 276808 B6 to 5A-V. 100 g of adsorbent 4A and 4A-V were separately contacted with glass tempering flasks with a poor condenser, twice, i.e. in two steps, after 150 ml with addition of fresh ion-exchange calcium formate at a concentration of 0.2mol / l after 1760 cm 3 to each degree. Contact is made 1 at the boiling point of the solution at 100 ° C.

After ion exchange was complete, 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.

Calcium adsorbent 5A and high-performance 5A-Vsa prepared in this way were also evaluated by equilibrium adsorption capacity to n-heptane at 25 ° C and steam in addition to the tests given in Examples 1 and 2. n-heptane pellet 1.5 KPa. From the results of the tests given in Tab. 3 shows that the high-performance adsorbent 5A-V has a markedly increased water capacity and excellent heptane-excellent kinetic characteristics compared to the adsorbent 5A, in particular the n-alkane adsorption rate and the increased particle strength.

Table 3 Calcium adsorbent 5A 5A-V RAK - H20, 25 ° C, g / 100 g 20.1 24.8 RAK - nC7, 25 ° C, g / 100 g 12.9 15.7 to, 5 "H2 0 , With 204 131 it. 5 - nC7, s 42 10 strength, N / particle rollers> / 1,6 mm 13,8 15,9 crush 0,8 to 1 mm 3,9 5,8 Example 4 Of pure 4A zeolite and natural aluminum powder of the silicate binder having a SiCl 2 molar ratio of Al 2 O 3 2.26%, prepared by the method of Example 1 starting and sodium hydroxide solution, formed formed zeolite adsorbents 4A with a binder content of 40% by weight, 50% by weight. and 100 wt. .- purefeed. Tab. 4 compares their equilibrium adsorption capacities, including the pair of adsorbents of Example 1 containing 20% by weight. binders. From changes in equilibrium adsorption capacities (RAK), it can be seen that up to 40 wt. of said binder in the formed 4A adsorbent was prepared by contacting with an aqueous solution

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.