RU2524607C2 - Method of producing recoverable carbon dioxide absorber - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing a recoverable carbon dioxide absorber. The method includes reacting basic zirconium carbonate and zinc oxide. The basic zirconium carbonate is fed for reaction with moisture content of 20-24 mol/kg. Granules are formed using acrylic lacquer as a binding agent in amount of 3-7% with respect to dry substances.

EFFECT: invention increases dynamic activity of the absorber for carbon dioxide and increases the strength of the granules of the absorber.

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Description

The invention relates to a method for producing a regenerable carbon dioxide absorber based on zirconium hydroxide and can be used in a technology for producing regenerable carbon dioxide absorbers for purifying atmospheric carbon dioxide from sealed objects, for creating a controlled gas environment in fruit storage, for purifying atmospheric air in fuel cells and other areas of technology where it is necessary to obtain gases free of carbon dioxide.

A known method of producing a regenerable carbon dioxide absorber based on zirconium hydroxide based on the interaction of solutions of zirconium salts with alkali solutions (AS USSR No. 865381, IPC B01J 20/06, 1981). The method is as follows.

Solutions of zirconyl nitrate and alkali solutions (KOH or NaOH) are prepared. Strong 3-4 n. a solution of zirconyl nitrate is introduced with stirring in 8-20 N. alkali solution. The resulting precipitate of zirconium hydroxide is separated from the mother liquor, dried at a temperature of 50-60 ° C, treated with a solution of alkali, washed with water until a negative reaction to the anions, dried.

To obtain granules, the powder is subjected to molding by known methods.

The disadvantages of this method are the complexity of manufacturing, consisting in a large number of operations, and the use of expensive zirconium salts of zirconium nitrate zirconyl zirconium oxychloride.

A known method of producing a regenerable carbon dioxide absorber based on zirconium hydroxide based on the interaction of a zirconium salt and a substance forming zirconium hydroxide, basic zirconium carbonate is used as the zirconium salt, and alkali and / or alkali and hydroxides are used as the substance forming the zirconium hydroxide and alkaline earth metals (RF Patent No. 2316391, IPC B01J 20/06, 2008).

Oxides and / or hydroxides of alkali and alkaline earth metals can be magnesium oxide (MgO), calcium oxide (CaO), lithium hydroxide (LiOH), magnesium hydroxide (Mg (OH) ₂ ), calcium hydroxide (Ca (OH) ₂ ) Barium hydroxide (Ba (OH) ₂ ).

The method consists in the interaction in the solid phase of powders of basic zirconium carbonate and one of the following substances: magnesium oxide or hydroxide, calcium oxide or hydroxide, barium hydroxide, lithium hydroxide with a molar ratio of metal to zirconium from 1: 0.5 to 1: 2.0 . Mixing is carried out in any suitable device for mixing powdered materials, for example in a two-blade mixer, for 1.0-1.5 hours.

In the process of mixing, the components interact with each other with the formation of a solid phase of zirconium hydroxide.

The resulting product is mixed with a conventional binder, for example polyvinyl alcohol or polyvinyl acetate emulsion, in an amount of 1-3% based on solids.

Then granules are formed by any known method (screwing, tableting, rolling), the obtained granules are dispersed and dried at a temperature of 20-110 ° C.

There is also known a method for producing a regenerable carbon dioxide absorber based on zirconium hydroxide, based on the interaction of a zirconium salt and a substance forming zirconium hydroxide, basic zirconium carbonate is used as a zirconium salt, and zinc oxide and / or zinc hydroxide is used as a substance forming zirconium hydroxide (RF patent No. 2359751, IPC B01J 20/06, 2009). The method is as follows.

The powder of the basic zirconium carbonate and the powder of zinc oxide or hydroxide are mixed at a molar ratio of zinc to zirconium elements from 1: 0.33 to 1: 2.5, preferably from 1: 1.0 to 1: 2.0. Mixing is carried out in any suitable device for mixing powdered materials, for example in a two-blade mixer, for 1.0-1.5 hours.

In the process of mixing, the components interact with each other with the formation of a solid phase of zirconium hydroxide.

To obtain granules, the powder is molded with polyvinyl alcohol or polyvinyl acetate emulsion by known methods. The obtained granules are dried at a temperature of 20-110 ° C.

The disadvantage of this method is the low dynamic activity of the resulting regenerated absorbent for carbon dioxide, which is 3.8-8.5 l / L. Moreover, the strength of the obtained granules of the absorber is insufficient.

The objective of the invention is to develop a method for producing a carbon dioxide absorber, providing improved operational characteristics of the absorber.

The technical result of the invention is to increase its dynamic activity of carbon dioxide and increase the strength of the granules of the absorber.

The technical result is achieved by the invention, according to which, in a method for producing a regenerable carbon dioxide absorber, comprising reacting by mixing the basic zirconium carbonate and zinc oxide with a molar ratio of zinc to zirconium equal to 1: (1-2), molding granules with a binder and drying the absorber, according to According to the invention, the main zirconium carbonate with a moisture content of 20-24 mol / kg is fed into the reaction, and acrylic lacquer in an amount of 3-7% based on dry matter is used as a binder.

The interaction of powders of zinc oxide and basic zirconium carbonate with a moisture content of 20-24 mol / kg leads to the release of water, and the mixture becomes pasty. The presence of a liquid phase in the reactions between solids significantly affects the synthesis conditions, mainly increases the area and surface of interaction between the reactants. This allows you to intensify the reaction between the basic zirconium carbonate and zinc oxide and increase the yield of zirconium hydroxide, which is an active substance in relation to the adsorption of carbon dioxide. Due to this, the resulting absorber has a high dynamic activity of carbon dioxide.

When the moisture content of the basic zirconium carbonate is less than 20 mol / kg, aggregation of particles of the main zirconium carbonate occurs and the formation of an inactive form of the basic zirconium carbonate, which does not interact with zinc oxide.

At a moisture content of the main zirconium carbonate of more than 24 mol / kg, a large amount of water is released as a result of the reaction, and upon subsequent drying, the resulting pasty mixture seizes with the formation of lumps, which virtually eliminates the possibility of further formation of the absorber.

The use of acrylic varnish as a binder allows to increase the mechanical strength of the molded product. This result is achieved due to the fact that acrylic varnish has a greater degree of polymerization compared to polyvinyl alcohol.

The method is as follows.

Mix the powder of the main zirconium carbonate [ZrO ₂ · (4 ÷ 7) H ₂ O · (0.3 ÷ 0.9) CO ₂ ] with a moisture content of 20-24 mol / kg and the powder of zinc oxide [ZnO] at a molar ratio of zinc elements to zirconium (Zn / Zr) from 1: 1.0 to 1: 2.0. In this case, preliminary, the humidity of the basic zirconium carbonate is set in the range of 20-24 mol / kg. To do this, determine the moisture content of the initial basic zirconium carbonate and, depending on the obtained value, the initial powder is either dried or moistened by adding water. The mixing is carried out in a mixer with z-shaped blades, which is used to mix bulk materials with increased particle cohesion, as well as wet. The powders are stirred for 4.0-4.5 hours.

In the process of mixing, the main zirconium carbonate and zinc oxide interact with each other with the formation of zirconium hydroxide [ZrO (OH) ₂ ], which is the target product of the reaction. Then, the resulting pasty mixture is dried to remove excess moisture, which makes it difficult to form absorber granules.

The resulting product is mixed with a binder. As a binder, Ticiana brand acrylic varnish is used, in an amount of 3-7% based on solids.

Then granules are formed by any known method (screwing, tableting, rolling), the obtained granules are dispersed and dried at a temperature of 20-110 ° C.

Example 1

200 g of basic zirconium carbonate with a moisture content of 20 mol / kg containing 0.93 mol of zirconium oxide (ZrO ₂ ) is mixed with 40 g of zinc oxide containing 0.49 mol of ZnO (molar ratio Zn / Zr = 1 / 1.9) and mixed in a mixer with z-shaped blades and for 4 hours, dried the resulting pasty mixture at a temperature of 50 ° C for 12 hours, then add 32 g of Ticiana acrylic varnish to the absorber (7% based on solids) ), mix and form the granules by forcing through 2 mm diameter die, the granules are dried at a temperature of 50 ° C, dispersed in and screens, select a fraction of 1.5 to 2.0 mm

Example 2

170 g of basic zirconium carbonate with a moisture content of 22 mol / kg containing 0.71 mol of ZrO ₂ is mixed with 41 g of zinc oxide containing 0.50 mol of ZnO (molar ratio of Zn / Zr = 1 / 1.4), and mixed in mixer with z-shaped blades for 4 hours, dried the resulting paste-like mixture at a temperature of 50 ° C for 12 hours, then 11 g of Ticiana acrylic varnish (3% based on dry matter) is added to the absorber, mixed and formed granules by pressing through dies with a diameter of 2 mm, the granules are dried at a temperature of 50 ° C, dispersed on sieves, selected TRAC 1.5-2.0 mm.

Example 3

170 g of basic zirconium carbonate with a moisture content of 24 mol / kg containing 0.59 mol of ZrO ₂ is mixed with 30 g of zinc oxide containing 0.37 mol of ZnO (molar ratio of Zn / Zr = 1 / 1.6) and mixed in mixer with z-shaped blades for 4 hours, dried the resulting pasty mixture at a temperature of 50 ° C for 12 hours, then add 14 g of Ticiana acrylic varnish (4% based on solids) to the absorber, mix and form granules by pressing through dies with a diameter of 2 mm, the granules are dried at a temperature of 50 ° C, dispersed on sieves, selected TRAC 1.5-2.0 mm.

Tests of the regenerated carbon dioxide absorber obtained by the claimed method were carried out at a facility simulating the operating conditions of the absorber for air purification of a sealed object; the regeneration of the absorber was carried out by blowing water vapor.

Test conditions:

- the volume of the sample absorber 150 cm ³ ;

- air flow through the absorber layer (16 ± 1) l / min;

- volume fraction of carbon dioxide in the gas medium (0.3 ± 0.02)%;

- air temperature (20-65) ° C;

- relative humidity (30-80)%.

The tests were carried out in sorption-desorption cycles.

The dynamic activity of the obtained absorber is presented as an average over 5 cycles and calculated by the formula

$$a_{cp}=\frac{a_{\mathrm{one}}+a_2+a_3+a_{\mathrm{four}}+a_5}{5},$$

where a _cf - the average dynamic activity of the absorber in CO ₂ , l / l;

and ₁ - the dynamic activity of the absorber by CO ₂ for the first cycle, l / l;

and ₂ is the dynamic activity of the absorber by CO ₂ for the second cycle, l / l;

and ₃ - the dynamic activity of the absorber by CO ₂ for the third cycle, l / l;

and ₄ - the dynamic activity of the absorber by CO ₂ for the fourth cycle, l / l;

and ₅ - the dynamic activity of the absorber by CO ₂ for the fifth cycle, l / l.

The mechanical strength of the absorber granules was determined by the usual crushing method (g / granule).

The test results of the absorber are presented in the table.

Table Absorber Preparation Examples Moisture content of the main zirconium carbonate, mol / kg The amount of binder per dry matter,% The average dynamic activity of CO ₂ l / l The strength of the granules, g / granule According to example 1 twenty 7 9.5 1670 According to example 2 22 3 11.3 820 For example 3 24 four 12.8 900

As can be seen from the data presented, the invention allows to increase the dynamic activity of the absorber based on zirconium hydroxide on carbon dioxide in 1.1-1.5 times in comparison with the prototype, as well as to increase the strength of the granules of the absorber by 2-4 times.

Claims (1)

A method for producing a regenerable carbon dioxide absorber, comprising reacting by mixing the basic zirconium carbonate and zinc oxide with a molar ratio of zinc to zirconium equal to 1: (1-2), molding granules with a binder and drying the absorber, characterized in that the main carbonate is fed into the interaction zirconium with a moisture content of 20-24 mol / kg, and as a binder use acrylic varnish in an amount of 3-7% per dry matter.