KR20240122714A - Composition for carbon dioxide absorbent - Google Patents

Abstract

The present invention provides a composition for a carbon dioxide absorbent, comprising: an active ingredient comprising a mixture of potassium carbonate and potassium bicarbonate; a support comprising a mixture of alpha-alumina, titanium dioxide (TiO ₂ ), and zirconium dioxide (ZrO ₂ ); an inorganic binder comprising a mixture of bentonite, pseudoboehmite, and synthetic calcium silicate; and activated carbon, wherein the mixture of potassium carbonate and potassium bicarbonate is characterized in that a mixing ratio of potassium carbonate to potassium bicarbonate is 0.9 to 1.8:1 by weight.

Description

COMPOSITION FOR CARBON DIOXIDE ABSORBENT

The present invention relates to a composition for a carbon dioxide absorbent. More specifically, it relates to a solid carbon dioxide absorbent in which a support is formed on an active material of the absorbent to increase porosity.

As the average temperature of the Earth rises due to the greenhouse effect caused by the increase in carbon dioxide concentration in the atmosphere, the damage of climate change is continuously occurring. Thermal power plants are the largest fixed emission source of anthropogenic carbon dioxide emissions. Carbon dioxide emissions reduction from thermal power plants can be achieved through carbon dioxide capture and storage (CCS). Methods for capturing carbon dioxide from large-scale carbon dioxide emitting facilities such as power plants include wet chemical absorption, absorption, membrane separation, and low-temperature cooling separation. However, these methods have the problem of high recovery costs or difficulty in applying them to power plants or large-scale industries.

In addition to the above methods, there is a dry _CO2 capture technology as _a method of capturing carbon dioxide. This technology captures carbon dioxide contained in exhaust gas by using a solid absorbent instead of a liquid absorbent used in conventional wet chemical cleaning, and then repeats the process of separating pure carbon dioxide and regenerating the absorbent using steam and an additional heat source. The dry _CO2 capture technology has the advantage of requiring a small installation area for the carbon dioxide capture facility and being easy to operate because it uses a fluidized bed process.

Conventional patents related to absorbents used in such dry _CO2 capture technology include U.S. Patent No. 7,045,483 and U.S. Patent No. 6,280,503. However, the above patents are mainly limited to combinations of active substances, supports, and inorganic and organic binders, or combinations of active substances and supports, or improvements in active ingredients, and there is a problem that the absorbents are manufactured by physical mixing or a support method, and are not suitable for mass production. In addition, since the carbon dioxide absorption performance and regeneration performance of the absorbents are low, there is a limit to using the absorbents for a long period of time, and there is also a problem that the use efficiency of the absorbents is low.

In addition, in the case of solid carbon dioxide absorbents, there is a problem that the carbon dioxide absorption capacity is reduced due to side reactions between the active ingredient and the support and binder for maintaining the solid form.

Therefore, there is an urgent need to develop a solid carbon dioxide absorbent that can be repeatedly regenerated by forming a support while increasing carbon dioxide absorption performance, thereby increasing usability.

Prior literature related to this includes US Patent No. 7,045,483 (May 16, 2006).

The present invention is intended to solve the above-described problems, and provides a composition for a carbon dioxide absorbent which prevents the carbon dioxide absorption capacity from being reduced due to the active ingredient reacting with a support or binder during the manufacture of the absorbent, and which improves the pores and specific surface area of the absorbent due to the support.

Another object of the present invention is to provide a method for manufacturing a solid carbon dioxide absorbent capable of mass producing a solid carbon dioxide absorbent having improved wear resistance and carbon dioxide absorption performance by controlling the composition of the solid carbon dioxide absorbent and the mixing ratio and homogenization of raw materials.

In addition, the present invention provides a solid carbon dioxide absorbent having an active ingredient and a support ingredient capable of maintaining carbon dioxide absorption capacity while sufficiently maintaining pores and specific surface area even when repeated absorption and regeneration cycles in a fluidized bed absorption process.

The above and other objects of the present invention can all be achieved by the present invention described below.

1. One aspect of the present invention relates to a composition for a carbon dioxide absorbent.

The composition for the above solid carbon dioxide absorbent comprises an active ingredient comprising a mixture of potassium carbonate and potassium bicarbonate;

A support comprising a mixture of alpha-alumina, titanium dioxide (TiO ₂ ), and zirconium dioxide (ZrO ₂ );

Inorganic binder comprising a mixture of bentonite, pseudoboehmite and synthetic calcium silicate; and

May contain activated carbon.

2. In the above specific example, the solid carbon dioxide absorbent composition may include 36 to 39 wt% of a mixture of potassium carbonate and potassium bicarbonate, 15 to 25 wt% of alpha-alumina, 5 to 10 wt% of titanium dioxide, 15 to 25 wt% of zirconium dioxide, 4 to 6 wt% of bentonite, 4 to 5 wt% of pseudo-boehmite, 6 to 8 wt% of synthetic calcium silicate, and 2 to 4 wt% of activated carbon based on the total weight of the composition.

3. In the above two specific examples, the mixture of potassium carbonate and potassium bicarbonate may have a mixing ratio of potassium carbonate to potassium bicarbonate of 0.9 to 1.8:1 by weight.

4. In the above specific examples 1 to 3, the specific surface area of the titanium dioxide may be 25 to 200 m2/g, the specific surface area of the pseudoboehmite may be 100 to 400 m2/g, and the specific surface area of the zirconium dioxide (ZrO ₂ ) may be 10 to 300 m2/g.

5. Another aspect of the present invention comprises the steps of (a) preparing a slurry by using the solid carbon dioxide absorbent composition as a solid raw material and adding a solvent;

(b) a step of stirring and homogenizing the slurry;

(c) a step of spray drying the homogenized slurry to form particles; and

(d) It provides a method for manufacturing a solid carbon dioxide absorbent, including the steps of drying and calcining the particles.

6. In the above five specific examples, the solvent may include water.

7. In the above 5 to 6 specific examples, the composition for carbon dioxide absorbent may be included in an amount of 40 to 60 wt% based on the total weight of the slurry.

8. In the above 5 to 7 specific examples, in the step (b), one or more additives selected from the group consisting of a dispersant, an antifoaming agent, and an organic binder may be added to the slurry.

9. In the above 9 specific examples, the additives may be added as 0.01 to 5 parts by weight of a dispersant, 0.01 to 0.5 parts by weight of a defoaming agent, and 1 to 5 parts by weight of an organic binder per 100 parts by weight of the solid raw material.

10. In the above 5 to 9 specific examples, the drying in step (d) may be performed at 110 to 150°C for 2 to 24 hours, and the calcination may be performed in a high-temperature calcination furnace in an air atmosphere by raising the temperature to 550 to 650°C at a rate of 1 to 5°C/min for 3 to 10 hours.

11. Another aspect of the present invention provides a solid carbon dioxide absorbent manufactured by the above-described method for manufacturing a solid carbon dioxide absorbent, characterized in that the attrition index (AI) according to the following formula 1 is 10% or less and the porosity measured by the mercury adsorption method is 18% or more:

[Formula 1]

Wear index (AI, %) = (W ₁ (g) / W ₀ (g)) × 100

(In the above formula 1, W ₁ is the total weight (g) of the absorbed fine powder collected by performing an abrasion test under the condition of a flow rate of 10.0 L/min (based on 273.15 K, 1 bar) in an abrasion tester according to ASTM D5757-95,

The above W ₀ is the initial weight of the absorbent (g, nominally 50 g).

12. In the above 11 specific examples, the solid carbon dioxide absorbent may have an average particle size of 60 to 200 ㎛, a particle size distribution of 30 to 400 ㎛, and a packing density of 0.6 to 2.0 g/cm ³ .

13. In the above 11 or 12 specific examples, the carbon dioxide absorption capacity of the solid carbon dioxide absorbent may be 6 wt% (6 g CO ₂ / 100 g sorbent) or more.

14. In the above 11 to 13 specific examples, the solid carbon dioxide absorbent may be spherical.

The composition for a solid carbon dioxide absorbent according to the present invention selects potassium carbonate and potassium bicarbonate as active ingredients, and selects alpha-alumina and pseudo-boehmite as supports capable of reducing the amount of carbon dioxide, thereby preventing the carbon dioxide absorbent from losing its carbon dioxide absorption capacity during the carbon dioxide absorption regeneration process.

In particular, potassium bicarbonate, which increases pore formation, is included in the active ingredient, titanium dioxide is selected to stabilize the active ingredient, and zirconium dioxide is selected to impart endothelial toxicity to regenerative and pollutant substances, bentonite, pseudoboehmite, and synthetic calcium silicate are used as inorganic binders, and activated carbon is added during the calcination process with an optimal solid raw material composition to maintain the physical properties of the solid carbon dioxide absorbent while minimizing the induction of side reactions of potassium carbonate and improving the overall porosity and carbon dioxide absorption capacity.

The efficiency of manufacturing a solid carbon dioxide absorbent can be greatly improved by manufacturing a slurry of a solid raw material containing an active ingredient and a support and mass-producing it by spray drying.

The final manufactured solid carbon dioxide absorbent is suitable as an absorbent in a fluidized bed reactor in a spherical shape.

Figure 1 is a flow chart showing a method for manufacturing a solid carbon dioxide absorbent according to one specific example of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the attached drawings. However, the drawings are provided only to help understand the present invention, and the present invention is not limited by the drawings. In addition, the shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings are exemplary, and the present invention is not limited to the matters illustrated.

Throughout the specification, the same reference numerals refer to the same components. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the present invention, the detailed description is omitted.

In the case where 'includes', 'has', 'consists of', etc. are used in this specification, other parts may be added unless 'only' is used. In the case where a component is expressed in the singular, it includes cases where the plural is included unless there is a special explicit description.

When interpreting a component, it is interpreted as including the error range even if there is no separate explicit description.

When the positional relationship between two parts is described as 'on top of', 'upper part of', 'lower part of', 'next to', etc., one or more other parts can be located between the two parts unless 'right away' or 'directly' is used.

Positional relationships such as 'upper', 'top surface', 'lower surface', and 'lower surface' are only described based on the drawing, and do not represent absolute positional relationships. In other words, depending on the observation position, the positions of 'upper' and 'lower' or 'upper surface' and 'lower surface' may change.

Composition for carbon dioxide absorbent

One aspect of the present invention relates to a composition for a solid carbon dioxide absorbent.

The above solid carbon dioxide absorbent comprises an active ingredient, a support, an inorganic binder and activated carbon.

The above active ingredient is a substance that selectively reacts with carbon dioxide to efficiently capture and separate carbon dioxide from a gas stream, and the types of the active ingredient include potassium carbonate and potassium bicarbonate and mixtures thereof, or precursors that can be converted into the above substances, and may be synthetic or natural raw materials, and preferably have a purity of 99% or higher, but are not limited thereto.

In one specific example, the active ingredient is a mixture of potassium carbonate and potassium bicarbonate.

The above potassium carbonate is less affected by moisture, has a faster reaction rate to carbon dioxide than sodium carbonate among alkali metal carbonates, and can undergo a reversible regeneration reaction by heat after combining with carbon dioxide.

The support increases the usability of the active ingredient by allowing the active ingredient to be well distributed within the solid carbon dioxide absorbent particles, and creates a passage for smooth diffusion of gas between the outside of the particles and the active substance before and after the reaction.

The above support simultaneously prevents agglomeration between particles and facilitates the adsorption and absorption of moisture necessary for the reaction between the active ingredient and carbon dioxide, thereby increasing the reaction rate.

In one specific example, the support is a mixture of alpha-alumina, titanium dioxide (TiO ₂ ), and zirconium dioxide (ZrO ₂ ).

When the above support is a mixture of alpha-alumina, titanium dioxide (TiO ₂ ), and zirconium dioxide (ZrO ₂ ), and when the above active ingredient is potassium carbonate, the active ingredient distributed within the support is stabilized during the absorbent calcination process, thereby suppressing side reactions that may occur during the repeated cycle of absorbing carbon dioxide and then regenerating it.

The above zirconium dioxide (ZrO ₂ ) also plays a role in preventing the deterioration of absorbent performance due to contact with air currents containing pollutants such as sulfur dioxide.

In one specific example, a pseudoboehmite that can act as both an inorganic binder to provide strength to the solid carbon dioxide absorbent and an active ingredient support can be used together.

The above-mentioned inorganic binder is densely packed between absorbent compositions to enable the manufacture of a high-density absorbent, enhances the binding force between the active ingredient and the support to provide strength to the absorbent, and enables the absorbent to be used without loss due to long-term wear.

In one specific example, the inorganic binder is a mixture of bentonite, pseudoboehmite, and synthetic calcium silicate.

Meanwhile, the composition for the solid carbon dioxide absorbent contains activated carbon as a pore forming agent.

When the above activated carbon is included, the porosity can be increased through the calcination process.

In one specific example, the composition for the solid carbon dioxide absorbent comprises 36 to 39 wt% of a mixture of potassium carbonate and potassium bicarbonate; 15 to 25 wt% of alpha-alumina; 5 to 10 wt% of titanium dioxide; 15 to 25 wt% of zirconium dioxide; 4 to 6 wt% of bentonite; 4 to 5 wt% of pseudoboehmite; 6 to 8 wt% of synthetic calcium silicate; and 2 to 4 wt% of activated carbon.

The composition for the above solid carbon dioxide absorbent comprises 36 to 39 wt% of a mixture of potassium carbonate and potassium bicarbonate.

The above potassium carbonate and potassium bicarbonate are active substances that react with carbon dioxide.

If the content of the mixture of potassium carbonate and potassium bicarbonate is less than 36 wt%, there is a concern that the carbon dioxide absorption capacity may decrease, resulting in a decrease in the capture efficiency.

If the content of the mixture of potassium carbonate and potassium bicarbonate exceeds 39 wt%, the active ingredient cannot be efficiently utilized, the shape of the solid carbon dioxide absorbent manufactured into a spherical shape may be deformed, the moisture absorption amount may increase, making it easy to stick to the structure in the fluidized bed absorption reactor, and there is a concern that physical properties such as strength and packing density may deteriorate.

In one specific example, the mixture of potassium carbonate and potassium bicarbonate has a weight ratio of potassium carbonate to potassium bicarbonate of 0.9 to 1.8:1.

If the mixing ratio of the above potassium carbonate and potassium bicarbonate is outside the above range, the effect of pore formation resulting from the addition of potassium bicarbonate may be minimal or a problem may occur in which the absorbent is not formed into a spherical shape.

It is preferable that the purity of the above active ingredient be 98% or higher.

The above alpha-alumina, titanium dioxide (TiO ₂ ), and zirconium dioxide (ZrO ₂ ) form a support.

The above support can increase the usability of the active ingredient by distributing the active ingredient well within the solid absorbent particles.

The above support stabilizes the active ingredient and suppresses side reactions in the regeneration cycle of the solid carbon dioxide absorbent.

The above alpha alumina is contained in an amount of 15 to 25 wt%.

The above alpha alumina has a low specific surface area and therefore a small water absorption capacity, which causes excessive contact between the active ingredient dispersed in the absorbent and water, resulting in the elution of the active ingredient, resulting in a decrease in performance and problems of coagulation between particles.

To prevent the above problem, titanium dioxide, zirconium dioxide, and pseudoboehmite having relatively large specific surface areas compared to alpha-alumina can be selected to alleviate the dissolution of the active ingredient.

When the content of the above alpha alumina exceeds 25 wt%, there is a problem of performance degradation due to elution of the active ingredient.

The above titanium dioxide is contained in an amount of 5 to 10 wt% and zirconium dioxide in an amount of 15 to 25 wt%.

When added within the above range, the dissolution of the active ingredient can be alleviated while limiting the alpha-alumina content.

In one specific example, the specific surface area of the titanium dioxide is 25 to 200 m2/g, the specific surface area of the pseudoboehmite is 100 to 400 m2/g, and the specific surface area of zirconium dioxide (ZrO ₂ ) is 10 to 100 m2/g or more, and the upper limit is 300 m2/g.

The support is contained in the solid carbon dioxide absorbent in an amount of 45 to 55 wt%.

Specifically, each substance is not added alone, but is included as a mixture containing one or more components.

When the above support is composed of a mixture, the properties of each material can appear as properties of the combination of materials.

If the support content is less than 45 wt%, the physical strength of the solid carbon dioxide absorbent may be reduced and the dispersion of the active ingredient may be affected, which may lower the absorption capacity of the absorbent or lower the performance due to coagulation between absorbents caused by moisture. If it exceeds 55 wt%, the physical strength may be excellent, but the content of the active ingredient may be relatively low, which may lower the performance.

The above bentonite, pseudoboehmite, and synthetic calcium silicate form an inorganic binder.

The above-mentioned inorganic binder can be used by mixing one or more selected from the group consisting of cements, clays, and ceramics.

The above-mentioned inorganic binder is densely packed between absorbent compositions to enable the manufacture of a high-density absorbent, enhances the binding force between the active ingredient and the support to provide strength to the absorbent, and enables the absorbent to be used without loss due to long-term wear.

In one specific example, the inorganic binder is a mixture of bentonite, pseudoboehmite, and synthetic calcium silicate.

The above synthetic calcium silicate is contained in an amount of 6 to 8 wt%.

The above synthetic calcium silicate is an inorganic binder for cement, and reacts with potassium carbonate, an active ingredient, to reduce the carbon dioxide absorption capacity of potassium carbonate, so its content is limited to 6 to 8 wt%, which is necessary for implementing strength.

The above bentonite is contained in an amount of 4 to 6 wt%.

The above bentonite is a clay-type inorganic binder, and is specifically Na-type bentonite.

The above pseudoboehmite is contained in an amount of 4 to 5 wt%.

When pseudoboehmite is added within the above range, it is advantageous for implementing the strength of the solid carbon dioxide absorbent and increasing the specific surface area. However, when it is outside the above range, there is a problem in that it reacts with potassium carbonate, which is an active ingredient, and the carbon dioxide absorption capacity of potassium carbonate is reduced.

The above-mentioned inorganic binder is contained in the range of 15 to 20 wt% in the above-mentioned solid carbon dioxide absorbent.

If the content of the above-mentioned inorganic binder is less than 15 wt%, there is a concern that the physical properties may deteriorate due to a decrease in the bonding strength between the active ingredient, support, and inorganic binder, which are raw materials, and if it exceeds 20 wt%, the content of the active ingredient and the specific surface area of the absorbent are relatively reduced, which deteriorates the dispersion of the active ingredient and lowers the carbon dioxide absorption capacity.

The composition for the above solid carbon dioxide absorbent includes activated carbon, and the activated carbon can form pores by burning during the calcination process.

The above activated carbon is manufactured by adding 2 to 4 wt% of the solid carbon dioxide absorbent raw material.

If the content of the activated carbon is less than 2 wt%, the pore-forming effect is minimal, and if it exceeds 4 wt%, there is a concern that the strength of the solid carbon dioxide absorbent produced after calcination may be reduced.

Another aspect of the present invention provides a method for producing a solid carbon dioxide absorbent, comprising the steps of (a) preparing a slurry by using the solid carbon dioxide absorbent composition as a solid raw material and adding a solvent; (b) stirring and homogenizing the slurry; (c) spray drying the homogenized slurry to form particles; and (d) drying and calcining the particles.

Figure 1 is a flow chart showing a method for manufacturing a solid carbon dioxide absorbent according to one specific example of the present invention.

Referring to Figure 1, first, a solid raw material including an active ingredient, a support, and an inorganic binder is mixed with a solvent to prepare a slurry (S100).

The above solid raw material includes an active ingredient which is a mixture of potassium carbonate and potassium bicarbonate, a support which is a mixture of alpha-alumina, titanium dioxide (TiO ₂ ), and zirconium dioxide (ZrO ₂ ), and an inorganic binder which is a mixture of bentonite, pseudoboehmite, and synthetic calcium silicate.

The composition for the above carbon dioxide absorbent is included in an amount of 40 to 60 wt% based on the total weight of the slurry.

The composition and content of the above solid raw material are as described above.

The type of the above solvent is not particularly limited, and solvents commonly used in the relevant field can be used.

In one specific example, water can be used as the solvent.

If the content of the solid raw material in the above slurry is less than 40 wt%, the amount of slurry for producing a solid carbon dioxide absorbent may increase, which may lower the production efficiency. If it exceeds 60 wt%, it is difficult to control the stability of the slurry as the concentration of the slurry increases, and the viscosity of the slurry increases, which lowers the fluidity, making it difficult to perform the spray drying step.

The above slurry is stirred to homogenize (S200).

In the step (b), one or more additives selected from the group consisting of a dispersant, an antifoaming agent, and an organic binder may be added to the slurry.

In order to impart plasticity and dispersibility to the solid raw material included in the above slurry, prevent the grinding efficiency from being reduced due to agglomeration when grinding into a fine powder having an average particle size of 10 nm to 5,000 nm, and control the strength and density of the particles after spray drying, one or more additives selected from the group consisting of a dispersant, an antifoaming agent, and an organic binder may be additionally included.

In one specific example, the additive comprises all of the dispersant, the defoaming agent, and the organic binder.

Specifically, the additives are added as 0.01 to 5 parts by weight of a dispersant, 0.01 to 0.5 parts by weight of a defoaming agent, and 1 to 5 parts by weight of an organic binder per 100 parts by weight of the solid raw material.

The above dispersant can be used as an anionic, amphoteric or zwitterion dispersant, or a combination thereof, and in this case, it is particularly suitable for producing a high-concentration slurry having a solid raw material content of 15 to 60 wt% in the slurry.

The above anionic dispersant may be at least one selected from the group consisting of polycarboxylic acid, polycarboxylic acid amine, polycarboxylic acid amine salt, and polycarboxylic acid soda salt.

The above anionic dispersant can be added in an amount of 0.01 to 5 parts by weight relative to the solid raw material.

The above-mentioned foaming agent is used to remove air bubbles in a slurry to which a dispersant and an organic binder are applied.

In one specific example, the antifoaming agent is a nonionic surfactant of metal soap type and polyester type, and is at least one selected from the group consisting of a silicone type antifoaming agent, a metal soap type antifoaming agent, an amide type antifoaming agent, a polyether type antifoaming agent, a polyester type antifoaming agent, a polyglycol type antifoaming agent, and an alcohol type antifoaming agent.

The above organic binder is added during the slurry manufacturing process to provide plasticity and fluidity to the slurry and ultimately maintain the shape of the porous particles formed by spray drying, thereby providing strength to the particles before drying and calcination, making it easy to handle the solid carbon dioxide absorbent.

In one specific example, the organic binder is at least one selected from the group consisting of polyvinyl alcohol, polyethylene glycol, and methyl cellulose.

The above organic binder is included in an amount of 1 to 5 parts by weight relative to the total solid raw materials.

If the above content is less than 1 part by weight, it is difficult to maintain a spherical shape until drying and firing due to a decrease in the binding force of the solid particles formed by spray drying, and if it exceeds 5 parts by weight, there is a concern that the performance of the final solid carbon dioxide absorbent may be reduced due to residual pollen after firing.

Meanwhile, a pH regulator may be additionally added to control the pH of the slurry.

The pH regulator may be an organic amine or ammonia water, and the amount may be adjusted so that the pH is between 9 and 12.

If the pH is too low, the viscosity may increase due to coagulation between particles during the slurry manufacturing process, making stirring and grinding impossible. If the pH is too high, it may cause damage, such as corrosion, to the slurry manufacturing device or the drying and calcining device.

The above slurry is homogenized after stirring.

The above stirring is performed using a stirrer, and stirring may be performed during the process of adding the solid raw material and the solvent or after both the solid raw material and the solvent have been added.

The above homogenization is performed by grinding the slurry after stirring using a grinder to form the particle size in the slurry into several microns (㎛) or less.

The above-mentioned crushed particles are more homogeneously dispersed in the slurry, and agglomeration of the particles in the slurry is suppressed by the already added dispersant, so a homogeneous and stable slurry is produced.

The above grinding process can be repeated several times, and the fluidity of the slurry is controlled by adding a dispersant and an anti-foaming agent between each grinding process. If the particle size of the raw material composition is less than several microns, the grinding process can be omitted.

At this time, an organic binder is added to maintain the particle shape during spray drying.

In one specific example, a wet milling method is used to improve the grinding effect and solve problems such as particle scattering that occur during dry grinding.

After the grinding is complete, the homogenized slurry has its characteristics such as concentration and viscosity adjusted using a dispersant, antifoaming agent, or additional solvent.

In one specific example, the step of removing foreign substances in the step of stirring and homogenizing the slurry may be additionally performed.

Through the above steps, foreign substances or lumpy raw materials that may cause nozzle clogging during spray molding can be removed, and specifically, the removal of the foreign substances can be performed through sieving.

The above homogenized slurry has no special restrictions on fluidity and can have any viscosity as long as it can be transported by a pump.

The homogenized slurry is spray dried to form particles (S300).

In one specific example, the homogenized slurry may be transported to a spray dryer using a pump, and then the transported slurry composition may be sprayed into the spray dryer using a pump or the like to form solid particles.

The above spray dryer forms a solid absorbent by spraying a fluid slurry in a countercurrent spraying manner using a pressurized nozzle in the opposite direction to the flow of drying air, and it is preferable to maintain the inlet temperature of the spray dryer at 250 to 300°C and the outlet temperature at 90 to 150°C.

Finally, the above particles are dried and calcined (S400).

The drying in the above step (d) can be performed at 110 to 150°C for 2 to 24 hours, and the calcination can be performed in a high-temperature calcination furnace in an air atmosphere by raising the temperature to 550 to 650°C at a rate of 1 to 5°C/min for 3 to 10 hours.

The above drying can be performed by drying solid particles formed through spray drying in a reflux dryer at 100 to 150° C. for 1 hour or more.

Preferably, it is performed at 110 to 150°C for 2 to 24 hours.

By performing drying at the above temperature and time, the phenomenon of moisture inside the particles expanding during firing and causing cracks to occur in the particles can be prevented.

At this time, drying is carried out in an air atmosphere.

The above firing is performed by placing the dried particles in a high-temperature firing furnace, raising the final firing temperature to 550 to 650°C at a rate of 1 to 5°C/min, and maintaining the temperature for 3 hours or more.

It is preferably performed for 3 to 10 hours.

If the above firing time is less than 3 hours, there is a risk that the strength of the particles may be weakened.

In one specific example, the firing may be performed after imparting a stagnation period of at least 30 minutes at two or more stagnation temperatures until the final firing temperature is reached.

In addition, sufficient air is supplied to the kiln so that the activated carbon introduced to form absorbent pores can be completely combusted by the oxygen in the air and discharged as gas.

It is preferable to use a kiln such as a box furnace (muffle furnace), a tubular furnace or a kiln for the above-mentioned calcination.

By the above firing, the additives added during the production of the slurry are burned, and bonds are formed between the solid raw materials, thereby improving the strength of the particles.

After calcination, the final solid carbon dioxide absorbent is recovered.

Another aspect of the present invention is to provide a solid carbon dioxide absorbent according to the method for producing the solid carbon dioxide absorbent.

In one specific example, the solid carbon dioxide absorbent is a solid carbon dioxide absorbent characterized by having an attrition index (AI) of 10% or less according to the following equation 1 and a porosity of 18% or more measured by a mercury adsorption method:

[Formula 1]

Wear index (AI, %) = (W ₁ (g) / W ₀ (g)) × 100

(In the above formula 1, W ₁ is the total weight (g) of the absorbed fine powder collected by performing an abrasion test under the condition of a flow rate of 10.0 L/min (based on 273.15 K, 1 bar) in an abrasion tester according to ASTM D5757-95,

The above W ₀ is the initial weight of the absorbent (g, nominally 50 g).

The above solid carbon dioxide absorbent has an average particle size of 60 to 200 ㎛, a particle size distribution of 30 to 400 ㎛, and a packing density of 0.6 to 2.0 g/cm ³ .

The above solid carbon dioxide absorbent is formed within the above range and has a particle size and particle distribution suitable for a fluidized bed or high-speed fluidized bed process.

The above solid carbon dioxide absorbent has an increased carbon dioxide absorption capacity when its porosity is 18% or higher.

The above solid carbon dioxide absorbent has a carbon dioxide absorption capacity of 6 wt% (6 g CO ₂ / 100 g sorbent) or more.

The above-mentioned solid carbon dioxide absorbent is spherical.

The above solid carbon dioxide absorbent has improved wear resistance, carbon dioxide absorption performance and durability by controlling the composition of the composition, the mixing ratio of the solid absorbent raw materials, and homogenizing, and has physical properties that enable fluidization, and selectively absorbs carbon dioxide in fuel combustion exhaust gas and releases the absorbed carbon dioxide when the temperature is raised, thereby being regenerated, so that it can be used continuously and repeatedly.

<Example 1> Manufacturing of solid carbon dioxide absorbent

An active ingredient, a support, and an inorganic binder were mixed in the composition ratio shown in Table 1 below to prepare a solid raw material for a carbon dioxide absorbent having a total mass of 8 kg. A dispersant and an antifoaming agent were added to distilled water, and the mixture was mixed with a stirrer. The solid raw material was added to the water mixed with the additive while stirring with a stirrer to prepare a mixed slurry. The mixed slurry was pulverized three times with a high energy ball mill. After the second pulverization, polyethylene glycol was added, and the third pulverization was performed to prepare a stable and homogeneous fluid colloidal slurry. The pulverized slurry was sieved to remove foreign substances, and the solid concentration in the final slurry was measured. The total amount of additive added and the measured solid concentration in the final slurry are as shown in Table 1.

The colloidal slurry prepared above was transferred to a spray dryer using a pump and spray dried to prepare solid particles.

The molded solid carbon dioxide absorbent assembly, i.e., the green body, was pre-dried in an air atmosphere reflux dryer at 120°C for more than 2 hours, and calcined in a kiln at 600°C for 4 hours to produce the final solid carbon dioxide absorbent.

Before reaching the sintering temperature, it was maintained at 200, 300, and 400 ℃ for about 1 hour, and the heating rate was about 5 ℃/min.

<Example 2>

The same procedure as Example 1 was followed, except that the composition of each component was changed according to Table 1.

<Comparative examples 1 to 14>

The same procedure as Example 1 was followed, except that the composition of each component was changed according to Table 1.

Comparative Examples 1 and 2 are examples manufactured outside the activated carbon content range suggested by the present invention, and Comparative Example 3 is an example manufactured without using potassium bicarbonate.

Comparative Examples 4 and 7 are examples manufactured with a potassium bicarbonate content exceeding the range suggested by the present invention, and Comparative Example 5 is an example manufactured with the aim of improving porosity by applying gamma alumina and increasing the content of synthetic calcium silicate.

Comparative Example 6 is an example manufactured by designing the composition after calcination to be the same as that of the example without using activated carbon and potassium bicarbonate.

Comparative examples 8 and 9 are examples manufactured without using activated carbon.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 K ₂ CO ₃ (wt%) 23.36 18.31 22.83 23.70 34.15 13.45 35.0 35 KHCO ₃ 13.55 19.91 13.24 13.74 - 26.01 - - α-Alumina (weight%) 19.63 19.22 19.18 19.91 20.49 18.83 21.0 21.0 TiO ₂ (Anatase)(wt%) 7.01 6.86 6.85 7.11 7.32 6.73 5.0 7.5 ZrO ₂ (wt%) 17.76 17.39 17.35 18.01 18.54 17.04 12.0 19.0 Na-Bentonite (weight%) 4.67 4.58 4.57 4.74 4.88 4.48 5.0 5.0 pseudoboehmite (weight %) 4.67 4.58 4.57 4.74 4.88 4.48 2.0 5.0 Synthetic calcium silicate (wt%) 7.01 6.86 6.85 7.11 7.32 6.73 13.0 7.5 γ-Alumina (wt%) - - - - - - 7.0 - Activated carbon (weight%) 2.34 2.29 4.56 0.94 2.42 2.25 - - Total solid raw materials (standard) 100 100 100 100 100 100 100 100 Dispersant (by weight) 0.25 0.25 0.25 0.25 0.15 0.25 0.25 0.25 parcel (by weight) 0.05 0.05 0.05 0.05 0.02 0.05 0.05 0.05 Organic binder (by weight) 2.25 2.25 2.25 2.25 1.34 2.25 2.25 2.25 Slurry concentration (weight parts) 39.5 42.0 41.5 40.8 51.7 46.3 36.7 38.4 Slurry pH 10.2 9.9 10.1 10.2 11.7 9.8 11.3 12.4 Viscosity (cP) 2130 1080 1960 2070 1830 1120 360 763

Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Comparative Example 13 Comparative Example 14 K ₂ CO ₃ (wt%) 13.76 23.92 18.74 21 20 - 23.36 24.36 KHCO ₃ 26.61 13.88 20.37 22 13.74 38 - 14.18 NaHCO ₃ - - - - - - 13.55 - α-Alumina (weight%) 19.27 20.10 19.67 16.66 21.91 18.49 19.63 14 TiO ₂ (Anatase)(wt%) 6.88 7.18 7.03 6.85 7.5 6.32 7.01 8.01 ZrO ₂ (wt%) 17.42 18.18 17.8 15.5 18.01 18.54 17.76 19.76 Na-Bentonite (weight%) 4.59 4.78 4.68 4.57 4.74 4.88 4.67 4.67 pseudoboehmite (weight %) 4.59 4.78 4.68 4.57 4.74 4.88 4.67 4.67 Synthetic calcium silicate (wt%) 6.88 7.18 7.03 6.85 7.36 6.45 7.01 7.01 γ-Alumina (wt%) - - - - - - - - Activated carbon (weight%) - - - 2 2 2.44 2.34 3.34 Total solid raw materials (standard) 100 100 100 100 100 100 100 100 Dispersant (by weight) 0.25 0.25 0.25 0.25 0.25 0.15 0.25 0.25 parcel (by weight) 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Organic binder (by weight) 2.25 2.25 2.25 2.25 2.25 2.25 2.25 2.25 Slurry concentration (weight parts) 47.7 48.4 44.0 43.5 44.8 47.6 46.9 51.1 Slurry pH 9.6 10.5 10.5 10.1 10.6 8.8 9.8 10.6 Viscosity (cP) 1240 1300 903 1090 1180 1410 1320 1520

Table 1 above summarizes the characteristics of the raw materials and the fluid colloid slurry for manufacturing solid carbon dioxide absorbents according to Examples 1 to 2 and Comparative Examples 1 to 6. Table 2 above summarizes the characteristics of the raw materials and the fluid colloid slurry for manufacturing solid carbon dioxide absorbents according to Comparative Examples 7 to 14.

Referring to Tables 1 and 2, the absorbents in the examples and comparative examples containing potassium bicarbonate or activated carbon were designed so that the final contents of potassium carbonate, alpha-alumina, titanium dioxide, zirconium dioxide, bentonite, pseudo-boehmite, and synthetic calcium silicate were 35 parts by weight, 21 parts by weight, 7.5 parts by weight, 19 parts by weight, 5 parts by weight, 5 parts by weight, and 7.5 parts by weight, respectively, based on the composition after potassium bicarbonate is converted to potassium carbonate during the calcination process and the activated carbon is completely combusted and removed as gas.

Comparative Examples 10 to 11 are examples manufactured in which the content of the active material is outside the content range suggested by the examples of the present invention, Comparative Example 12 is an example in which only potassium bicarbonate is used as the active material, Comparative Example 13 is an example in which sodium bicarbonate is mixed with potassium carbonate as the active material, and Comparative Example 14 is an example in which the content of alpha-alumina used as the support is outside the content range suggested by the present invention.

<Experimental Example> Property Evaluation

(1) Measurement of average particle size and particle size distribution

The average particle size and particle size distribution of the manufactured solid carbon dioxide absorbent were calculated by classifying a 10 g sample for 30 minutes using a MEINZER-ⅡShaker and a standard sieve based on ASTM E-11 of the American Society for Testing Materials (ASTM).

(2) Measurement of filling density

The packing density of the manufactured solid carbon dioxide absorbent was measured using an AutoTap (Quantachrome) packing density meter according to ASTM D 4164-88.

(3) Wear resistance measurement

The abrasion resistance of the manufactured solid carbon dioxide absorbent was measured by an abrasion tester according to ASTM D 5757-95. The particle abrasion index (AI) was determined at 10.0 L/min (at 273.15 K, 1 bar) for 5 hours as described in the ASTM method, and the particle abrasion index represents the ratio of fine powder generated for 5 hours. A lower particle abrasion index (AI) means stronger particles.

Here, the particle wear index is determined by the following equation 1.

[Formula 1]

Wear index (AI, %) = (W ₁ (g) / W ₀ (g)) × 100

(In the above formula 1, W ₁ is the total weight (g) of the absorbed fine powder collected by performing an abrasion test under the condition of a flow rate of 10.0 L/min (based on 273.15 K, 1 bar) in an abrasion tester according to ASTM D5757-95,

The above W ₀ is the initial weight of the absorbent (g, nominally 50 g).

For comparison, the wear index (AI) of a commercial Akzo FCC (Fluid Catalytic Cracking) catalyst used in a refinery, measured using the same method, was 22.5%.

(4) Measurement of porosity (%)

The porosity of the absorbent was measured using the mercury adsorption method. The porosity of the absorbent was measured from the penetration amount of mercury by pressurizing the absorbent. The weight of the absorbent used was 100 to 200 mg, and the mercury pressurization range was 0 to 61,000 psi.

(5) Measurement of carbon dioxide absorption capacity

Thermogravimetric analysis (TGA) was used to measure the absorbent sample three times (absorption-regeneration-absorption-regeneration-absorption). The weight of the absorbent sample used was 10 mg, and the total flow rate was 60 ml/min. The carbon dioxide absorption reaction was performed at 70 °C, and the absorbent regeneration reaction was performed at 220 °C. The gas composition used for the absorption reaction was 10 vol% carbon dioxide, 10 vol% water (water vapor), and 80 vol% nitrogen, and the gas composition used for the regeneration reaction was 90 vol% carbon dioxide, 10 vol% water (water vapor).

The physical properties and carbon dioxide absorption capacity (weight of carbon dioxide absorbed by the absorbent/unit weight of absorbent) percentage measurements and porosity of the solid carbon dioxide absorbents of the above examples and comparative examples are shown in Table 3 below.

shape Plasticity
temperature,
℃ average
particle size,
㎛ particle size
distribution,
㎛ Filling
density,
g/ml Wear index
(AI),
% Porosity
(%) CO2
Absorbency,
wt% Example 1 rectangle 600 131 67.5~231 1.17 1.9 18.4 8.1 Example 2 rectangle 600 134 56.5~231 1.12 6.6 19.4 8.1 Comparative Example 1 rectangle 600 139 67.5~231 1.09 10.8 18.6 - Comparative Example 2 rectangle 600 127 56.5~231 1.13 3.6 13.3 7.9 Comparative Example 3 rectangle 600 131 56.5~231 1.19 3.1 13.4 7.8 Comparative Example 4 Non-spherical 600 - - - >50 - - Comparative Example 5 rectangle 600 125 56.5~231 1.24 2.2 13.1 7.5 Comparative Example 6 rectangle 600 116 49~196 1.23 3.9 12.8 7.6 Comparative Example 7 Non-spherical 600 - - - >50 - - Comparative Example 8 rectangle 600 138 56.5~231 1.18 3.8 13.1 8.1 Comparative Example 9 rectangle 600 135 67.5~231 1.19 5.4 13.4 7.9 Comparative Example 10 Non-spherical 600 123 56.5~231 1.23 4.7 15.1 7.7 Comparative Example 11 rectangle 600 135 67.5~231 1.18 3.5 16.3 6.2 Comparative Example 12 Non-spherical 600 - - - >50 - - Comparative Example 13 rectangle 600 130 67.5~231 1.20 5.4 12.5 5.7 Comparative Example 14 rectangle 600 125 56.5~231 1.25 11.9 17.5 -

Referring to Table 3 above, a solid carbon dioxide absorbent manufactured by mixing activated carbon and potassium bicarbonate and calcining at 600°C according to an embodiment of the present invention exhibited a high absorbent porosity of 18% or more and a carbon dioxide absorption capacity of 8.1 parts by weight. In addition, it can be seen that the solid carbon dioxide absorbent exhibited high strength characteristics with a particle wear index of 10% or less and had properties suitable for a commercial fluidized bed process.

That is, the average particle size of the solid carbon dioxide absorbent is within the range of 60 to 150 ㎛, the particle size distribution is within the range of 30 to 400 ㎛, and the packing density is within the range of 0.6 to 2.0 g/cm ³ .

Meanwhile, the absorbent of Comparative Example 6, which did not use activated carbon but used the same raw material composition with 35 wt% potassium carbonate, showed a porosity of 12.8%. In comparison, it was confirmed that the absorbents of the examples maintained high strength even when activated carbon and potassium bicarbonate were applied, while the porosity and carbon dioxide absorption capacity increased.

It was confirmed that the absorbent of Comparative Example 1, which was manufactured with an activated carbon content exceeding 4 wt% using the same solid raw material as the example, had a wear index of 10% or more, and thus the wear loss of the absorbent may increase when the carbon dioxide capture process is operated for a long period of time.

The absorbent of Comparative Example 2, which used an activated carbon content of less than 2 wt% as a solid raw material similar to the example, showed a minimal increase in porosity compared to Comparative Example 6.

The absorbent of Comparative Example 3, which used only activated carbon as a pore-forming agent without using potassium bicarbonate, also showed a minimal increase in porosity. The absorbents of Comparative Examples 8 and 9, which used only potassium bicarbonate and did not use activated carbon, also showed a minimal increase in porosity compared to Comparative Example 6.

The absorbents of Comparative Examples 4 and 7, which were manufactured with potassium bicarbonate in an amount exceeding the amount suggested in the present invention, had particle abrasion indices exceeding 50% and were non-spherical in shape, making them unsuitable for use in the process.

The absorbent of Comparative Example 5 was manufactured by increasing the content of gamma alumina and synthetic calcium silicate to increase the specific surface area based on the composition of Comparative Example 6. Compared to Comparative Example 6, the increase in porosity was minimal, and the porosity was lower than that of the examples.

In addition, the solid carbon dioxide absorbent of the example used a raw material composition that minimizes the generation of side products by reacting with the active ingredient, potassium carbonate, and the raw material (gamma alumina, synthetic calcium silicate) that causes side reactions when used together, and thus it was confirmed that it could maintain high absorption capacity for a longer period of time compared to the absorbent according to Comparative Example 5.

Meanwhile, the absorbent of Comparative Example 10, manufactured with an active material content exceeding 39 wt% suggested by the present invention, and the absorbent of Comparative Example 12, which used only potassium bicarbonate as the active material, were found to have a non-spherical shape and thus were unsuitable for process use, and the absorbent of Comparative Example 11, manufactured with an active material content of 35 wt% or less, and the absorbent of Comparative Example 13, manufactured by mixing sodium bicarbonate instead of potassium bicarbonate, showed much lower absorption capacities than those of the examples.

In addition, the absorbent of Comparative Example 14, which was manufactured with a content of alpha-alumina as a support outside the content range suggested by the present invention, may have a particle wear index of 10% or more, which may increase the wear loss of the absorbent during operation of the carbon dioxide capture process.

Therefore, it was confirmed that a solid carbon dioxide absorbent suitable for a fluidized bed process capable of effectively absorbing carbon dioxide in fuel combustion exhaust gas in a dry carbon dioxide capture technology can be manufactured using a solid carbon dioxide absorbent raw material composition according to a specific example of the present invention and a method for manufacturing a solid carbon dioxide absorbent using the same.

The solid carbon dioxide absorbent according to the present invention uses a raw material composition capable of improving porosity, and has excellent carbon dioxide absorption capacity, so that it can be a competitive technology because it reduces the amount of absorbent used in the long term in a dry carbon dioxide capture process, thereby improving the economic feasibility of the process.

The present invention has been described with reference to embodiments. Those skilled in the art will understand that the present invention can be implemented in modified forms without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative rather than a restrictive perspective. The scope of the present invention is indicated by the claims, not the foregoing description, and all differences within the scope equivalent thereto should be interpreted as being included in the present invention.

Claims (2)

An active ingredient comprising a mixture of potassium carbonate and potassium bicarbonate; a support comprising a mixture of alpha-alumina, titanium dioxide (TiO ₂ ), and zirconium dioxide (ZrO ₂ ); an inorganic binder comprising a mixture of bentonite, pseudoboehmite, and synthetic calcium silicate; and activated carbon.
The above mixture of potassium carbonate and potassium bicarbonate is characterized in that the mixing ratio of potassium carbonate to potassium bicarbonate is 0.9 to 1.8:1 by weight.
Composition for carbon dioxide absorbent.
A composition for a carbon dioxide absorbent, comprising, based on the total weight of the composition for a carbon dioxide absorbent in claim 1, 36 to 39 wt% of a mixture of potassium carbonate and potassium bicarbonate, 15 to 25 wt% of alpha-alumina, 5 to 10 wt% of titanium dioxide, 15 to 25 wt% of zirconium dioxide, 4 to 6 wt% of bentonite, 4 to 5 wt% of pseudoboehmite, 6 to 8 wt% of synthetic calcium silicate, and 2 to 4 wt% of activated carbon.