KR101934404B1 - Method for producing magnesium oxide-based sorbent and the magnesium oxide-based sorbent produced thereby - Google Patents

Abstract

The present invention relates to a carbon dioxide absorbent and a method for producing the carbon dioxide absorbent, and more particularly, to a carbon dioxide absorbent and a method for producing the carbon dioxide absorbent which are capable of being produced through an eco-friendly yet economical and simple process that does not use a surfactant at all, Absorbing magnesium oxide-based absorbent, and a magnesium oxide-based absorbent prepared by the method.

Description

[0001] The present invention relates to a magnesium oxide-based sorbent and a magnesium oxide-based sorbent prepared by the method,

The present invention relates to a carbon dioxide absorbent and a method for producing the carbon dioxide absorbent, and more particularly, to a carbon dioxide absorbent and a method for producing the carbon dioxide absorbent which are capable of being produced through an eco-friendly yet economical and simple process that does not use a surfactant at all, Absorbing magnesium oxide-based absorbent, and a magnesium oxide-based absorbent prepared by the method.

Reducing carbon dioxide emissions, one of the main contributors to the greenhouse effect, is one of the most important social and industrial issues worldwide. Research is underway to capture carbon dioxide from a variety of mass-generating sources, including thermal power plants, and to reduce it to a series of processes that compress and transport and then store it on land or in the ocean. Carbon capture and storage (CCS) is the technology that stores carbon dioxide in marine or geological materials. This technology is emerging as a way to reduce the concentration of carbon dioxide.

In particular, the technology for collecting carbon dioxide is a technique for selectively capturing carbon dioxide by separating the carbon dioxide contained in the exhaust gas discharged from the combustion process of fossil fuels such as petroleum and coal natural gas. Various capture techniques have been developed, Dry, membrane capture process. At this time, it is an urgent task to develop an absorbent having a high absorption capacity and a high absorption rate for effective collection of various absorbents.

Among the various absorption conditions, materials that are used as dry absorbers include zeolite, metal-organic framework, carbon material, carbon dioxide which have a high specific surface area and a high carbon dioxide affinity. A basic metal oxide having a property of being a metal is being studied. Of these, the basic metal oxide is a highly valuable absorber with high carbon dioxide selectivity, high absorption capacity, and excellent regeneration in repeated adsorption / desorption processes under mixed flue-gas conditions (15% CO ₂ /85% N ₂ ) .

Of these various basic metal oxides, magnesium oxide is the material that is being studied extensively with dry adsorbents. Magnesium oxide, which is easily absorbed in the temperature range of flue gas and can be regenerated at a relatively low temperature, is highly regarded as a carbon dioxide dry absorbent. The MgO-based sorbent that can capture carbon dioxide can be made by processing dolomite at 300 ~ 450 ℃ and 20 atm. Conventional MgO composite processing methods include precipitation and simple mixing. The precipitation method uses water as a solvent, and separates the product and the solvent into a filter after the reaction. However, due to the use of the filter, there is a disadvantage that the salts to be synthesized in MgO are lost through the filter in the ion state. Simple mixing is a method of physically mixing powders to be a material of the MgO composite. Although the procedure is simple and easy, it is disadvantageous in that it is difficult to obtain a homogeneous composite because of low dispersion.

As a result of efforts to solve the above problems, the present inventors have completed the present invention by developing a method for producing a magnesium oxide-based absorbent through an eco-friendly and very economical and simple process that does not use a surfactant at all.

Accordingly, an object of the present invention is to provide a method for producing a magnesium oxide-based absorbent having high absorption capacity, fast absorption rate and excellent regeneration in repeated adsorption / desorption processes through an environmentally friendly but very economical and simple process that does not use a surfactant at all, And to provide a magnesium oxide absorbent produced by the method.

Another object of the present invention is to provide a magnesium oxide-based sorbent preparation method capable of controlling the carbon dioxide absorption rate and the carbon dioxide absorption amount of a magnesium oxide-based sorbent by controlling the kind and content of the metal salt contained in the magnesium oxide-based sorbent, And a magnesium-based absorbent.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to accomplish the objects of the present invention, the present invention provides a method for preparing a precursor mixture, comprising: preparing a precursor mixture solution for dissolving a magnesium oxide precursor, a carbonate precursor and a nitrate precursor in a solvent; Removing the solvent from the precursor mixture solution to obtain a dried precursor mixture; And a sintering step of sintering the precursor mixture to obtain a magnesium oxide-based absorbent.

In a preferred embodiment, the magnesium oxide precursor, carbonate precursor and nitrate precursor are prepared such that the molar ratio of magnesium oxide: carbonate: nitrate is 1: 0.1-5: 0.01-0.5.

In a preferred embodiment, the magnesium oxide precursor is any one of a magnesium oxide (MgO), magnesium carbonate (MgCO _3), magnesium nitrate (MgNO _3).

In a preferred embodiment, the carbonate precursor is any one of lithium carbonate, sodium carbonate, potassium carbonate, and calcium carbonate.

In a preferred embodiment, the nitrate precursor is any one of lithium nitrate, sodium nitrate, potassium nitrate, and calcium nitrate.

In a preferred embodiment, the preparing of the precursor mixture solution comprises: preparing a first precursor solution by adding and dissolving the carbonate precursor to a solvent; Preparing a second precursor solution by adding and dissolving the nitrate precursor to the first precursor solution; And preparing the precursor mixture solution by adding and dissolving a magnesium oxide precursor to the second precursor solution.

In a preferred embodiment, the solvent is a polar solvent.

In a preferred embodiment, the firing step is performed while supplying air at a temperature of 370 ° C to 430 ° C.

In a preferred embodiment, at least one of the carbon dioxide absorbing capacity and the carbon dioxide absorbing rate of the magnesium oxide-based absorbent is controlled by controlling the composition and content of the magnesium oxide precursor, the carbonate precursor, and the nitrate precursor.

The present invention also provides a magnesium oxide-based absorbent, which is produced by any one of the above-described production methods.

In a preferred embodiment, the magnesium oxide-based absorbent has a carbon dioxide absorption capacity of 8 wt% / g or more and a carbon dioxide absorption rate of 2.5 wt% / min or more.

In a preferred embodiment, the residual absorbing capacity of the magnesium oxide-based absorbent is maintained at 50% or more of the initial absorbing capacity after the absorption / desorption process is performed 20 times or more.

In a preferred embodiment, the desorption temperature of the magnesium oxide-based absorbent is 400 ° C to 500 ° C.

The present invention also provides a carbon dioxide capture module comprising the magnesium oxide-based absorbent described above.

In a preferred embodiment, the carbon dioxide absorbing capacity up to 30 wt% / g and the maximum 3 wt% / min at a temperature of 300-500 ° C, atmospheric pressure and mixed flue gas (2-15% CO ₂ / 85-98% N ₂ ) Of carbon dioxide.

The present invention has the following excellent effects.

First, according to the present invention, a magnesium oxide-based absorbent having a high absorption capacity, a high absorption rate, and excellent regeneration in a repeated adsorption / desorption process can be produced in an eco-friendly and very economical and simple process that does not use a surfactant at all.

Further, according to the present invention, the carbon dioxide absorption rate and the carbon dioxide absorption amount of the magnesium oxide-based absorbent can be controlled by controlling the kind and content of the metal salt contained in the magnesium oxide-based absorbent, so that magnesium oxide Based absorbent can be provided.

Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Of course.

FIG. 1 is a graph of an X-ray diffraction pattern of a magnesium oxide-based absorbent (MNN) carrying sodium carbonate and sodium nitrate and a pure magnesium oxide not carrying a metal salt.
2 is a nitrogen adsorption isotherm graph of a magnesium oxide-based absorbent (MNN) carrying sodium carbonate and sodium nitrate.
3 is a pore size distribution diagram derived from the nitrogen adsorption isotherm shown in FIG.
4 shows the results of differential thermal analysis of a magnesium oxide-based absorbent (MNN) carrying sodium carbonate and sodium nitrate, showing the ability of the MNN absorbent to absorb carbon dioxide.
5A and 5B show results of differential thermal analysis of a magnesium oxide-based absorbent (MNN) carrying sodium carbonate and sodium nitrate. FIG. 5A shows the result of repeated carbon dioxide absorption / regeneration experiments for 20 times, FIG. A graph summarizing the absorption capacity shown during carbon dioxide absorption / regeneration.
FIG. 6 is a graph showing the results of differential thermal analysis of magnesium oxide-based sorbents loaded with various carbonates and nitrates. FIG. 6 is a graph showing carbon dioxide absorption capacity.
FIG. 7 is a graph showing absorption capacity and absorption rate of each magnesium oxide-based absorbent, showing the absorption capacity of each magnesium oxide-based absorbent by the results of FIG. 6. FIG.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprising" or "having ", and the like, are intended to specify the presence of stated features, integers, steps, operations, elements, parts, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, or combinations thereof.

The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning of the context in the relevant art and, unless expressly defined in the present invention, are to be interpreted as an ideal or overly formal sense Do not.

Hereinafter, the technical structure of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals used to describe the present invention throughout the specification denote like elements.

The technical features of the present invention include a magnesium oxide-based system capable of controlling the carbon dioxide absorption rate and the carbon dioxide absorption amount of the magnesium oxide-based absorbent by controlling the kind and content of the metal salt contained in the environmentally friendly but very economical and simple process that does not use a surfactant at all, Absorbent preparation method and a high-performance magnesium oxide-based absorbent which has been produced by the method and has high absorption capacity, fast absorption rate and excellent regeneration in a repeated adsorption / desorption process.

 Accordingly, the magnesium oxide-based absorbent manufacturing method of the present invention comprises: preparing a precursor mixture solution for dissolving a magnesium oxide precursor, a carbonate precursor, and a nitrate precursor in a solvent; Removing the solvent from the precursor mixture solution to obtain a dried precursor mixture; And a calcination step of calcining the precursor mixture.

In preparing the precursor mixture solution, the magnesium oxide precursor, carbonate precursor and nitrate precursor are prepared such that the molar ratio of magnesium oxide: carbonate: nitrate is 1: 0.1-5: 0.01-0.5, wherein the carbonate precursor and the nitrate precursor are The carbonate precursors can be selected from the group consisting of lithium carbonate, sodium carbonate, potassium carbonate, and calcium carbonate, and the nitrate precursor is selected from the group consisting of lithium nitrate, nitrate Sodium, potassium nitrate, and calcium nitrate.

Particularly, as apparent from the experimental examples described later, according to the production method of the present invention, at least one of the carbon dioxide absorbing ability and the carbon dioxide absorbing rate of the magnesium oxide-based absorbent is controlled by controlling the composition and content of the magnesium oxide precursor, carbonate precursor and nitrate precursor It is possible to freely adjust the magnesium oxide-based absorbent in various compositions according to the intended use.

On the other hand, the step of preparing the precursor mixture solution may be carried out by using any known method as long as the magnesium oxide precursor, the carbonate precursor and the nitrate precursor are added to the solvent so that they can be homogeneously dissolved regardless of the order of addition. However, since the tendency that the order of addition of each precursor influences the performance of the magnesium oxide-based absorbent, which is the final product, has been experimentally demonstrated, it is preferable to prepare a first precursor solution by adding and dissolving the carbonate precursor in a solvent. Preparing a second precursor solution by adding a nitrate salt precursor to the first precursor solution and dissolving the nitrate precursor; And preparing a precursor mixture solution by adding and dissolving the magnesium oxide precursor to the second precursor solution.

If necessary, the prepared precursor mixture solution may be further stirred at room temperature, and the mixture may be stirred while heating to a temperature below the boiling point of the solvent.

In this case, the solvent is not limited as long as it can dissolve the magnesium oxide precursor, the carbonate precursor and the nitrate precursor. Preferably, the solvent may be a polar solvent, and in one embodiment, it may be water or a lower alcohol having 1 to 4 carbon atoms .

Removing the solvent from the precursor mixture solution using a rotary evaporator or a filter; And drying the solvent-removed precursor mixture.

The calcination step can be carried out by supplying the dried precursor mixture by using a known method at a temperature of 370 ° C to 430 ° C. The calcination step may be carried out by heating at a high temperature in the calcination step, The stable solid absorbent can be formed while the decomposition of the solid absorbent, the generation of stable crystalline material, and the densification phenomenon due to the shrinkage of plasticity occur.

The magnesium oxide-based absorbent prepared in the present invention was analyzed by X-ray diffraction analysis, nitrogen adsorption isotherm, electron microscope and the like as described later. The carbon dioxide absorption capacity was measured by using differential thermogravimetry And the absorption capacity of the absorbent in the repeating absorption / desorption process was checked using the same device. The following characteristics were exhibited.

 The magnesium oxide-based absorbent of the present invention had a carbon dioxide absorbing ability of 8 wt% / g or more and a carbon dioxide absorbing rate of 2.5 wt% / min or more, and the residual absorbing ability after the absorption / desorption process was maintained at 50% .

In particular, the desorption temperature of the magnesium oxide-based absorbent of the present invention is in the range of 400 ° C to 500 ° C, which is lower than that of the conventionally known absorbent, so that it is easy to apply for commercial application. That is, the conventional Ca-based absorbents are adsorbed at 600 to 700 ° C. However, since the adsorbent needs a high temperature of more than 800 ° C. for desorption, the absorbent having a high energy consumption in the desorption process for regeneration is commercialized Because it was difficult.

The present invention also provides a carbon dioxide capture module comprising a magnesium oxide-based sorbent having the above-described characteristics. Although not particularly limited, the carbon dioxide capture module may be used in a form filled with a magnesium oxide absorbent on a column or the like. Since the magnesium oxide-based absorbent contained in the carbon dioxide collecting module has excellent thermal stability and exhibits excellent adsorption performance between 300 ° C and 500 ° C, the carbon dioxide collecting module of the present invention can be used at a temperature of 300-500 ° C, _{2 ~ 15% CO 2/85} ~ may have an excellent operational performance in terms of 98% N _2), may have a carbon dioxide absorption rate of 30wt% / g and carbon dioxide absorption capacity up to 3wt% / min up to.

Therefore, if the carbon dioxide capture module of the present invention is applied to an industry, it is expected that the excellent collection performance as well as the additional process of lowering the temperature of the flue gas can be eliminated, thereby reducing the operation cost of the process.

Example 1

Sodium carbonate (Na ₂ CO ₃ ), sodium nitrate (NaNO ₃ ) and magnesium oxide (MgO) were purchased from Sigma Aldrich (USA) to synthesize magnesium oxide coprecipitated with a sodium carbonate precursor and a sodium nitrate precursor Distilled water was used as a solvent for the synthesis, and the molar ratio of magnesium oxide to sodium carbonate and sodium nitrate was 1: 0.19: 0.15. The specific manufacturing process is as follows. 0.5 g of sodium carbonate is dissolved in 5 mL of water, and then 0.320 g of sodium nitrate is further added. After stirring at room temperature for about 1 hour, 1 g of magnesium oxide is added and the mixture is stirred at room temperature for about 1 hour. Thereafter, the solvent (distilled water) is completely removed using a rotary evaporator, and the resultant is dried in an oven at 100 degrees for about 1 hour. The obtained solid materials were sintered for 4 hours while supplying air at 400 ^° C to prepare magnesium oxide absorbent 1 (MNN).

Examples 2 to 12

Magnesium oxide-based absorbents 2 to 12 were prepared in the same manner as in Example 1 except that the composition and content of the magnesium oxide, the carbonate precursor, and the nitrate precursor were adjusted as shown in Table 1 below.

Composition (component) Content (molar ratio) Absorber name Example 2 MgO: Li ₂ CO ₃ : LiNO ₃ 1: 0.19: 0.3 MLL Example 3 _{MgO: Na 2 CO 3: LiNO} 3 1: 0.19: 0.1 MNL Example 4 MgO: Li ₂ CO ₃ : NaNO ₃ 1: 0.19: 0.3 MLN Example 5 MgO: K ₂ CO ₃ : NaNO ₃ 1: 0.4: 0.03 MKN Example 6 MgO: CaCO _3: NaNO ₃ 1: 0.19: 0.2 MCN Example 7 _{MgO: Na 2 CO 3: KNO} 3 1: 0.19: 0.1 MNK Example 8 MgO: K ₂ CO ₃ : KNO ₃ 1: 0.4: 0.03 MKK Example 9 MgO: CaCO _3: KNO ₃ 1: 0.19: 0.2 MCK Example 10 _{MgO: Na 2 CO 3: Ca} (NO 3) 2 1: 0.19: 0.2 MNC Example 11 MgO: K ₂ CO ₃ : Ca (NO ₃ ) ₂ 1: 0.4: 0.1 MKC Example 12 _{MgO: CaCO 3: Ca (NO} 3) 2 1: 0.19: 0.3 MCC

Experimental Example 1

The crystal structure of the magnesium oxide-based absorbent 1 (MNN) synthesized in Example 1 was confirmed by X-ray diffraction analysis, and the results are shown in Fig. The adsorption isotherm through nitrogen adsorption analysis is shown in FIG. 2, and the pore distribution obtained from the adsorption isotherm is shown in FIG.

2 and 3, it was confirmed that the BET surface area of the magnesium oxide-based absorbent 1 (MNN) was 150 m ² / g, and the total pore volume was 0.45 cm ³ / g. It was also confirmed that the average pore size was obtained as a mesoporous material having 3.5 nm

Experimental Example 2

The BET surface area and the pore volume of the magnesium oxide-based absorbents 1 to 12 obtained in Examples 1 to 12 were analyzed and analyzed. The results are shown in Table 2.

Absorber name BET surface area (m ² / g) Pore volume (cm ³ / g) Example 1 MNN 150 0.45 Example 2 MLL 125 0.36 Example 3 MNL 135 0.38 Example 4 MLN 115 0.32 Example 5 MKN 145 0.39 Example 6 MCN 150 0.41 Example 7 MNK 155 0.43 Example 8 MKK 145 0.38 Example 9 MCK 135 0.35 Example 10 MNC 165 0.46 Example 11 MKC 175 0.45 Example 12 MCC 170 0.48

Experimental Example 3

The magnesium oxide-based absorbents 1 to 12 obtained in Examples 1 to 12 can be utilized as a carbon dioxide absorbent. The analysis of the magnesium oxide-based absorbent 1 prepared in Example 1 is shown in FIG. 4, and the differential thermal analysis is used to analyze the carbon dioxide absorption capacity. The analysis conditions of the differential thermogravimetric analysis method are as follows. (i) The temperature is increased from room temperature to 400 ^° C at a rate of 20 ^° C per minute while flowing nitrogen gas (100% N ₂ ). (ii) After reaching 400 ^° C, hold for 20 minutes and then drop to 300 ^° C. (iii) After reaching 300 ^o C, 15% carbon dioxide and 85% nitrogen are flowed for 50 minutes (absorption phase). After (iv), the temperature is raised to 500 ^° C at a rate of 20 ^° C per minute, and 100% of carbon dioxide gas is flowed at this time (desorption step). (v) After reaching 500 ^o C, 100% nitrogen gas is flowed and maintained for 25 minutes. (vi) are repeated (iii) ~ (v) a step onwards after sikimyeo lowered to 300 ^o C, reaches 300 ^o C (carbon dioxide absorption / desorption replicates).

According to FIG. 4 showing the absorption capacity of carbon dioxide over time using the differential thermal analysis, the MNN absorbent of Example 1 exhibited a maximum absorption rate per minute of 2.91 wt% / min, The absorption capacity at the maximum absorption rate per minute is 8.2 wt% (at the initial steep increase in absorption capacity). This absorption capacity increases up to 19.2 wt% in the absorption range.

Experimental Example 4

The carbon dioxide absorption / regeneration ability of the MNN absorbent was analyzed by repeating the carbon dioxide analysis conditions used in Experimental Example 3 20 times, and the results are shown in FIGS. 5A and 5B. FIG. 5A shows the result of repeated carbon dioxide absorption / regeneration experiments for 20 times, and FIG. 5B is a graph summarizing the absorption capacities shown during the carbon dioxide absorption / regeneration cycle of 20 times in FIG. 5A.

As shown in FIG. 5A and FIG. 5B, it was confirmed that the absorption ability (once) started at about 9 wt% / g of absorption during 20 times of repeated analysis was reduced to 4.5 wt% / g in 20 times of analysis.

Experimental Example 5

Based on the assay used in Experimental Example 3, the results of analyzing the carbon dioxide absorption capacity of the various absorbents prepared in Examples 2 to 12 are summarized in FIG. Each absorbent shows different absorption tendencies and shows various absorption rates and absorption capacities. Based on the results of FIG. 6, the maximum absorption rate per minute and the absorption ability at the maximum absorption rate per minute are summarized in FIG.

6 and 7, the magnesium oxide-based absorbent of the present invention can control at least one of the carbon dioxide absorbing ability and the carbon dioxide absorbing rate of the magnesium oxide-based absorbent by controlling the composition and content of the magnesium oxide precursor, the carbonate precursor and the nitrate precursor . That is, depending on the specific composition and the specific content, although the absorption ability is excellent, the absorption speed may be low, the absorption ability may be low but the absorption speed may be fast, the absorption ability and the absorption speed may be both low, This is because it is clear. Accordingly, it is possible to manufacture the magnesium oxide-based absorbent by freely adjusting various compositions according to the purpose of use for capturing carbon dioxide.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Various changes and modifications will be possible.

Claims (14)

Preparing a precursor mixture solution for dissolving a magnesium oxide precursor, a carbonate precursor, and a nitrate precursor in a solvent; Removing the solvent from the precursor mixture solution to obtain a dried precursor mixture; And a firing step of firing the precursor mixture,
Preparing the precursor solution by adding the carbonate precursor to the solvent and dissolving the carbonate precursor in the solvent to prepare a first precursor solution; Preparing a second precursor solution by adding and dissolving the nitrate precursor to the first precursor solution; And preparing a precursor mixture solution by adding and dissolving a magnesium oxide precursor to the second precursor solution,
The magnesium oxide precursor, the carbonate precursor and the nitrate precursor are prepared such that the molar ratio of magnesium oxide: carbonate: nitrate is 1: 0.1-5: 0.01-0.5,
The firing step is performed while supplying air at a temperature of 370 ° C to 430 ° C,
Wherein at least one of a carbon dioxide absorbing ability and a carbon dioxide absorbing rate of the magnesium oxide-based absorbent is controlled by controlling the composition and content of the magnesium oxide precursor, the carbonate precursor, and the nitrate precursor.
delete The method according to claim 1,
Wherein the carbonate precursor is any one of lithium carbonate, sodium carbonate, potassium carbonate, and calcium carbonate.
The method according to claim 1,
Wherein the nitrate precursor is any one of lithium nitrate, sodium nitrate, potassium nitrate, and calcium nitrate.
delete The method according to claim 1,
Wherein the solvent is a polar solvent.
delete delete A method for producing a carbon black having a carbon dioxide absorption capacity of 8 wt% / g or more and a carbon dioxide absorption rate of 2.5 wt% / min or more, / Residual adsorption capacity after the desorption process is maintained at 50% or more of the initial absorption capacity.
delete delete 10. The method of claim 9,
Wherein the desorption temperature of the magnesium oxide-based absorbent is 400 ° C to 500 ° C.
Claim 9 oxide as carbon capture module including a magnesium-based absorbent, the temperature, atmospheric pressure and a mixed off-gas _{(2 ~ 15% CO 2/} 85 ~ 98% N 2) conditions of 300 ~ 500 ℃, to 30wt% / g And a carbon dioxide absorption rate of up to 3 wt% / min. delete

Images