WO2008038484A1

WO2008038484A1 - Method of separating/recovering carbon dioxide

Info

Publication number: WO2008038484A1
Application number: PCT/JP2007/066535
Authority: WO
Inventors: Yoshinori Saito; Masaru Fujino
Original assignee: Murata Manufacturing Co., Ltd.
Priority date: 2006-09-28
Filing date: 2007-08-27
Publication date: 2008-04-03
Also published as: JPWO2008038484A1

Abstract

Carbon dioxide absorbed can be efficiently released in a shorter period and the carbon dioxide can be recovered after having been converted to carbon monoxide, which is usable in a wider range of applications. A carbon dioxide absorber is caused to absorb carbon dioxide. Thereafter, the carbon dioxide absorber having carbon dioxide absorbed therein is heated while feeding hydrogen gas or a hydrocarbon gas thereto to release the carbon dioxide. In the release step, the absorber may be heated at a temperature of 800-1,000°C. The carbon dioxide absorber may be one comprising an oxide of an alkali earth metal as the main component or one comprising, as the main component, a composite oxide including an alkaline earth metal oxide. The carbon dioxide absorber may be one comprising a composite oxide selected among Ba2TiO4, Sr2TiO4, and Ba3Ca2Ti2O9 as the main component.

Description

Specification

Carbon dioxide separation and recovery method

Technical field

TECHNICAL FIELD [0001] The present invention relates to a method for separating and recovering carbon dioxide.

The present invention also relates to a method for separating and recovering carbon dioxide using a carbon dioxide absorbent capable of releasing carbon dioxide absorbed under predetermined conditions.

Background art

[0002] As a method for separating carbon dioxide from high-temperature exhaust gas, for example, a method of separating carbon dioxide from exhaust gas at a temperature of 500 ° C or higher using lithium silicate as a carbon dioxide absorbent has been proposed. ! /, Ru (see Patent Document 1).

[0003] Besides, lithium silicate is used as an absorbent for carbon dioxide, and the gas containing carbon dioxide after steam reforming of the carbon-containing fuel is contacted with the absorbent at a temperature of 400 ° C to 700 ° C. A method has been proposed in which carbon dioxide is absorbed by allowing the carbon dioxide and the absorbent material to react with each other, and then the absorbent material that has absorbed carbon dioxide is regenerated at a temperature of 700 to 900 ° C (Patent Document 2). reference).

[0004] However, in the case of the methods described in Patent Documents 1 and 2, in order to recover carbon dioxide at a high concentration, it is necessary to perform treatment at a temperature higher than the absorption temperature, which consumes a great deal of energy. There is a problem.

[0005] Even if it is possible to recover carbon dioxide at a high concentration, measures for effective use of the recovered carbon dioxide have become clear! /, Na! / Technology such as storage in the sea is required, and the technical and economic burdens are large! /, And there is a problem of patent document 1: JP 2000-262890 A

Patent Document 2: Japanese Patent Laid-Open No. 2003-054927

Disclosure of the invention

Problems to be solved by the invention

[0006] The present invention solves the above-mentioned problems of the prior art, and the absorbed diacid It is possible to provide a method for separating and recovering carbon dioxide capable of efficiently releasing carbonized carbon in a shorter time and converting carbon dioxide into carbon monoxide, which is more versatile. Objective.

Means for solving the problem

[0007] In order to solve the above problems, the method for separating and recovering carbon dioxide according to the present invention (Claim 1) comprises:

(a) an absorption process in which carbon dioxide absorbing material absorbs carbon dioxide;

(b) Carbon dioxide absorbent material that absorbed carbon dioxide Release process that releases carbon dioxide and

A carbon dioxide separation and recovery method comprising:

In the releasing step (b), the carbon dioxide absorbing material that has absorbed carbon dioxide is heated while supplying hydrogen gas or hydrocarbon gas to release carbon dioxide.

[0008] Further, the method for separating and recovering carbon dioxide according to claim 2 is characterized in that, in the configuration of the invention according to claim 1, the heating temperature in the releasing step (b) is 800 to 1000 ° C.

Yes

[0009] Further, the method for separating and recovering carbon dioxide according to claim 3 is the structure of the invention according to claim 1 or 2, wherein the carbon dioxide absorbent mainly comprises an alkaline earth metal oxide, Alternatively, the main component is a composite oxide containing an alkaline earth metal oxide.

[0010] Further, in the method for separating and recovering carbon dioxide according to claim 4, in the configuration of the invention according to claim 3, the carbon dioxide absorbent is any one of BaTiO3, SrTiO2, and BaCaTiO.

2 4 2 4 3 2 2 9

It is characterized by having a composite oxide as a main component.

The invention's effect

[0011] In the carbon dioxide separation and recovery method of the present invention (Claim 1), the carbon dioxide absorbent that absorbs carbon dioxide When carbon dioxide is released, the carbon dioxide absorbent that absorbs carbon dioxide is used. Since carbon dioxide is released by heating while supplying hydrogen gas or hydrocarbon gas, carbon dioxide is converted to carbon monoxide and recovered. The power S to do.

[0012] For example, by using methane, which is a hydrocarbon-based gas, as a sweep gas, and releasing carbon dioxide by heating while supplying methane in the carbon dioxide emission step, the carbon dioxide released is As shown in Equation (1), carbon monoxide and hydrogen are produced by reacting with methane.

CO + CH → 2CO + 2H ...... (1)

[0013] Further, when hydrogen gas is used as the sweep gas and carbon dioxide is released by heating while supplying hydrogen gas in the carbon dioxide releasing step, the carbon dioxide released is expressed by the following formula (2) As shown in Fig. 1, it reacts with hydrogen to produce carbon monoxide and water.

CO + H → CO + H 0 …… (2)

[0014] In particular, when it is reacted with methane (see the above reaction formula (1)), the mixed gas of carbon monoxide and hydrogen is called synthesis gas, and it contains methanol (CH OH), formaldehyde (HCHO) C

Three

It is useful as a basic material for the so-called C 1 chemistry to synthesize a substance with the number 1. From this mixed gas of carbon monoxide and hydrogen, the following equations (3) and (4) By the reaction shown, methanol can synthesize various hydrocarbons.

CO + 2H → CH OH …… (3)

twenty three

CO + 2H → l / n-(-CH2-)-+ H O ...... (4)

2 n 2

[0015] Further, since carbon dioxide released from the carbon dioxide absorbent reacts with methane, an increase in the partial pressure of carbon dioxide in the gas phase is suppressed, so that it is possible to efficiently perform operations without performing decompression or the like. It is possible to release carbon dioxide and to regenerate the carbon dioxide absorbent in a short time.

Thus, according to the present invention, carbon dioxide can be recovered by being converted to carbon monoxide, which is more versatile than carbon dioxide, and the carbon dioxide absorbent can be efficiently regenerated (carbon dioxide Release of carbon dioxide and the energy required for the regeneration of the carbon dioxide absorbent can be suppressed as compared with the conventional method. , Very meaningful.

[0017] Further, as in the method for separating and recovering carbon dioxide according to claim 2, the heating temperature in the carbon dioxide releasing step is set to 800 to 1000 ° C. Carbon dioxide can be efficiently converted into carbon monoxide and hydrogen, and the present invention can be realized more effectively.

[0018] In the carbon dioxide separation and recovery method of the present invention, the temperature condition of the release step is

It is preferable to set the temperature in the range of 800 to 1000 ° C. When the temperature condition of the release process is less than 800 ° C, the carbon monoxide production rate tends to decrease, and the temperature condition of the release process When the temperature exceeds 1000 ° C, coking due to thermal decomposition of methane becomes severe and deterioration due to sintering of the carbon dioxide absorber is likely to occur.

[0019] In the method for separating and recovering carbon dioxide according to claim 3, the carbon dioxide absorbent is mainly composed of an alkaline earth metal oxide, or a composite oxide containing an alkaline earth metal oxide. Therefore, it is possible to improve the efficiency of the conversion of carbon dioxide to carbon monoxide and hydrogen, and to make the present invention more effective. .

[0020] Examples of the alkaline earth metal oxide include CaO and SrO.

Examples of the main component of the composite oxide containing an alkaline earth metal oxide include Ba TiO, Sr TiO, and Ba Ca Ti O.

2 4 2 4 3 2 2 9

[0021] Further, as in the carbon dioxide separation and recovery method according to claim 4, the main component is a composite oxide of Ba TiO, Sr TiO, and Ba Ca Ti O as a carbon dioxide absorbent.

2 4 2 4 3 2 2 9

Can be used to absorb carbon dioxide at high temperatures and improve the efficiency of conversion of carbon dioxide to carbon monoxide and hydrogen, further realizing the present invention. I can do it.

[0022] As the carbon dioxide absorbent, Ba TiO is one of the most effective forces from the standpoint of the regeneration temperature and the reaction rate during regeneration. In addition, Sr TiO and Ba Ca Ti O

2 4 2 4 3 2 2 etc. can be used, and CaO with a normal regeneration temperature of 800 ° C or less is also regenerated under pressure.

9

The same results can be obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

[0023] The features of the present invention will be described in more detail with reference to the following examples of the present invention.

Example 1 [0024] A cylindrical stainless steel container having an inner diameter of 22 mm and a length of 300 mm equipped with an external electric heater was filled with 22 g (approximately 10 mU) of Ba TiO (carbon dioxide absorbent) having an average particle diameter of 2 mm.

2 4 Then, nitrogen gas was circulated through this stainless steel container at a rate of 18 NL / h, and the nitrogen gas inlet temperature was controlled at 700 ° C by a heat transfer heater.

After the circulated nitrogen gas temperature was stabilized, carbon dioxide was circulated at a rate of 2 NL / h (carbon dioxide concentration was 10 mol%), and carbon dioxide absorption was started.

The reaction of carbon dioxide absorption by Ba TiO (carbon dioxide absorbent) is expressed by the following equation:

twenty four

(5)

Ba TiO + CO → BaTiO + BaCO …… (5)

2 4 2 3 3

[0025] The time-dependent change in the carbon dioxide concentration in the gas that passed through the carbon dioxide absorbent was measured by a gas analyzer (Gas Chromatograph manufactured by Shimadzu Corporation). When the carbon dioxide concentration became equal to the inlet concentration, Absorption cycle was completed.

[0026] The carbon dioxide absorbent that has absorbed carbon dioxide in this manner is heated using an electric heater equipped in the container, and the temperature of the carbon dioxide absorbent is controlled at 900 ° C, while the methane is removed. Carbon dioxide absorbed by the carbon dioxide absorbent was released at a rate of 10 NL / h.

The release reaction of carbon dioxide from the carbon dioxide absorbent that has absorbed carbon dioxide is expressed by the following equation (6).

BaTiO + BaCO → Ba TiO + CO † (6)

3 3 2 4 2

[0027] Then, the time-dependent change in the exhaust gas composition in the release process was measured with the gas analyzer, and the time until the release of carbon dioxide was completed and the ratio of carbon dioxide and carbon monoxide in the release process (CO / (CO + CO): volume ratio) was measured. The results are shown in Table 1. Example 2

[0028] The ratio of carbon dioxide to carbon monoxide in the carbon dioxide release process was measured by the same method as in Example 1 except that the absorbent material temperature during carbon dioxide release was controlled to 800 ° C. . The results are shown in Table 1.

Example 3 [0029] The ratio of carbon dioxide to carbon monoxide in the carbon dioxide releasing step was measured by the same method as in Example 1 except that the absorbent material temperature during carbon dioxide release was controlled to 1000 ° C. . The results are shown in Table 1.

Example 4

[0030] The ratio of carbon dioxide and carbon monoxide in the carbon dioxide releasing step was measured by the same method as in Example 1 except that hydrogen gas was used as the gas to be circulated when carbon dioxide was released (sweep gas). went. The results are shown in Table 1.

Example 5

[0031] A cylindrical stainless steel container having an inner diameter of 22 mm and a length of 300 mm equipped with an external electric heater was filled with 18 g (about 10 mL) of Sr TiO (carbon dioxide absorbent) having an average particle diameter of 2 mm.

2 4 Then, nitrogen gas was circulated through this stainless steel container at 18 NL / h, and the nitrogen gas inlet temperature was controlled at 700 ° C by a heat transfer heater.

The reaction of carbon dioxide absorption by Sr TiO (carbon dioxide absorbent) is expressed by the following formula (

twenty four

7) It is as follows.

Sr TiO + CO → SrTiO + SrCO …… (7)

2 4 2 3 3

[0032] The time-dependent change in the carbon dioxide concentration in the gas that passed through the carbon dioxide absorbent was measured by a gas analyzer (Gas Chromatograph manufactured by Shimadzu Corporation). When the carbon dioxide concentration became equal to the inlet concentration, Absorption cycle was completed.

[0033] Then, the carbon dioxide absorbent that has absorbed carbon dioxide is heated using an electric heater equipped in the container, and the temperature of the carbon dioxide absorbent is controlled at 900 ° C, while methane is reduced to 10 NL / h. The carbon dioxide absorbed in the carbon dioxide absorbent was released.

The release reaction of carbon dioxide from a carbon dioxide absorbent that has absorbed carbon dioxide is expressed by the following equation (8).

SrTiO + SrCO → Sr TiO + CO † (8) [0034] Then, the time-dependent change in the exhaust gas composition in the release process was measured with the gas analyzer, and the ratio of carbon dioxide and carbon monoxide in the release process was measured. The results are shown in Table 1.

Example 6

[0035] A cylindrical stainless steel container having an inner diameter of 22 mm and a length of 300 mm equipped with an external electric heater was charged with 14 g (about 10 mU) of CaO (carbon dioxide absorbent) having an average particle diameter of 2 mm. Nitrogen gas was circulated through a stainless steel container at 18 NL / h, and the temperature of the nitrogen gas inlet was controlled at 600 ° C with a heat transfer heater.

The reaction of carbon dioxide absorption by CaO (carbon dioxide absorbent) is expressed by the following equation (9).

CaO + CO → CaCO …… (9)

[0036] The time-dependent change in the carbon dioxide concentration in the gas that passed through the carbon dioxide absorbent was measured with a gas analyzer (Gas Chromatograph made by Shimadzu Corporation), and when the carbon dioxide concentration became equal to the inlet concentration, Absorption cycle was completed.

[0037] Then, the carbon dioxide absorbing material that has absorbed carbon dioxide is heated using an electric heater equipped in the container, and the temperature of the carbon dioxide absorbing material is controlled at 900 ° C, while methane is reduced to 10 NL / h. The carbon dioxide absorbed in the carbon dioxide absorbent was released.

The release reaction of carbon dioxide from the carbon dioxide absorbent that has absorbed carbon dioxide is expressed by the following equation (10).

CaCO → CaO + CO † (10)

[0038] The time-dependent change in the exhaust gas composition in the release process was measured with the gas analyzer, and the ratio of carbon dioxide and carbon monoxide in the release process was measured. The results are shown in Table 1. Example 7

[0039] The ratio of carbon dioxide to carbon monoxide in the carbon dioxide release process was measured by the same method as in Example 6 except that the absorbent material temperature during carbon dioxide release was controlled at 700 ° C. went. The results are shown in Table 1.

[Comparative Example 1]

[0040] The release of carbon dioxide is completed by the same method as in Example 1 except that nitrogen gas is used as the gas to be circulated at the time of carbon dioxide release (nitrogen (N ₂ ) gas flow rate: 10 NL / h). And the ratio of carbon dioxide and carbon monoxide in the release process was measured. The results are shown in Table 1.

[0041] [Evaluation]

With reference to Table 1 showing the above-described measurement results for Examples 1 to 7 and Comparative Example 1, evaluation was performed for Examples;! To 7 and Comparative Example 1.

[0042] [Table 1]

As shown in Table 1, as in Examples 1 to 3, when methane is circulated at a temperature condition of 800 ° C or higher in the carbon dioxide release step, carbon monoxide is produced at a high rate of /. It was confirmed. The reaction formula at this time is the same as the formula (1).

CO + CH → 2CO + 2H ...... (1)

[0044] Further, as shown in Example 4, it was confirmed that carbon monoxide was produced at a high rate at a high rate even when hydrogen was circulated instead of methane.

The reaction formula at this time is the same as the above-described reaction formula (2).

CO + H → CO + H 0 …… (2)

[0045] Further, as in Example 5, when a composite oxide containing another alkaline earth metal oxide (Sr TiO in Example 5) is used as the carbon dioxide absorbent, Like, two

twenty four

Even when an alkaline earth metal oxide (CaO in Example 6) is used as the carbon oxide absorbent, the carbon dioxide release process (temperature conditions in the release process are 900 ° C in both Examples 5 and 6). It was confirmed that carbon monoxide was produced at a high rate by circulating a hydrocarbon gas (methane gas in Examples 5 and 6) as the sweep gas.

[0046] In addition, in Example 7 in which CaO was used as the carbon dioxide absorbent and the temperature condition of the carbon dioxide release process was 700 ° C, the rate of carbon monoxide formation was not necessarily as high as 0.38. I understand that it is not. This result shows that the reaction between carbon dioxide and methane tends to proceed at high temperatures (above 800 ° C). However, also in Example 7, it was confirmed that carbon monoxide was reliably generated, and it was confirmed that the basic effect of the present invention was obtained.

[0047] As can be seen from the results of Example 7, the reaction between carbon dioxide and methane proceeds at a high temperature, and carbon monoxide can be generated immediately at 700 ° C. As described above, it is desirable that the temperature condition of the carbon dioxide release process is 800 ° C or higher.

[0048] It is possible to obtain carbon monoxide even when the temperature condition of the releasing process is a high temperature of 1000 ° C or higher. Coking due to thermal decomposition of methane becomes intense, and carbon dioxide is absorbed. It is desirable to release at a temperature of 1000 ° C or less because deterioration due to sintering of the material is likely to occur.

[0049] Further, as in the present invention, in the carbon dioxide release process, when carbon dioxide gas or hydrogen gas is heated as a sweep gas while heating is performed to release carbon dioxide, the release is performed. Carbon dioxide reacted with methane on the spot to produce carbon monoxide Thus, since the partial pressure of carbon dioxide in the gas phase is kept low, the release of carbon dioxide is promoted.

[0050] On the other hand, in the case of Comparative Example 1 in which nitrogen gas is used as a gas to be circulated at the time of carbon dioxide release without using a hydrocarbon-based gas or hydrogen gas as a sweep gas as in the conventional case, the diacid Since the carbon dioxide partial pressure in the reaction tube rises due to the release of carbon fluoride and the release of carbon dioxide is suppressed, the release time of carbon dioxide in Example 1 should be 10 times 300 min compared to 30 min. That is, according to the method of the present invention (Example 1), it was confirmed that the carbon dioxide release time can be shortened to 1/10 as compared with the method of Comparative Example 1.

[0051] It should be noted that in the above-described embodiment, the power described by taking as an example the case where methane is used as the hydrocarbon-based gas and the case where hydrogen is used as the sweep gas to be circulated in the release process. In the method, it is possible to use a hydrocarbon-based gas other than methane, for example, propane, butane, etc., in a carbon dioxide releasing step. Also, depending on the purpose, a mixed gas in which a hydrocarbon-based gas and hydrogen are mixed. Furthermore, it is also possible to use a hydrocarbon-based gas or a mixed gas of hydrogen gas and other gas, for example, a mixed gas of hydrocarbon-based gas and water vapor or oxygen, or obtained by reforming it. It is also possible to use a mixed gas of carbon monoxide and hydrogen.

[0052] In the above embodiment, the case where a granular carbon dioxide absorbing material is used as the carbon dioxide absorbing material has been described as an example. However, the carbon dioxide absorbing material is not limited to a granular form, and is in the form of a powder. Use of various forms such as forms, molded bodies formed into various shapes such as cubes, rectangular parallelepipeds, and spheres, sheet-like molded bodies, and structures having a combination of them. Is possible.

In the above embodiment, Ba TiO Sr TiO and CaO are used as the carbon dioxide absorbent.

2 4, 2 4

The force explained when using BaCa Ti O as a carbon dioxide absorber

In the case of 3 2 2 9, it has been confirmed that substantially the same effect as in the case of the above embodiment can be obtained.

[0053] It should be noted that the invention of the present application is not limited to the configuration of each of the above embodiments in other respects, but relates to carbon dioxide absorption conditions, release conditions, etc., and various applications within the scope of the invention. It is possible to add deformation. Industrial applicability

As described above, according to the present invention, absorbed carbon dioxide can be efficiently released in a shorter time, and carbon dioxide can be recovered by converting it to carbon monoxide, which is more versatile. It becomes possible.

Therefore, the present invention can be widely applied to separation and recovery of carbon dioxide before combustion in the hydrogen production process and separation and recovery of carbon dioxide in combustion exhaust gas generated in a factory.

Claims

The scope of the claims

[1] (a) an absorption process in which carbon dioxide absorbent absorbs carbon dioxide;

A carbon dioxide separation and recovery method comprising:

In the release step (b), the carbon dioxide absorbent that has absorbed carbon dioxide is heated while supplying hydrogen gas or a hydrocarbon-based gas to release carbon dioxide. Method.

[2] The method for separating and recovering carbon dioxide according to claim 1, wherein the heating temperature in the releasing step (b) is 800 to 1000 ° C.

[3] The carbon dioxide absorbent is mainly composed of an alkaline earth metal oxide or a composite oxide containing an alkaline earth metal oxide. The method for separating and recovering carbon dioxide according to any one of claims 1 and 2.

[4] The carbon dioxide absorbing material is Ba TiO Sr TiO and Ba Ca Ti O!

2 4, 2 4 3 2 2 9

4. The method for separating and recovering carbon dioxide according to claim 3, wherein the main component is a composite oxide.