JP2011152542A - Absorbing liquid, and apparatus and method of removing co2 or h2s from gas using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorbing liquid which can remove either one or both of CO<SB>2</SB>or/and H<SB>2</SB>S contained in a gas by a compact and energy-saving recovery unit, and an apparatus and a method of removing either one or both of CO<SB>2</SB>or/and H<SB>2</SB>S by using the absorbing liquid. <P>SOLUTION: The absorbing liquid absorbs either or both of CO<SB>2</SB>and H<SB>2</SB>S in the gas, and contains alkanolamine as a first compound component and a second component consisting of a nitrogen-containing compound having two or more of a primary nitrogen atom, a secondary nitrogen atom and a tertiary nitrogen atom in the molecule. As a result, the absorbing liquid can exhibit a more excellent absorptive capacity performance and absorption reaction heat performance compared to a single aqueous solution of the alkanolamine or nitrogen-containing compound having the same wt.% concentration and can recover either or both of CO<SB>2</SB>and H<SB>2</SB>S in the gas with low energy. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to an absorption liquid for removing CO ₂ (carbon dioxide) or H ₂ S (hydrogen sulfide) or both contained in a gas, a CO ₂ or H ₂ S or both removal apparatus using the absorption liquid, and Regarding the method.

In recent years, the greenhouse effect due to CO ₂ has been pointed out as one of the causes of global warming, and countermeasures have become urgent internationally to protect the global environment. The source of CO ₂ extends to all human activity fields where fossil fuels are burned, and there is a tendency to further demand for emission control. Along with this, for power generation facilities such as thermal power plants that use a large amount of fossil fuel, the boiler combustion exhaust gas is contacted with an alkanolamine aqueous solution, etc., and CO ₂ in the gas is removed and recovered. A method for storing the produced CO ₂ without releasing it to the atmosphere has been energetically studied. In addition, since the alkanolamine aqueous solution also reacts with acidic gases such as H ₂ S (hydrogen sulfide) in addition to CO ₂ (carbon dioxide), the chemical industry purifies various gases for the purpose of removing and recovering all acidic gases. Widely used in the process.

  Examples of the alkanolamine include monoethanolamine (MEA), ethylaminoethanol (EAE), triethanolamine, N-methyldiethanolamine (MDEA), diisopropanolamine, and diglycolamine. Amine (MEA) is preferably used.

  Furthermore, the effect which can have the performance which cannot be achieved only by those by mixing multiple types of the said alkanolamine is disclosed (for example, the performance of the liquid mixture of MEA and AMP is disclosed. Patent Document 1). In order to improve the absorption performance of alkanolamines, it has been proposed to use cyclic amines such as piperazine and linear amines such as ethylenediamine as absorption aids (Patent Document 2, Patent Document 3, Patent Document 4, Patents). Reference 5).

JP-A-6-343858 U.S. Pat. No. 4,336,233 Japanese Unexamined Patent Publication No. 1-223121 Japanese Examined Patent Publication No. 61-19286 US Pat. No. 6,436,174

When a large amount of CO ₂ is recovered in a large-scale plant, an apparatus capable of recovering with as little energy as possible is desired. In order to make this possible, it is necessary to reduce the circulating amount of the absorbing liquid and the amount of heat necessary for dissociating the absorbed CO ₂ . In order to reduce the amount of absorption liquid circulating, it is necessary to increase the absorption capacity per unit absorption liquid amount of the absorption liquid. For this reason, the concentration of the amine compound is often increased in the absorption liquid.

  However, it has been pointed out that when the concentration of the amine compound is increased, viscosity and corrosivity are increased (Patent Document 4). Among these, the corrosivity can be avoided by adding a corrosion inhibitor or selecting a piping material, but the viscosity is a problem that cannot be easily avoided in a normal process.

Also, depending on the type of amine compound, there are some which are difficult to increase in concentration due to low solubility in solvents. For example, piperazine described in Patent Document 3 has low solubility in water and low solubility of piperazine carbamate produced by reaction with CO _{2 in} the liquid, so the addition level is 0, 8 mol / liter or less. The concentration is limited.

  Patent Document 5 also shows that an absorption solution using a compound having a nitrogen atom in the ring and having a branched hydroxyl group or a branched alkyl group in a wide concentration range (0.1 to 50%) is useful. However, the addition of alcohols is an essential condition.

Known alkanolamines such as the MEA can be mixed with water at an arbitrary ratio, so that many of them can be easily concentrated. However, in an aqueous solution containing only one of them, the absorption capacity performance may not be proportional to the concentration when the concentration is increased. Therefore, depending on the type of amine, even if the concentration is increased, the expected effect of reducing the circulating amount of the absorbing solution may not be obtained. Therefore, in order to reduce CO ₂ recovery energy, the development of an absorbing solution that suppresses the increase in viscosity by effectively increasing the concentration of nitrogen-containing compounds and effectively improves the absorption capacity performance and absorption reaction heat performance. Was an issue.

In view of the above problems, the present invention is able to suppress an increase in viscosity even when the concentration of a nitrogen-containing compound is increased, and to effectively improve absorption capacity performance and absorption reaction heat performance. It is an object to provide an apparatus and method for removing ₂ or H ₂ S or both.

In view of the above problems, the present inventors have made extensive studies on an absorbing solution used when removing CO _{2 in} a gas. As a result, a mixed aqueous solution of an alkanolamine and a nitrogen-containing compound having a specific structure is obtained in a high concentration region. It was found that the increase in viscosity was suppressed, and CO ₂ absorption capacity performance / absorption reaction heat performance superior to an aqueous solution of the alkanolamine and nitrogen-containing compound having the same weight% concentration was exhibited, and CO ₂ or H _{2 in the} gas The present invention was completed, which provides an absorbing solution and a CO ₂ or H ₂ S removing apparatus and method using the absorbing solution, which can remove S with less energy.

A first invention of the present invention for solving the above-mentioned problems is an absorption liquid that absorbs CO _{2 and} / or H ₂ S in a gas, or both, and comprises monoethanolamine (MEA) or methyldiethanolamine (MDEA). And a second compound comprising at least one of 1- (2-aminoethyl) piperazine (AEPZ) or (1-methyl-aminoethyl) (4-methyl) piperazine. The first compound component is contained in the range of 15 wt% or more and 45 wt% or less, the second compound component is contained in the range of 15 wt% or more and 45 wt% or less, and 30 in total. The absorbent is characterized by being over 90% by weight and 90% by weight or less.

According to a second aspect of the invention, an absorption tower for removing CO ₂ or H ₂ S or both by bringing a gas containing CO ₂ or H ₂ S or both into contact with an absorbing solution, CO ₂ or H ₂ S or a regenerator for reproducing a solution which has absorbed the both regenerator in a CO ₂ or H ₂ S or CO ₂ removal or H ₂ S or both reusing solution was regenerated to remove both of the absorption tower An apparatus for removing CO _{2 and} / or H ₂ S, or both, characterized by using the absorbent of the first invention.

According to a third aspect of the present invention, there is provided an absorption tower for removing CO ₂ or H ₂ S or both by bringing a gas containing CO ₂ or H ₂ S or both into contact with an absorbing solution, and CO ₂ or H ₂ S or a regenerator for reproducing a solution which has absorbed the both regenerator in a CO ₂ or H ₂ S or CO ₂ removal or H ₂ S or both reusing solution was regenerated to remove both of the absorption tower a method, in CO ₂ or H ₂ S or CO ₂ or H ₂ S or the method of removing its both and removing the both using the absorbing liquid of the first invention.

According to the present invention, alkanolamine, which is a first nitrogen-containing compound component that absorbs CO _{2 and} / or H ₂ S in the gas, or both, and _two primary, secondary, and tertiary nitrogen atoms in the molecule. By using an absorption liquid containing the nitrogen-containing compound having the above or the second component comprising all of the nitrogen-containing compound, an increase in viscosity can be suppressed even in a high concentration region, and an alkanol having the same weight% concentration can be suppressed. Compared to an aqueous solution of an amine and a nitrogen-containing compound alone, it has excellent CO ₂ or H ₂ S removal performance, and can also provide an excellent absorption reaction heat performance.

In addition, when using a high concentration absorption liquid having an amine concentration of 30% by weight or more, an absorption liquid having excellent absorption capacity performance and absorption reaction heat performance compared to the use of the same concentration of amine alone is provided. Compared with the use alone, it is possible to reduce the circulating amount of the absorbing liquid and to reduce the amount of heat necessary for dissociating the absorbed CO _{2 and} / or H ₂ S. If the absorption liquid circulation amount can be reduced, not only can the measures be made compact, but the amount of heat required for dissociation can be reduced, and if the dissociation heat itself can be reduced, recovery can be achieved with less energy.

FIG. 1 is a schematic view of a CO ₂ removal apparatus.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment and an Example. In addition, constituent elements in the following embodiments and examples include those that can be easily assumed by those skilled in the art or those that are substantially the same.

ここで、式（Ｉ）〜（III）中、
ｘ、ｙは、１≦ｘ≦５、２≦ｙ≦１０であり、
Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝１〜２１、ｋ＝０〜５、ｌ＝０〜５である。）である。 [Embodiment of the Invention]
The absorbing liquid according to the present invention is an absorbing liquid that absorbs CO _{2 and} / or H ₂ S in the gas, or both, and includes first compound component, primary, secondary, and tertiary nitrogen in the molecule. And a second compound component comprising at least two or more nitrogen-containing compounds or all nitrogen-containing compounds.
Here, the first compound component is the following compound or a mixture thereof.

Here, in the formulas (I) to (III),
x and y are 1 ≦ x ≦ 5, 2 ≦ y ≦ 10,
R ¹ , R ² , R ³ , R ⁴ are —C _i H _j O _k N _l (where i = 0 to 10, j = 1 to 21, k = 0 to 5, l = 0 to 5 Yes.)

  Here, for example, monoethanolamine (MEA), methyldiethanolamine (MDEA), diethanolamine (DEA), triethanolamine (TEA), diisopropanolamine (DIPA) are used as absorption liquids according to formula (I) used in the present invention. 3-amino-1-propanol (AP), 2-amino-2-methylpropanol (AMP), ethyldiethanolamine (EDEA), 2-methylaminoethanol (MAE), 2-ethylaminoethanol (EAE), 2-n -Propylaminoethanol, 2-n-butylaminoethanol (n-BAE), 2-n-pentylaminoethanol, 2-isopropylaminoethanol, 2-sec-butylaminoethanol, 2-isobutylaminoethanol (IBAE), 2 -Dimethyla Bruno ethanol (DMAE), can be exemplified 2-diethylaminoethanol (DEAE) or the like.

  Here, the absorption liquid concerning Formula (II) used by this invention can illustrate 2, 3- diamino propionic acid (DAPA), glycine, etc., for example.

Here, the absorption liquid concerning following formula (III) used by this invention can illustrate a 1, 2- ethylenediamine etc., for example.
In addition, you may use these nitrogen-containing compounds in mixture of 2 or more types.

  In the present invention, the second compound component includes 1) a nitrogen-containing compound having secondary or tertiary nitrogen in the ring, and 2) a nitrogen-containing compound having secondary and tertiary nitrogen in the ring. 3) In the above 2) or 3), a nitrogen-containing compound having nitrogen in any of the substituents branched from the ring, and 4) In the above 3), the substituent branched from the ring has a primary nitrogen. A nitrogen compound, 5) a nitrogen-containing compound in which the second compound component has at least three or more nitrogen atoms in the molecule, and 6) a nitrogen-containing compound having at least a different grade of nitrogen in the molecule in 5) Can be used.

Hereinafter, examples of the nitrogen-containing compounds 1) to 6) are shown in the following formulas (III) to (XX), but the present invention is not limited thereto.
Here, the nitrogen-containing compounds represented by the formulas (IV) and (V) are linear nitrogen-containing compounds in the formula and have all of primary, secondary, and tertiary nitrogen.

  Further, the nitrogen-containing compounds represented by the formulas (VI) to (XIII) are cyclic nitrogen-containing compounds having all primary, secondary, and tertiary nitrogen.

  In addition, the nitrogen-containing compounds represented by the formulas (XIV) to (XIX) are cyclic nitrogen-containing compounds and have different nitrogen grades in the cyclic portion and the branched portion.

  Further, the nitrogen-containing compound represented by the formula (XX) is a cyclic nitrogen-containing compound, and contains at least 3 or more nitrogens, and has at least nitrogen grades different in the molecule.

  Here, examples of the absorbing solution according to the following formula (IV) used in the present invention include 4,7-diaza-2-amino-2-ethyl-7-methyloctane.

ここで、式（ＩＶ）中、
Ｒ⁵、Ｒ⁶は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ⁷、Ｒ⁸は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in formula (IV),
R ⁵ and R ⁶ are —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).
R ⁷ and R ⁸ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).

Here, the absorption liquid according to the following formula (V) used in the present invention is, for example, 4,7-diaza-
Examples include 2-amino-2,4-diethyloctane.

ここで、式（Ｖ）中、
Ｒ⁵、Ｒ⁶は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ⁷、Ｒ⁸は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in the formula (V),
R ⁵ and R ⁶ are —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).
R ⁷ and R ⁸ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).

  Here, examples of the absorbing solution according to the following formula (VI) used in the present invention include 1- (2-aminoethyl) piperazine (AEPZ).

ここで、式（ＶＩ）中、
Ｒ⁹、Ｒ¹¹は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ¹⁰は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in formula (VI),
R ⁹ and R ¹¹ are —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).
R ¹⁰ is —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).

  Here, the absorption liquid concerning the following formula (VII) used by this invention can illustrate 1-methyl-2-aminomethyl piperazine etc., for example.

ここで、式（ＶII）中、
Ｒ⁹、Ｒ¹¹は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ¹⁰、Ｒ¹²は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in the formula (VII),
R ⁹ and R ¹¹ are —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).
R ¹⁰ and R ¹² are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).

  Here, the absorption liquid concerning the following formula (VIII) used by this invention can illustrate (2-amino)-(5 dimethylamino) pyrrolidine etc., for example.

ここで、式（ＶIII）中、
Ｒ⁹は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ¹³、Ｒ¹⁴、Ｒ¹⁵、Ｒ¹⁶は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in the formula (VIII),
R ⁹ is —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).
R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5 Yes.)

  Here, examples of the absorbing solution according to the following formula (IX) used in the present invention include 2- (aminoethyl (methylamino)) pyrrolidine.

ここで、式（ＩＸ）中、
Ｒ⁹、Ｒ¹⁸は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ¹⁰、Ｒ¹⁵、Ｒ¹⁷は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in formula (IX),
R ⁹ and R ¹⁸ are —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, and l = 0 to 5).
R ¹⁰ , R ¹⁵ , and R ¹⁷ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5). It is.

Here, the absorption liquid according to the following formula (X) used in the present invention is, for example, (1-methyl) (2
-Amino)-(5 methylamino) pyrrolidine and the like can be exemplified.

ここで、式（Ｘ）中、
Ｒ⁹は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ¹³、Ｒ¹⁴、Ｒ¹⁶、Ｒ¹⁹は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in the formula (X),
R ⁹ is —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).
R ¹³ , R ¹⁴ , R ¹⁶ , and R ¹⁹ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5 Yes.)

Here, the absorption liquid according to the following formula (XI) used in the present invention is, for example, (1-methyl) (2
-Aminoethylamino) pyrrolidine and the like can be exemplified.

ここで、式（ＸＩ）中、
Ｒ⁹、Ｒ¹⁸は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ¹⁴、Ｒ¹⁷、Ｒ²⁰は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in formula (XI),
R ⁹ and R ¹⁸ are —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, and l = 0 to 5).
R ¹⁴ , R ¹⁷ and R ²⁰ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5). It is.

  Here, examples of the absorbing liquid according to the following formula (XII) used in the present invention include (1-aminomethyl) (4-methylamino) piperidine.

ここで、式（ＸII）中、
Ｒ⁹、Ｒ²¹は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ¹⁴、Ｒ¹⁶、Ｒ¹⁷は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in the formula (XII),
R ⁹ and R ²¹ are —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).
R ¹⁴ , R ¹⁶ and R ¹⁷ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5). It is.

Here, examples of the absorbing liquid according to the following formula (XIII) used in the present invention include (1-methylaminoethyl) 4-aminopiperidine.

ここで、式（ＸIII）中、
Ｒ⁹、Ｒ¹⁸は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ¹⁴、Ｒ¹⁶、Ｒ¹⁷は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in formula (XIII),
R ⁹ and R ¹⁸ are —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, and l = 0 to 5).
R ¹⁴ , R ¹⁶ and R ¹⁷ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5). It is.

Here, the absorption liquid concerning the following formula (XIV) used by this invention can illustrate 4-amino piperidine etc., for example.

ここで、式（ＸＩＶ）中、
Ｒ²²は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ²³、Ｒ²⁴は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in formula (XIV):
R ²² is —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).
R ²³ and R ²⁴ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).

Here, examples of the absorbing solution according to the following formula (XV) used in the present invention include (1-aminomethyl) piperidine.

ここで、式（ＸＶ）中、
Ｒ²⁵は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ²³、Ｒ²⁶は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in the formula (XV),
R ²⁵ is —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).
R ²³ and R ²⁶ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).

  Here, the absorption liquid concerning the following formula (XV1) used by this invention can illustrate N-methyl- 2 amino piperidine etc., for example.

ここで、式（ＸＶＩ）中、
Ｒ²³、Ｒ²⁷、Ｒ²⁸は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in the formula (XVI),
R ²³ , R ²⁷ and R ²⁸ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5). It is.

  Here, examples of the absorbing solution according to the following formula (XVII) used in the present invention include N, N dialkyl-4 aminopiperidine.

ここで、式（ＸＶII）中、
Ｒ²²は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ²³、Ｒ²⁴、Ｒ²⁷、Ｒ²⁹は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in the formula (XVII),
R ²² is —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).
R ²³ , R ²⁴ , R ²⁷ , R ²⁹ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5 Yes.)

  Here, examples of the absorbing solution according to the following formula (XVIII) used in the present invention include (N alkylaminomethyl) piperidine.

ここで、式（ＸＶIII）中、
Ｒ²⁵は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ²³、Ｒ²⁶、Ｒ²⁹は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in the formula (XVIII),
R ²⁵ is —C _i H _j O _k N _l (where i = 0 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).
R ²³ , R ²⁶ and R ²⁹ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5). It is.

Here, the absorbing liquid according to the following formula (XIX) used in the present invention can be exemplified by (N alkyl-4aminoalkyl) piperidine and the like.

ここで、式（ＸＩＸ）中、
Ｒ²³、Ｒ²⁷、Ｒ²⁸、Ｒ²⁹は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in the formula (XIX),
R ²³ , R ²⁷ , R ²⁸ and R ²⁹ are —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5 Yes.)

  Here, examples of the absorbing solution according to the following formula (XX) used in the present invention include (1-methyl-aminoethyl) (4-methyl) piperazine.

ここで、式（ＸＸ）中、
Ｒ³⁰、Ｒ³²、Ｒ³³、Ｒ³⁴は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝０〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。
Ｒ³¹は、−Ｃ_iＨ_jＯ_kＮ_l（ここで、ｉ＝１〜１０、ｊ＝０〜２６、ｋ＝０〜５、ｌ＝０〜５である。）である。

Here, in formula (XX),
R ³⁰ , R ³² , R ³³ , R ³⁴ are —C _i H _j O _k N _l (where i = 0-10, j = 0-26, k = 0-5, l = 0-5 Yes.)
R ³¹ is —C _i H _j O _k N _l (where i = 1 to 10, j = 0 to 26, k = 0 to 5, l = 0 to 5).

  Here, as the concentration of the amine component in the absorbing liquid used for contact with the gas of the present invention, the first compound component is contained in the range of 15 wt% to 45 wt%, and the second compound component is It is preferable that it is contained in the range of 15% by weight or more and 45% by weight or less, and more than 30% by weight and 90% by weight or less as a whole. The blending amount of both is more preferably in the range of 40 to 70% by weight.

  This is because an increase in viscosity cannot be suppressed if the content is outside these ranges, as shown in the examples described later. Moreover, it is because it does not contribute to the dramatic improvement in absorption capacity performance and absorption reaction heat performance.

  On the other hand, the component other than the amine is usually water, but may be another solvent or a mixture thereof. Furthermore, a corrosion inhibitor, a deterioration inhibitor, etc. are added as needed.

  In the present invention, the temperature of the absorbing liquid at the time of contact with the gas is usually in the range of 30 to 70 ° C.

The gas conditions to which the present invention can be applied are typified by a total pressure near atmospheric pressure and a CO ₂ concentration of 10%, but are not limited thereto.

Examples of the gas to be treated according to the present invention include coal gasification gas, synthesis gas, coke oven gas, petroleum gas, natural gas and the like, but are not limited thereto, and CO ₂ or H ₂ Any gas may be used as long as it contains an acid gas such as S.

The process that can be employed in the method for removing CO _{2 and} / or H ₂ S in the gas of the present invention is not particularly limited, but an example of a removal apparatus for removing CO ₂ will be described with reference to FIG.

FIG. 1 is a schematic view of a CO ₂ removal apparatus. As shown in FIG. 1, the gas is guided to the absorption tower 1 through the CO ₂ -containing gas supply port 4. The gas pushed into the absorption tower 1 is brought into countercurrent contact with the CO ₂ absorbing solution supplied from the nozzle 7 in the filling unit 2, and CO ₂ in the gas is absorbed and removed by the absorbing solution, and the gas is desorbed. It is discharged from the CO ₂ gas outlet 5. The absorbing solution supplied to the absorption tower 1 absorbs CO ₂ , is sent to the heat exchanger 14 and the heater 8, is heated, and is sent to the regeneration tower 15. In the regeneration tower 15, the absorption liquid flows from the nozzle 16 to the lower part through the filling part 17. During this time, CO ₂ is desorbed and the absorbing solution is regenerated. The regenerated absorption liquid is returned to the absorption tower 1 from the absorption liquid supply port 6 through the heat exchanger 14 and the absorption liquid cooler 26 by the pump 9. On the other hand, in the upper part of the regeneration tower 15, the CO ₂ separated from the absorption liquid comes into contact with the reflux water supplied from the nozzle 18, is cooled by the regeneration tower reflux cooler 23, and is entrained with CO ₂ by the reflux drum 21. The water vapor separated from the condensed water is led to the CO ₂ recovery step through the recovery CO ₂ line 22. The reflux water is sent to the regeneration tower 15 by the reflux water pump 20. In this embodiment, the outline is only described, and a part of the attached devices is omitted.

By using the absorption liquid according to the present invention as the absorption liquid of the above-described CO ₂ removal device, efficient absorption and removal of CO ₂ can be performed.

  Hereinafter, the present invention will be described in more detail based on examples.

  30% by weight of monoethanolamine (MEA) having a primary amino group as the first compound component in each glass reaction vessel on the sample side and the reference side of the reaction heat measuring device (Kalbe calorimeter), and second An aqueous solution containing 30% by weight of 1- (2-aminoethyl) piperazine (AEPZ) having primary, secondary, and tertiary amino groups as a compound component was mixed to obtain an absorbing solution (Example 1).

  Also, an absorption solution was prepared by mixing 30% by weight of 2-ethylaminoethanol having a secondary amino group (EAE) as the first compound component and 30% by weight of AEPZ as the second compound component. (Example 2).

  Further, an absorption solution was prepared by mixing an aqueous solution containing 30% by weight of methyldiethanolamine (MDEA) having a tertiary amino group as the first compound component and 30% by weight of AEPZ as the second compound component (Examples). 3).

5 g of each of the absorbents according to Examples 1 to 3 was added, and the thermostatic chamber temperature was set to 40 ° C. Then, while maintaining the temperature at 40 ° C., the test gas was brought into contact with the absorbing solution on the sample side and the reference side by bubbling at a flow rate of 50 ml / min under atmospheric pressure.
Here, as a test gas, a 40 ° C. model gas having a composition of CO ₂ : 10 mol% and N ₂ : 90 mol% is provided on the sample side, and 40 ° C. of N ₂ : 100 mol% is provided on the reference side. Gas was used.

Continue to vent the test gas, measure the time differential value (W) of the amount of heat generated on the sample side and the reference side, and calculate the calorific value (kJ) associated with the CO ₂ absorption reaction from the time variation of the difference (heat flow). Calculated. The time at which the heat flow value converged to a value of 2% or less of the peak was judged as the end (saturation) point of the CO ₂ absorption reaction, and the time from the start to the end of the aeration was taken as the reaction time (minutes). Calculated for CO ₂ contained in the CO ₂ absorbing solution after the completion of the reaction, was measured using a CO ₂ analyzer (total organic carbon meter), CO ₂ saturated absorption amount of the absorbent solution (molCO ₂ / kg absorbing solution) did.

The CO ₂ absorption reaction rate (molCO ₂ / min) and the CO ₂ absorption reaction heat (kJ / mol CO ₂ ) were calculated from the calorific value until the end of the reaction, the reaction time, and the CO ₂ saturated absorption amount.

  Further, in addition to the above-mentioned mixed solution of plural amines, the same test was performed on 30% by weight and 60% by weight aqueous solutions of MEA, EAE, MDEA, and AEPZ as comparative examples.

The results of CO ₂ saturation absorption amount, CO ₂ absorption reaction rate, and CO ₂ absorption reaction heat according to the examples and comparative examples are shown in “Table 1” below.

As shown in Table 1, 30% by weight of each of MEA, EAE, MDEA, and AEPZ (Comparative Examples 1-1, 2-1, 3-1, 4-1) and 60% by weight of the absorbent Comparing the performance of (Comparative Examples 1-2, 2-2, 3-2, 4-2), the CO ₂ saturated absorption capacity performance and the CO ₂ reaction heat performance are not proportional to the amine concentration, and one kind of amine It is clear that the performance improvement due to the increase in the amine concentration cannot be sufficiently expected in the aqueous solution containing only the salt.

On the other hand, the mixed absorbent of MEA and AEPZ (Example 1), the mixed absorbent of EAE and AEPZ (Example 2), and the absorbent of MDEA and AEPZ (Example 3) have the same weight% concentration. Compared to an aqueous solution of alkanolamine and an amine compound alone (Comparative Examples 1-2, 2-2, 3-2, 4-2), both CO ₂ absorption capacity performance and CO ₂ absorption reaction heat performance were excellent.

For example, 30% by weight of EAE in Example 2 + 30% by weight of AMPZ has a CO ₂ absorption capacity increased by 20% and a CO ₂ absorption reaction heat of 10% compared to 60% by weight of EAE in Comparative Example 2-2 consisting of the constituents alone. As a result, the CO ₂ absorption capacity increased by 15% and the CO ₂ absorption reaction heat decreased by 7% with respect to 60% by weight of AEPZ in Comparative Example 4-2.

Most of the energy required for CO ₂ recovery is dominated by the factors contributed by the CO ₂ absorption capacity performance and the factors contributed by the CO ₂ absorption reaction heat performance. Is possible.

1 Absorption tower 15 Regeneration tower

Claims (3)

An absorbent that absorbs CO ₂ or H ₂ S or both in the gas,
A first compound component comprising at least one of monoethanolamine (MEA) or methyldiethanolamine (MDEA);
1- (2-aminoethyl) piperazine (AEPZ), or a second compound component consisting of at least one of (1-methyl-aminoethyl) (4-methyl) piperazine,
The first compound component is contained in the range of 15% by weight or more and 45% by weight or less, the second compound component is contained in the range of 15% by weight or more and 45% by weight or less, and the total exceeds 30% by weight, An absorption liquid characterized by being 90% by weight or less. An absorption tower for removing CO ₂ or H ₂ S or both by bringing a gas containing CO ₂ or H ₂ S or both into contact with an absorbing solution, and a solution that has absorbed CO ₂ or H ₂ S or both Play and regenerator, a regenerator in a CO ₂ or H ₂ S or apparatus for removing CO ₂ or H ₂ S or both reusing solution was regenerated to remove both of the absorption tower, wherein An apparatus for removing CO ₂ or H ₂ S or both, characterized by using the absorbing liquid according to Item 1. An absorption tower for removing CO ₂ or H ₂ S or both by bringing a gas containing CO ₂ or H ₂ S or both into contact with an absorbing solution, and a solution that has absorbed CO ₂ or H ₂ S or both Play and regenerator, a regenerator in a CO ₂ or H ₂ S or CO ₂ or H ₂ S or the method of removing its both reuse in the absorption tower the solution was regenerated to remove both, wherein A method for removing CO _{2 and} / or H ₂ S or both, wherein CO _{2 and} / or H ₂ S or both are removed using the absorbing liquid according to Item 1.

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