WO2012007084A1

WO2012007084A1 - Co2 removal from gases with low co2 partial pressures by means of n-isopropyl-1,3-propanediamine

Info

Publication number: WO2012007084A1
Application number: PCT/EP2011/002825
Authority: WO
Inventors: Johannes Menzel; Olaf Von Morstein
Original assignee: Uhde Gmbh
Priority date: 2010-07-16
Filing date: 2011-06-09
Publication date: 2012-01-19
Also published as: DE102010027513A1

Abstract

The use of an absorbent for removal of acidic gases from a fluid stream comprising an aqueous solution of N-isopropyl-1,3-propanediamine, wherein the fluid stream is contacted with the absorbent at a partial pressure of < 200 mbar, and wherein the absorbent contains 40 to 65% of N-isopropyl-1,3-propanediamine based on the weight of the absorbent.

Description

C0 ₂ removal from gases with low C0 ₂ partial pressures using N-isopropyl-1,3-propanediamine

The invention relates to the use of an absorbent for removing C0 ₂ from industrial gases.

The removal of C0 ₂ from industrial gases is of particular importance for the reduction of C0 ₂ emissions, since C0 _{2 is} considered as the main cause of the greenhouse effect.

In the industry, for the removal of acid gas components, aqueous solutions of organic bases, e.g. Alkanolamines used as an absorbent. The absorbent is regenerated by supplying heat, pressure reduction, or stripping by means of suitable auxiliary media. After regeneration, the absorbent is a regenerated solvent for the absorption of

Sour gas components available again. Flue gases from the combustion of fossil fuels, now fall approximately at atmospheric pressure. Since the C0 ₂ content in the flue gases is typically about 3 to 13% by volume, the C0 ₂ partial pressure is correspondingly only 0.03 to 0.13 bar. In order to achieve a sufficient removal of C0 ₂ 's from the flue gases at these low C0 ₂ partial pressures, a suitable

Absorbents have a very high binding capacity for C0 ₂ . In particular, the highest possible absorption capacity should already be available even at low C0 ₂ partial pressures.

By the absorption capacity of the absorbent is essentially the required Absorptionsmittelumlaufmenge and thus determines the size and cost of the equipment required for it. Since the energy needed to heat and cool the absorbent is proportional to the amount of recirculation, the regeneration energy needed to regenerate the solvent is also substantially reduced if it succeeds in reducing the recirculating amount of the absorbent.

CONFIRMATION COPY In addition to a high absorption capacity should be a suitable

Absorbent in particular but also have the highest possible stability to oxygen, since in particular in flue gases always a certain amount of oxygen is present. It is known from the literature that many amine compounds, which otherwise have favorable absorption properties, are readily decomposed in the presence of oxygen, resulting in a high level of

Absorbent consumption and other leads to correspondingly high costs. The resulting decomposition products usually lead to significantly increased corrosion and can on the other hand significantly reduce the capacity of the absorbent.

Volatile decomposition products, such as ammonia would have the consequence that the C0 ₂ product and leaving the C0 ₂ scrubbing flue gas would be contaminated with impermissible emission components. The avoidance of these emissions necessitates further process steps, which further increase the costs of C0 ₂ scrubbing.

There is therefore a considerable need for an absorbent which has the highest possible absorption capacity for C0 ₂ at low partial pressures of <1 bar, in particular at <0.2 bar, and also under the conditions of

Absorbent regeneration is thermally stable. The cover of this need, ie the provision of such an absorbent, as well as a method for removing C0 ₂ from industrial gases, the present invention has made the task.

The object is achieved by the use of an absorbent containing N-isopropyl-1, 3-propanediamine in aqueous solution, wherein the fluid stream with the absorbent at a partial pressure of <200 mbar is brought into contact, and wherein the absorbent based on the weight of the

Absorbent 40 to 65% of N-isopropyl-1, 3propandamin contains.

In one embodiment of the invention, the absorbent to be used also contains at least one other of N-isopropyl-1, 3-propanediamine different amine. Thus, for example, the absorbent according to the invention may contain 5 to 45% by weight, preferably 10 to 40% by weight, of one or more amines thereof. The at least one other of N-isopropyl-1, 3-propanediamine different further amine is selected for example from:

A) tertiary amines of the general formula:

N (R1) ₂ . _n (R2) _{1 + n}

wherein R 1 is an alkyl group and R 2 is a hydroxyalkyl group or

tertiary amines of the general formula:

(R1) ₂ . _n (R2) _n NXN (R1) _2-m (R2) _m

where R 1 is an alkyl group, R 2 is a hydroxyalkyl group, X is an alkylene group which is interrupted one or more times by oxygen and n and m is an integer from 0 to 2, or two radicals R 1 and R 2 linked to different nitrogen atoms R 2 together represents an alkylene group, B) sterically hindered amines,

C) 5-, 6-, or 7-membered saturated heterocycles having at least one NH group in the ring which may contain one or two additional heteroatoms selected from nitrogen and oxygen in the ring,

D) primary or secondary alkonolamines,

E) alkylenediamines of the formula:

H ₂ N-R2-NH ₂

wherein R2 is a C ₂ - to C ₆ alkyl group.

In a preferred embodiment of the invention, the tertiary amines used in addition to N-isopropyl-1, 3-propanediamine are selected from a group comprising tris (2-hydroxyethyl) amine, tris (2-hydroxypropyl) amine , Tributanolamine, bis (2-hydroxyethyl) methylamine, 2-diethylaminoethanol, 2-dimethylaminoethanol, 3-dimethylamino-1-propanol, 3-diethylamino-1-propanol, 2-diisopropylaminoethanol, N, N-bis (2-hydroxypropyl) methylamine

(Methyldiisopropanolamine, MDIPA), Ν, Ν, Ν ', Ν'-tetramethylethylenediamine, N, N-diethyl-N', N'-dimethylethylenediamine, N, Ν, Ν ', Ν'-tetraethylethylenediamine, N, Ν, Ν' , Ν'-tetramethylpropanediamine, N, N, N ', N'-tetraethylpropanediamine, N, N'-dimethyl-N'.N'-diethylethylenediamine, 2- (2-dimethylaminoethoxy) -N, N-dimethylethanamine; 1, 4-

Diazabicyclo [2.2.2] octane (DABCO); N, N, N ^* -trimethylaminoethylethanolamine, N, N'-dimethylpiperazine and N, N'-bis (hydroxyethyl) piperazine. Other eligible Tertiary amines are disclosed in WO 2008/145658 A1, US 4,217,236 and US 2009/0199713 A1.

In another embodiment, the sterically hindered amines which are used in addition to N-isopropyl-1, 3-propanediamine, selected from a group comprising 2-amino-2-methyl-1-propanol, 2-amino 2-methyl-1-butanol, 3-amino-3-methyl-1-butanol, 3-amino-3-methyl-2-pentanol and 1-amino-2-methylpropan-2-ol. Other candidate sterically hindered amines are disclosed in WO

2008/145658 A1, US 4,217,236, US 2009/0199713 A1, US 5,700,437, US 6,500,397 B1 and US 6,036,931.

Optionally, the 5-, 6-, or 7-membered saturated heterocycles used in addition to N-isopropyl-1,3-propanediamine are selected from the group comprising, piperazine, 2-methylpiperazine, N-methylpiperazine , N-ethylpiperazine, N-aminoethylpiperazine, homopiperazine, piperidine and orpholine.

Other compounds that can be selected are described in WO 2008/145658 A1 and US 2009/0199713 A1.

Advantageously, the primary or secondary alkanolamines used in addition to N-isopropyl-1,3-propanediamine are selected from the group comprising 2-aminoethanol, N, N-bis (2-hydroxyethyl) amine, N, N-bis (2-hydroxypropyl) amine, 2- (methylamino) ethanol, 2- (ethylamino) ethanol, 2- (n-butylamino) ethanol, 2-amino-1-butanol, 3-amino-1 propanol and 5-amino-1-pentanol. Also for this purpose, further possible compounds in the documents WO 2008/145658 A1 and US 2009/0199713 A1 are disclosed.

In a further embodiment of the invention, the alkyldiamines, which are used in addition to N-isopropyl-1, 3-propanediamine, selected from a group comprising, hexamethylenediamine, 1, 4-diaminobutane, 1, 3-diaminopropane, 2, 2-Dimethyl 1, 3-diaminopropane, 3-methylaminopropylamine, 3

(Dimethylamino) propylamine, 3- (diethylamino) propylamine, 4-dimethylaminobutylamine and 5-dimethylaminopentylamine, 1,1,1 N, N-tetramethylethanediamine, 2,2, N, N-tetramethyl-1,3-propanediamine, N, N ' -Dimethyl-1,3-propanediamine, N, N'-bis (2-hydroxyethyl) ethylenediamine. In addition, all components come into consideration, in WO 2008/145658 A1 and US 2009/0199713 A1 as such

Marked are. Advantageously, the loaded absorbent is regenerated by heating, relaxation, stripping by means of stripping vapors generated by internal evaporation of the solvent, stripping with an inert fluid or a combination of two or all of these measures.

The present invention will be described below in detail by way of example.

Example: Determination of the CQ ₂ uptake capacity

For the synthetic gas solubility measurements (isothermal P-x data) a static phase equilibrium apparatus according to the synthetic measuring principle was used. In this arrangement, the pressure for different

Gross compositions of a mixture measured at constant temperature. The thermostated, purified and degassed solvent is removed by means of

Metering pumps which allow to show small volume differences, filled in an evacuated and thermostated measuring cell. Then the gas is added in small steps. That then at a certain pressure in the

Absorption solution C0 ₂ is determined by calculation, taking into account the gas space.

It was the C0 ₂ uptake for a C0 ₂ partial pressure of 0.1 bar at a temperature of 40 ° C and the relative absorption capacity of N-isopropyl-1, 3-propanediamine compared to monoethanolamine (MEA) determined ,

Tab. 1:

From the results shown in Table 1 shows that at the same amine concentration takes N-isopropyl-1, 3-propanediamine about 18% more C0 ₂ receives than the prior art detergent monoethanolamine. Surprisingly, it was now in equilibrium measurements under regeneration conditions (120 ° C) that N-isopropyl-1, 3-propanediamine solutions in contrast to MEA solutions are almost completely regenerated by C0 ₂ . Thus, at 120 ° C and 10 mbar C0 ₂ partial pressure only a C0 ₂

Residual concentration of less than 0.2% by weight of C0 _{2 found} in the solution. A 30% strength by weight MEA solution still has a CO ₂ residual concentration of about 2.5% by weight under these conditions.

The cyclic absorption capacity, which is determined as the difference in loading at 40 ° C and 120 ° C, is therefore at the same weight proportions of the respective amine in water about 1, 5 times the cyclic absorption capacity of MEA.

Thus, according to the invention there is a solvent for the absorption of C0 ₂ , in particular in the range of low C0 ₂ partial pressures, which has a higher cyclic absorption capacity, than a comparable solvent according to the prior art. This proves the particular suitability for the C0 ₂ removal of the amine of the invention from industrial gases with low partial pressures (<200 mbar).

Claims

claims

1. Use of an absorbent to remove acidic gases

a fluid stream comprising an aqueous solution of N-isopropyl-1,3-propanediamine, wherein the fluid stream with the absorbent in a

Partial pressure of <200 mbar is brought into contact, and wherein the

Absorbent based on the weight of the absorbent contains 40 to 65% of N-isopropyl-1,3-propanediamine.

2. Use of an absorbent according to any one of claims 1 or 2, wherein the absorbent contains at least one other of N-isopropyl-1, 3-propanediamine different amine.

3. Use of an absorbent according to claim 3, wherein the

Absorbent 5 to 45%, and preferably 10 to 40% of at least one of N-isopropyl-1, 3-propanediamine different amine.

4. Use of an absorbent according to any one of claims 3 or 4, wherein the at least one other N-isopropyl, 3-propanediamine different amine is selected from:

A) tertiary amines of the general formula:

N (R1) ₂ . _n (R2) _{1 + n}

wherein R 1 is an alkyl group and R 2 is a hydroxyalkyl group or

tertiary amines of the general formula:

(R1) ₂ , "(R2) _n NXN (R1) _2-m (R2) _m

where R 1 is an alkyl group, R 2 is a hydroxyalkyl group, X is an alkylene group which is interrupted one or more times by oxygen and n and m is an integer from 0 to 2, or two radicals R 1 and R 2 linked to different nitrogen atoms R2 together for one

Alkylene group, ß) sterically hindered amines, C) 5-, 6-, or 7-membered saturated heterocycles having at least one NH group in the ring which may contain one or two additional heteroatoms selected from nitrogen and oxygen in the ring,

D) primary or secondary alkonolamines,

E) alkylenediamines of the formula:

H ₂ N-R2-NH ₂

wherein R2 is a C ₂ to C ₆ alkyl group.

5. Use of an absorbent according to claim 5, wherein the tertiary amine is selected from a group comprising bis-dimethylaminoethyl ether, tris (2-hydroxyethyl) amine, tris (2-hydroxypropyl) amine, tributanolamine, bis (2-hydroxyethyl) methylamine , 2-diethylaminoethanol, 2-dimethylaminoethanol, 3-dimethylamino-1-propanol, 3-diethylamino-1-propanol, 2-diisopropylaminoethanol, N, N-bis (2-hydroxypropyl) methylamine

(Methyldiisopropanolamine, MDI PA), Ν, Ν, Ν ', Ν'-tetramethylethylenediamine, N, N-diethyl-N', N'-dimethylethylenediamine, N, Ν, Ν ', Ν'-tetraethylethylenediamine, N, N.N '.N'-tetramethylpropanediamine.NNN'.N'-tetraethylpropanediamine, N, N-dimethyl-N'.N'-diethylethylenediamine, 2- (2-dimethylaminoethoxy) -N, N-dimethylethanamine; 1, 4-diazabicyclo [2.2.2] octane (DABCO); Ν, Ν, Ν'- Trimethylaminoethylethanolamin, N, N'-dimethylpiperazine and Ν, Ν'-bis (hydroxyethyl) piperazine.

6. Use of an absorbent according to claim 5, wherein the steric

hindered amine is selected from the group comprising 2-amino-2-methyl-1-propanol, 2-amino-2-methyl-1-butanol, 3-amino-3-methyl-1-butanol, 3-amino-3 - methyl-2-pentanol and 1-amino-2-methylpropan-2-ol.

The use of an absorbent according to claim 5, wherein the 5-, 6-, or 7-membered saturated heterocycles are selected from a group comprising piperazine, 2-methylpiperazine, N-methylpiperazine, N-ethylpiperazine, N-aminoethylpiperazine, homopiperazine , Piperidine and morpholine.

The use of an absorbent according to claim 5, wherein the primary or secondary alkanolamines are selected from a group comprising 2-aminoethanol, N, N-bis (2-hydroxyethyl) amine, N, N-bis (2-hydroxypropyl ) amine, 2- (Methylamino) ethanol, 2- (ethylamino) ethanol, 2- (n-butylamino) ethanol, 2-amino-1-butanol, 3-amino-1-propanol and 5-amino-1-pentanol.

Use of an absorbent according to claim 5, wherein the alkyldiamines are selected from the group comprising hexamethylenediamine, 1,4-diaminobutane, 1,3-diaminopropane, 2,2-dimethyl-1,3-diaminopropane, 3-methylaminopropylamine, 3 (Dimethylamino) propylamine, 3- (diethylamino) propylamine, 4-dimethylaminobutylamine and 5-dimethylaminopentylamine, 1, 1, N, N-tetramethylethanediamine, 2,2, N, N-tetramethyl-1,3-propanediamine, N, N ' -Dimethyl-1,3-propanediamine, N, N'-bis (2-hydroxyethyl) ethylenediamine.

Use of an absorbent for removing carbon dioxide from a fluid stream according to any one of claims 1 to 12, wherein the loaded

Absorbent through

i) warming,

ii) relaxation,

iii) stripping by means of internal evaporation of the solvent

generated stripping vapors,

iv) stripping with an inert fluid

or a combination of two or all of these measures is regenerated.