FR2957268A1 - Absorbent solution, useful for absorbing acidic compounds contained in a gaseous effluent, comprises water and at least one amino compound - Google Patents

Abstract

Absorbent solution, comprises: water; and at least one amino compound (I). Absorbent solution, comprises: water; and at least one amino compound of formula (I). R1-R5 : groups A (comprising H), groups B1 (comprising 1-20C alkyl and/or -NH 2or NY1 2) or groups C1 (comprising amine group of formula ([-CR11R12-] m-NR13R14)); Y1 : 1-20C alkyl and/or OH, or -O-X-H; X : -[CR7R8-CR9R10-O-] n; R7-R10 : H or 1-20C alkyl; n : 1-20; R11, R12 : H or 1-20C alkyl; m : 1 or 2; R13, R14 : H or 1-20C alkyl; R6 : group A, group B1, group C, or phenyl group of formula (d); and Z : covalent bond or 1-20C alkylene unit (-R15-). Provided that when 2 or 3 groups of R1-R6 responds to the definition of group C, then at least one of R1-R6 responds to the definition of group A. An independent claim is included for process for removing acid compounds contained in a gaseous effluent comprising: absorption of acid compounds by contacting the effluent with an absorbent solution to obtain a gaseous effluent depleted in acid compounds and an absorbent solution laden with acid compounds; and at least one step of regeneration of the absorbent solution laden with acid compounds. [Image] [Image].

Description

Field of the Invention The present invention relates to the removal of acidic compounds in a gaseous effluent. The present invention relates to the treatment of acid gases (H2S, CO2, COS, CS2, mercaptans and SO2) by means of a compound or a mixture of compounds according to general formula (I) R4 (I) where R1 to R6 are defined and distributed according to precise rules set out below, in the form of an aqueous absorbent solution. It is advantageously applied to the treatment of natural gas and gas of industrial origin. PRIOR ART Treatment of gases of industrial origin The gaseous effluents that can be treated can be of different natures. The synthetic gases, the combustion fumes, the refinery gases, the gases obtained at the bottom of the Claus process, the fermentation gases of biomass, the cement gases and the blast furnace gases can be mentioned without limitation. . All of these gases contain acidic compounds such as carbon dioxide (CO2), hydrogen sulfide (H2S), carbon oxysulphide (COS), carbon disulfide (CS2), sulfur dioxide (SO2) and mercaptans (RSH), mainly methyl mercaptan (CH3SH), ethyl mercaptan (CH3CH2SH) and propyl mercaptans (CH3CH2CH2SH). For example, in the case of combustion fumes, CO2 is the acid compound that is to be removed. Indeed, carbon dioxide is one of the greenhouse gases largely produced by various human activities and has a direct impact on atmospheric pollution. In order to reduce the quantities of carbon dioxide emitted into the atmosphere, it is possible to capture the CO2 contained in a gaseous effluent. As an illustration, a post-combustion CO2 capture unit aims to reduce the CO2 emissions of a thermal power plant by 90%. Natural gas treatment

In the case of natural gas, three main treatment operations are considered: deacidification, dehydration and degassing. The first step, which is deacidification, is aimed at the elimination of acid compounds such as carbon dioxide (CO2), but also hydrogen sulphide (H2S), carbon oxysulphide (COS), disulphide of carbon (CS2) and mercaptans (RSH), mainly methylmercaptan (CH3SH), ethylmercaptan (CH3CH2SH) and propylmercaptans (CH3CH2CH2SH). The generally accepted specifications for the deacidified gas are 2% of CO2 or 50 ppm by volume of CO2 to subsequently liquefy the natural gas, 4 ppm by volume of H2S, and 30 mg of total sulfur per m3. The dehydration step then controls the water content of the deacidified gas against transport specifications. Finally, the step of degassing the natural gas makes it possible to guarantee the dew point of the hydrocarbons of the natural gas, again according to transport specifications. Deacidification is therefore often carried out first, in particular in order to eliminate toxic acid gases such as H 2 S in the first stage of the process chain and in order to avoid the pollution of the different unit operations by these acidic compounds, in particular the dehydration section and the condensation and separation section of the heavier hydrocarbons.

Removal of Acidic Compounds by Absorption The deacidification of gaseous effluents, such as for example natural gas and combustion fumes, as well as synthesis gases, refinery gases, bottoms gases from the Claus process Biomass fermentation, cement and blast furnace gases, is usually carried out by washing with an absorbent solution. The absorbent solution absorbs the acidic compounds present in the gaseous effluent (H 2 S, mercaptans, CO 2, COS, CS 2 and SO 2). The solvents commonly used today are aqueous solutions of primary, secondary or tertiary alkanolamine, with a possible physical solvent. For example, document FR 2 820 430 can be cited which proposes processes for deacidification of gaseous effluents. Another example is US Pat. No. 6,852,144, which describes a method for removing acidic compounds from hydrocarbons. The method uses a water-methyldiethanolamine or water-triethanolamine absorbent solution containing a high proportion of a compound belonging to the following group: piperazine and / or methylpiperazine and / or morpholine. For example, in the case of CO2 capture, the absorbed CO2 reacts with the alkanolamine present in solution according to a reversible exothermic reaction, well known to those skilled in the art and leading to the formation of hydrogenocarbonates, carbonates and / or carbamates, allowing a removal of CO2 in the gas to be treated. Similarly, for the removal of H2S in the gas to be treated, the absorbed H2S reacts with the alkanolamine present in solution according to a reversible exothermic reaction well known to those skilled in the art leading to the formation of hydrogen sulfide. An essential aspect of the operations of treatment of gases or industrial fumes by solvent is the regeneration of the separating agent. Depending on the type of absorption (physical and / or chemical), regeneration by expansion, and / or distillation and entrainment by a vaporized gas called "stripping gas" is generally considered. One of the main limitations of the solvents commonly used today is the need to implement high absorbent solution flow rates due to limited acid gas absorption capabilities, resulting in a significant energy consumption for the regeneration of the solvent, but also important equipment sizes (columns, pumps, etc.). This is particularly true in the case where the partial pressure of acid gases is low. For example, for an aqueous solution of MonoEthanolAmine (MEA) at 30% by weight used for the capture of CO2 in post-combustion in a thermal power plant smoke, where the partial pressure of CO2 is of the order of 0.12 bar, the regeneration energy represents about 3.7 GJ per tonne of CO2 captured (reference case, CASTOR project, post-combustion capture pilot of the Esbjerg thermal power plant, reference Knudsen, JN, Jensen, JN, Vilhelmsen, PJ; Biede, O. Experiment with CO2 capture from coal flue gas in pilot-scale: Testing of different amine solvents Energy Procedia, Volume 1, Issue 1, February 2009, Pages 783-790.

Such energy consumption represents a considerable operating cost for the CO2 capture process. Improved methods for treating acidic effluents are proposed to reduce this energy consumption, in particular in patents FR 2,877,858, FR 2,898,284, FR 2,900,841, which respectively disclose a process for deacidification of a gas with a solution. fractionally regenerated amine absorber, a method of deacidifying a gas by an amine absorbing solution with fractional regeneration by heating and a deacidification process using amine absorbing compounds with extraction of the reactive compounds.

In general, for the treatment of acidic effluents comprising acid compounds such as, for example, H 2 S, mercaptans, CO 2, COS, SO 2, CS 2, the use of amine-based compounds is interesting because of their ease. implementation in aqueous solution. However, during the deacidification of these effluents, the absorbent solution can degrade, either by thermal degradation or by secondary reaction with the acid gases to be captured, but also with other compounds contained in the effluent, such as, for example, oxygen, SOx and NOx, contained in industrial fumes. These degradation reactions are detrimental to the proper functioning of the process, decreasing the effectiveness of the solvent, corrosion, foaming, etc. Due to these degradations, it is necessary to carry out a purification of the solvent by distillation and / or ion exchange, and to make amine bonds. By way of example, the amine additions in a post-combustion CO 2 capture process, using a 30% by weight absorbent monoethanolamine solution, represent 1.4 kg of amine per tonne of CO2 captured, which increases considerably the operating costs of a catchment unit.

Finally, these degradation reactions limit the operating conditions of the process, in particular the temperature at which the regeneration of the solvent is carried out. The regeneration of aqueous solutions of alkanolamines, such as monoethanolamine, is therefore carried out at regenerator bottom temperatures of the order of 110 ° C., see 130 ° C. for the more stable amines, such as MethylDiEthanolAmine. Because of these temperatures at the bottom of the regenerator, the acid gases (CO2, H2S, COS, CS2, etc.) are obtained at moderate pressures, from 1 to 3 bars. Depending on the nature of the regenerated acid gas and the applications, the acid gas may be sent to a treatment unit, or reinjected for sequestration.

However, whatever the method used, it is difficult to find a stable absorbent compound, allowing the acid compounds to be removed in any type of effluent, and allowing the deacidification process to operate at a lower cost.

Solutions have been sought in the prior art by the use of aliphatic multiamines. US Pat. No. 6,267,939 describes, for example, the use of polyalkylene polyamine of general formula: R12N (CH2) nNR2 (CH2) nNR12 for the deacidification of acid gases, where n = 2 or 3; the groups R 1 represent methyl groups, or one of them is a hydrogen and the others are methyl groups; the group R2 is a hydrogen, a methyl group or a group of formula - (CH2) n-N (CH3) 2.

Moreover, patent WO 2004/082809 describes for the deacidification of acid gases the use of: • diamines of formula (R1) 2N (CR2R3) nN (R1) 2 • of triamines of formula (R1) 2N (CR2R3) nN ( R) (CR2R3) nN (R1) 2 • tetramines of formula (R1) 2N (CR2R3) nN (R) (CR2R3) nN (R) (CR2R3) nN (R1) 2 where n is an integer between 2 and 4 R is a substituted or unsubstituted alkyl group of 1 to 4 carbon atoms; R 1 is a substituted or unsubstituted alkyl group of 1 to 4 carbon atoms, or a bond between a nitrogen atom to form a heterocycle; R2 and R3 are independently hydrogen or a substituted or unsubstituted alkyl group of 1 to 4 carbon atoms. Surprisingly, the Applicant has discovered that compounds or a mixture of compounds of aromatic multiamine type according to the general formula (I) in which the groups R 1 to R 6 correspond to the specific definitions set out below, are also of great interest in all the processes for treating gaseous effluents for the removal of acidic compounds.

The object of the present invention is thus to overcome one or more of the disadvantages of the prior art by proposing a method for eliminating acidic compounds, such as CO2, H 2 S, COS, CS 2, SO2 and mercaptans, a gas by the use of a family of specific amines whose properties can limit the flow of absorbent solution used. In fact, the compounds according to the invention have several amine functions contributing to a strong increase in the absorption capacity of the acid gases. A first subject of the invention is an aqueous absorbent solution comprising at least one compound of the general formula (I): in which R 1 to R 5 are chosen from the following 3 groups A, B and C and arranged in accordance with the specified rules more away from group A: R is a hydrogen atom group B: R is an alkyl group of 1 to 20 carbon atoms and preferably 1 to 10 carbon atoms and / or o a group -NH 2 or NY 2, or Y is an alkyl group of 1 to 20 carbon atoms and preferably 1 to 10 carbon atoms

an -OH or -O-X-H group in which X corresponds to the general formula R7 R9

Wherein R7 to R10 are either hydrogen atoms or alkyl groups of 1 to 20 carbon atoms and preferably 1 to 10 carbon atoms and n is from 1 to 20 and preferably 1 to 10 group C: R is a unit having the general formula ## STR1 ## wherein R 11 and R 12 are either hydrogen atoms or alkyl groups of 1 to 20 carbon atoms; carbon and preferably 1 to 10 carbon atoms o where m is an integer equal to 1 or 2 o where R13 and R14 are indifferently hydrogen atoms or alkyl groups of 1 to 20 carbon atoms and preferably 1 to 10 carbon atoms and more preferably from 1 to 5 carbon atoms, the hydrocarbon group may contain one or more heteroatoms. R13 and R14 may be linked together to form a heterocycle preferably of 5 to 8 atoms.

R 6 may be as defined in R 1 to R 5 or may have the following general formula wherein Z is a covalent bond, a linear or branched alkylene R 15 - unit containing 1 to 20 carbon atoms and preferably 1 to 20 carbon atoms. 10 carbon atoms and possibly containing heteroatoms or halogen atoms.

According to the general formula of the invention, the groups R1 to R6 are distributed over the aromatic ring taking into account the following rules: at least 2 of the groups R1 to R6 are groups corresponding to the definition of group C, no more than 3 groups R1 to R6 meet the definition of group C o at least 1 of the groups R1 to R6 meets the definition of group A The present invention also relates to a process for the removal of acidic compounds contained in a gaseous effluent, such as natural gas and gases of industrial origin, comprising: a step of absorption of the acidic compounds by contacting the effluent with an aqueous solution comprising at least one compound according to the invention. optionally at least one liquid-liquid separation step of the solvent charged with acid gas, allowing fractional regeneration of the solvent. at least one regeneration step of the absorbent solution loaded with acidic compounds. The invention also relates to the application of said process for the elimination of acidic compounds to the treatment of natural gas or to the treatment of industrial gases, in particular the capture of CO2 after combustion.

Summary of the invention

An absorbent solution for absorbing acidic compounds of a gaseous effluent comprising: a. some water; b. at least one amine compound of formula (I) wherein: (I) R1 to R5 are selected from the following 3 groups A, B and C group A: R is hydrogen; group B: R is an alkyl group of 1 to 20 carbon atoms and / or a group -NH 2 or NY 2, where Y is an alkyl group of 1 to 20 carbon atoms and / or an -OH or -OXH group in which X has the general formula R7 R9

Wherein R7 to R10 are indifferently hydrogen atoms or alkyl groups of 1 to 20 carbon atoms and n is from 1 to 20; group C: R is a unit having the general formula R 11 C R 12 m / R 13 N R 14 where R 11 and R 12 are hydrogen atoms or alkyl groups of 1 to 20 carbon atoms, m is an integer equal to 1 or 2, R13 and R14 are hydrogen atoms or alkyl groups of 1 to 20 carbon atoms.

R 6 is selected from groups A, B and C or the group of formula: wherein Z is a covalent bond, a linear or branched alkylene-R 15 - unit containing 1 to 20 carbon atoms.

the groups R1 to R6 are distributed over the aromatic ring taking into account the following rules: 2 or 3 of the groups R1 to R6 meet the definition of group C and at least one group R1 to R6 meets the definition of group A.

In a preferred manner, the absorbent solution comprises from 10 to 90% by weight of compound of formula (I), very preferably from 20 to 60% by weight of compound of formula (I) and even more preferably from 30 to 50% by weight. weight of compound of formula (I).

In one embodiment, the absorbent solution further comprises a non-zero amount and less than 20% by weight of an organic activator compound.

The activator organic compound preferably consists of at least one primary or secondary amine, more preferably chosen from: MonoEthanolAmine, DiEthanolAmine, AminoEthylEthanolAmine, DiGlycolAmine, Piperazine, N- (2-Aminoethyl) piperazine, N- (2-Hydroxyethyl) ) Piperazine, Morpholine.

The absorbent solution may comprise a physical solvent.

The invention also relates to a process for eliminating the acidic compounds contained in a gaseous effluent, in which a step of absorption of the acidic compounds is carried out by bringing the effluent into contact with an absorbent solution as described previously so as to to obtain a gaseous effluent depleted of acidic compounds and an absorbent solution loaded with acidic compounds, at least one regeneration step of the absorbent solution loaded with acidic compounds. In one embodiment of the process, the absorption stage is carried out. so as to obtain a gaseous effluent depleted of acidic compounds and an absorbent solution loaded with two-phase liquid-liquid acid compounds, the absorption step being followed by at least one liquid-liquid separation step of the absorbent solution loaded with compounds acids, then at least one regeneration step of the absorbent solution fraction loaded with acidic compounds.

The absorption step of the acidic compounds is advantageously carried out at a pressure of between 1 bar and 120 bar, and at a temperature of between 30 ° C. and 90 ° C.

The thermal regeneration step is advantageously carried out at a pressure of between 1 bar and 10 bar and a temperature of between 100 ° C. and 180 ° C.

In a variant of the process, before the regeneration step, a first step is performed to relax the absorbent solution loaded with acidic compounds.

It is then possible to carry out a second step of relaxing the absorbent solution loaded with acidic compounds, the second expansion step being carried out after the first expansion step and before the regeneration step, the absorbent solution being heated before undergoing the second step of relaxation.

The process according to the invention can be implemented for the treatment of natural gas or for the treatment of gases of industrial origin, in particular for the capture of CO2. Other features and advantages of the invention will be better understood and will be clear from reading the description given below with reference to the appended figures given by way of example: FIG. general formula of the compounds according to the invention. FIG. 2 represents a schematic diagram of a process for treating acid gas effluents. FIG. 3 represents a schematic diagram of a process for treating acid gas effluents with fractional regeneration. FIG. 4 represents a schematic diagram of a process for treating acid gas effluents with fractional regeneration by heating. DETAILED DESCRIPTION OF THE INVENTION The compounds according to the invention are of interest in all processes for treating acid gases (natural gas, combustion fumes, etc.) in an aqueous absorbent solution composition.

The present invention proposes to eliminate the acidic compounds of a gaseous effluent by using at least one absorbent compound according to the invention in aqueous solution. The absorbent compounds according to the invention have a greater absorption capacity with acid gases (CO2, H2S, COS, SO2, CS2 and mercaptans) than the alkanolamines conventionally used. Indeed, the compounds according to the invention have the particularity of having very high filler levels (a = ngaz aclde / ncomposé), compared with the alkanolamines conventionally used. The use of an aqueous absorbent solution according to the invention makes it possible to save on the investment cost and the regeneration costs of a deacidification unit (gas treatment and capture of CO2).

Moreover, the absorbent compounds according to the invention have the particularity of being able to be optionally used in a deacidification process, as described above, for example a deacidification process with fractional regeneration (FR 2,877,858) or with regeneration fractionated by heating (FR 2 898 284) or with regeneration by extraction of the reactive compounds (FR 2 900 841).

Synthesis of the compounds according to the invention The compounds according to the invention can be obtained according to different modes of synthesis, according to the basic reagents used. For example, a mode of synthesis according to the invention can be based on the so-called Mannich reaction between an aromatic compound, an aldehyde or a ketone and a secondary amine according to the conditions well known to those skilled in the art.

The synthesis of 2,4,6-tris (dimethylaminomethyl) phenol from phenol, formaldehyde and dimethylamine is given here by way of example according to the procedure given by Bruson and MacMullen (HA Bruson and CW MacMullen, J. Amer., Chem Soc., 1941, 63, 270-272): A mixture of 28.2 g of phenol (0.3 mol) dissolved in 150 ml of a 40% The weight of dimethylamine (54 g, 1.2 mol) was added with stirring to 83 ml of a 37% by weight aqueous solution of formaldehyde (31.8 g, 1.06 mol) keeping the temperature below 30.degree. ° C. The mixture is stirred vigorously for 1 h at 25 ° C. and then 2 h at reflux. 60 g of NaCl are added hot and the mixture is stirred for 20 minutes under reflux. The organic phase is decanted and then distilled. 75 g (yield 85%) of a light yellow oil (the boiling point at 133 Pa is between 130 and 135 ° C.) are recovered, the NMR spectrum of which is in accordance with the proposed structure. Nature of the gaseous effluents The absorbent solutions according to the invention can be used to deacidify the following gaseous effluents: natural gas, synthesis gases, combustion fumes, refinery gases, gases obtained at the bottom of the process Claus, biomass fermentation gases, cement gases, incinerator fumes. These gaseous effluents contain one or more of the following acidic compounds: CO2, H2S, SO2, mercaptans, COS, CS2.

The combustion fumes are produced in particular by the combustion of hydrocarbons, biogas, coal in a boiler or for a combustion gas turbine, for example for the purpose of producing electricity. These fumes have a temperature of between 20 and 60 ° C., a pressure of between 1 and 5 bar and can comprise between 50 and 80% of nitrogen, between 5 and 40% of carbon dioxide, between 1 and 20% of oxygen, and between 0 and 1000 ppm by volume of SO2 and impurities such as NOx for example.

Natural gas consists mainly of gaseous hydrocarbons, but can contain several of the following acidic compounds: CO2, H2S, mercaptans, COS, CS2. The content of these acidic compounds is very variable and can be up to 40% for CO2 and H2S. The temperature of the natural gas can be between 20 ° C and 100 ° C. The pressure of the natural gas to be treated may be between 10 and 120 bar.

Composition of the absorbent aqueous solution The total concentration of compounds according to the invention, alone or as a mixture, is between 10% and 90% by weight, preferably between 15% and 60% by weight, very preferably between 20% and 50% by weight. % wt., in the aqueous solution. The absorbent solution may contain between 10% and 90% by weight of water.

Examples of molecules Among the molecules according to the invention, the molecules corresponding to the following general sub-formulas and illustrated by the molecules listed in Tables 1 to 5 are particularly advantageous. Embedded image H -NH 2 -NH 2 1,3-bis (aminomethyl) benzene H -NH 2 -NM 2 (1-aminomethyl-3-dimethylaminomethyl) benzene Table 1 ## STR2 ## H -NH 2 -NH 2 1,4-bis (aminomethyl) benzene H -NH 2 -N Me 2 (1-aminomethyl-4-dimethylaminomethyl) benzene Table 2 WR '1 R "R -NR'R" H -NMe 2 2,6-bis (dimethylaminomethyl) phenol H -Nt 2 2,6-bis (diethylaminomethyl) phenol H -N pyrolidine 2,6-bis (N -pyrolidinomethyl) phenol H -N piperidine 2,6-bis (N-piperidinomethyl) phenol H-N-morpholine 2,6-bis (N-morpholinomethyl) phenol Me-NMe 2 2,6-bis (dimethylamino-1-ethyl) phenol Me-N't 2 2,6-bis (diethylamino-1-ethyl) phenol Me-N pyrolidine 2,6-bis (N-pyrrolidino-1-ethyl) phenol Me-N piperidine 2,6-bis (N-piperidino) 1-ethyl) phenol Me-N-morpholine 2,6-bis (N-morpholino-1-ethyl) phenol Table 3 17 OH RR 'R -NR'R "name H -NMe 2 2,4-bis (dimethylaminomethyl) phenol H-Nt 2 2,4-bis (diethylaminomethyl) phenol H-N pyrrolidine 2,4-bis (N-pyrrolidinomethyl) p Henol H-N piperidine 2,4-bis (N-piperidinomethyl) phenol Me-NMe 2 2,4-bis (dimethylamino-1-ethyl) phenol Me-Nt 2 2,4-bis (diethylamino-1-ethyl) phenol Me - N pyrrolidine 2,4-bis (N-pyrrolidino-1-ethyl) phenol Me-N piperidine 2,4-bis (N-piperidino-1-ethyl) phenol Table 4 R 'R -NR'R "name H -NMeZ 2,4,6-tris (dimethylaminomethyl) phenol-Nt 2 2,4,6-tris (diethylaminomethyl) phenol-N pyrolidine 2,4,6-tris (N-pyrrolidinomethyl) phenol-N piperidine 2,4,6-tris (N-Piperidinomethyl) phenol-N-morpholine 2,4,6-tris (N-morpholinomethyl) phenol-N (CH 2 CH 2 OH) 2 2,4,6-tris (N-Bis (2-hydroxyethyl) aminomethyl) phenol Me - NMe 2 2,4,6-tris (dimethylamino-1-ethyl) phenol-Nt 2 2,4,6-tris (diethylamino-1-ethyl) phenol-N-pyrolidine 2,4,6-tris (N-pyrrolidino) ethyl) phenol-N piperidine 2,4,6-tris (N-piperidino-1-ethyl) phenol-N-morpholine 2,4,6-tris (N-morpholino-1-ethyl) phenol Table 5 18 HOC R ' ## STR2 ## H -NMe 2 1- (2-hydroxyethoxy) -2,6-bis (dimethylaminomethyl) benzene H -Nt 2 1- (2-hydroxyethoxy) -2,6-bis (diethylaminomethyl) benzene H-N-pyrolidine 1- (2-hydroxyethoxy) -2,6-bis (N-pyrrolidinomethyl) benzene H-N piperidine 1- (2-hydroxyethoxy) - 2,6-bis (N-piperidinomethyl) benzene HOCTable 6 R 'R -NR'R "H -NMe2-name 1- (2-hydroxyethoxy) -2,4,6-tris (dimethylaminomethyl) benzene H -NT2 1- ( 2-hydroxyethoxy) -2,4,6-tris (diethylaminomethyl) benzene H-N pyrolidine 1- (2-hydroxyethoxy) -2,4,6-tris (N-pyrrolidinomethyl) benzene H-N piperidine 1- (2- hydroxyethoxy) -2,4,6-tris (N-piperidinomethyl) benzene Table 7 R -NR'R "H -NMe2 name 1-methyl-2,6-bis (dimethylaminomethyl) benzene H -Nt2 1-methyl-2, 6-bis (diethylaminomethyl) benzene H-N pyrolidine 1-methyl-2,6-bis (N-pyrrolidinomethyl) benzene H-N piperidine 1-methyl-2,6-bis (N-piperidinomethyl) benzene Table 8 19 R ' R -NR'R "H -NMe2 name 1-methyl-2,4,6-tris (dimethylaminomethyl) benzene H -Nt2 1-methyl-2,4,6-tris (diethylaminomethyl) benzene H -N pyrolidine 1-methyl -2,4,6-tris (N-pyrrolidinomethyl) benzene H - N-piperidine 1-methyl-2,4,6-tris (N-piperidinomethyl) benzene Table 9 ## STR2 ## H -NR'R "H -NMe 2 2,5-bis (dimethylaminomethyl) hydroquinone H -NEt2 2,5-bis (diethylaminomethyl) hydroquinone H -N pyrolidine 2,5-bis (N-pyrrolidinomethyl) hydroquinone H -N piperidine 2,5-bis (N-piperidinomethyl) hydroquinone Table 10 R -NR'R "name H -NMe 2 2,6-bis (dimethylaminomethyl) resorcinol H -Nt 2 2,6-bis (diethylaminomethyl) resorcinol H -N pyrolidine 2,6-bis (N-pyrrolidinomethyl) resorcinol H -N piperidine 2,6-bis (N -piperidinomethyl) resorcinol Table 11 ## STR2 ## 2,4,6-tris (dimethylaminomethyl) resorcinol H -Nt 2 2,4,6-tris (diethylaminomethyl) resorcinol H -N pyrolidine 2,4,6-tris (N-pyrrolidinomethyl) resorcinol H -N piperidine 2,4,6-tris (N-piperidinomethyl) resorcinol Table 12 OH RRR "R" "-NR'R" name HHH -NMe2 bis [(4-hydroxy-3-dimethylaminomethyl) phenyl] methane HHH-NEt 2 bis [(4-hydroxy-3-diethylaminomethyl) phenyl] methane HHH - N bis [(4-hydroxy-3-N-pyrolidinomethyl) phenyl] methane pyrrolidine HHH-N bis [(4-hydroxy-3-N-piperidinomethyl) phenyl] methane piperidine H Me Me -NMe 2 2,2-bis "( 4-Hydroxy-3-dimethylaminomethyl) phenyl] propane H-Me Me-Nt 2 2,2-bis (4-hydroxy-3-diethylaminomethyl) phenyl] propane H 2 Me -N 2,2-bis [(4-hydroxy) 3-N-pyrrolidinomethyl) phenyl] propane pyrrolidine H Me Me-N 2,2-bis [(4-hydroxy-3-N-piperidinomethyl) phenyl] propane piperidine H CF3 CF3 -NMe2 2,2-bis [(4- hydroxy-3-dimethylaminomethyl) phenyl] -1,1,1,3,3,3-hexafluoropropane H CF3 CF3-NEt2 2,2-bis [(4-hydroxy-3-diethylaminomethyl) phenyl] -1.1.1 , 3,3,3-hexafluoropropane Table 13 ## STR2 ## HH -NMe 2 [4-hydroxy-3- (dimethylaminomethyl) phenyl] - [4'-hydroxy-3 ', 5'-bis (dimethylaminomethyl) phenyl] methane HHH-NEt 2 [4-hydroxy-3- (diethylaminomethyl) phenyl] - [4'-hydroxy-3 ', 5'-bis (diethylaminomethyl) phenyl] methane HHH -N [4 hydroxy-3- (N-pyrolidinomethyl) phenyl] - [4'-hydroxy-3 ', 5'-pyrolid] Bis (N-pyrrolidinomethyl) phenyl] methane HHH-N [4-hydroxy-3- (N-piperidinomethyl) phenyl] - [4'-hydroxy-3 ', 5'-piperidine bis (N-piperidinomethyl) phenyl] methane 2-Methyl-2- (4-hydroxy-3- (dimethylaminomethyl) phenyl] -2- [4'-hydroxy-3 ', 5'-bis (dimethylaminomethyl) phenyl] propane Me 2 -Nt 2 2- [4-hydroxy-3- (dimethylaminomethyl) phenyl] propane 3-hydroxy-3- (diethylaminomethyl) phenyl] -2- [4'-hydroxy-3 ', 5'-bis (diethylaminomethyl) phenyl] propane H 2 N -methyl-N- [4-hydroxy-3- (N-pyrrolidinomethyl) -N phenyl] -2- [4'-hydroxy-pyrrolidine 3 ', 5'-bis (N-pyrrolidinomethyl) phenyl] propane H Me Me-N 2 [4-hydroxy-3- (N-piperidinomethyl) phenyl] -2- [ 4'-hydroxy-3 ', 5'-piperidine bis (N-piperidinomethyl) phenyl] propane Table 14 RR "R" "-NR'R" name HHH -NMe 2 bis [(4-hydroxy-3,5-bis) (dimethylaminomethyl) phenyl] methane HHH-NEt2 bis [(4-hydroxy-3,5-bis (diethylaminomethyl) phenyl] methane HHH-N bis [(4-hydroxy-3,5-bis (N-pyrrolidinomethyl)) - pyrolidine phenyl] methane HHH -N bis [(4-hydroxy-3,5-bis (N-piperidinomethyl) pip eridine phenyl] methane Me 2 Me-NMe 2 2,2-bis [(4-hydroxy-3,5-bis (dimethylaminomethyl) phenyl] propane Me 2 -Nt 2 2,2-bis [(4-hydroxy-3, 5-bis (diethylaminomethyl) phenyl] propane H 2 Me -N 2,2-bis [(4-hydroxy-3,5-bis (N-pyrrolidinomethyl)) pyrrolidine phenyl] propane H Me Me -N 2.2 In one embodiment, the compounds of the invention may be formulated with one or more other "activator" compounds. not falling within the general formula, comprising at least one primary or secondary amine function, up to a concentration of 20% by weight, preferably less than 15% by weight, preferably less than 10% by weight. These compounds act as activators, which means that they increase the rate of CO2 absorption. This type of formulation is particularly interesting in the case of CO2 capture in industrial flue gases, or the treatment of natural gas containing CO2 above the desired specification. Indeed, for this type of applications, it is sought to increase the rate of absorption of CO2, in order to reduce the size of the equipment.

A non-exhaustive list of compounds having at least one primary or secondary amine function that may be used as activators is given below: Mono Ethanol Amine, Di Ethanol Amine Amino Ethyl Ethanol Amine, DiGlycol Amine, Piperazine, N- (2-Aminoethyl) Piperazine, N- ( 2-Hydroxyethyl) Piperazine, Morpholine.

In one embodiment, the absorbent solution based on compounds according to the invention may also contain other organic compounds. Thus, the absorbent solution according to the invention may contain organic compounds which are not reactive with respect to the acidic compounds, commonly referred to as "physical solvents", and which make it possible to increase the solubility of at least one or more acidic compounds of the gaseous effluent. For example, the absorbent solution may comprise between 5% and 50% by weight of physical solvents such as alcohols, glycol ethers, lactams, N-alkylated pyrrolidones, N-alkylated piperidones, cyclotetramethylenesulfone, N-alkylformamides, N-alkylacetamides, ethers-ketones or alkyl phosphates and their derivatives. By way of example and without limitation, it may be methanol, tetraethyleneglycoldimethylether, sulfolane or N-formyl morpholine.

Process for removing acidic compounds in a gaseous effluent (FIG 2) The implementation of an absorbent solution for deacidifying a gaseous effluent is carried out schematically by performing an absorption step followed by a regeneration step. The absorption step consists in bringing the gaseous effluent (-1) into contact with the absorbing solution (-4). During contact, the organic compounds provided with an amine function of the absorbing solution react with the acidic compounds contained in the effluent so as to obtain a gaseous effluent depleted in acidic compounds (-2) and an acid-enriched absorbent solution. (-3). The regeneration step consists in particular in heating and, optionally, expanding, the absorbent solution enriched in acidic compounds leaving the charge-effluent exchanger E1 (-5) in order to release the acid compounds in gaseous form (-7). The regenerated absorbent solution, that is to say depleted in acidic compounds (-6) is recycled to the absorption step through the charge-effluent exchanger El.

The absorption step of the acidic compounds can be carried out at a pressure of between 1 bar and 120 bar, preferably between 20 bar and 23 100 bar for the treatment of a natural gas, preferably between 1 and 3 bar for the treatment of industrial fumes, and at a temperature between 20 and 100 ° C, preferably between 30 ° C and 90 ° C. The regeneration step of the process according to the invention may be carried out by thermal regeneration, optionally supplemented by one or more expansion steps. Regeneration can be carried out at a pressure of between 1 bar and 10 bar, preferably between 1 and 5 bar, and at a temperature between 100 ° C and 180 ° C, preferably between 120 ° C and 180 ° C. A demixing phenomenon for a given absorbent solution (liquid-liquid phase separation within the absorbent solution) can be induced by an increase in the loading rate of the absorbent solution and / or by a rise in temperature. Said demixing phenomenon can be controlled by the choice of the operating conditions of the process and / or the composition of the absorbent solution. In this case, variants (Fig. 3 and Fig. 4) of the process according to the invention can be implemented, in particular a fractional regeneration of the absorbent solution.

Process for removing acidic compounds in a gaseous effluent with fractional regeneration (Fig. 31

The implementation of an absorbent solution for deacidifying a gaseous effluent is carried out schematically by performing an absorption step 25 followed by a liquid-liquid separation step of the absorbent solution, followed by a regeneration step ( according to the method described in patent FR 2 877 858). The absorption step consists in bringing the gaseous effluent (-1) into contact with the absorbing solution (-4). Upon contact, the organic compounds provided with an amine function of the absorbent solution react with the acidic compounds contained in the effluent so as to obtain a gaseous effluent depleted of acidic compounds (-2) and a compound-enriched absorbent solution. acids (-3), two-phase. The liquid-liquid separation step consists in separating, in a decanter BS1, the two liquid phases obtained in the absorption step by sending the enriched acid gas phase (-5) to the regeneration stage, and returning the phase depleted in acid gas (-8) at the absorption step. The regeneration step consists in particular in heating and optionally in expanding the absorbent solution enriched in acidic compounds (-5) in order to release the acidic compounds in gaseous form (-7). The regenerated absorbent solution, that is to say depleted of acid compounds (-6) is recycled to the absorption step. Various thermal integrations can be made to recover heat on the streams, in particular using exchangers E1 and E2.

The absorption step of the acidic compounds can be carried out at a pressure of between 1 bar and 120 bar, preferably between 20 bar and 100 bar for the treatment of a natural gas, preferably between 1 and 3 bar for the treatment of industrial fumes, and at a temperature between 30 ° C and 90 ° C. The regeneration step of the process according to the invention may be carried out by thermal regeneration, optionally supplemented by one or more expansion steps. The regeneration can be carried out at a pressure of between 1 bar and 5 bar, or even up to 10 bar and at a temperature of between 100 ° C. and 180 ° C., preferably between 120 ° C. and 180 ° C.

Process for removing acidic compounds in a gaseous effluent with fractional regeneration by heating (Fig. 41

The use of an absorbent solution for deacidifying a gaseous effluent is carried out schematically by carrying out an absorption step, followed by a step of heating the solvent, followed by a liquid-liquid separation step of the absorbent solution, followed by a regeneration step (according to the method described in patent FR 2 898 284). The absorption step consists in bringing the gaseous effluent (-1) into contact with the absorbing solution (-4). Upon contact, the organic compounds provided with an amine function of the absorbing solution react with the acidic compounds contained in the effluent to obtain a gaseous effluent depleted of acidic compounds (-2) and a compound-enriched absorbent solution. acids (-3). The heating step consists of raising the temperature of the solvent (-3), for example through a heat exchanger E1, to obtain a two-phase liquid-liquid solution (-5). The liquid-liquid separation step consists in separating, in the clarifier BS1, the two phases obtained in the heating step by sending the acid-enriched phase (-42) to the regeneration stage, and returning the depleted phase to the regeneration stage. acid gas (.44) at the absorption stage. The regeneration step consists in particular in heating and optionally in expanding the absorbent solution enriched in acidic compounds in order to release the acidic compounds in gaseous form (-7). The regenerated absorbent solution, that is to say depleted in acidic compounds (-.6) is recycled to the absorption step. Various thermal integrations can be made to recover heat on the streams, in particular by means of exchangers E2 and E3.

The absorption step of the acidic compounds can be carried out at a pressure of between 1 bar and 120 bar, preferably between 20 bar and 100 bar for the treatment of a natural gas, preferably between 1 and 3 bar for the treatment industrial fumes, and at a temperature of between 30 ° C and 90 ° C. The regeneration step of the process according to the invention can be carried out by thermal regeneration, optionally supplemented by one or more expansion steps. The regeneration can be carried out at a pressure of between 1 bar and 5 bar, or even up to 10 bar and at a temperature of between 100 ° C. and 180 ° C., preferably between 120 ° C. and 180 ° C.

Examples:

An aqueous solution of compound A, 2,4,6-Tris (dimethylaminomethyl) phenol, or compound B, 1,3-bis (aminomethyl) benzene, at 30% by weight, is used as the absorbent solution in this example. Their performances are compared to that of an aqueous solution of MonoEthanolAmine at 30% by weight, which constitutes the reference solvent for post-combustion fume extraction application, and that of a 30% by weight aqueous solution of methyldiethanolamine. which constitutes the reference solvent for a natural gas treatment application.

EXAMPLE 1 CO2 Capture Capacity By way of example, it is possible to compare the charge levels (number of moles of CO 2 based on the number of moles of amines) obtained between an absorbent solution according to the invention and an absorbent solution of MonoEthanolAmine at 30% by weight and an absorbent solution of MethylDiEthanolAmine at 30% by weight under the following conditions: a CO2 / N2 gas mixture containing 10% volume of CO2 is saturated with water by bubbling in acidified water and heated to 40 ° C. ° C. The gaseous mixture thus saturated with water is brought into contact with the absorbent solution at atmospheric pressure and at a flow rate of 20 Nl / h in a double-jacketed glass bubble column thermostated at 40 ° C. for 180 minutes. The gas at the outlet of the column is analyzed online by gas chromatography. This analysis makes it possible to determine over time the number of moles of CO2 absorbed by the absorbent solution. At the end of the contacting of the gas and the absorbent solution, the charge rate is determined. 27 Amine Concentration T (° C) Charge rate a (wt%) = nCO2 / namine A 30% 40 1.56 B 30% 40 1.07 MEA 30% 40 0.52 MDEA 30% 40 0.37 This example shows that the absorbent solutions according to the invention make it possible to obtain CO2 charge levels that are much higher than those obtained with the absorbent solutions according to the prior art. Example 2 Liquid-Liquid Phase Separation

Depending on the composition of the 2,4,6-tris (dimethylaminomethyl) phenol-based absorbent solution, the composition of the gas to be treated and the temperature of the absorbent solution, a liquid-liquid phase separation can occur. demixing). The conditions (concentration, operating conditions) in which demixing occurs for a given absorbent solution are determined by laboratory tests (perfectly stirred gas-liquid reactors). The formulation may then be carried out in a deacidification process with fractional regeneration, or with fractional regeneration by heating, as described in FIGS. 3 and 4.

For example, at 25 ° C., a solvent composed of 2,4,6-tris (dimethylaminomethyl) phenol at 50% by weight in water is monophasic for a partial pressure of 0.1 bar and two-phase CO2. for a partial pressure of CO2 of 0.3 bar and can thus be used in a deacidification process with fractional regeneration (as described in patent FR 2 877 858).

Claims (17)

Revendications1. Absorbent solution for absorbing acidic compounds from a gaseous effluent comprising: a. some water; b. at least one amine compound of formula (I) wherein: R 1 to R 5 are selected from the following 3 groups A, B and C group A: R is a hydrogen atom; group B: R is an alkyl group of 1 to 20 carbon atoms and / or a group -NH 2 or NY 2, where Y is an alkyl group of 1 to 20 carbon atoms and / or an -OH or -OXH group in which X has the general formula R 7 R 9 wherein R 7 to R 10 are either hydrogen atoms or alkyl groups of 1 to 20 carbon atoms and n is from 1 to 20; (I) group C: R is a unit having the general formula wherein R 11 and R 12 are hydrogen atoms or alkyl groups of 1 to 20 carbon atoms, m is an integer of 1 or 2, R13 and R14 are hydrogen atoms or alkyl groups of 1 to 20 carbon atoms. R 6 is chosen from groups A, B and C or the group of formula: ## STR2 ## in which Z is a covalent bond, a linear or branched alkylene-R15-unit containing 1 to 20 carbon atoms. the groups R1 to R6 are distributed over the aromatic ring taking into account the following rules: 2 or 3 of the groups R1 to R6 meet the definition of group C and at least one group R1 to R6 meets the definition of group A . 2. Absorbent solution according to claim 1 comprising from 10 to 90 weight of compound of formula (I). 3. Absorbent solution according to claim 2 comprising from 20 to 60% by weight of compound of formula (I). Absorbent solution according to claim 3 comprising from 30 to 50% by weight of compound of formula (I). R71 C R12 10 20 5. Absorbent solution according to one of the preceding claims further comprising a non-zero amount and less than 20% by weight of an organic activator compound. The absorbent solution of claim 5 wherein the organic activator compound is at least one primary or secondary amine. An absorbent solution according to claim 6 wherein the activator is selected from the group consisting of: - Monoethanolamine, - Diethanolamine - Aminoethylethylamine, - DiGlycolamine, - Piperazine, - N- (2-aminoethyl) piperazine, N- (2- HydroxyEthyl) Piperazine, Morpholine. 8. Absorbent solution according to one of the preceding claims comprising a physical solvent. 9. A process for removing the acidic compounds contained in a gaseous effluent, in which is carried out: a step of absorption of the acidic compounds by contacting the effluent with an absorbent solution according to one of claims 1 to 9; so as to obtain a gaseous effluent depleted of acidic compounds and an absorbent solution loaded with acidic compounds, at least one regeneration step of the absorbent solution loaded with acidic compounds. 10. A method of removing the acidic compounds contained in a gaseous effluent according to claim 9 wherein the absorption step is carried out so as to obtain a gaseous effluent depleted of acidic compounds and an absorbent solution loaded with liquid-liquid diphasic acid compounds the absorption step being followed by at least one liquid-liquid separation step of the absorbent solution loaded with acidic compounds and then at least one regeneration step of the absorbent solution fraction loaded with acidic compounds. 11. The method of claim 9 or 10 wherein the step of absorbing the acidic compounds is carried out at a pressure between 1 bar and 120 bar, and at a temperature between 30 ° C and 90 ° C. 10 12. Method according to one of claims 9 to 11, wherein the thermal regeneration step is carried out at a pressure between 1 bar and 10 bar and a temperature between 100 ° C and 180 ° C. 13. Method according to one of claims 9 to 12, wherein it is carried out, before the regeneration step, a first step of relaxation of the absorbent solution loaded with acidic compounds. 14. A method according to claim 13, wherein a second step of expanding the absorbent solution loaded with acidic compounds is carried out, the second expansion step being carried out after the first expansion step and before the regeneration step, the solution absorbent being heated before undergoing the second expansion step. 15. Process for treating natural gas according to one of claims 9 to 14. 16. Process for the treatment of industrial gases according to one of claims 9 to 14. 17. Process for the treatment of industrial gases according to claim 16 for the capture of CO2.