Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
  • B01D53/1493—Selection of liquid materials for use as absorbents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
  • B01D53/1456—Removing acid components
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
  • B01D53/1456—Removing acid components
  • B01D53/1468—Removing hydrogen sulfide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/38—Removing components of undefined structure
  • B01D53/40—Acidic components
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/77—Liquid phase processes
  • B01D53/78—Liquid phase processes with gas-liquid contact
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D211/00—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings
  • C07D211/04—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
  • C07D211/06—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having no double bonds between ring members or between ring members and non-ring members
  • C07D211/36—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having no double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D211/40—Oxygen atoms
  • C07D211/42—Oxygen atoms attached in position 3 or 5
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D211/00—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings
  • C07D211/04—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
  • C07D211/06—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having no double bonds between ring members or between ring members and non-ring members
  • C07D211/36—Heterocyclic compounds containing hydrogenated pyridine rings, not condensed with other rings with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having no double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D211/40—Oxygen atoms
  • C07D211/44—Oxygen atoms attached in position 4
  • C07D211/46—Oxygen atoms attached in position 4 having a hydrogen atom as the second substituent in position 4
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
  • C10L3/06—Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04
  • C10L3/10—Working-up natural gas or synthetic natural gas
  • C10L3/101—Removal of contaminants
  • C10L3/102—Removal of contaminants of acid contaminants
  • C10L3/104—Carbon dioxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/10—Inorganic absorbents
  • B01D2252/103—Water
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/204—Amines
  • B01D2252/20421—Primary amines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/204—Amines
  • B01D2252/20426—Secondary amines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/204—Amines
  • B01D2252/20431—Tertiary amines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/204—Amines
  • B01D2252/20436—Cyclic amines
  • B01D2252/20442—Cyclic amines containing a piperidine-ring
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/204—Amines
  • B01D2252/20478—Alkanolamines
  • B01D2252/20484—Alkanolamines with one hydroxyl group
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/50—Combinations of absorbents
  • B01D2252/504—Mixtures of two or more absorbents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2256/00—Main component in the product gas stream after treatment
  • B01D2256/22—Carbon dioxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/30—Sulfur compounds
  • B01D2257/304—Hydrogen sulfide
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
  • C10L2290/44—Deacidification step, e.g. in coal enhancing
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
  • C10L2290/54—Specific separation steps for separating fractions, components or impurities during preparation or upgrading of a fuel
  • C10L2290/541—Absorption of impurities during preparation or upgrading of a fuel

Definitions

• the present invention relates to the field of deacidification processes of a gaseous effluent.
• the invention is advantageously applicable to the treatment of industrial gas and natural gas.
• Absorption processes employing an aqueous amine solution are commonly used to remove the acidic compounds (in particular CO 2 , H 2 S, COS, CS 2 , SO 2 and mercaptans) present. in a gas.
• the gas is deacidified by contact with the absorbent solution, and the absorbent solution is thermally regenerated.
• US 6852144 discloses a method of removing acidic compounds from hydrocarbons. The method uses a water-N-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.
• a limitation of the absorbent solutions commonly used in deacidification applications is an insufficient selectivity of absorption of H 2 S with respect to C0 2 .
• selective removal of H 2 S is sought with a minimum of C0 2 absorption. This constraint is particularly important for gases to be treated already containing a CO 2 content less than or equal to the desired specification.
• a maximum absorption capacity of H 2 S is then sought with a maximum selectivity of absorption of H 2 S with respect to CO 2 . This selectivity makes it possible to recover an acid gas at the outlet of the regenerator having the highest concentration possible in H 2 S, which limits the size of the units of the sulfur chain downstream of the treatment and guarantees a better operation.
• an H 2 S enrichment unit is needed to concentrate the acid gas in H 2 S.
• the most selective amine is also sought.
• Tertiary amines such as N-methyldiethanolamine (or MDEA), or congested secondary amines with slow reaction kinetics with C0 2 are commonly used, but have limited selectivities at high H 2 S loading rates.
• Another limitation of the absorbent solutions commonly used in total deacidification applications is the kinetics of C0 2 or COS pickup that are too slow.
• the desired specifications on the C0 2 or in COS are very advanced, one seeks a kinetics of reaction as fast as possible so as to reduce the height of the column of absorption column. This pressurized equipment, typically between 40 bars and 70 bars, represents a significant part of the investment costs of the process.
• Another limitation of the absorbent solutions commonly used today is an energy consumption necessary for the regeneration of the solvent which is too important. This is particularly true in the case where the partial pressure of acid gases is low.
• the partial pressure of acid gases is low.
• the regeneration energy is about 3.7 GJ per tonne of CO 2 captured.
• Such energy consumption represents a considerable operating cost for the C0 2 capture process.
• the first two stations are proportional to the flow rates of absorbent solution that must be circulated in the unit to achieve a given specification. To reduce the energy consumption associated with the regeneration of the solvent, it is therefore preferable once again to maximize the cyclic capacity of the solvent.
• the last item concerns the energy to be supplied to break the bond created between the amine used and CO 2. To reduce the energy consumption associated with the regeneration of the absorbent solution, it is therefore preferable to minimize the ⁇ linkage enthalpy. Nevertheless, it is not easy to find a solvent with a high cyclic capacity and a low reaction enthalpy. The best solution absorbing from an energy point of view is therefore that which will have the best compromise between a strong cyclic capacity ⁇ and a low enthalpy of connection ⁇ .
• the chemical stability of the absorbent solution is also a key aspect in the deacidification and gas treatment processes.
• the degradation behavior is a limitation for the commonly used absorbent solutions, especially under regeneration conditions at temperatures between 160 and 180 ° C envisaged in CO 2 capture processes. These conditions make it possible to recover CO 2 at a pressure of between 5 and 10 bars, making it possible to save energy on the compression of the CO 2 captured for the purpose of its transport and storage.
• tertiary amines have a capture kinetics C0 2 slower than primary or secondary amines uncrowded.
• tertiary amines have H 2 S capture kinetics instantaneous, which allows for selective removal of H 2 S based on distinct kinetic performance.
• US Pat. No. 4,483,333 describes a process for the selective absorption of acid gases by an absorbent containing a tertiary alkanolamine or a tertiary aminoetheralcohol whose nitrogen is included in a heterocycle.
• a compound of interest is N-methyl-2-hydroxymethylpiperidine whose capture capacities and absorption rate are described.
• this document does not describe the performance of this molecule in terms of selective removal of H 2 S in a gas containing H 2 S and CO 2 .
• tertiary alkanolamines whose nitrogen is included in a heterocycle are not equivalent in performance for their use in absorbent solution formulations for the treatment of acid gases in an industrial process.
• Certain heterocyclic tertiary alkanolamine-type molecules have insufficient performances, in particular as regards the selective removal of H 2 S in a gas containing H 2 S and CO 2 .
• other molecules make it possible to improve the absorption selectivity of H 2 S relative to tertiary amines of reference, such as methyldiethanolamine.
• These same molecules also have acidic absorption performance, especially CO 2 and a particularly high chemical stability.
• the present invention relates to the use of particular molecules belonging to the family of tertiary heterocyclic alkanolamines having a optimum performance between C02 capture capacity, selective removal of H 2 S, and thermal stability, in the context of the deacidification of a gas.
• N-alkyl-hydroxypiperidines These molecules meet the general definition of N-alkyl-hydroxypiperidines. These heterocyclic tertiary alkanolamines have the particularity of having a single hydroxyl group directly bonded to one of the carbon atoms of the heterocycle, this heterocycle being a piperidine ring. More specifically, these molecules are N-alkyl-3-hydroxypiperidines and N-alkyl-4-hydroxypiperidines corresponding to the general formula (I):
• N-alkyl-hydroxypiperidines according to the invention are particularly distinguished from the document WO2009 / 1 10586A1 in which the R 2 group can in no case be a hydroxyl group.
• Another subject of the invention relates to a process for the elimination of acidic compounds contained in a gaseous effluent, in which an absorption step of the acidic compounds is carried out by bringing the effluent into contact with the absorbent solution according to the invention. .
• N-alkyl-hydroxypiperidine compounds according to the invention makes it possible to obtain greater acid gas absorption capacities than the reference amines. This performance is increased due to greater basicity.
• the compounds according to the invention have a selectivity towards H 2 S that is greater than the reference amines.
• the invention makes it possible to accelerate the absorption kinetics of the COS and C0 2 , relative to an MDEA solution containing the same amount of primary or secondary amine. This gain in COS and CO 2 absorption kinetics results in savings on the cost of the absorption column in cases where removal of this compound at high specifications (1 ppm) is required.
• the subject of the present invention is an absorbent solution for removing acidic compounds contained in a gaseous effluent, comprising:
• R is an alkyl radical containing one to six carbon atoms, and preferably one to three carbon atoms. carbon.
• the nitrogenous compound may be chosen from the following compounds listed by way of non-limiting example of the formula en above
• the solution may comprise between 10% and 90% by weight of said nitrogenous compound, preferably between 20% and 60% by weight, very preferably between 25% and 50% by weight; and the solution may comprise between 10% and 90% by weight of water, preferably between 40% and 80% by weight of water, very preferably from 50% to 75% of water.
• the solution may comprise an additional amine, said additional amine being a tertiary amine, such as methyldiethanolamine, or a secondary amine having two tertiary carbon atoms alpha to the nitrogen, or a secondary amine having at least one Quaternary carbon in alpha of nitrogen.
• the solution may comprise between 10% and 90% by weight of said additional amine, preferably between 10% and 50% by weight, very preferably between 10% and 30% by weight.
• the solution may comprise a compound containing at least one primary or secondary amine function.
• the solution may comprise a concentration up to 30% by weight of said compound, preferably less than 15% by weight, preferably less than 10% by weight, and at least 0.5% by weight.
• the solution may comprise a concentration of at least 0.5% by weight of said compound.
• the compound can be chosen from:
• 1,6-hexanediamine and all its variously N-alkylated derivatives such as, for example, N, N'-dimethyl-1,6-hexanediamine, N-methyl-1,6-hexanediamine or N, N ', N'- trimethyl-1,6-hexanediamine.
• the solution may comprise a physical solvent chosen from methanol and sulfolane.
• the invention also relates to a process for removing acidic compounds contained in a gaseous effluent, in which an absorption step of the acidic compounds is carried out by contacting the effluent with an absorbent solution according to the invention.
• the absorption step of the acid compounds can be carried out at a pressure between 1 bar and 120 bar, and at a temperature between 20 ⁇ and 100 ⁇ €.
• a gaseous effluent depleted of acidic compounds and an absorbent solution loaded with acidic compounds there is obtained a gaseous effluent depleted of acidic compounds and an absorbent solution loaded with acidic compounds, and at least one regeneration step of the absorbent solution loaded with acidic compounds is carried out.
• the regeneration step can be carried out at a pressure of between 1 bar and 10 bar and a temperature of between 100 ° C. and 180 ° C.
• the gaseous effluent may be chosen from natural gas, synthesis gases, combustion fumes, refinery gases, acid gases from an amine unit, gases from a tail reduction unit of Claus process, biomass fermentation gases, cement gases, incinerator fumes.
• FIG. 1 represents a schematic diagram of a process for treating acid gas effluents.
• FIG. 2 represents a synthesis scheme of an N-alkyl-hydroxypiperidine according to the invention from a picoline.
• FIG. 3 represents a synthesis scheme of the N-methyl-4-hydroxypiperidine according to the invention starting from methyl acrylate.
• the present invention provides an aqueous solution and a process for removing acidic compounds from a gaseous effluent.
• the aqueous solution according to the invention comprises at least one nitrogen compound chosen from the group of N-alkyl-3-hydroxypiperidines and N-alkyl-4-hydroxypiperidines
• the molecules according to the invention can be synthesized using all the routes allowed by organic chemistry. For each of the molecules of the invention, some may be cited without being exhaustive.
• N-alkyl-hydroxypiperidines of the invention can be synthesized by any pathway permitted by organic chemistry.
• the synthesis can be carried out from widely available industrial products which are the 3 or 4-methylpyridines also called 3 or 4-picolines according to a general reaction scheme illustrated in FIG.
• reaction 1 The ammoxidation reaction of the 3 or 4-picolines leads to 3 or 4 cyanopyridines which are then converted into 3 or 4-pyridinecarboxamides according to basic hydrolysis (reaction 2).
• the 3 or 4-pyridinecarboxamides can then be converted to 3 or 4-aminopyridines in basic medium and in the presence for example of sodium hypochlorite according to the so-called "Hofman reaction” reaction (reaction 3).
• the 3 or 4-aminopyridines can then be converted into 3 or 4-hydroxypyridines in a diazotization reaction which is carried out in the presence of alkaline nitrite, for example sodium nitrite followed by acid hydrolysis (reaction 4).
• the 3 or 4-hydroxypyridines obtained are then subjected to a hydrogenation of the aromatic ring (reaction 5).
• This well-known reaction leads to 3 or 4-hydroxypiperidines also called 3- or 4-piperidinols.
• the 3 or 4-hydroxypiperidines will undergo a so-called N-alkylation (reaction 6) to yield 1-alkyl-3 or 4-hydroxypiperidines.
• This N-alkylation reaction may be carried out for example by condensation of the 3 or 4-hydroxypiperidines with an alkyl halide.
• this N-alkylation reaction will be carried out by condensation of the 3 or 4-hydroxypiperidines with either an alcohol, an aldehyde or a ketone in the presence of hydrogen and a suitable catalyst.
• reaction 1 methyl-di- (2- (methylcarboxy) ethyl) amine
• reaction 2 methyl-di- (2- (methylcarboxy) ethyl) amine
• reaction 3 1-methyl-3-methylcarboxy-4-piperidone
• 1-methyl-4-piperidone is obtained by carrying out a decarboxylation reaction according to a well-known procedure (reaction 4). Finally, the carbonyl function of 1-methyl-4-piperidone is hydrogenated to yield 1-methyl-4-hydroxypiperidine (reaction 5).
• This sequence of reactions illustrated here with methylamine as a precursor may be applied to any other primary amine to yield the family of 1-alkyl-4-hydroxypiperidines.
• the absorbent solution used in the process according to the invention comprises: a - water
• R being an alkyl radical containing one to six carbon atoms, and preferably one to three carbon atoms.
• the hydroxyl radical may be located at the 3-position or at the 4-position with respect to the nitrogen atom of the piperidine ring.
• the absorbent solution according to the invention may comprise a compound te corresponding to the general formula (I), chosen from the following compounds:
• the alkylaminopiperazine may be in variable concentration in the absorbent solution, for example between 10% and 90% by weight, preferably between 20% and 60% by weight, very preferably between 25% and 50% by weight.
• the absorbent solution may contain from 10% to 90% by weight of water, preferably from 40% to 80% by weight of water, very preferably from 50% to 75% water.
• the absorbent solution may also contain a tertiary amine, for example methyldiethanolamine, triethanolamine, diethylmonoethanolamine, dimethylmonoethanolamine, ethyldiethanolamine, or secondary having a severe steric hindrance, this bulk being defined either by the presence of two tertiary carbons in alpha of the nitrogen, or by at least one quaternary carbon in alpha of the nitrogen.
• concentration of tertiary amine or secondary amine severely congested in the absorbent solution may be between 10% and 90% by weight, preferably between 10% and 50% by weight, very preferably between 10% and 30% by weight.
• the absorbent solution may contain a compound containing at least one primary or secondary amine function.
• the absorbent solution comprises up to a concentration of 30% by weight, preferably less than 15% by weight, preferably less than 10% by weight of said compound containing at least one primary or secondary amine function.
• the absorbent solution comprises at least 0.5% by weight of said compound containing at least one primary or secondary amine function. Said compound makes it possible to accelerate the absorption kinetics of the COS and, in certain cases, the CO 2 contained in the gas to be treated.
• 1,6-hexanediamine and all its variously N-alkylated derivatives such as, for example, N, N'-dimethyl-1,6-hexanediamine, N-methyl-1,6-hexanediamine or N, N ', N'- trimethyl-1,6-hexanediamine.
• the absorbent solution may contain a physical solvent selected from methanol and sulfolane.
• the absorbent solution can be used to deacidify the following gaseous effluents: natural gas, synthesis gases, combustion fumes, refinery gases, acid gases from an amine unit, gases from a unit Claus process bottoms, biomass fermentation gases, cement gases, incinerator fumes.
• gaseous effluents contain one or more acidic compounds: CO 2 , H 2 S, mercaptans, COS, CS 2, SO 2.
• 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.
• the method according to the invention can be used to absorb at least 70%, preferably at least 80% or even at least 90% of the CO 2 contained in the combustion fumes.
• These fumes generally have a temperature of between 20 and 60 ° C., a pressure of between 1 and 5 bar and may comprise between 50 and 80% of nitrogen, between 5 and 40% of carbon dioxide, and between 1 and 20% of carbon dioxide. oxygen, and some impurities such as SOx and NOx, if they have not been removed upstream of the deacidification process.
• the process according to the invention is particularly well adapted to absorb the CO 2 contained in combustion fumes comprising a low CO 2 partial pressure, for example a CO 2 partial pressure of less than 200 mbar.
• the invention also relates to a process for deacidifying a gaseous effluent from the aqueous solution according to the invention. This process is carried out, schematically, by performing an absorption step followed by a regeneration step, for example as shown in FIG.
• the absorption step consists of bringing the gaseous effluent 1 into contact with the absorbent solution 4.
• the gaseous effluent 1 is introduced at the bottom of C1, the absorbent solution is introduced at the head of C1 .
• Column C1 is provided with gas-liquid contacting means, for example loose packing, structured packing or distillation trays.
• gas-liquid contacting means for example loose packing, structured packing or distillation trays.
• the amine functions of the molecules 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 discharged at the head of C1, and an acid-enriched absorbent solution.
• 3 evacuated at the bottom of C1 to be regenerated.
• 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.
• the absorbent solution enriched in acidic compounds 3 is introduced into the heat exchanger E1, where it is heated by the stream 6 from the regeneration column C2.
• the heated solution at the outlet of E1 is introduced into the regeneration column C2.
• the regeneration column C2 is equipped with internal contacting between gas and liquid, for example trays, loose or structured packings.
• the bottom of column C2 is equipped with a reboiler R1 which provides the heat necessary for regeneration by vaporizing a fraction of the absorbent solution.
• the absorption step of the acidic compounds can be carried out at a pressure in C1 of between 1 bar and 120 bar, preferably between 20 bar and 100 bar for the treatment of a natural gas, preferably between 1 bar and 3 bar. for the treatment of industrial fumes, and at a temperature in C1 of between 20% and 80%, preferably between 30 ° C and 90 ° C, or even between 30 and 60 ° 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 in C2 of between 1 bar and 5 bar, or even up to 10 bar, and at a temperature in C2 of between ⁇ ⁇ ' ⁇ and 180 ° C., preferably of between 130 ° and 170 ° C. vs.
• the regeneration temperature in C2 is between 155 ° C and ⁇ ⁇ ' ⁇ in the case where it is desired to reinject the acid gases.
• the regeneration temperature in C2 is between 115 ° C and 130 ° in the case where the acid gas is sent to the atmosphere or in a downstream treatment process, such as a Claus process or a treatment method. of tail gas.
• the process according to the invention can be used to deacidify a synthesis gas.
• the synthesis gas contains carbon monoxide CO, hydrogen H 2 (generally in a ratio H 2 / CO equal to 2), water vapor (generally at saturation at the temperature where the washing is carried out) and carbon dioxide C0 2 (of the order of ten percent).
• the pressure is generally between 20 and 30 bar, but can reach up to 70 bar. It contains, in addition, sulfur impurities (H 2 S, COS, etc.), nitrogen (NH 3 , HCN) and halogenated impurities.
• the process according to the invention can be implemented to deacidify a natural gas.
• the natural gas consists mainly of gaseous hydrocarbons, but can contain several of the following acidic compounds: C0 2 , H 2 S, mercaptans, COS, CS2.
• the content of these acidic compounds is very variable and can be up to 40% for CO 2 and H 2 S.
• the temperature of the natural gas can be between 20 ° and 100 ° C.
• the pressure of the natural gas to be treated may be between 10 and 120 bar.
• the invention can be implemented to achieve specifications generally imposed on the deacidified gas, which are 2% of C0 2 , or even 50 ppm of C0 2 to then perform a liquefaction of natural gas and 4 ppm H 2 S and 10 to 50 ppm volume of total sulfur.
• the absorption is carried out in a liquid volume of 50 cm 3 by bubbling a gaseous stream consisting of a nitrogen mixture: carbon dioxide: hydrogen sulphide of 89: 10: 1 in volume proportions, of a flow rate of 30NL / h for 90 minutes.
• This selectivity S is defined as follows:
• This example illustrates the gains in the degree of charge and selectivity that can be achieved with an absorbent solution according to the invention, comprising 50% by weight of N-methyl-4-hydroxypiperidine or 50% by weight of N-methyl-3-hydroxypiperidine. or 49% by weight of N-ethyl-4-hydroxypiperidine compared to the reference absorbent solution (MDEA 47%)
• an absorbent solution according to the invention comprising 50% by weight of N-methyl-4-hydroxypiperidine or 50% by weight of N-methyl-3-hydroxypiperidine. or 49% by weight of N-ethyl-4-hydroxypiperidine compared to the reference absorbent solution (MDEA 47%)
• Example 2 CO 2 absorption rate of an amine formulation for a selective absorption process.
• a comparative CO 2 absorption test was carried out with an absorbent solution of 50% by weight N-methyl-4-hydroxypiperidine according to the invention relative to an aqueous solution of methyldiethanolamine at 47% by weight.
• the C0 2 absorption flux is measured by the aqueous solution in a closed reactor, such as a Lewis cell. 200 g of solution is introduced into the closed reactor, regulated at a temperature of 50 ° C. Four successive injections of carbon oxysulfide of 100 to 200 mbar are carried out in the vapor phase of the reactor having a volume of 200 cm 3 . The gas phase and the liquid phase are stirred at 100 revolutions / minute and fully characterized from the hydrodynamic point of view. For each injection, the rate of absorption of the carbon dioxide is measured by variation of pressure in the gas phase. An overall transfer coefficient Kg is thus determined by an average of the results obtained on the four injections.
• the absorption rate of CO 2 is compared with an absorbent solution containing 39% by weight of methyldiethanolamine and 6.7% by weight of piperazine in water to an absorbent solution according to the invention containing 39% by weight of N-methyl-4-hydroxypiperidine. and 6.7 wt% piperazine in water.
• a gas containing CO 2 is contacted with the absorbing liquid by operating in a vertical falling film reactor provided in its upper part with a gas outlet and an inlet for the liquid and in its lower part. an inlet for the gas and an outlet for the liquid.
• a gas containing 10% CO 2 and 90% nitrogen is injected at a flow rate of between 30 and 50 Nl / h and the liquid inlet is introduced with a flow rate of 0.5 l / h.
• a CO 2 depleted gas is evacuated and the liquid outlet is evacuated and the CO 2 enriched liquid is evacuated.
• the absolute pressure and the liquid temperature at the outlet are respectively equal to 1 bar and 40 ⁇ €.
• the flow of C0 2 absorbed between the gas inlet and the gas outlet is measured as a function of the incoming gas flow rate: for each gas flow setpoint: 30 - 35 - 40 - 45 - 50 Nl / h, the gas incoming and outgoing are analyzed by infrared ray absorption techniques in the gas phase to determine their C0 2 content. From all these measurements, by performing two ups and downs of the range of flow rates, the overall transfer coefficient Kg is deduced, characterizing the absorption speed of the absorbing liquid.
• the performance of the C0 2 capture capacity of the N-methyl-4-hydroxypiperidine according to the invention is compared in particular with those of an aqueous solution of MonoEthanolAmine at 30% by weight, which constitutes the reference solvent for a capture application.
• C0 2 contained in post-combustion fumes. They are also compared with those of a solution of aqueous N-methyl-2-hydroxymethylpiperidine, cited in US Patent 4,405,582 containing the same weight percentage of tertiary diamine and piperazine.
• An absorption test is carried out on aqueous amine solutions in a perfectly stirred closed reactor whose temperature is controlled by a control system.
• the absorption is carried out in a liquid volume of 50 cm 3 by injections of pure CO 2 from a reserve.
• the solvent solution is previously drawn under vacuum before any CO 2 injection.
• the feed rates (a nb of mole acid gas / nb of amine mole) obtained at 40 ° C. for various partial pressures of CO 2 between an aqueous solution of N-methyl- 4-hydroxypiperidine 30% by weight according to the invention, an aqueous solution of N-methyl-2-hydroxymethylpiperidine molecule described in the document WO2009 / 1 105586 at 30% by weight and an aqueous solution of MonoEthanolAmine, at 30% by weight for a post-combustion C0 2 capture application.
• the partial pressures of CO 2 in the effluent to be treated are typically 0.1 bar with a temperature of 40 ° C., and it is desired to slaughter 90 % of the acid gas.
• the cyclic capacity ⁇ ⁇ 0 expressed in moles of C0 2 per kg of solvent is calculated, considering that the solvent reaches its maximum thermodynamic capacity at the bottom of the absorption column and must at least be regenerated below its thermodynamic capacity under the conditions of the column head bar to achieve 90% reduction of C0 2 .
• [A] is the concentration of amine expressed in% by weight
• M is the molar mass of the amine in g / mol
• reaction enthalpy can be obtained by calculation from several CO 2 absorption isotherms by applying the Van't Hoff law.
• Table 4 For post-combustion fume extraction application where the partial pressure of C0 2 in the effluent to be treated is 0.1 bar, this example illustrates the greater cyclic capacity obtained thanks to an absorbing solution of N-methyl-4-hydroxypiperidine according to the invention, comprising 30% by weight of molecules to achieve a felling rate of 90% at the absorber outlet.
• the amine according to the invention makes it possible to obtain a much better compromise than the MEA, in terms of cyclic capacity and heat transfer. reaction.
• C0 2 capture capacity of an aqueous solution of N-methyl-4-hydroxypiperidine according to the invention in a mixture with piperazine is compared in particular with those of an aqueous solution of monoethanolamine at 30% by weight, which constitutes the reference solvent for a CO 2 capture application contained in post-combustion fumes. They are also compared with those of an aqueous solution of N-methyl-2-hydroxymethylpiperidine, described in document WO2009 / 1 105586 containing the same weight percentage of tertiary amine and piperazine.
• AOC pc [pCppco) '[ ⁇ ]' 10 M
• [A] is the total concentration of amine expressed as% by weight, and in the case of amine mixtures, M is the average molar mass of the amine mixture in g / mol:
• [A T ], [PZ] are the concentrations of tertiary amine and piperazine, expressed in weight%
• M AT and M PZ are respectively the molar masses of the tertiary amine and piperazine in mol / kg
• this example illustrates the greater cyclic capacity obtained thanks to the absorbent solution according to the invention, comprising 39% weight of N-methyl-4-hydroxypiperidine according to the invention and 6.7% by weight of piperazine to achieve a felling rate of 90% at the outlet of the absorber compared to MEA 30% by weight.
• Example 6 Absorption capacity of CO 2 of solutions of N-methyl-4-hydroxypiperidine activated with piperazine. Application to decarbonation in natural gas treatment
• the feed rates (a nb of mole acid gas / mole of amine mole) obtained at 40 ° C. for a partial pressure of CO 2 equal to 3 bar between an absorbent solution of N-methyl-4-hydroxypiperidine according to the invention at 39% by weight and containing 6.7% by weight of piperazine, an absorbent solution of methyldiethanolAmin at 39% by weight and containing 6.7% by weight of piperazine, as well as an absorbent solution of N-methyl-2-hydroxymethylpiperidine at 39% by weight and containing 6.7% by weight of piperazine.
• the partial pressures of C0 2 are typically centered between 1 and 10 bar with a temperature of 40 q C, and it is desired to eliminate almost all the C0 2 for liquefaction of natural gas.
• the maximum cyclic capacity Aa LN G, max expressed in moles of CO 2 per kg of solvent is calculated, considering that the solvent reaches its maximum thermodynamic capacity at the bottom of the absorption column. and is fully regenerated under the conditions of the column head.
• [A T ], [PZ] are the concentrations of tertiary amine and piperazine, expressed in weight%
• M AT and M PZ are respectively the molar masses of the tertiary amine and piperazine in mol / kg
• Table 6 For a total decarbonation application in natural gas treatment, this example illustrates the greater cyclic capacity obtained thanks to the absorbent solution according to the invention, comprising 39% by weight of N-methyl-4-hydroxypiperidine according to the invention. and 6.7% by weight of piperazine relative to the reference formulation containing 39% by weight of MDEA and 6.7% by weight of piperazine.
• the amines used according to the invention have the particularity of being particularly resistant to the degradations that may occur in a deacidification unit.
• a degradation test is carried out on aqueous solutions of amine in a closed reactor whose temperature is controlled by a control system. For each solution, the test is carried out in a liquid volume of 50 cm 3 injected into the reactor. The solvent solution is previously drawn under vacuum before any gas injection and the reactor is then placed in a heating shell at the set temperature and stirred magnetically. The gas in question is then injected at the desired partial pressure. This pressure is added to the initial pressure due to the vapor pressure of the aqueous amine solution. Different degradation conditions are tested:
• Table 7 gives the degradation rate TD, by degradation under C0 2 , of N-methyl-4-hydroxymethylpiperidine according to the invention, and of N-methyl-2-hydroxymethylpiperidine described in document WO2009 / 1 105586 as well as the MEA as reference amines, for a duration of 15 days, defined by the equation below:
• [A] where [A] is the concentration of the compound in the degraded sample, and [A] 0 is the concentration of the compound in the non-degraded solution.
• concentrations [A] and [A] 0 are determined by gas phase chromatography.
• Table 8 gives the degradation rate TD, by degradation under 0 2 , of the N-methyl-4-hydroxymethylpiperidine according to the invention, as well as the MEA as reference amine, for a period of 15 days, defined as above:
• Table 9 gives the degradation rate TD, by degradation under C0 2 of the N-methyl-4-hydroxymethylpiperidine according to the invention and piperazine mixed with the latter in an absorbent solution, and the MDEA as reference amine. , and piperazine mixed with the latter in another absorbent solution for a period of 15 days, the degradation rate of each amine being defined as above:

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