# US 5,348,714 A · Liquid absorbing acidic gases and use thereof in diacidification of gases > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,348,714 A - Document ID: US5348714A - Status: Granted - Kind: A - Application number: 08/058,096 - Filed: 1993-05-06 - Granted: 1994-09-20 - Earliest claimed: 1989-05-24 - Assignees: Elf Aquitaine Production - Inventors: Jean-Louis Peytavy; Philippe Le Coz; Olivier Oliveau - Web page: https://patentgrep.com/patent/US5348714A ## CPC - B01D 53/1493: {Selection of liquid materials for use as absorbents} - Y02C 20/40: of CO2 - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG] ## Abstract An absorbent liquid for improved absorption capacity for CO.sub.2 in a gas due to the presence of an activator for CO.sub.2 absorbent from the gas, the absorption liquid comprising a mixture of one or more tertiary alkanolamines and an activator of CO.sub.2 absorption by the tertiary alkanolamine, which activator has the general formula Y--(CpH.sub.2p)--NHZ wherein Y is a monovalent radical selected from the group consisting of piperazyl, piperidinyl, furyl, tetrahy-drothienyl and --OR.sub.2 radicals, Z is an R.sub.2 radical or hydrogen, R.sub.2 is a monovalent hydrocarbon residue, and p is an integer from 1 to 6. Also a process for using such absorbent liquid for improved CO.sub.2 absorption from a gas. ## Claims ### Claim 1 A process for improved CO.sub.2 absorption from a gas by an absorbent liquid which has an improved absorption capacity for CO.sub.2 which process comprises contacting said gas and the absorbent liquid in an absorption zone having an upper and lower part, thereby obtaining a treated gas with a reduced content of CO.sub.2 and the absorbent liquid with increased CO.sub.2 content, and regenerating the absorbent liquid which has an increased CO.sub.2 content, thereby releasing the CO.sub.2 and producing at least one gaseous fraction containing the released CO.sub.2 and at least one portion of the regenerated absorbent liquid and recycling said regenerated absorbent liquid to the absorption zone, the absorbent liquid being a mixture of one or more tertiary alkanolamines and an activator of improved CO.sub.2 absorption by said tertiary alkanolamines, the activator having the general formula Y--(C.sub.p H.sub.2p)--NHZ wherein Y is a monovalent radical selected from the group consisting of piperazyl, piperidinyl, furyl, tetrahydrofuryl, thienyl, tetrahydrothienyl and --OR.sub.2 radicals, Z is an --R.sub.2 radical or hydrogen, R.sub.2 is a monovalent hydrocarbon residue, and p is an integer from 1 to 6. ### Claim 2 (depends on 1) The process of claim 1 wherein Y is a monovalent radical selected from the group consisting of ##STR6## and C.sub.1 -C.sub.6 alkoxy radicals and Z is hydrogen. ### Claim 3 (depends on 1) The process of claim 1 wherein the activator is selected from the group consisting of methoxypropylamine, ethoxypropylamine, aminoethylpiperazine, aminopropylpiperazine, aminoethylpiperidine, aminopropylpiperidine and furfurylamine. ### Claim 4 (depends on 1) The process of claim 1 wherein in the formula for the activator, R.sub.2 is substituted by a functional group. ### Claim 5 (depends on 4) The process of claim 4 wherein the functional group is hydroxyl or phenyl. ### Claim 6 (depends on 1) The process of claim 1 wherein the activator is present in an activating amount. ### Claim 7 (depends on 1) The process of claim 1 wherein the gas is subjected to a treatment comprising an absorption stage and a regeneration stage during which the charged absorbent liquid is subjected to a regeneration treatment to release the CO.sub.2 which it has retained and to produce, on the one hand, at least one acidic gaseous fraction containing the released CO.sub.2 and, on the other hand, at least one regenerated absorbent liquid which is recycled towards the absorption zone. ### Claim 8 (depends on 7) The process of claim 7 wherein the regeneration is carried out by decompression in one or more stages of at least a part of the charged absorbent liquid. ### Claim 9 (depends on 1) The process of claim 1 wherein the regeneration of the charged absorbent liquid is carried out by subjecting all of the charged absorbent liquid to decompression in one or more stages to release most of the CO.sub.2 present in the said charged absorbent liquid, then subjecting the decompressed absorbent liquid to a complementary regeneration by steam-stripping by direct or indirect heating of the absorbent liquid, the absorbent liquid resulting from the complementary regeneration being recycled into the absorption zone. ### Claim 10 (depends on 1) The process of claim 1 wherein a part of the decompressed absorbent liquid is subjected to a complementary regeneration by stripping, the absorbent liquid resulting from the complementary regeneration being recycled into the upper part of the absorption zone while the part of the decompressed absorbent liquid which is not subjected to the complementary regeneration is being recycled into the absorbent zone below the absorbent liquid regenerated by stripping. ### Claim 11 (depends on 1) The process of claim 1 wherein the regeneration of the charged absorbent liquid is carried by subjecting a fraction of the charged absorbent liquid to decompression in one or more stages to release most of the CO.sub.2 which it contains while the remaining fraction of the charged absorbent liquid is subjected directly to a regeneration by steam-stripping, by direct or indirect heating of the absorbent liquid of the remaining fraction, the fraction of the absorbent liquid regenerated by stripping is being recycled into the upper part of the absorption zone while the decompressed fraction of absorbent liquid is being recycled into the absorption zone below the absorbent liquid regenerated by stripping. ### Claim 12 (depends on 1) The process of claim 1 wherein the CO.sub.2 -containing gas to be treated also comprises other acidic gas including H.sub.2 S and/or COS. ### Claim 13 (depends on 7) The process of claim 7 wherein the decompressed absorbent liquid is subjected to a complementary regeneration step which comprises steam-stripping the absorbent liquid by direct or indirect heating. ### Claim 14 An absorbent liquid for improved absorption capacity for CO.sub.2 in a gas due the presence of an activator for CO.sub.2 absorbent from said gas, the absorption liquid comprising a mixture of one or more tertiary alkanolamines and an activator of CO.sub.2 absorption by said tertiary alkanolamine, which activator has the general formula Y--(C.sub.p H.sub.2p)--NHZ wherein Y is a monovalent radical selected from the group consisting of piperazyl, piperidinyl, furyl, tetrahydrofuryl, thienyl, tetrahydrothienyl and --OR.sub.2 radicals, Z is an --R.sub.2 radical or hydrogen, R.sub.2 is a monovalent hydrocarbon residue, and p is an integer from 1 to 6. ### Claim 15 (depends on 14) The absorbent liquid of claim 14 wherein in the formula for the activator, R.sub.2 is substituted by a functional group. ### Claim 16 (depends on 15) The absorbent liquid of claim 15 wherein the functional group is hydroxyl or phenyl. ### Claim 17 (depends on 15) The absorbent liquid of claim 15 wherein the activator is present in an activating amount. ### Claim 18 (depends on 17) The absorbent liquid of claim 17 wherein the absorbent liquid is an aqueous solution of the tertiary alkanolamine and the activator. ### Claim 19 (depends on 18) The absorbent liquid of claim 18 wherein the absorbent liquid contains a minor quantity of at least one water-soluble organic solvent for the CO.sub.2, selected from the group consisting of sulpholane, methanol and N-methylpyrrolidone. ### Claim 20 (depends on 18) The absorbent liquid of claim 18 wherein the concentration of the tertiary alkanolamine in the aqueous solution is between 1N and 6N. ### Claim 21 (depends on 18) The absorbent liquid of claim 18 wherein the quantity of activator is such that the ratio of the number of moles of activator to the total number of moles of activator and of tertiary alkanolamine is between 0.01 and 0.5. ### Claim 22 (depends on 18) The absorbent liquid of claim 18 wherein the tertiary alkanolamine is selected from the group consisting of at least one of the tertiary alkanolamines N-methyldiethanolamine, triethanolamine, 2-dimethylaminoethanol, 3-dimethylamino-1-propanol and 1-diethylamino-2-propanol. ### Claim 23 (depends on 18) The absorbent liquid of claim 18 wherein the activating amount of the activator in the absorbent liquid is between 0.05 mole and about 2 moles per liter. ### Claim 24 (depends on 23) The absorbent liquid of claim 23 wherein the activating amount is from about 0.1 mole to about 1 mole per liter. ### Claim 25 (depends on 20) The absorbent liquid of claim 20 wherein the concentration of the tertiary alkanolamine is between 2.5N and 5N. ### Claim 26 (depends on 21) The absorbent liquid of claim 21 wherein the ratio is between 0.05 and 0.25.