# US 10,500,540 B2 · Method for dehumidifying humid gas mixtures using ionic liquids > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,500,540 B2 - Document ID: US10500540B2 - Status: Granted - Kind: B2 - Application number: 15/742,436 - Filed: 2016-06-28 - Published: 2018-06-21 - Granted: 2019-12-10 - Earliest claimed: 2015-07-08 - Assignees: Evonik Degussa GmbH - Applicants: Evonik Degussa GmbH - Inventors: Olivier Zehnacker; Xinming Wang; Benjamin Willy; Rolf Schneider; Marc-Christoph Schneider - Web page: https://patentgrep.com/patent/US10500540B2 ## CPC - B01D 53/28: Selection of materials for use as drying agents - B01D 53/1493: {Selection of liquid materials for use as absorbents} - B01D 53/263: {by absorption} - C09K 5/047: {for absorption-type refrigeration systems} - F24F 3/1417: {with liquid hygroscopic desiccants} - F25B 15/02: without inert gas ({F25B15/004, F25B15/006, F25B15/008}, F25B15/12, F25B15/14, F25B15/16 take precedence) - F25B 15/06: the refrigerant being water vapour evaporated from a salt solution, e.g. lithium bromide {(F25B15/025 takes precedence)} - F25B 30/04: of the sorption type - B01D 2252/30: Ionic liquids and zwitter-ions - B01D 2257/80: Water - B01D 2259/4508: for cleaning air in buildings - 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) - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02) - F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS ## Abstract The invention relates to a process for dehumidifying a moist gas mixture. The invention further relates to an apparatus for dehumidifying a moist gas mixture and to the use of said apparatus in the process according to the invention. ## Claims ### Claim 1 A process for dehumidifying a moist gas mixture G in an apparatus V1, comprising the steps of: (a) contacting the moist gas mixture G with a liquid absorption medium AVE comprising at least one salt selected from the group consisting of: Q+(RO)2PO2−; (Q+)2ROPO32−; and Q+M+ROPO32−; wherein the liquid absorption medium AVE at least partially absorbs water from the moist gas mixture G, to obtain a liquid absorption medium AVE1 having an elevated water content compared to the liquid absorption medium AVE and a gas mixture G1 having a relatively low water content compared to the moist gas mixture G; (b) at least partially removing water from the liquid absorption medium AVE1 to obtain a liquid absorption medium AVE2 having a relatively low water content compared to the liquid absorption medium AVE1; wherein the apparatus V1 at least partially comprises a surface made of an aluminium material of construction OAl and in the apparatus V1, at least one of the liquid absorption media selected from the group consisting of AVE, AVE1, AVE2 contacts the surface made of OAl via at least one contact surface; and wherein: Q+ is a 1,3-dialkylimidazolium in which the alkyl groups are, independently of one another, unbranched or branched C1-C6 alkyl groups; R is an unbranched or branched C2-C6 alkyl group; and M+ is an alkali metal ion. ### Claim 2 (depends on 1) The process of claim 1, wherein R is selected from the group consisting of: an ethyl group and a n-butyl group. ### Claim 3 (depends on 1) The process of claim 1, wherein Q+ is selected from the group consisting of 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium. ### Claim 4 (depends on 3) The process of claim 3, wherein the salt is selected from the group consisting of: 1,3-diethylimidazolium diethylphosphate; 1-ethyl-3-methylimidazolium diethylphosphate; and 1-n-butyl-3-methylimidazolium di-n-butylphosphate. ### Claim 5 (depends on 1) The process of claim 1, wherein the liquid absorption medium AVE is an aqueous solution in which the total weight of all salts of structure Q+(RO)2PO2−, (Q+)2ROPO32− and Q+M+ROPO32− is at least 70 wt % based on the total weight of the aqueous solution. ### Claim 6 (depends on 1) The process of claim 1, wherein said process is carried out in continuous fashion. ### Claim 7 (depends on 2) The process of claim 2, wherein: a) Q+ is selected from the group consisting of 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium; and b) the liquid absorption medium AVE is an aqueous solution in which the total weight of all salts of structure Q+(RO)2PO2−, (Q+)2ROPO32− and Q+M+ROPO32− is at least 70 wt % based on the total weight of the aqueous solution. ### Claim 8 (depends on 1) The process of claim 1, wherein said process is carried out using an apparatus V2 for dehumidifying a moist gas mixture, wherein said apparatus comprises the components: a) a liquid absorption medium AVO comprising at least one salt selected from the group consisting of: Q+(RO)2PO2−; (Q+)2ROPO32−; and Q+M+ROPO32−; b) at least one water absorption unit Wabs2 for contacting the moist gas mixture with the liquid absorption medium AVO; c) at least one water desorption unit Wdes2 which comprises a heat exchanger Wx2 and is set up for at least partially removing water from a liquid absorption medium AVO; and d) a circuit U2 which connects the water absorption unit Wabs2 with the water desorption unit Wdes2 and by means of which the liquid absorption medium AVO may be circulated; wherein at least one of the components Wabs2, Wdes2, and U2 at least partially comprises a surface made of an aluminium material of construction OAl; and wherein disposed in the apparatus V2 is at least one contact surface at which the liquid absorption medium AVO contacts the surface made of OAl; and wherein: Q+ is a 1,3-dialkylimidazolium where the alkyl groups are independently of one another unbranched or branched C1-C6 alkyl groups; R is an unbranched or branched C2-C6 alkyl group; and M+ is an alkali metal ion. ### Claim 9 (depends on 8) The process of claim 8, wherein R is selected from the group consisting of: an ethyl group and a n-butyl group. ### Claim 10 (depends on 9) The process of claim 9, wherein: a) Q+ is selected from the group consisting of 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium; and b) the liquid absorption medium AVE is an aqueous solution in which the total weight of all salts of structure Q+(RO)2PO2−, (Q+)2ROPO32− and Q+M+ROPO32− is at least 70 wt % based on the total weight of the aqueous solution. ### Claim 11 An apparatus V2 for dehumidifying a moist gas mixture, comprising the components: a) a liquid absorption medium AVO comprising at least one salt selected from the group consisting of: Q+(RO)2PO2−; (Q+)2ROPO32−; and Q+M+ROPO32−; b) at least one water absorption unit Wabs2 for contacting the moist gas mixture with the liquid absorption medium AVO; c) at least one water desorption unit Wdes2 which comprises a heat exchanger Wx2 and is set up for at least partially removing water from a liquid absorption medium AVO; and d) a circuit U2 which connects the water absorption unit Wabs2 with the water desorption unit Wdes2 and by means of which the liquid absorption medium AVO may be circulated; wherein at least one of the components Wabs2, Wdes2, and U2 at least partially comprises a surface made of an aluminium material of construction OAl; and wherein disposed in the apparatus V2 is at least one contact surface at which the liquid absorption medium AVO contacts the surface made of OAl; and wherein: Q+ is a 1,3-dialkylimidazolium where the alkyl groups are independently of one another unbranched or branched C1-C6 alkyl groups; R is an unbranched or branched C2-C6 alkyl group; and M+ is an alkali metal ion. ### Claim 12 (depends on 11) The apparatus V2 of claim 11, wherein R is selected from the group consisting of: an ethyl group and a n-butyl group. ### Claim 13 (depends on 11) The apparatus V2 of claim 11, wherein Q+ is selected from the group consisting of 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium. ### Claim 14 (depends on 13) The apparatus V2 of claim 13, wherein the salt is selected from the group consisting of: 1,3-diethylimidazolium diethylphosphate; 1-ethyl-3-methylimidazolium diethylphosphate; and 1-n-butyl-3-methylimidazolium di-n-butylphosphate. ### Claim 15 (depends on 11) The apparatus V2 of claim 11, wherein AVO is an aqueous solution in which the total weight of all salts of structure Q+(RO)2PO2−, (Q+)2ROPO32− and Q+M+ROPO32 is at least 70 wt % based on the total weight of the aqueous solution. ### Claim 16 (depends on 11) The apparatus V2 of claim 11, wherein at least one of the components Wabs2, and Wdes2 is a falling film. ### Claim 17 (depends on 11) The apparatus V2 of claim 11, comprising a further heat exchanger Wy2 positioned so that liquid absorption medium AVO sent from the water absorption unit Wabs2 to the water desorption unit Wdes2 is suppliable with heat from liquid absorption medium AVO, said medium being conducted away from the water desorption unit Wdes2. ### Claim 18 (depends on 12) The apparatus of claim 12, wherein: a) Q+ is selected from the group consisting of 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-n-butyl-3-methylimidazolium; and b) the liquid absorption medium AVE is an aqueous solution in which the total weight of all salts of structure Q+(RO)2PO2−, (Q+)2ROPO32− and Q+M+ROPO32 is at least 70 wt % based on the total weight of the aqueous solution. ### Claim 19 (depends on 18) The apparatus of claim 18, comprising a further heat exchanger Wy2 positioned so that liquid absorption medium AVO sent from the water absorption unit Wabs2 to the water desorption unit Wdes2 is suppliable with heat from liquid absorption medium AVO, said medium being conducted away from the water desorption unit Wdes2. ### Claim 20 (depends on 11) An absorption heat pump, comprising the apparatus V2 of claim 11, as further components, a condenser, an evaporator and a coolant, wherein the coolant is water.