USOO9724642B2 (12) United States Patent (10) Patent No.: US 9,724,642 B2 Murai et al. (45) Date of Patent: Aug. 8, 2017 (54) ACID GAS ABSORBENT, ACID GAS (56) References Cited REMOVAL DEVICE, AND ACID GAS REMOVAL METHOD U.S. PATENT DOCUMENTS 3,478,096 A 11/1969 Cyba (71) Applicant: Kabushiki Kaisha Toshiba, Minato-ku 4,112,052 A 9, 1978 Sartori et al. (JP) (Continued) (72) Inventors: Shinji Murai, Sagamihara (JP); FOREIGN PATENT DOCUMENTS Yukishige Maezawa, Hachioji (JP); Yasuhiro Kato, Kawasaki (JP); CA 2 692 154 12/2008 Takehiko Muramatsu, Yokohama (JP); CN 102553395 A T 2012 Masatoshi Hodotsuka, Saitama (JP); (Continued) Satoshi Saito, Yamato (JP) OTHER PUBLICATIONS (73) Assignee: KABUSHIKI KAISHA TOSHIBA, Combined Office Action and Search Report issued Mar. 23, 2016 in Minato-ku (JP) Chinese Patent Application No. 201410725780.6 (with English translation of category of cited documents). (*) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 (Continued) U.S.C. 154(b) by 102 days. Primary Examiner — Daniel Berns (74) Attorney, Agent, or Firm — Oblon, McClelland, (21) Appl. No.: 14/555,787 Maier & Neustadt, L.L.P. (22) Filed: Nov. 28, 2014 (57) ABSTRACT An acid gas absorbent includes at least one kind of second (65) Prior Publication Data ary amine compound represented by formula (1): US 2015/O151246 A1 Jun. 4, 2015 (30) Foreign Application Priority Data General formula 1 (1) Dec. 3, 2013 (JP) ................................. 2013-25O241 RI V N-R-O-R-OH (51) Int. Cl. M C07C 21 7/28 (2006.01) H C07C 217/08 (2006.01) (Continued) where R' is a cyclopentyl group or a cyclohexyl group which (52) U.S. Cl. may be substituted by a substituted or non-substituted alkyl CPC ......... BOID 53/62 (2013.01); B0ID 53/1475 group having 1 to 3 carbon atoms, R and Reach indicate (2013.01); B0ID 53/1493 (2013.01); an alkylene group having 2 to 4 carbon atoms, and R and (Continued) R may each be the same or different, and be a straight chain (58) Field of Classification Search or have a side chain. None See application file for complete search history. 14 Claims, 1 Drawing Sheet 1. 4. CO2 US 9,724,642 B2 Page 2 (51) Int. Cl. 6,036,931 A 3/2000 Yoshida et al. C07C 21 7/52 (2006.01) 6,500,397 B1 12/2002 Yoshida et al. CD7C 25/12 (2006.01) 8,597.418 B2 12/2013 Inoue et al. BOLD 53/62 (2006.01) 2012fO161071 A1 6, 2012 Murai et al. BOLD 53/14 (2006.01) 2013,0078170 A1* 3, 2013 Dai ..................... BO1F 17 OO64 (52) U.S. Cl. 423.223 CPC. C07C 217/08 (2013.01); B01D 2252/2023 2014/0056792 A1 2/2014 Inoue et al. (2013.01); B01D 2252/20426 (2013.01); B01D 2252/20484 (2013.01); B0ID 2252/502 FOREIGN PATENT DOCUMENTS (2013.01); B0ID 2252/602 (2013.01); B01D EP O 084 943 A2 8, 1983 2252/606 (2013.01); B0ID 2252/608 EP O 087 207 A1 8/1983 (2013.01); B0ID 2257/304 (2013.01); B01D EP O 087 208 A1 8, 1983 2257/.504 (2013.01); B01D 2258/0283 EP O 558 019 A2 9, 1993 (2013.01); Y02C 10/06 (2013.01) EP 2 1892O7 A1 5, 2010 EP 2 468 385 A2 6, 2012 GB 1238 696. A 7, 1971 (56) References Cited JP 58-124520 T 1983 JP 63-27336 6, 1988 U.S. PATENT DOCUMENTS JP 2871334 3, 1999 JP 2008-307519 12/2008 4,312.959 A * 1/1982 Treadwell ............... Co.'s JP 2009-006275 1, 2009 4.405,580 A 9/1983 Stogryn et al. JP 2009-213974 9, 2009 4.405,581 A 9/1983 Savage et al. WO WO 2008,156085 A1 12/2008 4.405,585 A 9, 1983 Sartori et al. 4,405,811 A 9/1983 Stogryn et al. OTHER PUBLICATIONS 4,471,138 A 9/1984 Stogryn 3:63 A 1 E. SEal Extended European Search Report issued May 20, 2015 in Patent 4,665,234 A 5/1987 Stogryn Application No. 14195550.0. 5,413,627 A * 5/1995 Landeck ................ BOD 53/14 423,210 * cited by examiner U.S. Patent Aug. 8, 2017 US 9,724,642 B2 US 9,724,642 B2 1. 2 ACID GAS ABSORBENT, ACID GAS regeneration. On the other hand, methyldiethanolamine REMOVAL DEVICE, AND ACID GAS being tertiary amine has low corrosiveness and requires low REMOVAL METHOD energy for regeneration, but has a defect that an absorption speed is low. Accordingly, a development of a new absorbent CROSS-REFERENCE TO RELATED in which these disadvantages are improved is required. APPLICATION Besides, an amine compound which is difficult to be released from an absorption tower and a regeneration tower is This application is based upon and claims the benefit of required. priority from Japanese Patent Application No. 2013-250241, In recent years, a study on particularly alkanolamine filed on Dec. 3, 2013; the entire contents of all of which are 10 having structural steric hindrance, among amine compound, incorporated herein by reference. has been tried as the absorbent of acid gas. Alkanolamine having the steric hindrance has advantages that selectivity of FIELD acid gas is very high and the energy required for regenera tion is Small. Embodiments described herein relate generally to an acid 15 The reaction speed of the amine compound having the gas absorbent, an acid gas removal device, and an acid gas steric hindrance depends on the degree of reaction hindrance removal method. determined by the steric structure thereof. There is a method to use the alkanolamine which has both BACKGROUND the ether bond and the chained alkyl group which is directly coupled to a nitrogen atom. In recent years, a greenhouse effect resulting from an However, the alkanolamine suffers from the disadvantages increase in carbon dioxide (CO) concentration has been of the latively low boiling point, the insufficient suppression pointed out as a cause of global warming phenomena, and of the diffusion from the absorption tower, and high heat of there is an urgent need to devise an international counter reaction with acid gas. measure to protect environment in a global scale. Industrial 25 On the other hand, there is a method to use a cyclic amine activities have a large responsibility as a generation Source compound which has a chemical structure different from that of CO, and there is a trend to suppress discharge of CO. of alkanolamine. As technologies to suppress the increase of the concen tration of acid gas, typically, CO, there are a development BRIEF DESCRIPTION OF THE DRAWINGS of energy saving products, technologies to use the acid gas 30 as a resource and to isolate and store the acid gas, a FIG. 1 is a schematic diagram of an acid gas removal switching to alternate energies such as natural energy, device according to an embodiment. atomic energy, and so on which do not discharge the acid gas, and so on, and a separation and recovery technology of DETAILED DESCRIPTION discharged acid gas is known as one of them. 35 As separation technologies of the acid gas that have been Hereinafter, an embodiment of the present invention will studied up to now, there are an absorption process, a Suction be explained in detail. An acid gas absorbent according to an process, a membrane separation process, a cryogenic pro embodiment includes at least one kind of secondary amine cess, and so on. Among them, the absorption process is compound represented by the following general formula (1). Suitable for processing a large amount of gas, and its 40 application in a factory and a power station is considered. Mainly, as a method whose targets are facilities such as a (1) RI thermal power station using fossil fuels (coal, coal oil, V natural gas, and so on), a method in which exhaust com N-R-O-R-OH bustion gas generated when the fossil fuel is burned is 45 M brought into contact with a chemical absorbent, and thereby H CO in the exhaust combustion gas is removed and recov ered, and further a method of storing the recovered CO are In the above-described formula (1), R' indicates a cyclo known. Further, there is proposed to remove acid gas Such pentyl group or a cyclohexyl group which may be substi as hydrogen sulfide (H2S) in addition to CO by using the 50 tuted by a Substituted or non-Substituted alkyl group having chemical absorbent. 1 to 3 carbon atoms. R and Reach indicate an alkylene In general, alkanolamine typified by monoethanolamine group having 2 to 4 carbon atoms. R and R may each be (MEA) have been developed in the 1930s as the chemical the same or different, and be a straight chain or have a side absorbent used in the absorption process, and are still used chain. at present. A method of using the alkanolamine is economi 55 Conventionally, it has been known that a steric hindrance cal, and further it is easy to enlarge the removal device in held by an amine compound has a large effect on a product size. at a carbon dioxide absorption, and plays an advantageous AS alkanolamine used in the absorption process, there are role in generation of bicarbonate ion exhibiting low heat of monoethanolamine, 2-amino-2-methylpropanol, methylam reaction. As a result that based on Such knowledge, the inoethanol, ethylaminoethanol, propylaminoethanol, dietha 60 present inventor conducted Studies to obtain a larger effect nolamine, methyldiethanolamine, dimethylethanolamine, of the steric hindrance, it was found that it is possible to diethylethanolamine, triethanolamine, dimethylamino-1- obtain further lower heat of reactivity, higher carbon dioxide methylethanol, and so on.