- Email: [email protected]
Phase equilibria of tetra-iso-amyl ammonium bromide (TiAAB) semiclathrates with CO2, N2, or CO2 + N2
J. Chem. Thermodynamics 142 (2020) 106024
Contents lists available at ScienceDirect
J. Chem. Thermodynamics journal homepage: www.elsevier.com/locate/jct
Phase equilibria of tetra-iso-amyl ammonium bromide (TiAAB) semiclathrates with CO2, N2, or CO2 + N2 Soyoung Kim a, Gyeol Ko b, Ki-Sub Kim c,⇑, Yongwon Seo b,⇑ a
Accident Coordination and Traning Division, National Institute of Chemical Safety, Daejeon 34111, Republic of Korea School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea c School of Chemical and Materials Engineering, Korea National University of Transportation, Chungbuk 27469, Republic of Korea b
a r t i c l e
i n f o
Article history: Received 7 November 2019 Received in revised form 3 December 2019 Accepted 4 December 2019 Available online 7 December 2019 Keywords: CO2 N2 Flue gas Tetra-iso-amyl ammonium bromide Semiclathrate
a b s t r a c t This study examined the thermodynamic stability and guest gas inclusion of tetra-iso-amyl ammonium bromide (TiAAB) semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%), with a primary focus on semiclathrate phase equilibria and Raman spectra. The three-phase (H-LW-V) equilibria of TiAAB semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%) were measured at a stoichiometric concentration (TiAAB 3.7 mol%) using both a conventional isochoric method and a stepwise differential scanning calorimeter (DSC) method. The phase equilibria demonstrated that TiAAB (3.7 mol%) semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%) were significantly stabilized compared with the corresponding CO2, N2, or CO2 (20%) + N2 (80%) gas hydrates. The enclathration of CO2 and N2 molecules in the cages of TiAAB semiclathrates was clearly confirmed via Raman spectroscopy. The experimental results indicate that TiAAB semiclathrates can incorporate CO2 and N2 into the cage lattices at elevated temperatures and lowered pressures and are potential materials for CO2 capture. Ó 2019 Elsevier Ltd.
1. Introduction Clathrate hydrates are crystalline inclusion compounds that consist of hydrogen-bonded cage frameworks called ‘‘host” and small-sized ‘‘guest” molecules [1]. They are generally classified as true clathrates and semiclathrates, depending on the types of interactions between host and guest molecules, even though their strict distinction has blurred [2,3]. True clathrates exhibit van der Waals interactions between encapsulated guest molecules and host water molecules. Well-known gas hydrates belong to true clathrates. On the other hand, semiclathrates have chemical or ionic interactions between host and guest molecules. Quaternary ammonium salts (QASs) such as tetra-n-butyl ammonium bromide (TBAB), tetra-n-butyl ammonium chloride (TBAC), and tetra-nbutyl ammonium fluoride (TBAF) form semiclathrates with water under atmospheric pressure [4–6]. In QAS semiclathrates, TBA cations are captured in the partially broken large cages, while anions (Br-, Cl- or F-) participate in building up host frameworks [2,3,7]. QAS semiclathrates have much higher thermodynamic
⇑ Corresponding authors. E-mail addresses: [email protected] (K.-S. Kim), [email protected] (Y. Seo). https://doi.org/10.1016/j.jct.2019.106024 0021-9614/Ó 2019 Elsevier Ltd.
stability compared to gas hydrates and have vacant small (512) cages, which are available for encapsulating small-sized gas molecules [7–10]. Due to these unique features of QAS semiclathrates, TBAB, TBAC, and TBAF semiclathrates have been extensively explored for potential gas storage, CO2 capture, and cold energy storage applications [7–18]. Recently, tetra-iso-amyl ammonium bromide (TiAAB) has been suggested as a promising semiclathrate former for CO2 capture and gas storage because TiAAB semiclathrate has greater thermodynamic stability than that of TBAB, TBAC, and TBAF semiclathrates [19,20,21]. This indicates that the formation of TiAAB semiclathrates with guest gases can occur at lower pressures and higher temperatures. However, accurate phase equilibria in a wide pressure range and spectroscopic observation of guest enclathration in TiAAB semiclathrates for CO2 capture applications have rarely been reported in the literature. In this study, as a first step of TiAAB semiclathrate-based CO2 capture, semiclathrate phase equilibria of CO2 + TiAAB + water, N2 + TiAAB + water, and CO2 (20%) + N2 (80%) + TiAAB + water mixtures were experimentally measured using both a conventional isochoric (pVT) method and a stepwise differential scanning calorimeter (DSC) method. The enclathration of CO2 and N2 in the TiAAB semiclathrates was confirmed using Raman spectroscopy.
2
S. Kim et al. / J. Chem. Thermodynamics 142 (2020) 106024
2. Experimental 2.1. Materials CO2 with a purity of 99.999% was provided by Deokyang Co. (Republic of Korea), and N2 with a purity of 99.99% was supplied by KOSEM Co. (Republic of Korea). The gas mixture of CO2 (20%) + N2 (80%) was supplied by MS Gas Co. (Republic of Korea). The tetra-iso-amyl ammonium bromide (TiAAB) used in this study was synthesized using Menschutkin reaction [22]. The 1H NMR (D2O) spectrum of TiAAB consisted of the following peaks: 0.85– 0.87 (m, 24H), 1.46–1.49 (t, 8H), 1.53–1.59 (m, 4H), 3.12–3.16 (t, 8H). The detailed procedure of the TiAAB synthesis was described in a previous paper [20]. Deionized doubly distilled water was used for the experiment. The suppliers and purity of the materials used in this study are presented in Table 1.
2.2. Apparatus and procedures The equilibrium cell used to measure the semiclathrate phase equilibria was made of 316 stainless steel and had an inner volume of 50 cm3. An impeller-type mechanical stirrer was used to vigorously agitate the solutions inside the cell to accelerate semiclathrate formation and dissociation. The equilibrium cell was immersed in a circulator (RW-2025G, Jeio Tech, Republic of Korea) to control the temperature. A resistance temperature detector (RTD) sensor was used to measure the cell temperature after being calibrated using an ASTM 63C thermometer (H-B Instrument Company, USA). A pressure transducer (S-10, WIKA, Germany) was used to measure the cell pressure and was calibrated using a Heise Bourdon tube pressure gauge (CMM-140830, 0–20.0 MPa, Ashcroft, Inc. USA). The uncertainties associated with the temperature (T) and pressure (p) measurements were 0.1 K and 0.02 MPa, respectively. An isochoric (pVT) method with step heating and cooling was adopted to determine the semiclathrate phase equilibria. The cell was charged with approximately 20 cm3 of TiAAB (3.7 mol%) solution and then pressurized with the CO2, N2, or CO2 (20%) + N2 (80%) gas to the desired pressure. The cell was cooled down at a rate of 1.0 K∙h 1 to induce semiclathrate formation. After the formation of semiclathrates, which was indicated by an abrupt pressure drop, the cell was slowly heated at a rate of 0.1 K per 90 min for the dissociation. The three-phase (semiclathrate (H) - liquid water (LW) vapor (V)) equilibrium point was determined by the intersection of the semiclathrate dissociation curve and the thermal expansion line at each pressure condition. A high-pressure micro-differential scanning calorimeter (HP lDSC7 evo, Setaram Inc., France) was also used to measure the semiclathrate phase equilibria. The HP lDSC device consists of a
Table 1 Materials used in this study.
a b c d e
Chemical Name
Supplier
Purity
Water in mass fraction/10-6
Analysis
CO2 N2 CO2 (20%) + N2 (80%) TiAABc
Deokyang KOSEM MS Gas
0.99999 0.9999 –
– – –
GCa,b GCa,b GCa,b
Synthesis
–
<150
NMRd, KFe
Analysis done by supplier. Gas chromatography. TiAAB: tetra-iso-amyl ammonium bromide. Nuclear magnetic resonance. Karl Fischer titration.
Fig. 1. Heat flow changes during stepwise heating of the CO2 + TiAAB (3.7 mol%) semiclathrate at 2.9 MPa.
reference cell and a sample cell, with an operating pressure range from 0 MPa to 40.0 MPa and an operating temperature range from 228.15 K to 393.15 K. The HP m-DSC had a resolution of 0.02 lW. The DSC can be used to determine equilibrium dissociation temperature of semiclathrates using either dynamic or stepwise methods [23–25]. In this study, the stepwise DSC method, which was found to be more reliable and accurate, was also employed to confirm the semiclathrate phase equilibrium points measured by the isochoric (pVT) method. For the stepwise DSC experiments, the sample cell was charged with approximately 10 mg of TiAAB (3.7 mol%) solution, whereas the reference cell was left empty. Because stirring was not available, a multi-cycle mode of cooling and heating was applied to the cells in order to completely convert the TiAAB solution to TiAAB semiclathrates. The HP lDSC cells were initially cooled to T = 253 K at a cooling rate of 1.0 K∙min 1, and then, they were firstly heated to a temperature 1 K lower than the expected dissociation temperature in 2 K increments with 3 h intervals. The temperature was further increased in 0.1 K increments with a 3 h isothermal duration at each step until there were no endothermic peaks from semiclathrate dissociation. As shown in Fig. 1, the temperature at the point at which the endothermic peaks disappeared was determined to be the equilibrium dissociation temperature of semiclathrates at a given pressure. A fiber-coupled Raman spectrometer (SP550, Horiba, France) with a multichannel air cooled CCD detector and 1800 grooves/ mm grating was used to obtain Raman spectra of TiAAB semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%). A fiber-optic Raman probe was attached to the high-pressure equilibrium cell with a water jacket to allow the collection of the Raman spectra. A more detailed description of the experimental methods and procedure has been provided in our previous papers [20,26,27].
3. Results and discussion 3.1. Thermodynamic stability of TiAAB semiclathrates with CO2, N2, or CO2 + N2 TiAAB is known to form semiclathrates with a chemical formula of TiAAB26 H2O, which has a stoichiometric TiAAB concentration
S. Kim et al. / J. Chem. Thermodynamics 142 (2020) 106024
Fig. 2. Semiclathrate phase equilibria of the CO2 + TiAAB (3.7 mol%) + water mixture.
of 3.7 mol% [19,20]. The maximum equilibrium dissociation temperature (303.6 K) of TiAAB semiclathrates under atmospheric pressure was observed at the stoichiometric concentration (3.7 mol%). In this study, semiclathrate phase equilibria of the CO2 + TiAAB + water, N2 + TiAAB + water, and CO2 (20%) + N2 (80%) + TiAAB + water mixtures were measured to examine the thermodynamic stability of TiAAB semiclathrates with guest gases at 3.7 mol% TiAAB. CO2 is one of the major components of flue gas from fossil fuelfired power plants and a target component that needs to be separated through the semiclathrate-based capture process [28]. Fig. 2 shows three-phase (H-LW-V) equilibria of the CO2 + TiAAB (3.7 mol %) semiclathrate along with relevant literature data of CO2 + TiAAB (0.8 mol%) semiclathrate and CO2 hydrate [21,29]. Compared to the CO2 hydrate, the CO2 + TiAAB (3.7 mol%) semiclathrate exhibited a significant thermodynamic promotion. The equilibrium curve of the CO2 + TiAAB (3.7 mol%) semiclathrate was located at temperatures higher than 300 K across the entire pressure range (from 0.64 MPa to 3.35 MPa) examined in this study. The equilibrium temperature difference between CO2 + TiAAB (3.7 mol%) semiclathrate and CO2 hydrate, i.e., the thermodynamic promotion was approximately 28 K at 2.9 MPa. In this study, both an isochoric (pVT) method and a stepwise DSC method were used to measure phase (H-LW-V) equilibria of the CO2 + TiAAB (3.7 mol%) semiclathrate. As seen in Fig. 2, an equilibrium point measured by the stepwise DSC method was located exactly on the H-LW-V equilibrium curve of the CO2 + TiAAB (3.7 mol%) semiclathrate measured by the isochoric (pVT) method. N2 is also a primary component of flue gas, which generally consists of 10–20% CO2 and 80–90% N2 [28]. Due to the small molecular size of N2, N2 hydrate requires significantly higher pressure than CO2 hydrate at a given temperature [1]. The larger equilibrium pressure difference between N2 hydrate and CO2 hydrate makes hydrate or semiclathrate-based CO2 capture feasible. Fig. 3 shows that the N2 + TiAAB (3.7 mol%) semiclathrate was significantly stabilized compared to the N2 hydrate. N2 hydrate requires an equilibrium pressure as high as 16 MPa even at 273.2 K [1], whereas the N2 + TiAAB (3.7 mol%) semiclathrate is thermodynam-
3
Fig. 3. Semiclathrate phase equilibria of the N2 + TiAAB (3.7 mol%) + water mixture. (See above-mentioned references for further information).
ically stable even at temperatures above 300 K for the entire pressure range (from 1.37 MPa to 8.19 MPa) examined. The equilibrium curve of the CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate also shifted significantly to the thermodynamically promoted regions, which are represented by a lower pressure at any given temperature or a higher temperature at any given pressure compared with the CO2 (20%) + N2 (80%) hydrate. Fig. 4 illustrates that the CO2 (20%) + N2 (80%) gas mixture can form semiclathrates in the presence of TiAAB 3.7 mol% solution at temperatures above 300 K and at pressures just above atmospheric pressure even though the experimental measurements of
Fig. 4. Semiclathrate phase equilibria of the CO2 (20%) + N2 (80%) + TiAAB (3.7 mol %) + water mixture. (See above-mentioned references for further information).
4
S. Kim et al. / J. Chem. Thermodynamics 142 (2020) 106024
Table 2 Semiclathrate phase equilibrium data of the CO2 + TiAAB (3.7 mol%) + water, N2, + TiAAB (3.7 mol%) + water, and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) + water systems.a. CO2
N2
pVT
a
DSC
CO2 (20%) + N2 (80%)
pVT
DSC
pVT
DSC
T/K
p/MPa
T/K
p/MPa
T/K
p/MPa
T/K
p/MPa
T/K
p/MPa
T/K
p/MPa
305.2 306.4 307.2 308.0 308.6 309.1
0.64 1.15 1.54 2.14 2.79 3.35
308.4
2.90
304.3 305.3 306.6 307.4 308.0
1.37 2.69 4.63 6.47 8.19
305.7
3.03
304.7 306.3 307.8 308.7 309.9
1.35 2.85 4.93 6.50 8.46
306.4
2.90
Standard uncertainties u are u (T) = 0.1 K and u (p) = 0.02 MPa.
the semiclathrate phase equilibria were performed across a wide pressure range (from 1.35 MPa to 8.46 MPa). The semiclathrate equilibrium point of the CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate measured by the stepwise DSC method closely matched that measured by the conventional isochoric (pVT) method, and was located exactly on the equilibrium curve of the CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate. The overall three-phase (H-LW-V) equilibrium data of the CO2 + TiAAB (3.7 mol%), N2 + TiAAB (3.7 mol%), and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrates measured using both methods are presented in Table 2. The phase equilibria of TiAAB semiclathrates with guest gases suggest that semiclathrate-based CO2 capture using a TiAAB solution can be performed at significantly lowered pressures and above room temperature.
3.2. Raman analysis Raman spectroscopy was used to detect the inclusion of CO2 and N2 in TiAAB semiclathrates. Fig. 5a shows a stacked plot of Raman spectra for the CO2 hydrate, TiAAB (3.7 mol%) semiclathrate, CO2 + TiAAB (3.7 mol%) semiclathrate, and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate between the wavenumbers 1000 cm 1 and 1500 cm 1. CO2 hydrate exhibited two Raman peaks at 1276 cm 1 and 1380 cm 1, which correspond to enclathrated CO2 molecules in sI hydrate whereas TiAAB semiclathrate had many Raman peaks from enclathrated TiAA cations. Compared to the TiAAB semiclathrate, the CO2 + TiAAB semiclathrate had an additional peak at 1380 cm 1, which originated from CO2 molecules captured in the TiAAB semiclathrate. In our previous study, two additional peaks from CO2 molecules encapsulated in TBAB, TABC, and TBAF semiclathrates appeared at 1273 cm 1 and 1380 cm 1 [32]. However, for the CO2 + TiAAB semiclathrate, the peak at 1273 cm 1 was not distinguishable from other neighboring peaks because it overlapped with peaks from TiAA cations. The CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate also showed an additional peak from captured CO2 molecules at 1380 cm 1, which was lower in peak intensity than that from the CO2 + TiAAB semiclathrate because the feed gas was N2-rich. Fig. 5b shows a stacked plot of TiAAB (3.7 mol%) semiclathrate, CO2 + TiAAB (3.7 mol%) semiclathrate, and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate between the wavenumbers 2250 cm 1 and 2350 cm 1. For the CO2 + N2 + TiAAB semiclathrate, one Raman peak from enclathrated N2 molecules appeared at 2324 cm 1. The Raman peak at around 2329 cm 1 came from residual air inside the Raman probe. Neither TiAAB semiclathrate nor CO2 + TiAAB semiclathrate exhibited any Raman peaks between the wavenumbers 2250 cm 1 and 2350 cm 1 except for that caused by residual air. Raman analysis demonstrated that CO2 and N2 were captured in the small (512) cages of TiAAB semiclathrates without affecting the structure of TiAAB semiclathrates.
Fig. 5a. Raman spectra of the CO2 hydrate, TiAAB (3.7 mol%) semiclathrate, CO2 +TiAAB (3.7 mol%) semiclathrate, and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate in the range of 1000–1500 cm 1.
4. Conclusions The thermodynamic stability and guest gas enclathration of CO2 + TiAAB (3.7 mol%), N2 + TiAAB (3.7 mol%), and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrates were investigated by measuring semiclathrate phase equilibria and Raman spectra. The three-phase (H-LW-V) equilibria of semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%) were measured using both the isochoric (pVT) method and the stepwise DSC method. Compared to CO2, N2, or CO2 (20%) + N2 (80%) gas hydrates, TiAAB (3.7 mol%) semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%)
S. Kim et al. / J. Chem. Thermodynamics 142 (2020) 106024
5
Foundation of Korea (NRF) funded by the Ministry of Education (2018R1D1A1A02085828). Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.jct.2019.106024. References
Fig. 5b. Raman spectra of the TiAAB (3.7 mol%) semiclathrate, CO2 + TiAAB (3.7 mol %) semiclathrate, and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate in the range of (2250–2350) cm 1. The Raman peak located next to 2324 cm 1 originated from residual air in the Raman probe.
showed a significant thermodynamic promotion, represented by a remarkable pressure reduction or temperature increase. The enclathration of CO2 and N2 molecules in the cages of TiAAB semiclathrates was clearly confirmed by Raman spectroscopy. The overall thermodynamic and spectroscopic results provide a better understanding of guest gas inclusion in TiAAB semiclathrates and indicate that TiAAB semiclathrate-based CO2 capture can be performed at temperatures above 300 K and at significantly lowered pressure ranges. CRediT authorship contribution statement Soyoung Kim: Writing - original draft, Conceptualization, Methodology. Gyeol Ko: Data curation, Investigation. Ki-Sub Kim: Methodology, Writing - review & editing. Yongwon Seo: Writing - review & editing, Supervision. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgements This work was supported by the 2018 Open R&D Program of Korea Electric Power Corporation (KEPCO) (R18XA06-28) and also supported by the Mid-career Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (NRF-2019M2D2A1A02054875) and by the Basic Science Research Program through the National Research
[1] E.D. Sloan, C.A. Koh, Clathrate Hydrates of Natural Gases, third ed., CRC Press, Boca Raton, 2008. [2] W. Shin, S. Park, J.-W. Lee, Y. Seo, D.-Y. Koh, J. Seol, H. Lee, Structural transition from semi- to true clathrate hydrates induced by CH4 enclathration, J. Phys. Chem. C 116 (2012) 16352–16357. [3] M. Arjmandi, A. Chapoy, B. Tohidi, Equilibrium data of hydrogen, methane, nitrogen, carbon dioxide, and natural gas in semi-clathrate hydrates of tetrabutyl ammonium bromide, J. Chem. Eng. Data 52 (2007) 2153–2158. [4] K. Sato, H. Tokutomi, R. Ohmura, Phase equilibrium of ionic semiclathrate hydrates formed with tetrabutylammonium bromide and tetrabutylammonium chloride, Fluid Phase Equilib. 337 (2013) 115–118. [5] H. Ohmura, W. Shimada, T. Ebinuma, Y. Kamata, S. Takeya, T. Uchida, J. Nagao, H. Narita, Phase diagram, latent heat, and specific heat of TBAB semiclathrate hydrate crystals, Fluid Phase Equilib. 234 (2005) 131–135. [6] V.Y. Komarov, T. Rodionova, I. Terekhova, N. Kuratieva, The cubic superstructure-I of tetrabutylammonium fluoride (C4H9)4NF29.7H2O clathrate hydrate, J. Incl. Phenom. Macrocycl. Chem. 59 (2007) 11–15. [7] S. Muromachi, K.A. Udachin, K. Shin, S. Alavi, I.L. Moudrakovski, R. Ohmura, J.A. Ripmeester, Guest-induced symmetry lowering of an ionic clathrate material for carbon capture, Chem. Comm. 50 (2014) 11476–11479. [8] S. Kim, I.-H. Baek, J.-K. You, Y. Seo, Guest gas enclathration in tetra-n-butyl ammonium chloride (TBAC) semiclathrates: potential application to natural gas storage and CO2 capture, Appl. Energy 140 (2015) 107–112. [9] S. Lee, Y. Lee, S. Park, Y. Kim, J.D. Lee, Y. Seo, Thermodynamic and spectroscopic identification of guest gas enclathration in the double tetra-n-butylammonium fluoride semiclathrates, J. Phys. Chem. B 116 (2012) 9075–9081. [10] D. Zhong, Y. Ye, C. Yang, Y. Bian, K. Ding, Experimental investigation of methane separation from low-concentration coal mine gas (CH4/N2/O2) by tetra-n-butyl ammonium bromide semiclathrate hydrate crystallization, Ind. Eng. Chem. Res. 51 (2012) 14806–14813. [11] T. Kobori, S. Muromachi, R. Ohmura, Phase equilibria for ionic semiclathrate hydrate formed in the system of water + tetra-n-butylammonium bromide pressurized with carbon dioxide, J. Chem. Eng. Data 60 (2015) 299–303. [12] X.-S. Li, C.-G. Xu, Z.-Y. Chen, H.-J. Wu, Tetra-n-butyl ammonium bromide semiclathrate hydrate process for post-combustion capture of carbon dioxide in the presence of dodecyl trimethyl ammonium chloride, Energy 35 (2010) 3902– 3908. [13] C.-G. Xu, Y.-S. Yu, Y.-L. Ding, J. Cai, X.-S. Li, The effect of hydrate promoters on gas uptake, Phys. Chem. Chem. Phys. 19 (2017) 21769–21776. [14] C.-G. Xu, Y.-S. Li, W.-J. Xie, Z.-M. Xia, Z.-Y. Chen, X.-S. Li, Study on developing a novel continuous separation device and carbon dioxide separation by process of hydrate combined with chemical absorption, Appl. Energy 255 (2019) 113791. [15] H. Komatsu, M. Ota, Y. Sato, M. Watanabe, R.L. Smith, Hydrogen and carbon dioxide adsorption with tetra-n-butyl ammonium semi-clathrate hydrates for gas separations, AIChE J. 61 (2014) 992–1003. [16] A. Mohammadi, M. Manteghian, A.H. Mohammadi, Phase equilibria of semiclathrate hydrates for methane + tetra-n-butylammonium chloride (TBAC), carbon dioxide + TBAC, and nitrogen + TBAC aqueous solution systems, Fluid Phase Equilib. 381 (2014) 102–107. [17] H.P. Veluswamy, R. Kumar, P. Linga, Hydrogen storage in clathrate hydrates: Current state of the art and future directions, Appl. Energy 122 (2014) 112– 132. [18] X. Wang, M. Dennis, L. Hou, Clathrate hydrate technology for cold storage in air conditioning systems, Renew. Sust. Energ. Rev. 36 (2014) 34–51. [19] L. Aladko, Y.A. Dyadin, T. Rodionova, I. Terekhova, Clathrate hydrates of tetrabutylammonium and tetraisoamylammonium halides, J Struct. Chem. 43 (2002) 990–994. [20] S. Kim, K.-S. Kim, Y. Seo, CH4 enclathration in tetra-iso-amyl ammonium bromide (TiAAB) semiclathrate and its significance for natural gas storage, Chem. Eng. J. 330 (2017) 1160–1165. [21] A. Majumdar, B. Maini, P.R. Bishnoi, M.A. Clarke, Three-phase equilibrium conditions of TiAAB semiclathrates formed from N2, CO2, and their mixtures, J. Chem. Eng. Data 57 (2012) 2322–2327. [22] N. Menschutkin, Beiträgen zur Kenntnis der Affinitätskoeffizienten der Alkylhaloide und der organischen Amine, Z. Phys. Chem. 5 (1890) 589–600. [23] J. Zhang, J.W. Lee, Equilibrium of hydrogen + cyclopentane and carbon dioxide + cyclopentane binary hydrates, J. Chem. Eng. Data 54 (2008) 659–661. [24] W. Lin, D. Dalmazzone, W. Fürst, A. Delahaye, L. Fournaison, P. Clain, Accurate DSC measurement of the phase transition temperature in the TBPB-water system, J. Chem. Thermodynamics 61 (2013) 132–137. [25] D. Lee, Y. Lee, W. Choi, S. Lee, Y. Seo, Accurate measurement of phase equilibria and dissociation enthalpies of HFC-134a hydrates in the presence of NaCl for
6
[26]
[27]
[28] [29]
S. Kim et al. / J. Chem. Thermodynamics 142 (2020) 106024 potential application in desalination, Korean J. Chem. Eng. 33 (2016) 1425– 1430. S. Kim, I.-H. Baek, J.K. You, Y. Seo, Phase equilibria, dissociation enthalpies, and Raman spectroscopic analyses of N2 + tetra-n-butyl ammonium chloride (TBAC) semiclathrates, Fluid Phase Equilib. 413 (2016) 86–91. E. Kim, Y.K. Jin, Y. Seo, Structural transition and phase behavior of N2 gas hydrates with pinacolyl alcohol and tert-amyl alcohol, Fluid Phase Equilib. 393 (2015) 85–90. A.A. Olajire, CO2 capture and separation technologies for end-of-pipe applications – a review, Energy 35 (2010) 2610–2628. S. Adisasmito, R.J. Frank, E.D. Sloan, Hydrates of carbon dioxide and methane mixtures, J. Chem. Eng. Data 36 (1991) 69–71.
[30] A. van Cleeff, G.A.M. Diepen, Gas hydrates of nitrogen and oxygen. II, Recl. Trav. Chim. Pays-Bas 84 (1965) 1085–1093. [31] Y. Lee, S. Lee, J. Lee, Y. Seo, Structure identification and dissociation enthalpy measurements of the CO2 + N2 hydrates for their application to CO2 capture and storage, Chem. Eng. J. 246 (2014) 20–26. [32] S. Kim, Y. Seo, Semiclathrate-based CO2 capture from flue gas mixtures: an experimental approach with thermodynamic and Raman spectroscopic analyses, Appl. Energy 154 (2015) 987–994.
JCT 2019-868
Contents lists available at ScienceDirect
J. Chem. Thermodynamics journal homepage: www.elsevier.com/locate/jct
Phase equilibria of tetra-iso-amyl ammonium bromide (TiAAB) semiclathrates with CO2, N2, or CO2 + N2 Soyoung Kim a, Gyeol Ko b, Ki-Sub Kim c,⇑, Yongwon Seo b,⇑ a
Accident Coordination and Traning Division, National Institute of Chemical Safety, Daejeon 34111, Republic of Korea School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea c School of Chemical and Materials Engineering, Korea National University of Transportation, Chungbuk 27469, Republic of Korea b
a r t i c l e
i n f o
Article history: Received 7 November 2019 Received in revised form 3 December 2019 Accepted 4 December 2019 Available online 7 December 2019 Keywords: CO2 N2 Flue gas Tetra-iso-amyl ammonium bromide Semiclathrate
a b s t r a c t This study examined the thermodynamic stability and guest gas inclusion of tetra-iso-amyl ammonium bromide (TiAAB) semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%), with a primary focus on semiclathrate phase equilibria and Raman spectra. The three-phase (H-LW-V) equilibria of TiAAB semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%) were measured at a stoichiometric concentration (TiAAB 3.7 mol%) using both a conventional isochoric method and a stepwise differential scanning calorimeter (DSC) method. The phase equilibria demonstrated that TiAAB (3.7 mol%) semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%) were significantly stabilized compared with the corresponding CO2, N2, or CO2 (20%) + N2 (80%) gas hydrates. The enclathration of CO2 and N2 molecules in the cages of TiAAB semiclathrates was clearly confirmed via Raman spectroscopy. The experimental results indicate that TiAAB semiclathrates can incorporate CO2 and N2 into the cage lattices at elevated temperatures and lowered pressures and are potential materials for CO2 capture. Ó 2019 Elsevier Ltd.
1. Introduction Clathrate hydrates are crystalline inclusion compounds that consist of hydrogen-bonded cage frameworks called ‘‘host” and small-sized ‘‘guest” molecules [1]. They are generally classified as true clathrates and semiclathrates, depending on the types of interactions between host and guest molecules, even though their strict distinction has blurred [2,3]. True clathrates exhibit van der Waals interactions between encapsulated guest molecules and host water molecules. Well-known gas hydrates belong to true clathrates. On the other hand, semiclathrates have chemical or ionic interactions between host and guest molecules. Quaternary ammonium salts (QASs) such as tetra-n-butyl ammonium bromide (TBAB), tetra-n-butyl ammonium chloride (TBAC), and tetra-nbutyl ammonium fluoride (TBAF) form semiclathrates with water under atmospheric pressure [4–6]. In QAS semiclathrates, TBA cations are captured in the partially broken large cages, while anions (Br-, Cl- or F-) participate in building up host frameworks [2,3,7]. QAS semiclathrates have much higher thermodynamic
⇑ Corresponding authors. E-mail addresses: [email protected] (K.-S. Kim), [email protected] (Y. Seo). https://doi.org/10.1016/j.jct.2019.106024 0021-9614/Ó 2019 Elsevier Ltd.
stability compared to gas hydrates and have vacant small (512) cages, which are available for encapsulating small-sized gas molecules [7–10]. Due to these unique features of QAS semiclathrates, TBAB, TBAC, and TBAF semiclathrates have been extensively explored for potential gas storage, CO2 capture, and cold energy storage applications [7–18]. Recently, tetra-iso-amyl ammonium bromide (TiAAB) has been suggested as a promising semiclathrate former for CO2 capture and gas storage because TiAAB semiclathrate has greater thermodynamic stability than that of TBAB, TBAC, and TBAF semiclathrates [19,20,21]. This indicates that the formation of TiAAB semiclathrates with guest gases can occur at lower pressures and higher temperatures. However, accurate phase equilibria in a wide pressure range and spectroscopic observation of guest enclathration in TiAAB semiclathrates for CO2 capture applications have rarely been reported in the literature. In this study, as a first step of TiAAB semiclathrate-based CO2 capture, semiclathrate phase equilibria of CO2 + TiAAB + water, N2 + TiAAB + water, and CO2 (20%) + N2 (80%) + TiAAB + water mixtures were experimentally measured using both a conventional isochoric (pVT) method and a stepwise differential scanning calorimeter (DSC) method. The enclathration of CO2 and N2 in the TiAAB semiclathrates was confirmed using Raman spectroscopy.
2
S. Kim et al. / J. Chem. Thermodynamics 142 (2020) 106024
2. Experimental 2.1. Materials CO2 with a purity of 99.999% was provided by Deokyang Co. (Republic of Korea), and N2 with a purity of 99.99% was supplied by KOSEM Co. (Republic of Korea). The gas mixture of CO2 (20%) + N2 (80%) was supplied by MS Gas Co. (Republic of Korea). The tetra-iso-amyl ammonium bromide (TiAAB) used in this study was synthesized using Menschutkin reaction [22]. The 1H NMR (D2O) spectrum of TiAAB consisted of the following peaks: 0.85– 0.87 (m, 24H), 1.46–1.49 (t, 8H), 1.53–1.59 (m, 4H), 3.12–3.16 (t, 8H). The detailed procedure of the TiAAB synthesis was described in a previous paper [20]. Deionized doubly distilled water was used for the experiment. The suppliers and purity of the materials used in this study are presented in Table 1.
2.2. Apparatus and procedures The equilibrium cell used to measure the semiclathrate phase equilibria was made of 316 stainless steel and had an inner volume of 50 cm3. An impeller-type mechanical stirrer was used to vigorously agitate the solutions inside the cell to accelerate semiclathrate formation and dissociation. The equilibrium cell was immersed in a circulator (RW-2025G, Jeio Tech, Republic of Korea) to control the temperature. A resistance temperature detector (RTD) sensor was used to measure the cell temperature after being calibrated using an ASTM 63C thermometer (H-B Instrument Company, USA). A pressure transducer (S-10, WIKA, Germany) was used to measure the cell pressure and was calibrated using a Heise Bourdon tube pressure gauge (CMM-140830, 0–20.0 MPa, Ashcroft, Inc. USA). The uncertainties associated with the temperature (T) and pressure (p) measurements were 0.1 K and 0.02 MPa, respectively. An isochoric (pVT) method with step heating and cooling was adopted to determine the semiclathrate phase equilibria. The cell was charged with approximately 20 cm3 of TiAAB (3.7 mol%) solution and then pressurized with the CO2, N2, or CO2 (20%) + N2 (80%) gas to the desired pressure. The cell was cooled down at a rate of 1.0 K∙h 1 to induce semiclathrate formation. After the formation of semiclathrates, which was indicated by an abrupt pressure drop, the cell was slowly heated at a rate of 0.1 K per 90 min for the dissociation. The three-phase (semiclathrate (H) - liquid water (LW) vapor (V)) equilibrium point was determined by the intersection of the semiclathrate dissociation curve and the thermal expansion line at each pressure condition. A high-pressure micro-differential scanning calorimeter (HP lDSC7 evo, Setaram Inc., France) was also used to measure the semiclathrate phase equilibria. The HP lDSC device consists of a
Table 1 Materials used in this study.
a b c d e
Chemical Name
Supplier
Purity
Water in mass fraction/10-6
Analysis
CO2 N2 CO2 (20%) + N2 (80%) TiAABc
Deokyang KOSEM MS Gas
0.99999 0.9999 –
– – –
GCa,b GCa,b GCa,b
Synthesis
–
<150
NMRd, KFe
Analysis done by supplier. Gas chromatography. TiAAB: tetra-iso-amyl ammonium bromide. Nuclear magnetic resonance. Karl Fischer titration.
Fig. 1. Heat flow changes during stepwise heating of the CO2 + TiAAB (3.7 mol%) semiclathrate at 2.9 MPa.
reference cell and a sample cell, with an operating pressure range from 0 MPa to 40.0 MPa and an operating temperature range from 228.15 K to 393.15 K. The HP m-DSC had a resolution of 0.02 lW. The DSC can be used to determine equilibrium dissociation temperature of semiclathrates using either dynamic or stepwise methods [23–25]. In this study, the stepwise DSC method, which was found to be more reliable and accurate, was also employed to confirm the semiclathrate phase equilibrium points measured by the isochoric (pVT) method. For the stepwise DSC experiments, the sample cell was charged with approximately 10 mg of TiAAB (3.7 mol%) solution, whereas the reference cell was left empty. Because stirring was not available, a multi-cycle mode of cooling and heating was applied to the cells in order to completely convert the TiAAB solution to TiAAB semiclathrates. The HP lDSC cells were initially cooled to T = 253 K at a cooling rate of 1.0 K∙min 1, and then, they were firstly heated to a temperature 1 K lower than the expected dissociation temperature in 2 K increments with 3 h intervals. The temperature was further increased in 0.1 K increments with a 3 h isothermal duration at each step until there were no endothermic peaks from semiclathrate dissociation. As shown in Fig. 1, the temperature at the point at which the endothermic peaks disappeared was determined to be the equilibrium dissociation temperature of semiclathrates at a given pressure. A fiber-coupled Raman spectrometer (SP550, Horiba, France) with a multichannel air cooled CCD detector and 1800 grooves/ mm grating was used to obtain Raman spectra of TiAAB semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%). A fiber-optic Raman probe was attached to the high-pressure equilibrium cell with a water jacket to allow the collection of the Raman spectra. A more detailed description of the experimental methods and procedure has been provided in our previous papers [20,26,27].
3. Results and discussion 3.1. Thermodynamic stability of TiAAB semiclathrates with CO2, N2, or CO2 + N2 TiAAB is known to form semiclathrates with a chemical formula of TiAAB26 H2O, which has a stoichiometric TiAAB concentration
S. Kim et al. / J. Chem. Thermodynamics 142 (2020) 106024
Fig. 2. Semiclathrate phase equilibria of the CO2 + TiAAB (3.7 mol%) + water mixture.
of 3.7 mol% [19,20]. The maximum equilibrium dissociation temperature (303.6 K) of TiAAB semiclathrates under atmospheric pressure was observed at the stoichiometric concentration (3.7 mol%). In this study, semiclathrate phase equilibria of the CO2 + TiAAB + water, N2 + TiAAB + water, and CO2 (20%) + N2 (80%) + TiAAB + water mixtures were measured to examine the thermodynamic stability of TiAAB semiclathrates with guest gases at 3.7 mol% TiAAB. CO2 is one of the major components of flue gas from fossil fuelfired power plants and a target component that needs to be separated through the semiclathrate-based capture process [28]. Fig. 2 shows three-phase (H-LW-V) equilibria of the CO2 + TiAAB (3.7 mol %) semiclathrate along with relevant literature data of CO2 + TiAAB (0.8 mol%) semiclathrate and CO2 hydrate [21,29]. Compared to the CO2 hydrate, the CO2 + TiAAB (3.7 mol%) semiclathrate exhibited a significant thermodynamic promotion. The equilibrium curve of the CO2 + TiAAB (3.7 mol%) semiclathrate was located at temperatures higher than 300 K across the entire pressure range (from 0.64 MPa to 3.35 MPa) examined in this study. The equilibrium temperature difference between CO2 + TiAAB (3.7 mol%) semiclathrate and CO2 hydrate, i.e., the thermodynamic promotion was approximately 28 K at 2.9 MPa. In this study, both an isochoric (pVT) method and a stepwise DSC method were used to measure phase (H-LW-V) equilibria of the CO2 + TiAAB (3.7 mol%) semiclathrate. As seen in Fig. 2, an equilibrium point measured by the stepwise DSC method was located exactly on the H-LW-V equilibrium curve of the CO2 + TiAAB (3.7 mol%) semiclathrate measured by the isochoric (pVT) method. N2 is also a primary component of flue gas, which generally consists of 10–20% CO2 and 80–90% N2 [28]. Due to the small molecular size of N2, N2 hydrate requires significantly higher pressure than CO2 hydrate at a given temperature [1]. The larger equilibrium pressure difference between N2 hydrate and CO2 hydrate makes hydrate or semiclathrate-based CO2 capture feasible. Fig. 3 shows that the N2 + TiAAB (3.7 mol%) semiclathrate was significantly stabilized compared to the N2 hydrate. N2 hydrate requires an equilibrium pressure as high as 16 MPa even at 273.2 K [1], whereas the N2 + TiAAB (3.7 mol%) semiclathrate is thermodynam-
3
Fig. 3. Semiclathrate phase equilibria of the N2 + TiAAB (3.7 mol%) + water mixture. (See above-mentioned references for further information).
ically stable even at temperatures above 300 K for the entire pressure range (from 1.37 MPa to 8.19 MPa) examined. The equilibrium curve of the CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate also shifted significantly to the thermodynamically promoted regions, which are represented by a lower pressure at any given temperature or a higher temperature at any given pressure compared with the CO2 (20%) + N2 (80%) hydrate. Fig. 4 illustrates that the CO2 (20%) + N2 (80%) gas mixture can form semiclathrates in the presence of TiAAB 3.7 mol% solution at temperatures above 300 K and at pressures just above atmospheric pressure even though the experimental measurements of
Fig. 4. Semiclathrate phase equilibria of the CO2 (20%) + N2 (80%) + TiAAB (3.7 mol %) + water mixture. (See above-mentioned references for further information).
4
S. Kim et al. / J. Chem. Thermodynamics 142 (2020) 106024
Table 2 Semiclathrate phase equilibrium data of the CO2 + TiAAB (3.7 mol%) + water, N2, + TiAAB (3.7 mol%) + water, and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) + water systems.a. CO2
N2
pVT
a
DSC
CO2 (20%) + N2 (80%)
pVT
DSC
pVT
DSC
T/K
p/MPa
T/K
p/MPa
T/K
p/MPa
T/K
p/MPa
T/K
p/MPa
T/K
p/MPa
305.2 306.4 307.2 308.0 308.6 309.1
0.64 1.15 1.54 2.14 2.79 3.35
308.4
2.90
304.3 305.3 306.6 307.4 308.0
1.37 2.69 4.63 6.47 8.19
305.7
3.03
304.7 306.3 307.8 308.7 309.9
1.35 2.85 4.93 6.50 8.46
306.4
2.90
Standard uncertainties u are u (T) = 0.1 K and u (p) = 0.02 MPa.
the semiclathrate phase equilibria were performed across a wide pressure range (from 1.35 MPa to 8.46 MPa). The semiclathrate equilibrium point of the CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate measured by the stepwise DSC method closely matched that measured by the conventional isochoric (pVT) method, and was located exactly on the equilibrium curve of the CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate. The overall three-phase (H-LW-V) equilibrium data of the CO2 + TiAAB (3.7 mol%), N2 + TiAAB (3.7 mol%), and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrates measured using both methods are presented in Table 2. The phase equilibria of TiAAB semiclathrates with guest gases suggest that semiclathrate-based CO2 capture using a TiAAB solution can be performed at significantly lowered pressures and above room temperature.
3.2. Raman analysis Raman spectroscopy was used to detect the inclusion of CO2 and N2 in TiAAB semiclathrates. Fig. 5a shows a stacked plot of Raman spectra for the CO2 hydrate, TiAAB (3.7 mol%) semiclathrate, CO2 + TiAAB (3.7 mol%) semiclathrate, and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate between the wavenumbers 1000 cm 1 and 1500 cm 1. CO2 hydrate exhibited two Raman peaks at 1276 cm 1 and 1380 cm 1, which correspond to enclathrated CO2 molecules in sI hydrate whereas TiAAB semiclathrate had many Raman peaks from enclathrated TiAA cations. Compared to the TiAAB semiclathrate, the CO2 + TiAAB semiclathrate had an additional peak at 1380 cm 1, which originated from CO2 molecules captured in the TiAAB semiclathrate. In our previous study, two additional peaks from CO2 molecules encapsulated in TBAB, TABC, and TBAF semiclathrates appeared at 1273 cm 1 and 1380 cm 1 [32]. However, for the CO2 + TiAAB semiclathrate, the peak at 1273 cm 1 was not distinguishable from other neighboring peaks because it overlapped with peaks from TiAA cations. The CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate also showed an additional peak from captured CO2 molecules at 1380 cm 1, which was lower in peak intensity than that from the CO2 + TiAAB semiclathrate because the feed gas was N2-rich. Fig. 5b shows a stacked plot of TiAAB (3.7 mol%) semiclathrate, CO2 + TiAAB (3.7 mol%) semiclathrate, and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate between the wavenumbers 2250 cm 1 and 2350 cm 1. For the CO2 + N2 + TiAAB semiclathrate, one Raman peak from enclathrated N2 molecules appeared at 2324 cm 1. The Raman peak at around 2329 cm 1 came from residual air inside the Raman probe. Neither TiAAB semiclathrate nor CO2 + TiAAB semiclathrate exhibited any Raman peaks between the wavenumbers 2250 cm 1 and 2350 cm 1 except for that caused by residual air. Raman analysis demonstrated that CO2 and N2 were captured in the small (512) cages of TiAAB semiclathrates without affecting the structure of TiAAB semiclathrates.
Fig. 5a. Raman spectra of the CO2 hydrate, TiAAB (3.7 mol%) semiclathrate, CO2 +TiAAB (3.7 mol%) semiclathrate, and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate in the range of 1000–1500 cm 1.
4. Conclusions The thermodynamic stability and guest gas enclathration of CO2 + TiAAB (3.7 mol%), N2 + TiAAB (3.7 mol%), and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrates were investigated by measuring semiclathrate phase equilibria and Raman spectra. The three-phase (H-LW-V) equilibria of semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%) were measured using both the isochoric (pVT) method and the stepwise DSC method. Compared to CO2, N2, or CO2 (20%) + N2 (80%) gas hydrates, TiAAB (3.7 mol%) semiclathrates with CO2, N2, or CO2 (20%) + N2 (80%)
S. Kim et al. / J. Chem. Thermodynamics 142 (2020) 106024
5
Foundation of Korea (NRF) funded by the Ministry of Education (2018R1D1A1A02085828). Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.jct.2019.106024. References
Fig. 5b. Raman spectra of the TiAAB (3.7 mol%) semiclathrate, CO2 + TiAAB (3.7 mol %) semiclathrate, and CO2 (20%) + N2 (80%) + TiAAB (3.7 mol%) semiclathrate in the range of (2250–2350) cm 1. The Raman peak located next to 2324 cm 1 originated from residual air in the Raman probe.
showed a significant thermodynamic promotion, represented by a remarkable pressure reduction or temperature increase. The enclathration of CO2 and N2 molecules in the cages of TiAAB semiclathrates was clearly confirmed by Raman spectroscopy. The overall thermodynamic and spectroscopic results provide a better understanding of guest gas inclusion in TiAAB semiclathrates and indicate that TiAAB semiclathrate-based CO2 capture can be performed at temperatures above 300 K and at significantly lowered pressure ranges. CRediT authorship contribution statement Soyoung Kim: Writing - original draft, Conceptualization, Methodology. Gyeol Ko: Data curation, Investigation. Ki-Sub Kim: Methodology, Writing - review & editing. Yongwon Seo: Writing - review & editing, Supervision. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgements This work was supported by the 2018 Open R&D Program of Korea Electric Power Corporation (KEPCO) (R18XA06-28) and also supported by the Mid-career Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (NRF-2019M2D2A1A02054875) and by the Basic Science Research Program through the National Research
[1] E.D. Sloan, C.A. Koh, Clathrate Hydrates of Natural Gases, third ed., CRC Press, Boca Raton, 2008. [2] W. Shin, S. Park, J.-W. Lee, Y. Seo, D.-Y. Koh, J. Seol, H. Lee, Structural transition from semi- to true clathrate hydrates induced by CH4 enclathration, J. Phys. Chem. C 116 (2012) 16352–16357. [3] M. Arjmandi, A. Chapoy, B. Tohidi, Equilibrium data of hydrogen, methane, nitrogen, carbon dioxide, and natural gas in semi-clathrate hydrates of tetrabutyl ammonium bromide, J. Chem. Eng. Data 52 (2007) 2153–2158. [4] K. Sato, H. Tokutomi, R. Ohmura, Phase equilibrium of ionic semiclathrate hydrates formed with tetrabutylammonium bromide and tetrabutylammonium chloride, Fluid Phase Equilib. 337 (2013) 115–118. [5] H. Ohmura, W. Shimada, T. Ebinuma, Y. Kamata, S. Takeya, T. Uchida, J. Nagao, H. Narita, Phase diagram, latent heat, and specific heat of TBAB semiclathrate hydrate crystals, Fluid Phase Equilib. 234 (2005) 131–135. [6] V.Y. Komarov, T. Rodionova, I. Terekhova, N. Kuratieva, The cubic superstructure-I of tetrabutylammonium fluoride (C4H9)4NF29.7H2O clathrate hydrate, J. Incl. Phenom. Macrocycl. Chem. 59 (2007) 11–15. [7] S. Muromachi, K.A. Udachin, K. Shin, S. Alavi, I.L. Moudrakovski, R. Ohmura, J.A. Ripmeester, Guest-induced symmetry lowering of an ionic clathrate material for carbon capture, Chem. Comm. 50 (2014) 11476–11479. [8] S. Kim, I.-H. Baek, J.-K. You, Y. Seo, Guest gas enclathration in tetra-n-butyl ammonium chloride (TBAC) semiclathrates: potential application to natural gas storage and CO2 capture, Appl. Energy 140 (2015) 107–112. [9] S. Lee, Y. Lee, S. Park, Y. Kim, J.D. Lee, Y. Seo, Thermodynamic and spectroscopic identification of guest gas enclathration in the double tetra-n-butylammonium fluoride semiclathrates, J. Phys. Chem. B 116 (2012) 9075–9081. [10] D. Zhong, Y. Ye, C. Yang, Y. Bian, K. Ding, Experimental investigation of methane separation from low-concentration coal mine gas (CH4/N2/O2) by tetra-n-butyl ammonium bromide semiclathrate hydrate crystallization, Ind. Eng. Chem. Res. 51 (2012) 14806–14813. [11] T. Kobori, S. Muromachi, R. Ohmura, Phase equilibria for ionic semiclathrate hydrate formed in the system of water + tetra-n-butylammonium bromide pressurized with carbon dioxide, J. Chem. Eng. Data 60 (2015) 299–303. [12] X.-S. Li, C.-G. Xu, Z.-Y. Chen, H.-J. Wu, Tetra-n-butyl ammonium bromide semiclathrate hydrate process for post-combustion capture of carbon dioxide in the presence of dodecyl trimethyl ammonium chloride, Energy 35 (2010) 3902– 3908. [13] C.-G. Xu, Y.-S. Yu, Y.-L. Ding, J. Cai, X.-S. Li, The effect of hydrate promoters on gas uptake, Phys. Chem. Chem. Phys. 19 (2017) 21769–21776. [14] C.-G. Xu, Y.-S. Li, W.-J. Xie, Z.-M. Xia, Z.-Y. Chen, X.-S. Li, Study on developing a novel continuous separation device and carbon dioxide separation by process of hydrate combined with chemical absorption, Appl. Energy 255 (2019) 113791. [15] H. Komatsu, M. Ota, Y. Sato, M. Watanabe, R.L. Smith, Hydrogen and carbon dioxide adsorption with tetra-n-butyl ammonium semi-clathrate hydrates for gas separations, AIChE J. 61 (2014) 992–1003. [16] A. Mohammadi, M. Manteghian, A.H. Mohammadi, Phase equilibria of semiclathrate hydrates for methane + tetra-n-butylammonium chloride (TBAC), carbon dioxide + TBAC, and nitrogen + TBAC aqueous solution systems, Fluid Phase Equilib. 381 (2014) 102–107. [17] H.P. Veluswamy, R. Kumar, P. Linga, Hydrogen storage in clathrate hydrates: Current state of the art and future directions, Appl. Energy 122 (2014) 112– 132. [18] X. Wang, M. Dennis, L. Hou, Clathrate hydrate technology for cold storage in air conditioning systems, Renew. Sust. Energ. Rev. 36 (2014) 34–51. [19] L. Aladko, Y.A. Dyadin, T. Rodionova, I. Terekhova, Clathrate hydrates of tetrabutylammonium and tetraisoamylammonium halides, J Struct. Chem. 43 (2002) 990–994. [20] S. Kim, K.-S. Kim, Y. Seo, CH4 enclathration in tetra-iso-amyl ammonium bromide (TiAAB) semiclathrate and its significance for natural gas storage, Chem. Eng. J. 330 (2017) 1160–1165. [21] A. Majumdar, B. Maini, P.R. Bishnoi, M.A. Clarke, Three-phase equilibrium conditions of TiAAB semiclathrates formed from N2, CO2, and their mixtures, J. Chem. Eng. Data 57 (2012) 2322–2327. [22] N. Menschutkin, Beiträgen zur Kenntnis der Affinitätskoeffizienten der Alkylhaloide und der organischen Amine, Z. Phys. Chem. 5 (1890) 589–600. [23] J. Zhang, J.W. Lee, Equilibrium of hydrogen + cyclopentane and carbon dioxide + cyclopentane binary hydrates, J. Chem. Eng. Data 54 (2008) 659–661. [24] W. Lin, D. Dalmazzone, W. Fürst, A. Delahaye, L. Fournaison, P. Clain, Accurate DSC measurement of the phase transition temperature in the TBPB-water system, J. Chem. Thermodynamics 61 (2013) 132–137. [25] D. Lee, Y. Lee, W. Choi, S. Lee, Y. Seo, Accurate measurement of phase equilibria and dissociation enthalpies of HFC-134a hydrates in the presence of NaCl for
6
[26]
[27]
[28] [29]
S. Kim et al. / J. Chem. Thermodynamics 142 (2020) 106024 potential application in desalination, Korean J. Chem. Eng. 33 (2016) 1425– 1430. S. Kim, I.-H. Baek, J.K. You, Y. Seo, Phase equilibria, dissociation enthalpies, and Raman spectroscopic analyses of N2 + tetra-n-butyl ammonium chloride (TBAC) semiclathrates, Fluid Phase Equilib. 413 (2016) 86–91. E. Kim, Y.K. Jin, Y. Seo, Structural transition and phase behavior of N2 gas hydrates with pinacolyl alcohol and tert-amyl alcohol, Fluid Phase Equilib. 393 (2015) 85–90. A.A. Olajire, CO2 capture and separation technologies for end-of-pipe applications – a review, Energy 35 (2010) 2610–2628. S. Adisasmito, R.J. Frank, E.D. Sloan, Hydrates of carbon dioxide and methane mixtures, J. Chem. Eng. Data 36 (1991) 69–71.
[30] A. van Cleeff, G.A.M. Diepen, Gas hydrates of nitrogen and oxygen. II, Recl. Trav. Chim. Pays-Bas 84 (1965) 1085–1093. [31] Y. Lee, S. Lee, J. Lee, Y. Seo, Structure identification and dissociation enthalpy measurements of the CO2 + N2 hydrates for their application to CO2 capture and storage, Chem. Eng. J. 246 (2014) 20–26. [32] S. Kim, Y. Seo, Semiclathrate-based CO2 capture from flue gas mixtures: an experimental approach with thermodynamic and Raman spectroscopic analyses, Appl. Energy 154 (2015) 987–994.
JCT 2019-868