- Email: [email protected]
A microporous manganese-based metal–organic framework for gas sorption and separation
Accepted Manuscript A Microporous Manganese-based Metal-Organic Framework for Gas Sorption and Separation Ying-Ping Zhao, Hui Yang, Fei Wang, Zi-Yi Du PII: DOI: Reference:
S0022-2860(14)00519-5 http://dx.doi.org/10.1016/j.molstruc.2014.05.033 MOLSTR 20632
To appear in:
Journal of Molecular Structure
Received Date: Revised Date: Accepted Date:
17 March 2014 15 May 2014 15 May 2014
Please cite this article as: Y-P. Zhao, H. Yang, F. Wang, Z-Y. Du, A Microporous Manganese-based Metal-Organic Framework for Gas Sorption and Separation, Journal of Molecular Structure (2014), doi: http://dx.doi.org/10.1016/ j.molstruc.2014.05.033
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
A Microporous Manganese-based Metal-Organic Framework for Gas Sorption and Separation
Ying-Ping Zhao a, a
Hui Yang b, Fei Wang b,* and Zi-Yi Du a,b, *
College of Chemistry and Chemical Engineering, Gannan Normal University, Ganzhou 341000, b
P. R. China. State Key Laboratory of Structural Chemistry, Fujian Institute of Research
on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 35002, China.
E-mail:
[email protected];
(+86)-591-83714946; Tel: (+86)-591-83715075.
1
[email protected].
Fax:
A Microporous Manganese-based Metal-Organic Framework for Gas Sorption and Separation
Ying-Ping Zhao a, Hui Yang b, Fei Wang b,* and Zi-Yi Du a,b, * a
College of Chemistry and Chemical Engineering, Gannan Normal University, Ganzhou 341000, b
P. R. China. State Key Laboratory of Structural Chemistry, Fujian Institute of Research
on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 35002, China.
E-mail:
[email protected];
[email protected].
Fax:
(+86)-591-83714946; Tel: (+86)-591-83715075. Abstract: A metal-organic framework [Mn3(HCOO)6]·DMF (1) with in-situ generated formate ligand from the decomposition of N,N-dimethylformamide (DMF) solvent has been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), Infrared Spectroscopy (IR) and Elemental analysis (EA). Each formate ligand acts as µ3-bridge to link three octahedral Mn(II) centers to form a neutral three-dimensional (3D) framework with interesting 1D zigzag channel along the b axis, in which the DMF fill the free spaces. The desolvated samples exhibit interesting adsorption properties and show high selectivity for the adsorption of CO2 over N2 under ambient conditions. Keywords: Metal-organic framework / in-situ / adsorption / selectivity / CO2 capture and storage
2
Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) are a class of crystalline solid-state material featuring regular and designable channel structures with permanent porosity [1]. Porous MOFs with high surface areas and tunable structures have recently attracted considerable interest not only for their fascinating architectures and intriguing topologies, but also for their potential applications in sensing, heterogeneous catalysis, gas storage and separation [2]. Flue gases consist of nitrogen (typically more than two-thirds), carbon dioxide, water vapor, oxygen, and minor components such as carbon monoxide, nitrogen oxides, and sulfur oxides. Economical and efficient CO2 capture and storage (CCS) has been attracting tremendous attention due to the culprit for causing the greenhouse effect [3]. Several technologies have been considered for CO2 capture and separation from nitrogen-rich streams, including absorption, adsorption and membranes separations [4]. In particular, for separation of CO2/N2, because of the relatively similar kinetic diameters of the molecules (3.3 and 3.64 Å, respectively), it would require materials operating on a size-selective mechanism to possess very small pores, which may limit the diffusion of gases throughout the material. Therefore, to find a suitable pore size material is a necessary condition for CO2/N2 separation. Herein, we report an compound [Mn3(HCOO)6]·DMF (1), synthesized by Mn salt and in situ generated formate ligand from the decomposition of DMF solvent [5], which exhibits high CO2 adsorption and selectivity of CO2 over N2 under ambient conditions.
Single crystal X-ray diffraction study revealed that 1 crystallizes in a monoclinic space group P21/n [6]. The asymmetric unit contains four crystallogra phically 3
independent Mn(II) (occupation factor of Mn3 and Mn4 is 0.5), six formate anions and one DMF as guest (Figure 1a). Each formate ligand acts as µ3-bridge to link three octahedral Mn(II) centers to form a neutral three-dimensional (3D) framework with interesting 1D zigzag channel along the b axis, in which the DMF fill the free spaces (Figure 1b). The free solvent accessible pore volume ratio in 1 is about 30% without considering the DMF guest molecules, as calculated with the PLATON program. The coordination geometry of Mn and formate, as well as the overall framework topology, closely resemble those of the Mn(II) and Co(II) formate that has been reported earlier [7, 8]. Differently, in compound 1, the HCOO- generates in situ from the decomposition of DMF and DMF acts as the guest.
Insert figure 1
To study the thermal behavior of compound 1, thermogravimetric analysis (TGA) in N2 atmosphere with a heating rate of 10 oC min-1 were performed on polycrystalline sample to determine its thermal behavior from 25 to 800
o
C. TGA on the
as-synthesized sample of 1 indicated weight loss of 14.72% before 300 °C, which corresponding to the release of solvent (DMF) molecules. The TGA curve of 1 indicates that the framework is stable up to ca. 300 oC (Figure S1). After that temperature, the framework begins to decompose. We notice that the compound 1 has less thermal stability than that of [Mn3(HCOO)6]·[1,4-dioxane] reported by K. Kim [7]. We also check the PXRD patterns between the desolvated and as-synthesized samples, and find that the main peaks of the desolvated one shift to high angles
4
(Figure 2). Interestingly, after immersing in DMF or MeOH again, it will restore to its original look. We deduce that the guest DMF in 1 is irregular, and has higher boiling point and bigger spatial volume than that of 1,4-dioxane, so the framework of 1 shows a little expansion to encapsule big guest molecule and less thermal stability after releasing the guest.
Insert figure 2
The permanent microporosity of 1 degassed under a dynamic vacuum at 160 °C for 5h, was established by reversible gas sorption experiments using N2 at 77 K. Gas adsorption measurements (N2, H2, and CO2) were performed on a Micromeritics ASAP 2020 surface area and pore size analyzer. The experiments shows typical type I behavior (Figure 3), which is characteristic of microporous materials. The maximum N2 uptake at 1 bar for 1 is 28.36 cm3g-1 (STP). The Brunauer-Emmett-Teller (BET) and Langmuir surface areas for 1 are estimated to be 78.1 and 113.9 m2g-1, respectively. The N2 uptake is higher than those for [Mn3(HCOO)6]·dioxane previously reported at 77K, mainly due to the flexibility of the framework mentioned above.
Insert figure 3
Considering its low adsorption amount of N2 and the difference between it and the former reported one, low-pressure hydrogen adsorption-desorption isotherms for 1 at 77 and 87 K were furtherly measured (Figure 4a-d). No hysteresis was observed in
5
these isotherms at both temperatures. The adsorption isotherms revealed that 1 can adsorb 4.29 mmol g-1 (96 cm3g-1) and 3.38 mmol g-1 (75.6 cm3g-1) of H2 at 77 and 87 K, respectively. These results are almost equal to the former one [5], also suggest that the samples are fully activated. The isosteric heat of adsorption (Qst) of 1 was also calculated. At zero coverage, the Qst is 6.66 kJ/mol (Figure S3). This value of the isosteric heat of adsorption is moderate compared with the many famous porous materials, such as ZIF-8, MIL-100, PCN-10, HKUST-1, MOF-5, IRMOF-1 and IRMOF-8 [9a].
Since the samples were fully activated, what attract us is its CO2 capture and storage. The adsorption isotherms of CO2 for 1 were measured up to 1 bar at 273 K and 298 K, respectively. As shown in Figure 4e-h, the CO2 uptake values are 2.55 mmol g-1 (57 cm3g-1) at 273 K, and 1.92 mmol g-1 (43 cm3g-1) at 298 K, respectively. The carbon dioxide uptake values of 1 are higher than that of many famous porous materials at 273 and 298K, respectively, such as ZIFs, SNUs, MOFs, BIF-9-Li, and MILs (Table S1) [9b]. Virial analysis of the CO2 adsorption isotherms revealed that the isosteric heat of adsorption of 1 at zero surface coverage is 24.5 kJ/mol (Figure S5). The potential of this rigid framework material in CO2/N2 gas separation was also explored. As shown in Figure 4i and j, N2 was hardly adsorbed at all at 273 K (3.96 cm3g-1) and 298 K (3.73 cm3g-1). We employed the Henry’s constants to estimate the adsorption selectivity of 1 for CO2 /N2 [10], which has been shown to be valid for calculating the gas selectivity of MOFs, 1 is calculated to exhibit an adsorption selectivity of 36.6 for CO2 over N2 at 273 K and 25.3 at 298K respectively, which 6
indicated that 1 has excellent CO2/N2 adsorption selectivity. To our knowledge, these selectivity values are the particularly well reported to date for MOF materials [9b, 11].
Insert figure 4
In summary, we report a microporous Mn-formate framework via solvothermal method with in situ generated formate ligand decomposited by DMF solvent. The desolvated framework of 1 exhibits high CO2 adsorption and excellent selectivity of CO2 over N2 at 273K and 298K, which suggests that this simple framework can also be as the suitable CO2 capture material because of its excellent size-selective effect.
Acknowledgments This work is supported by NSFC (21103189) and the Young Scientists Training Program of Jiangxi Province (No. 20122BCB23020). Reference [1] (a) Férey, G, Hybrid porous solids: past, present, future, Chem. Soc. Rev. 37 (2008) 191-214;
(b) O. M. Yaghi, M. O'Keeffe, N. W. Ockwig, H. K. Chae, M. Eddaoudi and J. Kim, Reticular synthesis
and the design of new materials, Nature 423 (2003) 705-715;
(c) S. Kitagawa, R. Kitaura and S. Noro, Functional Porous Coordination Polymers, Angew. Chem. Int. Ed.
43 (2004) 2334-2375;
(d) H.-X. Zhang, F. Wang, H. Yang, Y.-X. Tan, J. Zhang and X. Bu, Interrupted Zeolite LTA and
ATN-type Boron Imidazolate Frameworks, J. Am. Chem. Soc. 133 (2011) 11884-11887.
[2] (a) J.-R. Li, R. J. Kuppler and H.-C. Zhou, Selective gas adsorption and separation in metal-organic
frameworks, Chem. Soc. Rev. 38 (2009) 1477-1504;
7
(b) B.-L. Chen, S.-G. Xiang and G.-D. Qian, Metal-Organic Frameworks with Functional Pores for
Recognition of Small Molecules, Acc. Chem. Res. 43 (2010) 1115-1124;
(c) F. Wang, Z. S. Liu, H. Yang, Y. X. Tan and J. Zhang, Hybrid Zeolitic Imidazolate Frameworks with
Catalytically Active TO4 Building Blocks, Angew. Chem. Int. Ed. 50 (2011) 450-453; (d) B. Kesanli and W. Lin, Chiral porous coordination networks: rational design and applications in
enantioselective processes, Coord. Chem. Rev. 246 (2003) 305-326;
(e) L. Ma, C. Abney and W. Lin, Enantioselective catalysis with homochiral metal-organic frameworks,
Chem. Soc. Rev. 38 (2009) 1248-1256.
[3] (a) C. Song, Global challenges and strategies for control, conversion and utilization of CO2 for sustainable development involving energy, catalysis, adsorption and chemical processing, Catal. Today 115 (2006)
2-32;
(b) T. Sakakura, J. C. Choi and H. Yasuda, Transformation of Carbon Dioxide, Chem. Rev. 107 (2007)
2365-2387.
[4] (a) Y. S. Bae, O. K. Farha, J. T. Hupp and R. Q. Snurr, Enhancement of CO2/N2 selectivity in a metal-organic framework by cavity modification, J. Mater. Chem. 19 (2009) 2131-2134;
(b) J. An, S. J. Geib and N. L. Rosi, High and Selective CO2 Uptake in a Cobalt Adeninate Metal-Organic Framework Exhibiting Pyrimidine- and Amino-Decorated Pores, J. Am. Chem. Soc. 132
(2010) 38-39;
(c) L. Liu, A. Chakma and X. Feng, CO2/N2 separation by poly(ether block amide) thin film hollow fiber composite membranes, Ind. Eng. Chem. Res. 44 (2005) 6874-6882.
[5] Synthesis of the compound [Mn3(HCOO)6]·DMF (1): The mixture of 50% Mn(NO3)2 water solution(0.5mmol, 0.178g), 4,5-Imidazoledicarboxylic acid (0.5 mmol, 0.078g) and 5ml DMF was sealed
8
in a 20 ml vial and heated to 120 oC for 3 days. Cool down to room temperature and washed by methanol,
colorless
block
crystals
were
obtained
(73%
yield).
Elemental
analysis
(EA)
for
1,
C9H13Mn3NO13(508.02): Calcd. C 21.28, H 2.58, N 2.76. Found. C 21.15, H 2.63, N 2.71. [6] Crystal data for 1: C9H13Mn3NO13, Mw = 508.02, Monoclinic, a = 11.6976(3) Å, b = 10.2455(3) Å, c = 15.1724(4) Å, β = 91.621(2)°, V = 1817.65(9) Å3, T = 293(2) K, space group P2(1)/n, Z = 4, 6782 reflections measured, 3197 independent reflections (Rint = 0.0184). The final R1 value was 0.0351 (I > 2σ(I)). The final wR(F2) value was 0.1040 (I > 2σ(I)). The final R1 value was 0.0426 (all data). The final wR(F2) value was 0.1061 (all data). The goodness of fit on F2 was 1.118. CCDC: 962617.
[7] D. N. Dybtsev, H. Chun, S. H. Yoon, D. Kim and K. Kim, Microporous Manganese Formate: A Simple
Metal-Organic Porous Material with High Framework Stability and Highly Selective Gas Sorption
Properties, J. Am. Chem. Soc. 126 (2004) 32-33.
[8] (a) Z.-M. Wang, B. Zhang, H. Fujiwara, H. Kobayashi and M. Kurmoo, Mn3(HCOO)6: a 3D porous magnet of diamond framework with nodes of Mn-centered MnMn4 tetrahedron and guest-modulated ordering temperature, Chem. Commun. (2004) 416-417;
(b) Z.-M. Wang, B. Zhang, M. Kurmoo, M. A. Green, H. Fujiwara, T. Otsuka and H. Kobayashi,
Synthesis and Characterization of a Porous Magnetic Diamond Framework, Co3(HCOO)6, and Its N2 Sorption Characteristic, Inorg. Chem. 44 (2004) 1230-1237;
(c) K. Li, D. H. Olson, J. Y. Lee, W. Bi, K. Wu, T. Yuen, Q. Xu and Jing Li, Multifunctional
Microporous MOFs Exhibiting Gas/Hydrocarbon Adsorption Selectivity, Separation Capability and
Three-Dimensional Magnetic Ordering, Adv. Funct. Mater. 18 (2008) 2205-2214.
[9] (a) L. J. Murray, M. Dincă and J. R. Long, Hydrogen storage in metal-organic frameworks, Chem. Soc.
Rev. 38 (2009) 1294-1314;
9
(b) K. Sumida, D. L. Rogow, J. A. Mason, T. M. McDonald, E. D. Bloch, Z. R. Herm, T.-H. Bae and J. R.
Long, Carbon Dioxide Capture in Metal-Organic Frameworks, Chem. Rev. 112 (2012) 724-781.
[10] (a) R. Banerjee, A. Phan, B. Wang, C. Knobler, H. Furukawa, M. O’Keeffe, and O. M. Yaghi,
High-throughput synthesis of zeolitic imidazolate frameworks and application to CO2 capture, Science 319 (2008) 939-943;
(b) B. Wang, A. P. Côté, H. Furukawa, M. O’Keeffe, and O. M. Yaghi, Colossal cages in zeolitic
imidazolate frameworks as selective carbon dioxide reservoirs, Nature 453 (2008) 207-212;
(c) H. Kim, Y. Kim, M. Yoon, S. Lim, S. M. Park, G. Seo and K. Kim, Highly Selective Carbon Dioxide
Sorption in an Organic Molecular Porous Materials, J. Am. Chem. Soc. 132 (2010) 12200-12202.
[11] J.-R. Li, J. Sculley and H.-C. Zhou, Metal-Organic Frameworks for Separations, Chem. Rev. 112 (2012)
869-932.
Figure 1. (a) The asymmetric unit of 1; (b) view of the 3D framework of 1 along b-axis.
10
Figure 2. The Powder XRD pattern of 1: (a) simulated; (b) experiment; (c) after adsorption; (d) after adsorption soaked in DMF; (e) after adsorption soaked in MeOH.
Figure 3. N2 sorption isotherms of 1 recorded at at 77K.
11
Figure 4. Gas sorption isotherms of 1: (a, b) H2 adsorption and desorption at 77 K; (c, d) H2 adsorption and desorption at 87 K; (e, f) CO2 adsorption and desorption at 273 K; (g, h) CO2 adsorption and desorption at 298 K; (i) N2 adsorption and desorption at 273 K; (j) N2 adsorption and desorption at 298 K.
12
Graphical abstract
Presented here is a microporous Mn-based metal-organic framework, which exhibits high selectivity for the adsorption of CO2 over N2 under ambient conditions. Highlights:
1. Presented here is a microporous formate framework. 2. The HCOO- was in-situ generated from the decomposition of DMF. 3. The desolvated framework shows highly selective CO2 capture.
13
S0022-2860(14)00519-5 http://dx.doi.org/10.1016/j.molstruc.2014.05.033 MOLSTR 20632
To appear in:
Journal of Molecular Structure
Received Date: Revised Date: Accepted Date:
17 March 2014 15 May 2014 15 May 2014
Please cite this article as: Y-P. Zhao, H. Yang, F. Wang, Z-Y. Du, A Microporous Manganese-based Metal-Organic Framework for Gas Sorption and Separation, Journal of Molecular Structure (2014), doi: http://dx.doi.org/10.1016/ j.molstruc.2014.05.033
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
A Microporous Manganese-based Metal-Organic Framework for Gas Sorption and Separation
Ying-Ping Zhao a, a
Hui Yang b, Fei Wang b,* and Zi-Yi Du a,b, *
College of Chemistry and Chemical Engineering, Gannan Normal University, Ganzhou 341000, b
P. R. China. State Key Laboratory of Structural Chemistry, Fujian Institute of Research
on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 35002, China.
E-mail:
[email protected];
(+86)-591-83714946; Tel: (+86)-591-83715075.
1
[email protected].
Fax:
A Microporous Manganese-based Metal-Organic Framework for Gas Sorption and Separation
Ying-Ping Zhao a, Hui Yang b, Fei Wang b,* and Zi-Yi Du a,b, * a
College of Chemistry and Chemical Engineering, Gannan Normal University, Ganzhou 341000, b
P. R. China. State Key Laboratory of Structural Chemistry, Fujian Institute of Research
on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 35002, China.
E-mail:
[email protected];
[email protected].
Fax:
(+86)-591-83714946; Tel: (+86)-591-83715075. Abstract: A metal-organic framework [Mn3(HCOO)6]·DMF (1) with in-situ generated formate ligand from the decomposition of N,N-dimethylformamide (DMF) solvent has been solvothermally synthesized and structurally characterized by single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), Infrared Spectroscopy (IR) and Elemental analysis (EA). Each formate ligand acts as µ3-bridge to link three octahedral Mn(II) centers to form a neutral three-dimensional (3D) framework with interesting 1D zigzag channel along the b axis, in which the DMF fill the free spaces. The desolvated samples exhibit interesting adsorption properties and show high selectivity for the adsorption of CO2 over N2 under ambient conditions. Keywords: Metal-organic framework / in-situ / adsorption / selectivity / CO2 capture and storage
2
Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) are a class of crystalline solid-state material featuring regular and designable channel structures with permanent porosity [1]. Porous MOFs with high surface areas and tunable structures have recently attracted considerable interest not only for their fascinating architectures and intriguing topologies, but also for their potential applications in sensing, heterogeneous catalysis, gas storage and separation [2]. Flue gases consist of nitrogen (typically more than two-thirds), carbon dioxide, water vapor, oxygen, and minor components such as carbon monoxide, nitrogen oxides, and sulfur oxides. Economical and efficient CO2 capture and storage (CCS) has been attracting tremendous attention due to the culprit for causing the greenhouse effect [3]. Several technologies have been considered for CO2 capture and separation from nitrogen-rich streams, including absorption, adsorption and membranes separations [4]. In particular, for separation of CO2/N2, because of the relatively similar kinetic diameters of the molecules (3.3 and 3.64 Å, respectively), it would require materials operating on a size-selective mechanism to possess very small pores, which may limit the diffusion of gases throughout the material. Therefore, to find a suitable pore size material is a necessary condition for CO2/N2 separation. Herein, we report an compound [Mn3(HCOO)6]·DMF (1), synthesized by Mn salt and in situ generated formate ligand from the decomposition of DMF solvent [5], which exhibits high CO2 adsorption and selectivity of CO2 over N2 under ambient conditions.
Single crystal X-ray diffraction study revealed that 1 crystallizes in a monoclinic space group P21/n [6]. The asymmetric unit contains four crystallogra phically 3
independent Mn(II) (occupation factor of Mn3 and Mn4 is 0.5), six formate anions and one DMF as guest (Figure 1a). Each formate ligand acts as µ3-bridge to link three octahedral Mn(II) centers to form a neutral three-dimensional (3D) framework with interesting 1D zigzag channel along the b axis, in which the DMF fill the free spaces (Figure 1b). The free solvent accessible pore volume ratio in 1 is about 30% without considering the DMF guest molecules, as calculated with the PLATON program. The coordination geometry of Mn and formate, as well as the overall framework topology, closely resemble those of the Mn(II) and Co(II) formate that has been reported earlier [7, 8]. Differently, in compound 1, the HCOO- generates in situ from the decomposition of DMF and DMF acts as the guest.
Insert figure 1
To study the thermal behavior of compound 1, thermogravimetric analysis (TGA) in N2 atmosphere with a heating rate of 10 oC min-1 were performed on polycrystalline sample to determine its thermal behavior from 25 to 800
o
C. TGA on the
as-synthesized sample of 1 indicated weight loss of 14.72% before 300 °C, which corresponding to the release of solvent (DMF) molecules. The TGA curve of 1 indicates that the framework is stable up to ca. 300 oC (Figure S1). After that temperature, the framework begins to decompose. We notice that the compound 1 has less thermal stability than that of [Mn3(HCOO)6]·[1,4-dioxane] reported by K. Kim [7]. We also check the PXRD patterns between the desolvated and as-synthesized samples, and find that the main peaks of the desolvated one shift to high angles
4
(Figure 2). Interestingly, after immersing in DMF or MeOH again, it will restore to its original look. We deduce that the guest DMF in 1 is irregular, and has higher boiling point and bigger spatial volume than that of 1,4-dioxane, so the framework of 1 shows a little expansion to encapsule big guest molecule and less thermal stability after releasing the guest.
Insert figure 2
The permanent microporosity of 1 degassed under a dynamic vacuum at 160 °C for 5h, was established by reversible gas sorption experiments using N2 at 77 K. Gas adsorption measurements (N2, H2, and CO2) were performed on a Micromeritics ASAP 2020 surface area and pore size analyzer. The experiments shows typical type I behavior (Figure 3), which is characteristic of microporous materials. The maximum N2 uptake at 1 bar for 1 is 28.36 cm3g-1 (STP). The Brunauer-Emmett-Teller (BET) and Langmuir surface areas for 1 are estimated to be 78.1 and 113.9 m2g-1, respectively. The N2 uptake is higher than those for [Mn3(HCOO)6]·dioxane previously reported at 77K, mainly due to the flexibility of the framework mentioned above.
Insert figure 3
Considering its low adsorption amount of N2 and the difference between it and the former reported one, low-pressure hydrogen adsorption-desorption isotherms for 1 at 77 and 87 K were furtherly measured (Figure 4a-d). No hysteresis was observed in
5
these isotherms at both temperatures. The adsorption isotherms revealed that 1 can adsorb 4.29 mmol g-1 (96 cm3g-1) and 3.38 mmol g-1 (75.6 cm3g-1) of H2 at 77 and 87 K, respectively. These results are almost equal to the former one [5], also suggest that the samples are fully activated. The isosteric heat of adsorption (Qst) of 1 was also calculated. At zero coverage, the Qst is 6.66 kJ/mol (Figure S3). This value of the isosteric heat of adsorption is moderate compared with the many famous porous materials, such as ZIF-8, MIL-100, PCN-10, HKUST-1, MOF-5, IRMOF-1 and IRMOF-8 [9a].
Since the samples were fully activated, what attract us is its CO2 capture and storage. The adsorption isotherms of CO2 for 1 were measured up to 1 bar at 273 K and 298 K, respectively. As shown in Figure 4e-h, the CO2 uptake values are 2.55 mmol g-1 (57 cm3g-1) at 273 K, and 1.92 mmol g-1 (43 cm3g-1) at 298 K, respectively. The carbon dioxide uptake values of 1 are higher than that of many famous porous materials at 273 and 298K, respectively, such as ZIFs, SNUs, MOFs, BIF-9-Li, and MILs (Table S1) [9b]. Virial analysis of the CO2 adsorption isotherms revealed that the isosteric heat of adsorption of 1 at zero surface coverage is 24.5 kJ/mol (Figure S5). The potential of this rigid framework material in CO2/N2 gas separation was also explored. As shown in Figure 4i and j, N2 was hardly adsorbed at all at 273 K (3.96 cm3g-1) and 298 K (3.73 cm3g-1). We employed the Henry’s constants to estimate the adsorption selectivity of 1 for CO2 /N2 [10], which has been shown to be valid for calculating the gas selectivity of MOFs, 1 is calculated to exhibit an adsorption selectivity of 36.6 for CO2 over N2 at 273 K and 25.3 at 298K respectively, which 6
indicated that 1 has excellent CO2/N2 adsorption selectivity. To our knowledge, these selectivity values are the particularly well reported to date for MOF materials [9b, 11].
Insert figure 4
In summary, we report a microporous Mn-formate framework via solvothermal method with in situ generated formate ligand decomposited by DMF solvent. The desolvated framework of 1 exhibits high CO2 adsorption and excellent selectivity of CO2 over N2 at 273K and 298K, which suggests that this simple framework can also be as the suitable CO2 capture material because of its excellent size-selective effect.
Acknowledgments This work is supported by NSFC (21103189) and the Young Scientists Training Program of Jiangxi Province (No. 20122BCB23020). Reference [1] (a) Férey, G, Hybrid porous solids: past, present, future, Chem. Soc. Rev. 37 (2008) 191-214;
(b) O. M. Yaghi, M. O'Keeffe, N. W. Ockwig, H. K. Chae, M. Eddaoudi and J. Kim, Reticular synthesis
and the design of new materials, Nature 423 (2003) 705-715;
(c) S. Kitagawa, R. Kitaura and S. Noro, Functional Porous Coordination Polymers, Angew. Chem. Int. Ed.
43 (2004) 2334-2375;
(d) H.-X. Zhang, F. Wang, H. Yang, Y.-X. Tan, J. Zhang and X. Bu, Interrupted Zeolite LTA and
ATN-type Boron Imidazolate Frameworks, J. Am. Chem. Soc. 133 (2011) 11884-11887.
[2] (a) J.-R. Li, R. J. Kuppler and H.-C. Zhou, Selective gas adsorption and separation in metal-organic
frameworks, Chem. Soc. Rev. 38 (2009) 1477-1504;
7
(b) B.-L. Chen, S.-G. Xiang and G.-D. Qian, Metal-Organic Frameworks with Functional Pores for
Recognition of Small Molecules, Acc. Chem. Res. 43 (2010) 1115-1124;
(c) F. Wang, Z. S. Liu, H. Yang, Y. X. Tan and J. Zhang, Hybrid Zeolitic Imidazolate Frameworks with
Catalytically Active TO4 Building Blocks, Angew. Chem. Int. Ed. 50 (2011) 450-453; (d) B. Kesanli and W. Lin, Chiral porous coordination networks: rational design and applications in
enantioselective processes, Coord. Chem. Rev. 246 (2003) 305-326;
(e) L. Ma, C. Abney and W. Lin, Enantioselective catalysis with homochiral metal-organic frameworks,
Chem. Soc. Rev. 38 (2009) 1248-1256.
[3] (a) C. Song, Global challenges and strategies for control, conversion and utilization of CO2 for sustainable development involving energy, catalysis, adsorption and chemical processing, Catal. Today 115 (2006)
2-32;
(b) T. Sakakura, J. C. Choi and H. Yasuda, Transformation of Carbon Dioxide, Chem. Rev. 107 (2007)
2365-2387.
[4] (a) Y. S. Bae, O. K. Farha, J. T. Hupp and R. Q. Snurr, Enhancement of CO2/N2 selectivity in a metal-organic framework by cavity modification, J. Mater. Chem. 19 (2009) 2131-2134;
(b) J. An, S. J. Geib and N. L. Rosi, High and Selective CO2 Uptake in a Cobalt Adeninate Metal-Organic Framework Exhibiting Pyrimidine- and Amino-Decorated Pores, J. Am. Chem. Soc. 132
(2010) 38-39;
(c) L. Liu, A. Chakma and X. Feng, CO2/N2 separation by poly(ether block amide) thin film hollow fiber composite membranes, Ind. Eng. Chem. Res. 44 (2005) 6874-6882.
[5] Synthesis of the compound [Mn3(HCOO)6]·DMF (1): The mixture of 50% Mn(NO3)2 water solution(0.5mmol, 0.178g), 4,5-Imidazoledicarboxylic acid (0.5 mmol, 0.078g) and 5ml DMF was sealed
8
in a 20 ml vial and heated to 120 oC for 3 days. Cool down to room temperature and washed by methanol,
colorless
block
crystals
were
obtained
(73%
yield).
Elemental
analysis
(EA)
for
1,
C9H13Mn3NO13(508.02): Calcd. C 21.28, H 2.58, N 2.76. Found. C 21.15, H 2.63, N 2.71. [6] Crystal data for 1: C9H13Mn3NO13, Mw = 508.02, Monoclinic, a = 11.6976(3) Å, b = 10.2455(3) Å, c = 15.1724(4) Å, β = 91.621(2)°, V = 1817.65(9) Å3, T = 293(2) K, space group P2(1)/n, Z = 4, 6782 reflections measured, 3197 independent reflections (Rint = 0.0184). The final R1 value was 0.0351 (I > 2σ(I)). The final wR(F2) value was 0.1040 (I > 2σ(I)). The final R1 value was 0.0426 (all data). The final wR(F2) value was 0.1061 (all data). The goodness of fit on F2 was 1.118. CCDC: 962617.
[7] D. N. Dybtsev, H. Chun, S. H. Yoon, D. Kim and K. Kim, Microporous Manganese Formate: A Simple
Metal-Organic Porous Material with High Framework Stability and Highly Selective Gas Sorption
Properties, J. Am. Chem. Soc. 126 (2004) 32-33.
[8] (a) Z.-M. Wang, B. Zhang, H. Fujiwara, H. Kobayashi and M. Kurmoo, Mn3(HCOO)6: a 3D porous magnet of diamond framework with nodes of Mn-centered MnMn4 tetrahedron and guest-modulated ordering temperature, Chem. Commun. (2004) 416-417;
(b) Z.-M. Wang, B. Zhang, M. Kurmoo, M. A. Green, H. Fujiwara, T. Otsuka and H. Kobayashi,
Synthesis and Characterization of a Porous Magnetic Diamond Framework, Co3(HCOO)6, and Its N2 Sorption Characteristic, Inorg. Chem. 44 (2004) 1230-1237;
(c) K. Li, D. H. Olson, J. Y. Lee, W. Bi, K. Wu, T. Yuen, Q. Xu and Jing Li, Multifunctional
Microporous MOFs Exhibiting Gas/Hydrocarbon Adsorption Selectivity, Separation Capability and
Three-Dimensional Magnetic Ordering, Adv. Funct. Mater. 18 (2008) 2205-2214.
[9] (a) L. J. Murray, M. Dincă and J. R. Long, Hydrogen storage in metal-organic frameworks, Chem. Soc.
Rev. 38 (2009) 1294-1314;
9
(b) K. Sumida, D. L. Rogow, J. A. Mason, T. M. McDonald, E. D. Bloch, Z. R. Herm, T.-H. Bae and J. R.
Long, Carbon Dioxide Capture in Metal-Organic Frameworks, Chem. Rev. 112 (2012) 724-781.
[10] (a) R. Banerjee, A. Phan, B. Wang, C. Knobler, H. Furukawa, M. O’Keeffe, and O. M. Yaghi,
High-throughput synthesis of zeolitic imidazolate frameworks and application to CO2 capture, Science 319 (2008) 939-943;
(b) B. Wang, A. P. Côté, H. Furukawa, M. O’Keeffe, and O. M. Yaghi, Colossal cages in zeolitic
imidazolate frameworks as selective carbon dioxide reservoirs, Nature 453 (2008) 207-212;
(c) H. Kim, Y. Kim, M. Yoon, S. Lim, S. M. Park, G. Seo and K. Kim, Highly Selective Carbon Dioxide
Sorption in an Organic Molecular Porous Materials, J. Am. Chem. Soc. 132 (2010) 12200-12202.
[11] J.-R. Li, J. Sculley and H.-C. Zhou, Metal-Organic Frameworks for Separations, Chem. Rev. 112 (2012)
869-932.
Figure 1. (a) The asymmetric unit of 1; (b) view of the 3D framework of 1 along b-axis.
10
Figure 2. The Powder XRD pattern of 1: (a) simulated; (b) experiment; (c) after adsorption; (d) after adsorption soaked in DMF; (e) after adsorption soaked in MeOH.
Figure 3. N2 sorption isotherms of 1 recorded at at 77K.
11
Figure 4. Gas sorption isotherms of 1: (a, b) H2 adsorption and desorption at 77 K; (c, d) H2 adsorption and desorption at 87 K; (e, f) CO2 adsorption and desorption at 273 K; (g, h) CO2 adsorption and desorption at 298 K; (i) N2 adsorption and desorption at 273 K; (j) N2 adsorption and desorption at 298 K.
12
Graphical abstract
Presented here is a microporous Mn-based metal-organic framework, which exhibits high selectivity for the adsorption of CO2 over N2 under ambient conditions. Highlights:
1. Presented here is a microporous formate framework. 2. The HCOO- was in-situ generated from the decomposition of DMF. 3. The desolvated framework shows highly selective CO2 capture.
13