N2 on Amino-MIL

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Enhanced CO2 adsorption and selectivity of CO2/N2 on amino-MIL-53(Al) synthesized by polar co-solvents Hussein Abid, Zana Hassan Rada, Xiaoguang Duan, Hongqi Sun, and Shaobin Wang Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b03240 • Publication Date (Web): 17 Dec 2017 Downloaded from http://pubs.acs.org on December 23, 2017

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Enhanced CO2 adsorption and selectivity of CO2/N2 on amino-MIL-53(Al) synthesized by polar co-solvents Hussein Rasool Abida,b , Zana Hassan Radaa, Xiaoguang Duana, Hongqi Sunc and Shaobin Wanga* a

b

Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth, WA, 6845, Australia.

Environmental Health Department, Faculty of Applied Medical Science, Karbala University, GPO Box 1152, Karbala, Iraq. c

School of Engineering, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA, 6027, Australia

*Corresponding author. Email: [email protected] Abstract Amino-MIL-53(Al) was solvothermally synthesized using co-solvents, such as methanol (M), ethanol (E), methanol/acetic acid (MA), or ethanol/acetic acid (EA) as modulators with dimethylformamide (D). The effects of co-solvents on physicochemical properties of amino-MIL-53(Al) were investigated. It was found that addition of co-solvents in the synthesis leads to the reduction of crystallinity and crystal size of the samples. The textural properties such as specific surface area and porous structure were manipulated. Amino-MIL-53-DMA exhibited the highest BET surface area of 632 m2/g, due to loss of bridging hydroxyl group while amino-MIL-53, amino-MIL-53-DE, amino-MIL-53-DEA and amino-MIL-53-DM presented the surface areas of 400, 356, 321, 348 m2/g, respectively. However, the primary amine groups were maintained on the surface of all the amino-MIL-53 samples. The cosolvents enhanced CO2 adsorption on the modified amino-MIL-53. CO2 adsorption capacities on amino-MIL-53, amino-MIL-53-DM, amino-MIL-53-DE, amino-MIL-53-DEA, and amino-MIL-53DMA are 48, 71, 67, 54, and 75 cc/g, respectively, at standard conditions (1 atm and 273 K). CO2 adsorption heat could be reduced to 24 kJ/mol on amino-MIL-53-DMA, giving it as a promising adsorbent for carbon dioxide storage at ambient conditions. Besides, the selectivity of CO2/N2 on amino-MIL-53-DEA and amino-MIL-53-DE demonstrates an unprecedentedly separating factor of 637 at 1 atm and 273 K whereas the separating factors of CO2/N2 on amino-MIL-53, amino-MIL-53-DMA and amino-MIL-53-DM are only 43, 43, 153, respectively. Amino-MIL-53-DEA and amino-MIL-53DE impressively outperforms other MOFs and exhibits as an auspicious adsorbent for CO2/N2 separation.

1 ACS Paragon Plus Environment

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Key words: Co-solvent; amino-MIL-53(Al); CO2 adsorption; separation.

1. Introduction Nowadays, porous materials such as activated carbon1, zeolites2, porous silica, metal oxides3, and metal organic frameworks have been widely studied for different applications4-6. In particular, crystalline metal organic frameworks (MOFs), with ultrahigh specific surface areas, tunable porous structure and surface chemistry, have been utilized as promising materials for adsorption, gas separation, energy storage and conversions, and catalysis7. Generally, metallic ions can be linked with organic ligands to generate extended frameworks with a large surface area, pore volume, and different functional groups. Particularly, Zn2+, Mg2+, Al3+, Zr4+-based MOFs have been intensively studied and have exhibited more flexibilities for structure and surface modifications than zeolites and activated carbon8. Functionality of MOFs via direct synthesis can be readily achieved using functionalized organic linkers such as nitroterephthalic acid, hydroxy-terephthalic acid, and amino-terephthalic acid 9-11. Amino-functionalized MOFs were reported to be synthesized using different metal centers. For example, IRMOF-3(Zn)12, amino-MIL-53(Al)13, and amino-UiO-66(Zr)14 were prepared with different methods for different applications15, 16. It is believed that the amino groups on MOF can improve carbon dioxide capture and storage17. Amino-MIL-53 could be synthesized using different solvents such as H2O, methanol, and dimethylformamide (DMF). However, it was difficult to remove coordinated molecules of the solvents and non-reacted organic acid linkers from the pores. A better synthesis strategy was proposed using aminoterephthalic acid (amino-BDC) as a linker, AlCl3•6H2O as an Al precursor, and H2O as a solvent for amino-MIL-53(Al)18. Some researchers have used Al(NO3)3•9H2O and amino-BDC with DMF as the solvent, and the resulting amino-MIL-53 manifested a high separating factor for CO2 separation in the flowing gas mixture19, 20. It was reported that the effects of solvents on MOF synthesis and structure are complicated due to various solution-solvent interaction mechanisms 21. The reaction medium in a synthesis procedure can be greatly affected by the polar properties, therefore the selection of solvents may profoundly impact the derived product. Moreover, the polarity of solvents can be enriched by adding less polar constituents

22

. Synthesis of NH2-MIL-101(Al) with co-solvents of DMF, methanol, acetonitrile, and

isopropyl alcohol has been achieved by Yang and Clark. They found that exchange interaction of a coordinated solvent could be easily achieved, while the dynamic solvent organization resulted in the migration of solvent through the spacing between the coordination angles of the BDC-Al3O-BDC connections

23

. Furthermore, textural properties of MOF can be tailored during the synthesis by

modulation technique

24

. In the synthesis of Zr-MOF, acetic acid and benzoic acid were used to 2 ACS Paragon Plus Environment

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enlarge the crystal size 25, whereas ammonium hydroxide was used to minimize the crystal size 26. The trifluoroacetic acid was used as a modulator for more Lewis acid sites which contribute to a more open MOF structure, while hydrochloric acid could be used as a crystallizing agent to produce highly crystalline materials with superior catalytic performances

27

. Herein, the texture of solvents

significantly influences the formation procedure of MOFs 24. In recent decades, capture of greenhouse gases has become a hot topic in the scientific community because the future of life on the blue planet has been threatened by the climate change associated with carbon dioxide and methane28-30. Metal organic frameworks with high adsorptive capacities have demonstrated great potential to capture31 and store carbon dioxide

32, 33

. Also, the separation of CO2

from other gases can be achieved by regulating the textural properties of MOFs34, 35. Amino-MIL-53 has been used for capturing carbon dioxide with a larger separating factor for separation of CO2 and CH4. 36, 37 In previous studies, amino-MIL-53 synthesis was generally involved a single-solvent method 38

. However, since single solvent leads to a low CO2 adsorption (48 cc g-1 at 273 K)39, and thus a co-

solvent strategy could be adopted for the enhancement of CO2 capture. Herein, in this paper, we report the synthesis of amino-MIL-53 using mixture of methanol, ethanol, methanol/acetic acid, or ethanol/acetic acid with DMF as co-solvents to manipulate the microporous structure and to enhance the capacity in CO2 uptake and selectively adsorptive performance in a mixture of CO2/N2 at an ambient pressure.

2. Materials and methods 2.1

Chemicals and synthesis. All chemicals including aminoterephthalic acid (NH2-BDC, 98%),

dimethylformamide (DMF, 98.9%), aluminium nitrate nonahydrate (Al(NO3)3•9H2O, 98%), acetic acid (98%), methanol (≥99.8%), and ethanol (99.7%) were obtained from Sigma-Aldrich (Australia) and used without further purification. A solvothermal method was employed to prepare various aminoMIL-53 samples. In a typical synthesis procedure, Al(NO3)3•9H2O (5.82 mmol) and amino-BDC (8.66 mmol) were dissolved and mixed homogeneously in 83 mL DMF and transferred into a 125 mL autoclave, which was then sealed and maintained at 403 K for 2 d. For ethanol co-solvent synthesized amino-MIL-53-DE, Al(NO3)3•9H2O (9.59 mmol) and amino-BDC (5.24 mmol) were mixed with 25 mL ethanol and 60 mL DMF, then the solution was transfered to an autoclave (125 mL) and heated at 418 K for 2 d.


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For methanol co-solvent synthesized amino-MIL-53-DM, Al(NO3)3•9H2O (7.8 mmol) and amino-BDC (5.52 mmol) were mixed with 40 mL methanol and 43 mL DMF, then the solution was transfered to an autoclave (125 mL) and heated at 418 K for 2 d. For amino-MIL-53-DEA, 9.59 mmol of Al(NO3)3•9H2O and 4.842 mmol of amino-BDC were mixed with co-solvent of 70 and 10 mL of DMF and ethanol, respectively, in a PTFE Teflon-liner. After 15 min, 0.03 mL H2O and 0.04 mL acetic acid were introduced to the solution. Finally, the autoclave was assembly, tightly closed and placed in a preheating oven at 423 K for 2 d. Amino-MIL-53-DMA was synthesized in the similar procedure with amino-MIL-53-DEA. Firstly, 7.19 mmol of Al(NO3)3•9H2O and 2.55 mmol of amino-BDC were mixed with co-solvent solution of 55 mL DMF and 25 mL methanol inside a PTFE Teflon-liner autoclave. Then, 0.03 mL H2O and 0.04 mL acetic acid were introduced to the solution and the autoclave was placed in a preheating oven at 423 K for 2 d. After the oven was natually cooled down to room temperature, the greenish yellow powder was collected after filtrered under vacuum condition. 2.2

Guest molecule removal. A solvent exchange evacuation approach was used to remove the

solvents (DMF, methanol, acetic acid, and ethanol) and non-coordinated organic ligand (amino-BDC) molecules. First, about 100 mg of each sample was immersed in 50 mL methanol for 5 d, and the soaking solution was replaced by fresh methanol every day. Then the samples were filtered and dried at 373 K for 2 h. Then the wet samples were heated under vacuum at 493 K for 3 d. 2.3

Characterization. X-ray powder diffraction (XRD) patterns were acquired by an X-ray

diffractometer (D8 Advance- Bruker). FTIR spectra were measured by a Spectrum 100-FT-IR Spectrometer (Perkin Elmer) to investigate the organic functional groups. The scan range was from 650 to 4000 cm-1 with a resolution of 4 cm-1 using a Universal ATR-Diamond/ZnSe detector. A Quantachrome instrument (Autosorb-1) was operated at 77 K for nitrogen adsorption-desorption isotherms to determine the BET and Langmuir specific surface areas as well as pore size distributions. Samples were degassed at 423 K under vacuum overnight. Thermal stability and weight loss profiles of the MOFs were determined on a thermogravimetric analysis (TGA) instrument with a TGA/DSC1 STARe system (METTLER TOLEDO). In a typical analysis, the sample was loaded into an alumina pan in the TGA furnace under 20 mL min-1 air flow at a ramping rate of 10 K/min from room temperature to 1173 K. 2.4

CO2 and N2 adsorption on various amino-MIL-53 samples. The specific adsorbed volume of

pure CO2 (99.995%) was measured using a static volumetric method on a Micromeritics instrument 4 ACS Paragon Plus Environment

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(Gemmini I-2360) at 273 and 296 K at atmospheric pressure. In evaluation of CO2 adsorption, about 0.08-0.1 g of the samples was weighed in a tube and activated by heating at 473 K under vacuum for 2 d. The carbon dioxide adsorption heat on the samples was determined by the Clausius-Claperyron equation at different temperatures. A Micromeritics ASAP2050 instrument was used for acquiring nitrogen sorption profiles at 273 K and 1 atm. The samples were degassed for 8 h at 423 K by the degassing port, then transferred to the analysis port for N2 sorption test.

3. Results and discussion Using co-solvents in the synthesis of amino-MIL-53 may multiplicatively lead to coordination of the solvents with metal cores and interaction of these solvents with amino-groups of linkers via hydrogen bonding. It was previously reported that methanol was the best solvent for obtaining pure crystals with excellent crystallinity40 because methanol has high acidity relative to ethanol41 in DMF. Moreover, an increased methanol content in the mixture can reduce the affinity between DMF and methanol molecules while increase the association of methanol molecules with each other42. Therefore, the activation by methanol exchange will enhance the removal efficiency of the solvents from the pore structure. It is well known that methanol molecules have a small size for fast diffusion through the pores by heating. Ethanol molecules inside the pores may exhibit a similar behavior as methanol whereas the methanol-ethanol-metal core interaction is stronger than methanol-methanol-metal core43. Moreover, molecular size of ethanol is larger for removal from the pores by methanol exchange. As a result, the majority of pores in amino-MIL-53-DMA may be mostly opened after guest evacuation processes, while some residuals of amino-BDC coordinated ethanol or DMF remain in the pores of amino-MIL-53-DE and amino-MIL-53-DEA. Meanwhile the additive of acetic acid can make a change in the textural properties and crystalline structure of amino-MIL-53. XRD patterns of the synthesized samples are shown in Fig.1. The XRD profiles of amino-MIL-53-DE, amino-MIL-53-DEA, amino-MIL-53-DMA, and amino-MIL-53 were found to be much similar to the pattern of MIL-53(Al)18, 44, while the spectra of amino-MIL-53-DM shows a similar pattern to aminoMIL-53.

19

The intensities of the peaks in modified samples were decreased and the positions were

moved to lower 2θ values (higher d-spacing). Besides, the peaks were distinctly broadened for cosolvents samples compared with amino-MIL-53, suggesting a lower crystallinity and a smaller crystal size. Moreover, the main peak for amino-MIL-53 at 12ºwas significantly reduced on amino-MIL-53DE and amino-MIL-53-DEA, and almost disappeared on amino-MIL-53-DM. The same peak for amino-MIL-53-DMA presents a positive shift (10º), which may be attributed to the internal stresses, 5 ACS Paragon Plus Environment

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twin boundaries, stacking faults, or chemical heterogeneities. The broadened peak also suggests that the lattice parameters are decreased

45, 46

. In addition, amino-MIL-53, amino-MIL-53-DE, amino-MIL-53-

DM, and amino-MIL-53-DEA expose a peak at 15ºwhereas a peak at 12° emerges for amino-MIL-53DMA. The results confirm the presence of protonated amino-BDC linkers inside the pores.

40000

Amino MIL-53-DM Amino-MIL-53-DMA Amino-MIL-53-DE Amino-MIL-53-DEA Amino-MIL-53

35000

Intensity(a.u)

30000 25000 20000 15000 10000 5000 0 10

20

30

40

50

60

2ϴ (degree) Fig.1 XRD patterns of Amino-MIL-53, Amino-MIL-53-DM, Amino-MIL-53-DE, Amino-MIL-53DEA, and Amino-MIL-53-DMA.

(a)

(b)

1000

Amino-MIL-53-DMA Amino-MIL-53-DEA Amino-MIL-53-DM Amino-MIL-53-DE Amino-MIL-53

1250

1500

1750

Amino-MIL-53-DEA Amino-MIL-53 Amino-MIL-53-DM Amino-MIL-53-DE Amino-MIL-53- DMA

Transmitance(a.u)

Transmitanc (a.u)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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2000

3200

-1 Wavenumber(cm )

3400

3600

3800

-1 Wavenumber(cm )

Fig.2 FTIR spectra of amino-MIL-53, amino-MIL-53-DM, amino-MIL53-DE, amino-MIL-53-DEA and amino-MIL-53-DMA, (a) full spectrum, (b) specific spectrum at 3200-3800 cm-1.


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FTIR spectra of Amino-MIL-53 samples are displayed in Fig. 2. Trace amount of unreacted aminoBDC and coordinated DMF are observed at 1622-1700 cm-1, which belongs to carboxyl groups of free organic linkers. Furthermore, the fingerprint regions (≤ 1000 cm-1) display the same patterns for all the samples, indicating the integrity of bulk structure in the co-solvent synthesis. Fig. 2b shows that the characteristic peaks for primary amino groups could be identified for all the samples at 3398 and 3500 cm-1 despite that the peaks were slightly attenuated by the co-solvents

47

. The peak intensity for

bridging hydroxyl groups located at 3630 cm-1 are reduced in the spectra of all samples, because the hydroxyl groups can interact with the solvent molecules and amino groups of coordinated and noncoordinated-amino-BDC inside the pores.

Table 1 Textural properties of synthesized amino-MIL-53 samples. SBET

Volume

(m2/g)

(cc/g)

(nm)

(%)

amino-MIL-53

400

1.03

4.9

0.5

amino-MIL-53-DE

356

0.71

4.0

18.6

amino-MIL-53-DEA

321

0.65

4.0

23.3

amino-MIL-53-DM

348

0.51

2.9

14.8

amino-MIL-53-DMA

632

0.33

1.0

70.8

Samples

Average Pore Radius

Micropore

The BET surface area and porous structure of synthesized amino-MIL-53 samples are presented in Table 1. Using methanol as a co-solvent and acetic acid as the additive in the synthesis procedure would obviously enhance the specific surface areas (SSAs) whereas using ethanol and acetic acid could decrease SSAs of amino-MIL-53. Amino-MIL-53-DMA demonstrates the largest BET surface area. The pore volume and average pore size of amino-MIL-53-DE, amino-MIL-53-DEA, amino-MIL-53DMA and amino-MIL-53-DM are lower than those of amino-MIL-53. In addition, using methanol or ethanol and methanol-acetic acid or ethanol-acetic acid as the co-solvents would greatly increase the micorpore ratio, which is in good agreement with the decrease in average pore size. More specifically, amino-MIL-53-DMA exhibits the highest micropore ratio and lowest pore size, while amino-MIL-53 sample displays the lowest micropore volume but largest pore size. 7 ACS Paragon Plus Environment

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Fig. 3 manifests nitrogen adsorption/desorption isotherms of the samples. For amino-MIL-53 (Fig. 3a), a uniform and narrow H3 hysteresis cycle occurs at P/Po = 0.35 - 0.95, suggesting a majority of mesopores

48, 49

. The presence of macropores and large mesopores could be presented by a vertical line

between P/Po = 0.95 and P/Po=0.98750, 51.

-1

Nitrogen adsorption/desorption(cc g )

(a) 500 Adsorption Desorption

400

300 200 100

0 0.0

0.2

0.4

0.6

0.8

Relative Pressure(P/Po)

-1

Nitrogen Adsorption/desorption(cc g )

(b) 500

400

Adsorption-Amino-MIL-53-DE Desorption- Amino-MIL-53-DE Adsorption- Amino-MIL-53-DM Desorption-Amino-MIL-53-DM

300 200

100 0 0.0

0.2

0.4

0.6

0.8

Relative Pressure(P/Po) (c) -1

Nitrogen adsorption/desorption(cc g )

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400

300

Adsorption-Amino-MIL-53-DEA Desorption-Amino-MIL-53-DEA Adsorption-Amino-MIL-53-DMA Desorption-Amino-MIL-53-DMA

200

100

8 0 0.0

ACS Paragon Plus Environment 0.2

0.4

0.6

Relative Pressure(P/Po)

0.8

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Fig. 3 Nitrogen adsorption/desorption isotherms of a) Amino-MIL-53, b) Amino-MIL-53-DM and Amino-MIL-53-DE, and c) Amino-MIL-53-DEA and Amino-MIL-DMA.

Fig. 3b shows nitrogen sorption isotherms of amino-MIL-53 for co-solvents of methanol and ethanol with DMF. A H2 hysteresis loop was displayed and closed at 0.05 (P/P0), suggesting an interconnected network of pores with varying shapes, curvatures, and sizes 49. This phenomenon is more obvious with an abundance of mesopore and macro-pore content in amino-MIL-53-DE. Fig. 3c shows nitrogen sorption isotherms of amino-MIL-53 with co-solvents methanol-acetic acid and ethanol-acetic acid with DMF. The adsorption/desorption behaviors of these samples were clearly different. Amino-MIL-53-DEA has a hysteresis loop of H2 type, which is similar to amino-MIL-53DE. The proportion of micropores is increased in amino-MIL-53-DMA (H4 hysteresis loop), therefore, the step almost disappeared in the adsorption curve. Furthermore, the vertical line in the low relative pressure (≥ 0.005) in amino-MIL-53-DMA’s isotherm is two-fold as high as that in amino-MIL-53DEA’s isotherm.

0.06 0.05

Amino-MIL-DMA Amino-MIL-53 Amino-MIL-53-DM Amino-MIL-53-DE Amino-MIL-53-DEA

0.04

-1 dV(r) ccg

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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0.03 0.02 0.01 0.00 0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Pore Radius (nm)

Fig. 4. Micropore distributions of various amino-MIL-53 samples. The micropore distributions are presented in Fig. 4. The profiles of micropore distribution of the five samples are similar in a single mode. However, the pore sizes are slightly different except for amino9 ACS Paragon Plus Environment

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MIL-53-DMA with a much lower pore size. The average micropore size distributions were centered at 0.92, 0.82, 0.96, 0.78, and 0.55 nm for amino-MIL-53, amino-MIL-53-DE, amino-MIL-53-DM, amino-MIL-53-DEA, and amino-MIL-53-DMA, respectively. The results suggest that the presence of co-solvent enhances micro pore size especially for the samples using acetic acid as the additive with DMF/methanol or DMF/ethanol. This is in agreement with previous studies that using acetic acid in a hydrothermal synthesis may lead to more microporous structures 52. It was believed that the presence of acetic acid can serves as a modulator with methanol and ethanol, because acetic acid leads to the formation of hetero-complexes due to the intermolecular hydrogen bonds 53. The mesoporous size distributions of all amino-MIL-53 samples are presented in Fig.5. Fig. 5a shows a bimodal distribution with two dominant peaks at 2.2 and 7.2 nm, respectively, on amino-MIL-53. A similar bimodal pore size distribution was discovered for Amino-MIL-53-DE with the peaks centered at 3.5 and 10 nm, and Amino-MIL-53-DEA at 3.5 and 15 nm (Fig. 5b). Meanwhile, in Fig. 5c, aminoMIL-53-DM shows a broad peak at 4.2 nm and a sharp peak on the shoulder at 3.11 nm, while aminoMIL-53-DMA only exhibited a single peak at 4.8 nm. It seems that modulation with ethanol or ethanol/acetic acid can increase the mesopore size.

However, modulation with methanol or

methanol/acetic acid will reduce the mesopore size. In preparation of porous materials, the pore size distribution may depend on the molecular size and hydrophobic properties of solvents applied in the synthesis procedure. Therefore, using methanol can minimize the mesopore size whereas ethanol may enlarge the mesopore size, especially when ethanol is used as a co-solvent with acetic acid as an additive. (a) 1.0

-1

0.8

dV(r) cc g

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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0.6 0.4 0.2 0.0 5

10

15

20

25

Pore Radius(nm)


30

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(b)

Amino-MIL-53-DE Amino-MIL-53-DEA

1.0

dV(r) cc g-1

0.8

0.6 0.4 0.2

0.0 0

5

10

15

20

25

Pore Radius (nm)

(c) 1.0

Amino-MIL-53-DM Amino-MIL-DMA

-1

0.8

dV(r) cc g

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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0.6 0.4 0.2 0.0 0

5

10

15

20

Pore Radius (nm)

Fig. 5 Mesopore distributions of a) Amino-MIL-53, b) Amino-MIL-53-DE and Amino-MIL-53-DEA, and c) Amino-MIL-53-DM and Amino-MIL-DMA.

Thermal stabilities of amino-MIL-53, amino-MIL-53-DM, amino-MIL-53-DE, amino-MIL-53-DMA, and amino-MIL-53-DEA are shown in Fig. 6. TGA profiles indicate that amino-MIL-53 presents a higher thermal stability than the other samples. All the samples show a weight loss before 393 K, due to evaporation of surface adsorbed moisture and organics. The greatest weight loss appears on aminoMIL-53-DMA. Amino-MIL-53 shows a notable weight loss from 673 until 823 K while amino-MIL53-DE, amino-MIL-53-DEA, amino-MIL-53-DM and amino-MIL-53-DMA present a significant weight loss from 573 until 823 K. The modulated samples showed two steps in weight loss, which may be attributed to the excessive modulator on the parent crystals

24

or the produced interconnection

between the co-solvents or the pore surface. More specifically, since methanol and ethanol have a stronger affinity to coordinate with metal centers than DMF, part of the metal sites could be occupied by the alcohol molecules

54, 55

. Besides, the hydrogen bond in alcohol molecules can induce more 11 ACS Paragon Plus Environment

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attractive interactions with -NH2 56. As a result, some of methanol, acetic acid, or ethanol will be retained in the pores and cannot be easily removed by methanol exchange, which was responsible for the weight loss before 573 K.

1.1 Amino-MIL-53 Amino-MIL-53-DMA Amino-MIL-53-DM Amino-MIL-53-DEA Amino-MIL-53-DE

1.0 0.9

Weight loss

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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0.8 0.7 0.6 0.5 0.4 400

600

800

1000

1200

Temperature (K)

Fig. 6 TGA profiles of different Amino-MIL-53 samples.

Fig. 7 shows CO2 adsorption isotherm on five amino-MIL-53 samples at different temperatures (273 and 296 K). Amino-MIL-53 demonstrates a type I CO2 isotherm for microporous structure with a sharp knee at a low pressure (100 mm Hg) and then a plateau (Fig. 7a) 57. At 1 bar, CO2 adsorption capacities for amino-MIL-53 at 273 and 296 K are 48.4 and 42.1 cc/g, respectively. Amino-MIL-53-DMA demonstrates a rapid rise in CO2 adsorption (Fig.7b), while the saturation capacity has not been reached because CO2 uptake would continually increase with the absolute pressure. The CO2 adsorption is higher than the other samples 58. CO2 adsorption capacities at 1 bar are 75.0 and 44.6 cc/g at 273 and 296 K, respectively. It is suggested that the primary amino-functional groups have a good affinity toward CO2 adsorption. Additionally, the large surface area, uniform pore distribution, and microporous structure are the dominating factors for improving CO2 adsorption58, 59. Furthermore, amino-MIL-53-DM adsorbs CO2 more rapidly than amino-MIL-53-DMA (Fig.7c), and then the rate decreased gradually. Although CO2 uptake amounts are 71 and 46.9 cc/g at 273 and 296 K on amino-MIL-53-DM at 1 atm, a higher capacity for CO2 adsorption is supposed to be reached before 12 ACS Paragon Plus Environment

Page 13 of 21

the saturation level. Herein, it is seen that the adsorption capacity (up to 56% for amino-MIL-53) could be enhanced using methanol or methanol/acetic acid co-solvents. (b) -1

40 30

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Energy & Fuels

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Fig. 7. CO2 adsorption isotherms on Amino-MIL-53 (a), Amino-MIL-DMA (b), Amino-MIL-53-DM (c), Amino-MIL-53-DE (d) and Amino-MIL-53-DEA (e).

CO2 uptakes on amino-MIL-53-DE (Fig. 7d) and amino-MIL-53-DEA (Fig. 7e) are slightly higher than amino-MIL-53. Specifically, the CO2 adsorption capacities of 66.7 and 44.92 cc/g are found on aminoMIL-53-DE at 273 and 296 K, respectively and meanwhile amino-MIL-53-DEA demonstrates CO2 adsorption volumes of 54.3 and 40.5 cc/g at 273 and 296 K, respectively. Therefore, these samples have a greater micro-porosity than amino-MIL-53, consequently leading to a promoted CO2 uptake 59. From the adsorption capacity at 1 atm and different temperatures, CO2 adsorption heat for the five samples was calculated based on the Clausius-Clapeyron equation and is shown in Fig. 8. The average values of CO2 adsorption heat were estimated to be 28, 29, 28, 28 and 24 kJ/mol for amino-MIL-53, amino-MIL-53-DE, amino-MIL-53-DM, amino-MIL-53-DEA, and amino-MIL-53-DMA, respectively. There is no significant differences in the adsorption heat for ethanol or methanol co-solvent samples. However, the reduced adsorption heat was found for amino-MIL-53-DMA compared with the parent sample. The values of heat of CO2 adsorption suggest that the regeneration of the five MOFs requires a 13 ACS Paragon Plus Environment

Energy & Fuels

low energy with half of the required energy for the traditional adsorbents such as zeolites60. Due to the high CO2 adsorption capacity and the lowest heat of CO2 adsorption, amino-MIL-53-DMA demonstrates a better potential for CO2 capture and storage.

35

-1 CO2 Heat of Adsorption(KJ mol )

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 21

Amino-MIL-53-DE Amino-MIL-53-DM Amino-MIL-53 Amino-MIL-53-DEA Amino-MIL-53-DMA

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Fig. 8 Heat of adsorption of CO2 on the amino-MIL-53 and the modulated samples. Fig. 9a shows nitrogen adsorption profiles of the as-made materials at 273 K. Nitrogen adsorption capacity of 1.17 cc/g was achieved on amino-MIL-53, which is higher than that of 0.10 and 0.085 cc/g of amino-MIL-53-DE) and amino-MIL-53-DEA. Whereas, nitrogen adsorption of 1.6 cc/g on methanol/acetic acid modulated was higher than the parent sample (Fig. 9b). On the other hand, methanol modulated sample exposed a lower capacity of 0.46 cc/g. Both of methanol modulated samples demonstrated a higher nitrogen capacity than ethanol modulated samples. It seems that nitrogen adsorption capacity on ethanol modulated samples was decreased owing to an enlarged pore size and promoted catenation phenomenon61.


Page 15 of 21

(b) 2.0

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0.8 0.6 0.4

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Fig. 9 Nitrogen adsorption on Amino-MIL-53 and the modulated samples (a) Amino-MIL-53-DE and amino-MIL-53-DEA (b) Amino-MIL-53-DM and amino-MIL-53-DMA at 273K.

Fig. 10 shows CO2/N2 separation factor (selectivity) profiles of different materials at 273 K. AminoMIL-53-DE and amino-MIL-53-DEA manifest the highest selectivity for CO2 vs N2 at the ratio of 637 at 1 atm and 273 K. The CO2/N2 selectivity is 153 on amino-MIL-53-DM, whereas amino-MIL-53 and amino-MIL-53-DMA exhibited the lowest ratio of 42.3 under the same conditions. Table 2 displays the selectivity of CO2/N2 on different porous materials. The modulated metal organic frameworks by ethanol (Amino-MIL-53-DE) exhibited an unprecedented separating factor of CO2 to nitrogen among the MOFs. CO2 and N2 exhibit similar kinetic diameters of 0.33 and 0.36 nm, respectively. However, CO2 molecules have higher quadrupole moments and polarizability, which are accordingly 2.85 and 1.5 folds of nitrogen, respectively. Since CO2 possesses an electron–deficient carbon center, the molecule presents favorable bonding with the electronegative molecules via strong acid-base interactions, whereas such an effect for N2 is insignificant62-64. Moreover, pore size and catenation are also important factors that would impact the selective capacity of MOFs for CO2/N2 separation61, 65. This could be interpreted that amino-MIL-53-DE and amino-MIL-53-DEA are likely to have a high catenated mesoporous content due to residual ethanol molecules inside the pores apart from the improved microporosity, therefore the selectivity of CO2 over N2 was increased. The residual alcohol molecules may lead to the reduced affinities toward nitrogen adsorption because ethanol effectively prevents the interaction between nitrogen molecules and the surface adsorbents 66.


Energy & Fuels

100000

Selectivity(CO/N) 2 2

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Page 16 of 21

Amino-MIL-53-DE Amino-MIL-53-DEA Amino-MIL-53-DM Amino-MIL-53 Amino-MIL-53-DMA

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Fig. 10 Selectivity of CO2/N2 by static adsorption at STP conditions

Table 2 Comparison of the selectivity among different porous materials. Material NUT-1 Amino-MIL-53-DEA COPs Zeolite-5A Amino-MIL-53-DM Mg-MOF-74 APS-MCM-48 Zeolite-NaX UiO-66-NO2-NH2 Amino-MIL-53 Cu-BTC Zn-MOF ZIF-8 MOF-177 Amino-MIL-53 MIL-53(Al) Activated carbon

Selectivity 10 140 637 288 240 153 148 >>100 88 64 43 (20–25) 20 23 17 18 7.5 5.8

(P, T) References (1 bar and 298K)67 (1 bar and 273K)This Work (1 bar and 323 K) 68 (1 bar and 298K)69 (1 bar and 273K)This work (1 bar and 323K)70 (1 bar and 298K)71 (1 bar and 323K)70 (1 bar and 273K)64 (1 bar and 298K) This Work (1 bar and 298K)72 (4.5Mpa and 298K)73 (0.1 bar and 298K)74 (1 bar and 298K)69 (1 bar and 303K)75 (5bar and 350K)76 (1 bar and 303K)77

4. Conclusion Several amino-MIL-53 were successfully synthesized by a protocol using co-solvent of DMF with methanol, ethanol, methanol/acetic acid, or ethanol/acetic acid. Due to the strong interactions of carbon dioxide with amino groups, the co-solvents can enhance the micropore size of the modified samples, 16 ACS Paragon Plus Environment

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Energy & Fuels

hence effectively improving CO2 adsorption capacity and selectivity of CO2/N2. The experiment reveals that amino-MIL-53-DMA demonstrates the greatest CO2 adsorption capacities and the lowest adsorption heat among the amino-MIL-53 samples, which is beneficial for facile regeneration of the material after adsorption for multiple uses. Besides, the separation performances of NH2-MIL-53-DEA and NH2-MIL-53-DE have been significantly improved compared with previous studies due to the large amounts of micro-porosity content with some mesopores in high catenation, benefited from the ethanol molecules inside the pores. Therefore, these materials can be applied as promising and green adsorbents for future applications of carbon dioxide storage and gas separation.

Acknowledgement We thank the Australian Research Council for partially financial support under project DP170104264. References 1.

V. Gupta, S. Srivastava, D. Mohan and S. Sharma, Waste Management, 1998, 17, 517-522.

2.

M. E. Davis, Nature, 2002, 417, 813-821.

3.

P. Yang, D. Zhao, D. I. Margolese, B. F. Chmelka and G. D. Stucky, Nature, 1998, 396, 152155.

4.

A. Jain, V. Gupta, A. Bhatnagar and Suhas, Separation Science and Technology, 2003, 38, 463481.

5.

T. A. Saleh and V. K. Gupta, Advances in Colloid and Interface Science, 2014, 211, 93-101.

6.

V. K. Gupta, R. Kumar, A. Nayak, T. A. Saleh and M. Barakat, Advances in Colloid and Interface Science, 2013, 193, 24-34.

7.

S. L. James, Chemical Society Reviews, 2003, 32, 276-288.

8.

A. R. Millward and O. M. Yaghi, Journal of the American Chemical Society, 2005, 127, 1799817999.

9.

R. Xiong, K. Odbadrakh, A. Michalkova, J. P. Luna, T. Petrova, D. J. Keffer, D. M. Nicholson, M. A. Fuentes-Cabrera, J. P. Lewis and J. Leszczynski, Sensors and Actuators B: Chemical, 2010, 148, 459-468.

10.

Q. Shuai, S. Chen and S. Gao, Structural Chemistry, 2007, 18, 689-695.

11.

Z. Chen, S. Xiang, H. D. Arman, J. U. Mondal, P. Li, D. Zhao and B. Chen, Inorganic Chemistry, 2011, 50, 3442-3446. 17 ACS Paragon Plus Environment

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

12.

Page 18 of 21

D. Britt, D. Tranchemontagne and O. M. Yaghi, Proceedings of the National Academy of Sciences, 2008, 105, 11623-11627.

13.

E. Stavitski, E. A. Pidko, S. Couck, T. Remy, E. J. M. Hensen, B. M. Weckhuysen, J. Denayer, J. Gascon and F. Kapteijn, Langmuir, 2011, 27, 3970-3976.

14.

M. Kandiah, M. H. Nilsen, S. Usseglio, S. Jakobsen, U. Olsbye, M. Tilset, C. Larabi, E. A. Quadrelli, F. Bonino and K. P. Lillerud, Chemistry of Materials, 2010, 22, 6632-6640.

15.

Z. Wang and S. M. Cohen, Journal of the American Chemical Society, 2007, 129, 12368-12369.

16.

D. Himsl, D. Wallacher and M. Hartmann, Angewandte Chemie International Edition, 2009, 48, 4639-4642.

17.

F. Su, C. Lu, S.-C. Kuo and W. Zeng, Energy & Fuels, 2010, 24, 1441-1448.

18.

T. Ahnfeldt, D. Gunzelmann, T. Loiseau, D. Hirsemann, J. r. Senker, G. Férey and N. Stock, Inorganic Chemistry, 2009, 48, 3057-3064.

19.

S. Couck, J. F. M. Denayer, G. V. Baron, T. Rémy, J. Gascon and F. Kapteijn, Journal of the American Chemical Society, 2009, 131, 6326-6327.

20.

X. Y. Chen, H. Vinh-Thang, D. Rodrigue and S. Kaliaguine, Industrial & Engineering Chemistry Research, 2012, 51, 6895–6906.

21.

O. A. El Seoud, Química Nova, 2010, 33, 2187-2192.

22.

T. M. K. Romuald I . Zalewski, John Shorter, Similarity Models in Organic Chemistry, Biochemistry and Related Fields (Studies in Organic Chemistry), ELSEVIER, New York, 1991.

23.

X. Yang and A. E. Clark, Inorganic Chemistry, 2014, 53, 8930-8940.

24.

C. V. McGuire and R. S. Forgan, Chemical Communications, 2015, 51, 5199-5217.

25.

A. Schaate, P. Roy, A. Godt, J. Lippke, F. Waltz, M. Wiebcke and P. Behrens, Chemistry – A European Journal, 2011, 17, 6643-6651.

26.

H. R. Abid, H. M. Ang and S. Wang, Nanoscale, 2012, 4, 3089-3094.

27.

F. Vermoortele, B. Bueken, G. Le Bars, B. Van de Voorde, M. Vandichel, K. Houthoofd, A. Vimont, M. Daturi, M. Waroquier, V. Van Speybroeck, C. Kirschhock and D. E. De Vos, Journal of the American Chemical Society, 2013, 135, 11465-11468.

28.

C. Goldblatt and A. J. Watson, Philosophical Transactions of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, 2012, 370, 4197-4216.

29.

P. R. Epstein and D. Ferber, Changing planet, changing health: how the climate crisis threatens our health and what we can do about it, Univ of California Press, 2011.


Page 19 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

30.

Energy & Fuels

J. A. Foley, N. Ramankutty, K. A. Brauman, E. S. Cassidy, J. S. Gerber, M. Johnston, N. D. Mueller, C. O’Connell, D. K. Ray and P. C. West, Nature, 2011, 478, 337-342.

31.

D. Farrusseng, Metal-organic frameworks: applications from catalysis to gas storage, John Wiley & Sons, 2011.

32.

P. K. Thallapally, J. Tian, M. Radha Kishan, C. A. Fernandez, S. J. Dalgarno, P. B. McGrail, J. E. Warren and J. L. Atwood, Journal of the American Chemical Society, 2008, 130, 1684216843.

33.

Y.-S. Bae, K. L. Mulfort, H. Frost, P. Ryan, S. Punnathanam, L. J. Broadbelt, J. T. Hupp and R. Q. Snurr, Langmuir, 2008, 24, 8592-8598.

34.

Z. H. Rada, H. R. Abid, J. Shang, H. Sun, Y. He, P. Webley, S. Liu and S. Wang, Industrial & Engineering Chemistry Research, 2016, 55, 7924–7932.

35.

Z. Zhang, Y. Zhao, Q. Gong, Z. Li and J. Li, Chemical Communications, 2013, 49, 653-661.

36.

B. Arstad, H. Fjellvåg, K. O. Kongshaug, O. Swang and R. Blom, Adsorption, 2008, 14, 755762.

37.

S. Couck, J. F. Denayer, G. V. Baron, T. Rémy, J. Gascon and F. Kapteijn, Journal of the American Chemical Society, 2009, 131, 6326-6327.

38.

A. Boutin, S. Couck, F.-X. Coudert, P. Serra-Crespo, J. Gascon, F. Kapteijn, A. H. Fuchs and J. F. M. Denayer, Microporous and Mesoporous Materials, 2011, 140, 108-113.

39.

H. R. Abid, Z. H. Rada, J. Shang and S. Wang, Polyhedron, 2016, 120, 103-111.

40.

W. Li, Y. Zhang, C. Zhang, Q. Meng, Z. Xu, P. Su, Q. Li, C. Shen, Z. Fan, L. Qin and G. Zhang, Nature Communications, 2016, 7, 11315.

41.

T. P. Silverstein and S. T. Heller, Journal of Chemical Education, 2017, 94, 690-695.

42.

M. Jóźwiak, H. Piekarski, A. Bińkowska and K. Łudzik, Journal of Thermal Analysis and Calorimetry, 2016, 126, 1645-1655.

43.

M. M. Hoffmann and M. S. Conradi, The Journal of Physical Chemistry B, 1998, 102, 263-271.

44.

T. Loiseau, C. Serre, C. Huguenard, G. Fink, F. Taulelle, M. Henry, T. Bataille and G. Férey, Chemistry – A European Journal, 2004, 10, 1373-1382.

45.

T. Ungár, Scripta Materialia, 2004, 51, 777-781.

46.

P. Vermeulen, R. A. H. Niessen and P. H. L. Notten, Electrochemistry Communications, 2006, 8, 27-32.

47.

H. R. Abid, J. Shang, H.-M. Ang and S. Wang, International Journal of Smart and Nano Materials, 2013, 4, 72-82. 19 ACS Paragon Plus Environment

Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

48.

Page 20 of 21

S. J. Gregg and K. S. W. Sing, Adsorption, surface area, and porosity, Academic Press, London; New York, 1982.

49.

K. Morishige and N. Tateishi, The Journal of Chemical Physics, 2003, 119, 2301-2306.

50.

E. P. Barrett, L. G. Joyner and P. P. Halenda, Journal of the American Chemical Society, 1951, 73, 373-380.

51.

G. Leofanti, M. Padovan, G. Tozzola and B. Venturelli, Catalysis Today, 1998, 41, 207-219.

52.

M. Absi-Halabi, A. Stanislaus and H. Al-Zaid, Applied Catalysis A: General, 1993, 101, 117128.

53.

M. Wagner, A. Apelblat and A. Tamir, The Journal of Chemical Thermodynamics, 1980, 12, 181-186.

54.

I. Persson, Pure and Applied Chemistry, 1986, 58, 1153.

55.

O. M. Yaghi, C. E. Davis, G. Li and H. Li, Journal of the American Chemical Society, 1997, 119, 2861-2868.

56.

C. Chmelik, H. Bux, J. Caro, L. Heinke, F. Hibbe, T. Titze and J. Kärger, Physical Review Letters, 2010, 104, 085902.

57.

D. Lozano-Castelló, D. Cazorla-Amorós and A. Linares-Solano, Carbon, 2004, 42, 1233-1242.

58.

G. Li and Z. Wang, Macromolecules, 2013, 46, 3058-3066.

59.

B. Liu, Y.-H. Jiang, Z.-S. Li, L. Hou and Y.-Y. Wang, Inorganic Chemistry Frontiers, 2015, 2, 550-557.

60.

R. V. Siriwardane, M.-S. Shen, E. P. Fisher and J. Losch, Energy & Fuels, 2005, 19, 11531159.

61.

B. Liu and B. Smit, Langmuir, 2009, 25, 5918-5926.

62.

D. M. D'Alessandro, B. Smit and J. R. Long, Angewandte Chemie International Edition, 2010, 49, 6058-6082.

63.

M.-S. Lee, M. Park, H. Y. Kim and S.-J. Park, Scientific reports, 2016, 6, 23224.

64.

Z. H. Rada, H. R. Abid, H. Sun and S. Wang, Journal of Chemical & Engineering Data, 2015, 60, 2152-2161.

65.

J. Kim, S.-T. Yang, S. B. Choi, J. Sim, J. Kim and W.-S. Ahn, Journal of Materials Chemistry, 2011, 21, 3070-3076.

66.

K. Kaneko, R. F. Cracknell and D. Nicholson, Langmuir, 1994, 10, 4606-4609.

67.

L.-B. Sun, Y.-H. Kang, Y.-Q. Shi, Y. Jiang and X.-Q. Liu, ACS Sustainable Chemistry & Engineering, 2015, 3, 3077-3085. 20 ACS Paragon Plus Environment

Page 21 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

68.

Energy & Fuels

H. A. Patel, S. Hyun Je, J. Park, D. P. Chen, Y. Jung, C. T. Yavuz and A. Coskun, Nature Communications, 2013, 4, 1357.

69.

D. Saha, Z. Bao, F. Jia and S. Deng, Environmental Science & Technology, 2010, 44, 18201826.

70.

J. A. Mason, K. Sumida, Z. R. Herm, R. Krishna and J. R. Long, Energy & Environmental Science, 2011, 4, 3030-3040.

71.

S. Kim, J. Ida, V. V. Guliants and Y. S. Lin, The Journal of Physical Chemistry B, 2005, 109, 6287-6293.

72.

Q. Yang, C. Xue, C. Zhong and J.-F. Chen, AIChE Journal, 2007, 53, 2832-2840.

73.

J. R. Karra and K. S. Walton, The Journal of Physical Chemistry C, 2010, 114, 15735-15740.

74.

Z. Zhang, S. Xian, Q. Xia, H. Wang, Z. Li and J. Li, AIChE Journal, 2013, 59, 2195-2206.

75.

S. Couck, E. Gobechiya, C. E. A. Kirschhock, P. Serra-Crespo, J. Juan-Alcañiz, A. Martinez Joaristi, E. Stavitski, J. Gascon, F. Kapteijn, G. V. Baron and J. F. M. Denayer, ChemSusChem, 2012, 5, 740-750.

76.

P. Mishra, H. P. Uppara, B. Mandal and S. Gumma, Industrial & Engineering Chemistry Research, 2014, 53, 19747-19753.

77.

C. Shen, C. A. Grande, P. Li, J. Yu and A. E. Rodrigues, Chemical Engineering Journal, 2010, 160, 398-407.


N2 on Amino-MIL

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