C2 Hydrocarbon Capture and Separation

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Tuning the CO2 and C1/C2 Hydrocarbon Capture and Separation Performance for Zn-F-Triazolate Framework through the Functional Amine Groups Haipeng Li, Shu-ni Li, Huaming Sun, Mancheng Hu, Yucheng Jiang, and Quan-Guo Zhai Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.8b00389 • Publication Date (Web): 09 Apr 2018 Downloaded from http://pubs.acs.org on April 11, 2018

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Crystal Growth & Design

Tuning the CO2 and C1/C2 Hydrocarbon Capture and Separation Performance for Zn-F-Triazolate Framework through the Functional Amine Groups Hai-Peng Li, Shu-Ni Li, Hua-Ming Sun, Man-Cheng Hu, Yu-Cheng Jiang, Quan-Guo Zhai* Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry & Chemical Engineering, Shaanxi Normal University, Xi’an, Shaanxi, 710062, China

ABSTRACT: The functionalization by amine groups has been recognized as an effective route to promote the gas capture and separation performance of MOF materials, however, it keeps elusive to date what is the optimal number of functional amine groups and which specific MOFs are suitable to be functionalized. To answer these questions, systemic investigations on the interactions between gas molecules and NH2-functionalized MOFs are necessary. Here a microporous Zn-F-triazolate framework which can be easily decorated by different -NH2 groups is selected (Zn-F-TRZ, Zn-F-ATRZ and Zn-F-DATRZ; TRZ = 1,2,4-triazole, ATRZ = 3-amino-1,2,4-triazole, DATRZ = 3,5-diamino-1,2,4-triazole) to discuss the effect of amine groups on the CO2 and C1/C2 hydrocarbon capture and separation. When the pressure is lower than about 0.15 atm, the CO2 uptakes increase directly with the number of anime groups (Zn-F-TRZ < Zn-F-ATRZ < Zn-F-DATRZ). But at 1 atm, the decoration of one amine group effectively improves the CO2 adsorption of Zn-F-triazolate framework, and the addition of the second amine group clearly decreases the CO2 uptakes. Similar uptake trend has been observed for C1/C2 hydrocarbons except for C2H2, which decrease dramatically 1

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with the number of amine groups. These results show that the combination of amine functional groups and appropriate pore size is responsible for the low-pressure binding and uptake of CO2 and C1/C2 hydrocarbon molecules in Zn-F-triazolate MOFs. Furthermore, thanks to the functionalization by amine groups, these Zn-F-triazolate frameworks all show excellent gas separation performance. Specially, the initial C2H2/CH4 selectivity (107.0) for Zn-F-ATRZ, and initial CO2/CH4 (115.7), C2H4/CH4 (78.9) and CO2/C2H2 (5.9) selectivities for Zn-F-DATRZ at room temperature all surpass most of the reported MOFs up to now.

■ INTRODUCTION Metal organic frameworks (MOFs) also known as porous coordination polymers (PCPs) have received tremendous interest due to their adjustable composition, designable pore size, and easily modified pore surface.1-10 According to the size of the pore channels and the interaction between host and guest in the framework, MOFs can be used to restrict the entry and exit of different kinds of gas molecules to realize the selective uptake and separation. However, the performance of many reported MOF materials cannot reach industrial demands to date. Therefore, the functionalization of MOFs has attracted considerable attention because this strategy usually can lead to higher gas uptake performance or separation efficiency compared with the original MOFs.11-14 Lewis basic amine group, which could afford stronger interactions with acidic gas molecules such as CO2 and thereby lead to enhanced selective gas adsorption ability. In the literature, a larger number of amine-functionalized MOFs have been synthesized and tested for CO2 uptakes.15-17 For example, Zhang and Chen et al. have systematically investigated the 2


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design and synthesis of anime-functionalized porous frameworks, which demonstrate high CO2 adsorption capacity and high gas selectivity.18 Vaidhyanathan et al. reported the low-pressure binding and large uptake of amine-functionalized MOFs for CO2 trough a crystallographic resolution.19 Long and coworkers showed that ethylenediamine modified CuBTTri MOF exhibits an extremely high isosteric heat of CO2 adsorption up to 90 kJ mol-1 at zero coverage.20 Wang et al. have synthesized a series of anime-functionalized transition metal triazolate polycarboxylate frameworks, which all show high CO2 uptake and highly selective sorption of CO2 over N2.21 While a wide variety of MOFs can be modified for CO2 uptake and separation, it remains elusive which specific MOFs are suitable to be functionalized, and what is the optimal number of functional amine groups. It is thus of great significance to systemically investigate on the interactions between CO2 molecules and NH2-functionalized MOFs. On the other hand, although the amine-functionalized MOFs have exhibited high CO2 uptake performance, only a small number of them show outstanding selectivity for CO2 over CH4.22-25 Furthermore, the adsorption and separation of C2 hydrocarbons (C2H2 and C2H4) from CH4 mixtures utilizing amine-functionalized MOFs has been much less explored. In fact, the separation of CO2 and C2 hydrocarbons from CH4 is important for the natural gas upgrading. It is noted that just like CO2, C2H2 and C2H4 both are acidic gas molecules, which may also have strong interactions with Lewis basic amine group. Thus, amine-functionalized MOFs should be ideal agents to realize high adsorption capacity and separations of CO2 or C2 hydrocarbons from CH4. Prior to this work, a Zn-BDC-triazolate MOF consisting of amino-decorated polyhedral 3



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cages have been designed by our group, which show high CO2 uptake capacity.26 Also, we have reported a systematic design of functionalized Zn-triazolate-dicarboxylate pillar-layered MOFs, which show high CO2 uptake capacity as well as CO2 over CH4 and C2 hydrocarbons over CH4 selectivity.27 In this work, three members of microporous Zn-F-triazolate MOFs, Zn-F-TRZ,

Zn-F-ATRZ

and

Zn-F-DATRZ

(TRZ

=

1,2,4-triazole,

ATRZ

=

3-amino-1,2,4-triazole, DATRZ = 3,5-diamino-1,2,4-triazole) decorated by different number of NH2 groups are selected to discuss the effect of amine groups on the CO2 and C1/C2 hydrocarbon capture and separation. Our results show that the combination of amine functional groups and appropriate pore size is responsible for the low-pressure binding and uptake of CO2 and C1/C2 hydrocarbon molecules in Zn-F-triazolate MOFs. Furthermore, thanks to the functionalization by amine groups, these Zn-F-triazolate frameworks all show excellent gas separation performance at room temperature.

■ EXPERIMENTAL SECTION General Methods. All chemicals and reagents were used as received without further purification. The FT-IR spectra (KBr pellets) were recorded on a Nicolet Avatar 360 FT-IR spectrometer in the range of 4000-400 cm-1 (Figure S1). The powder X-ray diffraction patterns (PXRD) were recorded on a Rigaku DMAX 2500 powder diffractmeter at 40 kV and 100 mA using Cu-Kα (λ = 1.54056Å), with a scan speed of 0.2 s/step at room temperature. Thermal stability studies were carried out on a NETSCHZ STA-449C thermoanalyzer under air atmosphere (30-700 oC range) at a heating rate of 5 oC/min (Figure S2). Synthesis of Zn-F-Triazolate Frameworks. Three Zn-F-triazolate MOFs were 4


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synthesized by a slightly modified route according to the literature reported by Su et al.28 A mixture of 2 mmol 1,2,4-triazole derivatives (0.14 g TRZ or 0.17 g ATRZ or 0.2 g DATRZ), zinc fluoride tetrahydrate (0.35 g, 2 mmol) and 10 mL H2O were placed into a 25 mL Teflon lined autoclave and heated at 180 oC 5 days. The mixture was then cooled to room temperature. Pure colorless hexagonal needle-shaped crystals of Zn-F-TRZ and Zn-F-ATRZ, and polycrystalline sample of Zn-F-DATRZ were obtained and dried under air. Their phase pure of these MOF materials were confirmed by powder X-ray diffraction. Gas Adsorption. Gas sorption isotherms were measured on a Micromeritics ASAP 2020 HD88 surface-area. All used gases were of 99.99% purity. Prior to sorption analysis, the Zn-F-triazolate MOFs were loaded into the sample tube and dried at 120 oC for 12 h by using the “outgas” function of the surface area analyzer. The gas sorption isotherms for N2 and H2 were measured at 77 K with liquid nitrogen. The gas sorption isotherms for CO2, CH4, C2H2, and C2H4 were measured at 273 or 298 K, respectively. Isosteric Analysis of the Heat of Adsorption. To extract the coverage-dependent isosteric heat of adsorption, the adsorption data were modeled with a virial-type expression29 composed of parameters ai and bi, which are independent of temperature: lnP = lnN +

1 T

m

n

∑ ai N i +

∑b N

i =0

i =0

i

(1)

i

m

Qst = - R ∑ ai N i

(2)

i =0

Where P is pressure, N is the amount adsorbed (or uptake), T is temperature, m and n determine the number of terms required to adequately describe the isotherm. R is the universal gas constant. The coverage dependencies of Qst calculated from fitting the 5



adsorption data at 273 and 298 K under the pressure range from 0-1 bar. Selectivity Prediction for Binary Mixture Adsorption. We used the ideal adsorbed solution theory (IAST) to predict binary mixture adsorption from the experimental pure-gas isotherms.30 To perform the integrations required by IAST, the single-component isotherms should be fitted by a proper model. The DSLF equation was found to the best fit to the experimental pure isotherms for CO2, C2H2, and C2H4 and CH4. On the base of the equation parameters of pure gas adsorption, the IAST model was further used to investigate the separation of CO2/CH4, CO2/C2H2, CO2/C2H4, C2H2/CH4, C2H4/CH4, and C2H2/C2H4. The adsorption selectivity is defined by sA/ B =

xA / y A xB / yB

(3)

Where xi and yi are the mole fractions of component i (i = A and B) in the adsorbed and bulk phases, respectively. Note that in the Henry regime SA/B is identical to the ratio of the Henry constants of the two species.

■ RESULTS AND DISCUSSION Syntheses and Crystal Structures. As stated above, amine group can provide stronger interactions with acidic gas molecules and thus amine-functionalized MOFs should be ideal candidates for CO2 and C1/C2 hydrohcarbon capture and separation. However, the adsorption and separation of C1/C2 hydrocarbons via amine-functionalized MOFs is rarely explored. Moreover, most of the reported amine-functionalized MOFs were casually obtained by trial-and-error, resulting in the absence of systematic investigation for the effect of amine functional groups on gas capture and separation performance. 6


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Fig. 1 Microporous Zn-F-triazolate frameworks investigated in this work. The single crystal structures of Zn-F-triazolate frameworks investigated in this work were firstly reported by Su and co-worker28 in 2004, which are of exceptionally high thermally stability and have 1-D honeycomb tubular channels (Figure 1). In the homogenous framework, each Zn2+ center has a trigonal bipyramidal geometry with the three equatorial sites occupied by a nitrogen atom from three separate TRZ ligands and the two apical positions occupied by F anion. All three nitrogen atoms in TRZ ring are coordinated to different Zn2+ centers, and the Zn2+ centers are further connected by F anions that act as µ2-bridging atoms to link two neighboring Zn2+ centers. Thus, propagation of the structure in the crystal involves the µ3-TRZ units and the µ2-F anions to generate a 3D framework containing hexagonal channels (Figure 1). As indicted in the FT-IR spectra (Figure S1), two series of bands in the ranges of 1000–1750 and 3000–3750 cm-1 all are ascribed to the 1,2,4-traizolate derivatives. It is interesting that substituent groups on the 3 and 5-postions of the 1,2,4-triazole ring just 7



point into the hexagonal channels, creating a functionalizable inner environment. Obviously, this provides an ideal model to systematically study the effect of amine groups on gas capture and separation performance since the amino-substituted 1,2,4-triazole derivatives are cheap and easily achieved. A simple and effective synthetic procedure led to three Zn-F-triazolate frameworks decorated by different NH2 groups, namely, Zn-F-TRZ, Zn-F-ATRZ and

Zn-F-DATRZ. As shown in Figure 1, the effective diameter of the hexagonal tubes Zn-F-triazolate frameworks is reduced by the number of the amine groups, which is about 6.3 Å, 5.2 Å and 4.7 Å for Zn-F-TRZ, Zn-F-ATRZ and Zn-F-DATRZ, respectively (Figure 1). Thus, the tunable pore size together with the amine-functionalized inner environment makes Zn-F-triazolate MOFs ideal candidates for CO2 and C1/C2 hydrocarbon capture and separation. To the best of our knowledge, Su and co-works25 only investigated the thermal stability, guest removal and solid-state transformation of these compounds and no gas uptake and separation results reported to date.

Fig. 2 PXRD patterns for three Zn-F-triazolate frameworks. 8


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Gas Adsorption. The adsorption properties of Zn-F-triazolate frameworks for small molecule gases such as N2, H2, CO2, CH4, C2H2 and C2H4 were systematically done to investigate the effect of Lewis basic amine groups. Before the gas adsorption experiments, MOF samples were heated at 120 oC to remove the guest molecules. As shown in Figure 2, the well-matched PXRD patterns proved not only the purity but also the stability of Zn-F-triazolate frameworks. The N2 sorption isotherms at 77 K indicate negligible uptakes for three Zn-F-triazolate MOFs, which should be ascribed to their small pore sizes. It is noted that at 77 K and 1 atm, the H2 uptakes also are very low, which are of 4.9 cm3 g−1 for Zn-F-TRZ, 23.8 cm3 g−1 for

Zn-F-ATRZ, 5.7 cm3 g−1 for Zn-F-DATRZ (Figure S3). The low sorption behaviors may be ascribed to the formation of different guest dependent sorption states instead of simple pore filling. Such special sorption phenomena have been scarcely reported and similar phenomenon had been observed by Chen and co-works for the methyl-functionalized Zn-F-triazolate MOF.31 CO2 adsorption-desorption isotherms were measured at 273 and 298 K. As shown in Figure 3 and Table S1, the CO2 uptakes are 39.1 cm3 g−1 for Zn-F-TRZ, 61.9 cm3 g−1 for

Zn-F-ATRZ, and 28.4 cm3 g − 1 for Zn-F-DATRZ at 273 K and 1 atm. At 298 K, Zn-F-ATRZ exhibits the highest CO2 uptake of 34.8 cm3 g−1, and Zn-F-DATRZ shows the lowest value of 22.7 cm3 g−1. Zn-F-TRZ shows the modest value of 25.9 cm3 g−1. It is noted that when the pressure is lower than about 0.15 atm, the CO2 uptakes increase directly with the number of anime groups (Zn-F-TRZ < Zn-F-ATRZ < Zn-F-DATRZ). But at 1 atm, the decoration of one amine group effectively improves the CO2 adsorption, and the addition of 9



the second amine group clearly decreases the CO2 uptakes. That is the CO2 uptake amounts at 1 atm follow the order: Zn-F-TRZ < Zn-F-DATRZ < Zn-F-ATRZ. Obviously, the pore size and amine-functionality work together to decide the CO2 adsorption of Zn-F-triazolate MOFs. In the Zn-F-ATRZ MOF, amino groups play an important role, but in Zn-F-DATRZ are the pore size. Moreover, the CO2 uptake (28.4 cm3 g−1) of Zn-F-DATRZ at 273 K and 1 atm is basically equal to that of CH3-functionalized MOF31 at 195 K, which demonstrates the stronger interactions between NH2 groups and CO2 molecules once again.

Fig. 3 CO2, CH4, C2H2 and C2H4 uptakes for three Zn-F-triazolate frameworks at 273 K. The CH4 uptake capacities are of 7.2 and 4.0 cm3 g−1 for Zn-F-TRZ, 10.5 and 6.7 cm3 g−1 for Zn-F-ATRZ, and 5.6 and 2.0 cm3 g−1 for Zn-F-DATRZ at 273 K and 298 K (1 atm, Figure 3). The significantly lower CH4 uptake values should be due to the weak interaction 10


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between CH4 molecules and the frameworks with narrow cross pores. As sated above, the separation of CO2 and C2 hydrocarbons from CH4 is important for the natural gas upgrading. Just like CO2, C2H2 and C2H4 both are acidic gas molecules, which may also have strong interactions with Lewis basic amine group. Thus, the adsorption of C2H2 and C2H4 for these Zn-F-triazolate MOFs are further done (Figure 3). At 273 K and 1 atm, the C2H2 and C2H4 uptakes are 41.8 and 21.9 cm3 g 1 for Zn-F-TRZ, 31.9 and 22.9 cm3 g 1 for Zn-F-ATRZ, −

−

10.7 and 13.6 cm3 g 1 for Zn-F-DATRZ. At 298 K and 1 atm, Zn-F-TRZ shows the highest −

C2H2 uptake of 29.9 cm3 g 1 (Table S1). Obviously, the C2H2 uptake amounts decrease rapidly −

with the number of anime groups (Zn-F-TRZ > Zn-F-ATRZ > Zn-F-DATRZ), which show that the pore size should a crucial factor for the C2H2 adsorption. Although the C2H2 and C2H4 gas adsorption capacities of these Zn-F-triazolate MOFs are not very impressive, their accessible starting materials and easily handled situations still make them promising for C2 hydrocarbons over CH4 separation applications.

Fig. 4 The isosteric heats of adsorption (Qst) for three Zn-F-triazolate frameworks. Isosteric Heats of Adsorption. To further understand the above gas adsorption properties of 11



Zn-F-triazolate frameworks, the isosteric heat of adsorption (Qst) of CO2, C2H2, C2H4 and CH4 was determined by fitting the adsorption data collected at 273 and 298 K to the virial model (Figures 4 and S4-S6). The Qst values for C2H2 C2H4, CH4, and CO2 at zero coverage are 54.9, 23.1, 20.7, and 14.7 kJ mol-1 for Zn-F-TRZ, 26.3, 52.8, 13.5, and 9.6 kJ mol-1 for

Zn-F-ATRZ, and 20.0, 20.8, 15.6 and 24.9 kJ mol-1 for Zn-F-DATRZ. The highest Qst value for CO2 of Zn-F-DATRZ among three isomers also indicates the strongest interactions between NH2 groups and CO2 molecules. On the other hand, the Qst for C2H2 of Zn-F-TRZ are much higher than many top C2H2 uptake MOFs such as ZJU-30a (31.3 kJ mol-1),32 UTSA-33a (33 kJ mol-1),33 UTSA-67a (32 kJ mol-1)34 and HKUST-1 (30.4 kJ mol-1).35 This may be caused by the existence of F anions in the framework. The Qst values for C2H2 decrease to 26.3 and 20.0 kJ mol-1 for Zn-F-ATRZ and Zn-F-DATRZ, which may be caused that the decoration of NH2 groups will hinder the F anions and thus decrease the interaction between C2H2 and F anions. Overall, the Qst values for CO2 and C1/C2 hydrocarbons in Zn-F-triazolate frameworks are clearly lower than those in MOFs with high densities of open metal sites such as MOF-74 series (41-46 kJ mol-1)36 and UTSA-60a (36 kJ mol-1),37 however, these results suggest that energy required to regenerate MOF adsorbents will be lower than them.

CO2/CH4 and CO2/C2 Hydrocarbons Selectivity. The above-mentioned isothermal adsorption results indicate that these Zn-F-triazolate MOFs can selectively adsorb CO2 and C1/C2 hydrocarbons over CH4. To predict CO2/CH4, CO2/C2H2, and CO2/C2H4 binary mixture selectivity, an ideal adsorbed solution theory (IAST) calculation based on a dual site Langmuir-Freundlich (DSLF) simulation was employed on the basis of the single-component 12


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CO2, C2H2, C2H4, and CH4 adsorption isotherms.

Fig. 5 Comparison of experimental and simulated adsorption isotherms (Left Y axis), and mixture adsorption selectivity predicted by IAST (Right Y axis) of Zn-F-DATRZ, and summary of CO2/CH4, CO2/C2H2 and CO2/C2H4 selectivity at 298 K for three Zn-F-triazolate frameworks. Table S2 and Figure 5 shows the adsorption selectivity of three MOFs for CO2 (50%) and CH4 (50%). At 298 K, the initial CO2/CH4 selectivity values are estimated to be 3.3 for

Zn-F-TRZ, 10.2 for Zn-F-ATRZ, and 115.7 for Zn-F-DATRZ, which are significantly higher than the values of many reported MOFs, such as ZIF-6938 and NOTT-101a.39 These values are estimated to be 1.0, 13.6 and 28.4 at 273 K, respectively. It is clear that the

Zn-F-DATRZ has the highest selective for CO2/CH4 due to the presence of two amino groups in the pore of the framework providing a Lewis base site that enhances the effect of CO2 on the framework. In addition, steric hindrance may also play an important role for the 13



gas selectivity since the molecule sizes of CO2 and CH4 are different. Also, the predicted mixture adsorption selectivity for CO2/C2H2 (50:50) and CO2/C2H4 (50:50) were calculated (Figures 5 and S7-S9). At 298 K, the initial CO2/C2H2 and CO2/C2H4 selectivity values are estimated to be 0.07 and 0.1 for Zn-F-TRZ, 0.09 and 4.8 for

Zn-F-ATRZ, 5.9 and 1.9 for Zn-F-DATRZ. The CO2/C2H4 (4.8) for Zn-F-ATRZ and CO2/C2H2 (5.9) for Zn-F-DATRZ both are impressive since limited MOF materials show selective adsorption for CO2, C2H2 and C2H4 molecules because of their similarity. The initial CO2/C2H2 selectivity is comparable to SNNU-65-Cu-Sc (6.7) and SNNU-65-Cu-In (7.0) recently reported by our group.40 To the best of our knowledge, the most promising MOFs for C2H2/CO2 separation such as HKUST-1 (11.0),41 ZJU-40 (11.5),42 UTSA-50 (13.3)43 and SNNU-65-Cu-Ga (18.7)40 all are benefited from open metals sites (OMSs). Moreover, taking advantages of strong C-H···F hydrogen bonds, a series of SIFSIX-MOF ultramicroporous MOF materials44,45 have exhibited promising CO2 and C2H4 exclusion from C2H2 under ambient conditions. Herein, Zn-F-DATRZ presents a rare example without OMSs or SiF62anions but shows high C2H2/CO2 separation performance, which should mainly be ascribed to the functionalized amine groups since the molecule sizes of CO2 and C2H2 are similar.

C2 Hydrocarbons/CH4 and C2H2/C2H4 Selectivity. Figure 6 shows the predicted selectivity between C1/C2 hydrocarbons. At 298 K, the initial C2H2/CH4 and C2H4/CH4 selectivity values are estimated to be 82.2 and 47.2 for Zn-F-TRZ, 107.0 and 12.7 for Zn-F-ATRZ, 2.4 and 78.9 for Zn-F-DATRZ (Table S1). At 273 K, these values increase to be 255.9 and 68.3, 215.3 and 35.1, and 15.14 and 219, respectively. Even more, Zn-F-TRZ and Zn-F-ATRZ both have potential separation ability for C2H2 and C2H4 mixture. The initial selectivity 14


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values are estimated to be 2.4 for Zn-F-TRZ, and 27.5 for Zn-F-ATRZ at 298 K. These values all are considered of very high selectivity among the limited MOFs investigated so far for separations of C1/C2 hydrocarbons.40,

46, 47

Overall, the high and tunable C2H2/CH4,

C2H4/CH4 and C2H2/C2H4 selective performance (Figures S10-S13) could be due to the synergistic effect of NH2 functional groups and their narrow cross pores, which make microporus Zn-F-triazolate framework a potential adsorbent for the natural gas upgrading application.

Fig. 6 Comparison of gas selectivity predicted by IAST at 298 K for three Zn-F-triazolate frameworks.

■ CONCLUSIONS 15



In summary, by utilizing the cheap and easily achieved 1,2,4-triazole derivative ligands, three members of microporus Zn-F-triazolate framework decorated by different NH2 groups are obtained via a simple and effective synthetic route. Thanks to the synergistic effect of NH2 functional groups and narrow and tunable cross pores, Zn-F-triazolate frameworks exhibit selectively binding and uptake of CO2 and C1/C2 hydrocarbon molecules. Specially, the C2H2/C2H4 selectivity for Zn-F-ATRZ, and CO2/CH4, C2H4/CH4 and CO2/C2H2 selective values for Zn-F-DATRZ at room temperature all are among the top-high MOF materials investigated so far. These results clearly demonstrate that Zn-F-triazolate frameworks are of potential applications for the separation of CO2 and C2 hydrocarbons from CH4 during natural gas upgrading.

■ ASSOCIATED CONTENT Supporting Information FT-IR spectra, TGA curves, gas adsorption isotherms, gas selective figures and tables. The Supporting Information is available free of charge on the ACS Publications website.

■ AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected] (Q.-G. Zhai)

Notes The authors declare no competing financial interest.

■ ACKNOWLEDGMENTS 16


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This work is financially supported by the National Natural Science Foundation of China (21671126), the Fundamental Research Funds for the Central Universities (GK201701003), and the Natural Science Foundation of Shaanxi Province (2014KJXX-50).

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For Table of Contents Use Only

The CO2 and C1/C2 hydrocarbon capture and separation performance for Zn-F-triazolate microporous framework were systematically investigated through tuning the Lewis base NH2 sites on the pore surface.

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C2 Hydrocarbon Capture and Separation

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