Microporous Polybenzoxazoles with Tunable Porosity and Heteroatom

Article Cite This: J. Phys. Chem. C XXXX, XXX, XXX−XXX

pubs.acs.org/JPCC

Microporous Polybenzoxazoles with Tunable Porosity and Heteroatom Concentration for Dynamic Adsorption/Separation of CO2 Mixed Gases Biao Zhang, Jun Yan, and Zhonggang Wang* State Key Laboratory of Fine Chemicals, Department of Polymer Science and Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China S Supporting Information *

ABSTRACT: Three hyper-cross-linked microporous polybenzoxazoles (PBO-M, PBO-Ad, and PBO-Si) with uniform pores are synthesized through “one-pot” condensation polymerizations from 3,3′-diamino-4,4′-dihydroxybiphenyl with tetrakis(4-formylphenyl)methane, 1,3,5,7-tetrakis(4formyphenyl)adamantane, and tetrakis(4-formylphenyl)silane, respectively. Their porosity parameters and chemical compositions, such as microporous sizes (0.98−1.46 nm), ratios of microporous volume to total porous volume (0.36−0.53), ratios of O/C (0.156−0.195), and N/C (0.079−0.095), are finely tunable. The adsorption properties of CO2, N2, and CH4 measured through the static adsorption isotherms of singlecomponent gases and dynamic breakthrough curves are comparatively studied. Among the three polymers, PBO-M possesses the smallest pore size and the highest concentrations of heteroatoms, and consequently shows the largest CO2 adsorption capacity (11.6 wt %, 273 K/1 bar) and highest separation factors of CO2/N2 (96.6) and CO2/CH4 (12.4). The results are interpreted in terms of the porous structure, isosteric enthalpies of adsorption, and the physicochemical parameters of polymer skeletons and gases in detail.

■

separation under the real flowing condition of the mixed gases. Nevertheless, the breakthrough experiment still is seldom employed for microporous organic polymers although it has been reported in the other adsorbents, such as metal−organic frameworks (MOFs)27 and molecularly imprinted adsorbent.28 Heteroaromatic polybenzoxazoles (PBOs) have been widely used in aeronautics and astronautics as reinforcing fibers for advanced composites29 and functional membrane materials30−34 due to the outstanding mechanical strength, chemical, and thermal-oxidative stability. However, hyper-cross-linked microporous PBOs for gas adsorption/separation have been seldom reported. Additionally, PBOs are usually synthesized through tedious two-step synthesis procedures, i.e., presynthesis of the precursors and the subsequent thermal cyclization at a very high temperature (350−450 °C).31 Recently, El-Kaderi et al. reported benzoxazole-linked polymers with Brunauer− Emmett−Teller (BET) surface areas of 658−759 m2 g−1.35 McGrier and co-workers prepared two-dimensional benzobisoxazole-linked covalent organic frameworks in the presence of sodium cyanide catalyst.36 On the basis of the above considerations, herein, a series of hyper-cross-linked microporous polybenzoxazoles are designed

INTRODUCTION Microporous organic polymers (MOPs) are currently a subject of considerable academic and industrial interest1−4 because of their large specific surface area, excellent thermal and chemical stability, tunable chemical and porous structure, as well as fascinating potential applications in heterogeneous catalysis,5−7 chemical sensing,8−10 ultralow dielectricity,11 and gas adsorption/separation,12−21 including CO2 capture from flue gas, stripping CO2 from natural gas and landfill gas, CO2 removal from mixtures with H2 in reformer gas for fuel cells, etc. Moreover, in CO2 capture area, the economical and convenient adsorption/recovery process by means of MOPs is competitive with traditional fluidized bed of aqueous amine solution because of the drawbacks, such as corrosion and volatility of amines and high energy cost of regeneration.22 As CO2 capture materials, high adsorption selectivity of CO2 over N2 and CH4 is essentially important to efficiently adsorb CO2 from postcombustion flue gas or precombustion natural gas and landfill gas. Previously, for microporous organic polymers, the adsorption selectivity was commonly assessed by means of the ratios of the initial adsorption slopes of two gases in Henry’s law region23−25 or the calculations using ideal adsorbed solution theory.26 The above-mentioned static theoretical methods cannot reflect the actual adsorption/ separation situation. As an alternative tool, the dynamic breakthrough adsorption experiment is able to evaluate the © XXXX American Chemical Society

Received: March 30, 2018 Revised: May 15, 2018

A

DOI: 10.1021/acs.jpcc.8b03031 J. Phys. Chem. C XXXX, XXX, XXX−XXX

Article

The Journal of Physical Chemistry C Scheme 1. Synthesis Routes to the Microporous Polybenzoxazoles

tetraaldehyde monomers tetrakis(4-formylphenyl)methane,47 tetrakis(4-formylphenyl)silane, 48 and 1,3,5,7-tetrakis(4formyphenyl)adamantane49 were synthesized according to the procedure reported in previous papers. Synthesis of Tetraphenyladamantane-Based Microporous Polybenzoxazole (PBO-Ad). Under nitrogen protection, a 50 mL Schlenk flask was charged with the solution of 3,3′-diamino-4,4′-dihydroxybiphenyl (0.2508 g, 1.16 mmol) in DMF (5 mL). The system was cooled to −30 °C, and a solution of 1,3,5,7-tetrakis(4-formyphenyl)adamantane (0.3194 g, 0.58 mmol) in DMF (10 mL) was added dropwise. After stirring at −30 °C for 12 h, the mixture was heated to room temperature and continually reacted for 24 h. The reaction system was flushed with air for 10 min and capped. Then, the temperature was raised to 130 °C and kept at this temperature for 72 h. The resultant brown solid was collected and successively washed with DMF, acetone, CH2Cl2, and THF. Finally, the product was extracted with THF in a Soxhlet apparatus for 24 h and dried at 120 °C under vacuum to give PBO-Ad (0.49 g, 88%). Elemental analysis (wt %) for theoretical values: C, 81.92; H, 4.88; N, 6.16. Found: C, 77.14; H, 4.73; N, 6.13. Synthesis of Tetraphenylmethane-Based Microporous Polybenzoxazole (PBO-M). The synthetic procedure of PBO-M is the same as that of PBO-Ad except that the

and synthesized via one-pot polymerization technique. The selection of different building blocks tetraphenyladamantane, tetraphenymethane, and tetralphenylsilane is intended to tune porosity parameters and N, O concentrations in the networks. The previous reports have revealed that the modification of porous adsorbents with heteroatoms, including porous silicas or zeolites,37−42 MOFs,43 and MOPs,16,44−46 indeed can greatly improve their adsorption capacity of CO2 and selectivity over other gases. The gas adsorption and separations of CO2, N2, and CH4 are investigated by means of both dynamic breakthrough curves of CO2/N2 and CO2/CH4 mixed gases and static adsorption isotherms of single-component gases. The results are studied by relating to the tuned porosity parameters and the varied N/C and O/C elemental ratios, which will be helpful for deeply understanding the effect of porous and chemical structures on the adsorption/separation behaviors of CO2 mixed gases in microporous polymers under the actual gas flowing condition.

■

EXPERIMENTAL SECTION

Materials. N,N-Dimethyformamide (DMF), tetrahydrofuran (THF), acetone, dichloromethane, and other reagents were purchased from Shanghai Chemical Reagent Co. and used as received. DMF was purified by distillation under reduced pressure. 3,3′-diamino-4,4′-dihydroxybiphenyl32 and three B


Article

The Journal of Physical Chemistry C tetraaldehyde monomer charged in the system was tetrakis(4formylphenyl)methane instead of 1,3,5,7-tetrakis(4formyphenyl)adamantane. Elemental analysis (wt %) for theoretical values: C, 80.70; H, 4.09; N, 7.10. Found: C, 74.37; H, 4.03; N, 7.09. Synthesis of Tetraphenylsilane-Based Microporous Polybenzoxazole (PBO-Si). The synthetic procedure of PBO-Si is the same as that of PBO-Ad except that the tetraaldehyde monomer charged in the system was tetrakis(4formylphenyl)silane instead of 1,3,5,7-tetrakis(4-formyphenyl)adamantane. Elemental analysis (wt %) for theoretical values: C, 77.59; H, 4.01; N, 6.96. Found: C, 73.61; H, 3.97; N, 6.84. Instrumentation. Fourier transform infrared (FT-IR) spectra were recorded on a Nicolet 20XB FT-IR spectrophotometer in 400−4000 cm−1. Solid-state 13C cross polarization magic angle spinning (CP/MAS) spectra were recorded using a Varian Infinity-Plus 400 spectrometer at 100.61 MHz at an MAS rate of 10.0 kHz. Elemental analyses were determined with an Elementar Vario EL III elemental analyzer. Wide-angle X-ray diffractions (WAXD) from 5 to 80° were performed on a Rigaku D/max-2400 X-ray diffractometer (40 kV, 200 mA) with a copper target at a scanning rate of 2° min−1. Thermogravimetric analysis curves were recorded on a NETZSCH TG 209 thermal analyzer by heating the sample up to 800 °C at a rate of 10 °C min−1 under nitrogen flow. Adsorption and desorption measurements for all of the gases were conducted on an Autosorb iQ (Quantachorme) analyzer. The dynamic breakthrough curves were recorded on the dynamic gas adsorption apparatus built in our group (see Supporting Information for the details).

Figure 1. Solid-state 13C MAS NMR spectra (right) for the PBO networks. Asterisks (*) indicate peaks arising from spinning side bands.

quaternary carbons in PBO-Ad are found at 40 and 47 ppm, respectively.49 The elemental analyses show that the measured contents of hydrogen and nitrogen agree well with the theoretical values. The lower carbon contents probably are caused by the absorbed moisture from air of the porous samples during measurement operation. Porosity Parameters in PBOs and the Relations with Building Blocks. The adsorption isotherms of nitrogen at 77 K are illustrated in Figure 2a, from which the porosity parameters of PBOs are calculated and summarized in Table 1. The BET surface areas in PBO-Ad, PBO-Si, and PBO-M are in the range from 625 to 745 m2 g−1. Additionally, each sample shows a rapid uptake of nitrogen at the initial relative pressure, exhibiting the characteristic of microporous materials.51 Meanwhile, the isotherm of PBO-Ad shows the continuous rise of N2 uptake with pressure, indicative of the existence of mesopores in the network. The adsorption−desorption isotherms of the three polymers are nearly reversible, implying that the hypercross-linked polybenzoxazole skeletons are quite rigid and much different from many other MOPs, which often show apparent adsorption−desorption hysteresis loops because of the deformation of pores under the measurement pressure due to the softness of organic segments. The pore sizes and distributions of the three polybenzoxazole networks analyzed from the adsorption isotherms by nonlocal density functional theory are illustrated in Figure 2b. Their major pores locate in the microporous region, agreeing with the observation in the adsorption isotherms of nitrogen at 77 K. Their pore sizes are ranked in the order of PBO-Ad (1.41 nm) > PBO-Si (1.22 nm) > PBO-M (0.99 nm). As expected, the incorporation of bulky rigid tetraphenyladamantanes in the network effectively forces the polymer segments apart. Consequently, PBO-Ad exhibits the largest micropore size among the three polymers and even shows small amounts of mesopore at 4.39 nm (Table 1). Its micropore size increases by 42% compared to that of PBO-M. In addition, the lower electronegativity of silicon relative to carbon atom leads to the longer Si−C bond (1.87 Å) than C−C bond (1.55 Å), as calculated by Materials Studio software. As a result, the relatively larger molecular volume of tetralphenylsilane than tetraphenymethane can explain why the micropore size of PBO-Si (1.22 nm) exceeds that of PBO-M (0.99 nm) although the tetrahedron configurations of tetrakis(4-formylphenyl)methane and tetrakis(4-formylphenyl)silane are quite similar.

■

RESULTS AND DISCUSSION Synthesis and Characterization of Microporous Polybenzoxazoles. As shown in Scheme 1, microporous polybenzoxazoles PBO-Ad, PBO-M, and PBO-Si were synthesized via condensation polymerizations under air atmosphere from 1,3,5,7-tetrakis(4-formyphenyl)adamantane, tetra kis(4-formylphenyl)methane, and t etrakis(4formylphenyl)silane with 3,3′-diamino-4,4′-dihydroxybiphenyl, respectively. The abundant oxygen and nitrogen heteroatoms in the oxazole rings are homogeneously distributed within the polymer networks. The resultant products are insoluble in common organic solvents, reflecting the typical characteristic of hyper-cross-linked polymers. All of the three polybenzoxazoles are amorphous, as indicated by the wide-angle X-ray diffraction patterns (Figure S1, Supporting Information). In addition, they show excellent thermal stabilities with the decomposition temperatures of skeleton over 500 °C and the char yields over 57 wt % in the thermogravimetric curves (Figure S2, Supporting Information) recorded under N2 atmosphere. The FT-IR spectra (Figure S3, Supporting Information) confirm the formation of the polybenzoxazoles by the appearances of bands at 1615, 1465, and 1056 cm−1 belonging to the stretching vibrations of CN, C−N, and C−O bonds in the oxazole ring, respectively.31 In addition, the bands at 2854 and 2930 cm−1 are attributed to the cycloaliphatic C−H bonds in PBO-Ad. In the solid-state 13C CP/MAS NMR spectra (Figure 1), the signal at 163 ppm belongs to the carbon of −O−CN− in oxazole ring,35 the peak at 137 ppm in PBO-Si is due to the phenyl carbon adjacent to the silicon atom,50 whereas the overlapping peaks from 105 to 153 ppm are corresponded to the other aromatic carbons. The quaternary carbon in PBO-M locates at 65 ppm, and the secondary and C


Article

The Journal of Physical Chemistry C

Figure 2. (a) Adsorption (filled) and desorption (empty) isotherms of N2 at 77 K for PBO-M (+400), PBO-Si (+200), and PBO-Ad and (b) pore size distributions for PBO-M, PBO-Si, and PBO-Ad.

Table 1. Porosity Parameters of PBOs Obtained by N2 Adsorption samples

SBETa (m2 g−1)

Smicrob (m2 g−1)

Vmicroc (cm3 g−1)

Vtotald (cm3 g−1)

Vmicro/Vtotal

pore size (nm)

PBO-M PBO-Si PBO-Ad

745 625 741

541 422 418

0.24 0.19 0.20

0.45 0.43 0.55

0.53 0.44 0.36

0.99 1.22 1.41, 4.39

a Calculated by the Brunauer−Emmett−Teller method. bMicroporous surface area calculated by the t-plot method. cMicroporous volume calculated by the t-plot method. dTotal porous volume calculated at P/Po = 0.90.

The CO2 adsorption data are summarized in Table 2. At 273 K and 1 bar, the adsorption capacities of CO2 for PBO-M, PBO-Ad, and PBO-Si are 11.6, 10.1, and 9.6 wt %, respectively, which are comparable to the amine-functionalized silica SBA1 5/AP 3, 3 8 m i c r o p o r o u s le a d −o r g a n i c f r a m e w o r k {[Pb 4 (MTB) 2 ]} n , 52 zinc(II) metal−organic framework {[Zn2(μ4-MTB)(κ4-CYC)2]·2DMF·7H2O}n,53 and many other microporous polymer-like microporous cyanate resins,50,54,55 microporous poly(Schiff base)s,56 microporous polyimides.57,58 Besides, it is noted that PBO-M has the smaller total pore volume (0.45 m3 g−1) than PBO-Ad (0.55 m3 g−1), but its CO2 uptake exceeds that of PBO-Ad. This peculiar result is attributed to two reasons. First, as shown in Table 1, PBO-M has the smaller pore size and larger micropore surface area (Smicro) than PBO-Ad, and the ratio of Vmicro/Vtotal (0.53) is considerably superior to higher than that of PBO-Ad (0.36). A larger proportion of micropores in porous materials is favorable for CO2 adsorption,59−61 especially for its separation ability from other gases like nitrogen and methane (the detailed separation property of CO2 gas will be discussed below). Second, relative to PBO-Ad, PBO-M contains more CO2-philic heteroatoms in the skeleton. Both N/C and O/C elemental ratios in PBO-M are considerably higher than those in PBO-Ad (Table 2). The above two factors commonly contribute to the higher CO2 uptake in PBO-M. The interaction between CO2 and porous PBO skeletons was studied in terms of the adsorption enthalpies (Qst) calculated by Clausius−Clapeyron equation from the adsorption isotherms at two measurement temperatures. As shown in Figure 4a, the Qst values of CO2 drop with the loading amount, meaning that the interaction between CO2 and the pore wall is stronger than that between CO2 molecules. The virial plots of CO2 for PBOs at both 273 and 298 K exhibit quite good

Moreover, compared to PBO-Ad and PBO-Si, the smaller micropore size in PBO-M also results in the largest microporous specific surface area (541 m2 g−1) and microporous volume (0.24 m3 g−1) among the three polymers. Adsorption of CO2 by Static Method and Their Correlations with Pore Structure in PBOs. The sorption isotherms of pure CO2 gas measured by physical sorption instrument at 273 and 298 K are presented in Figure 3. The adsorption−desorption curves are completely reversible. Hence, the adsorbed CO2 gas in the microporous PBOs can be readily released under the reduced pressure, which is desirable taking account of the subsequent requirements for recovery of CO2 gas and reusability of the adsorbents.

Figure 3. Adsorption (filled) and desorption (empty) isotherms of CO2 for PBOs at 273 and 298 K. D


Article


Table 2. Capacity and Enthalpy of Adsorption for CO2, Selectivities of CO2/N2 and CO2/CH4, and O, N Concentrations in PBOs CO2 uptake (wt %)a PBO-M PBO-Si PBO-Ad

selectivityb

273 K

298 K

CO2/N2

CO2/CH4

Q0c (kJ mol−1)

N/Cd

O/Cd

11.6 9.6 10.1

5.4 4.9 5.2

96.6 80.8 68.9

12.4 8.5 7.3

34.4 33.0 32.1

0.095 0.093 0.079

0.195 0.165 0.156

a c

Uptakes at 1 bar. bAdsorption selectivity measured by the breakthrough method for the gas mixtures of CO2/N2 (15/85) and CO2/CH4 (50/50). Limiting enthalpy of adsorption. dN/C and O/C ratios obtained from elemental analysis.

Figure 4. (a) Variations of enthalpies of adsorption with the adsorbed amount of CO2 and (b) virial plots of CO2 gas in PBO-M, PBO-Si, and PBOAd at 273 K and 298 K.

Figure 5. Breakthrough curves of PBOs for mixed gases of CO2/N2 (15/85) (a−c) and CO2/CH4 (50/50) (a′−c′) at 273 K. E


Article


Table 3. Adsorption Capacities for CO2 at 0.15 and 0.5 bar, N2 at 0.85 bar, and CH4 at 0.5 bar Obtained by Breakthrough Experiments and Single-Component Adsorption Isotherms at 273 K breakthrough experimenta CO2

a

single-component adsorption isothermsa

N2

CH4

N2

CH4

sample

0.15 bar

0.50 bar

0.85 bar

0.50 bar

0.15 bar

CO2 0.50 bar

0.85 bar

0.50 bar

PBO-M PBO-Si PBO-Ad

4.05 3.61 3.75

8.41 7.01 7.48

0.15 0.16 0.20

0.25 0.30 0.37

3.77 3.33 3.23

8.08 6.85 7.00

0.63 0.43 0.37

0.75 0.57 0.68

The unit of the adsorption capacity is weight percentage (wt %).

experiments under the flowing mixed gas condition show the higher CO2 adsorption capacities, and on the contrary the considerably lower uptakes of N2 and CH4. Consequently, all of the three microporous polybenzoxazoles show excellent separation ability of CO2 over N2 and CH4. Moreover, for PBO-M, its CO2/N2 selectivity (96.6) is the highest among the three polymers (Table 2). Similar to CO2/N2, the selectivity of CO2/CH4 for PBO-M (12.4) is also superior to those of PBOSi (8.5) and PBO-Ad (7.3) because PBO-M has the higher nitrogen and oxygen contents as well as the smaller pore size and larger ratio of Vmicro/Vtotal than the other two polymers. In addition, using PBO-M as a representative sample, the breakthrough experiments for the mixed CO2/N2 (15/85) gas at three different gas flowing rates of 5.0, 7.5, and 10.0 mL min−1 were performed (Figure S6). The results in Table S1 show that with the increase of flowing rate, the adsorption capacity of CO2 slightly decreases, whereas that of N2 increases, and the selectivity of CO2/N2 correspondingly drops from 96.6 to 80.4.

straight lines (Figure 4b), from which Henry’s constants (KH) are obtained, and the limiting enthalpies of adsorption (Q0) at zero surface CO2 coverage are derived from the plots of ln KH vs 1/T. Table 2 shows that the Q0 values in this series of porous PBOs are ranked in the order of PBO-M (34.4 KJ mol−1) > PBO-Si (33.0 KJ mol−1) > PBO-Ad (32.1 KJ mol−1), which is inversely related to their microporous sizes, and has the same sequence as the N/C and O/C ratios, suggesting that the smaller microporous size and the higher contents of heteroatom are indeed advantageous for the affinity of polymer skeleton for CO2 molecule. PBOs have the higher adsorption enthalpies than zeolite ITQ-6 but lower than the aminefunctionalized ITQ-6/AP (47 KJ mol−1), owing to the formation of ammonium carbamate between CO2 molecule and amine group.41 In addition, for PBO-Si, despite its higher adsorption enthalpy than PBO-Ad, its adsorption capacity is the lowest among the three polymers because of its apparently smaller BET surface area and total pore volume than the other two polymers. Adsorption/Separations of CO 2/N 2 and CO 2/CH 4 Gases by the Dynamic Breakthrough Method. To confirm the actual gas adsorption/separation ability of porous PBOs under flowing mixed gases conditions, their breakthrough experiments at 273 K for the binary gas mixtures of CO2/N2 (15/85) and CO2/CH4 (50/50) were conducted with the column with the length of 10 cm and internal diameter of 6 mm packed with the polymer samples. The obtained breakthrough curves measured with the gas flowing rate of 5 mL min−1 are illustrated in Figure 5. It is seen that the nonpolar N2 and CH4 gases without a strong interaction with polymer skeleton breakthrough the column first, followed by CO2 after 6−10 min for CO2/N2 and 2−3 min for CO2/CH4 mixed gases. During this time interval, the detected concentrations of out-flowing gas by gas chromatography are nearly 0% for CO2 and 100% for N2 or CH4, meaning that either CO2/N2 or CO2/CH4 mixed gas can be completely separated through the column packed with any of the three microporous PBOs. The fed mixed gas of CO2/N2 for the breakthrough experiment contains 15% CO2 and 85% N2, implying that the partial pressures of CO2 and N2 are 0.15 and 0.85 bar, respectively. Likewise, the partial pressures of CO2 and CH4 in the fed mixed gas of CO2/CH4 (50/50) are 0.50 and 0.50 bar, respectively. To elucidate the competitive adsorption of CO2 against N2 and CH4 gases, the adsorption capacities for CO2 at 0.15 and 0.50 bar, N2 at 0.85 bar, and CH4 at 0.50 bar were calculated from the breakthrough curves according to eq S1 (Supporting Information), and the obtained data together with those from the single-component gas adsorption isotherms (Figure S5) are summarized in Table 3. It is seen that at the same gas pressure, in comparison with the adsorption measurements of the static pure gases, the breakthrough

■

CONCLUSIONS Three nitrogen- and oxygen-rich microporous polybenzoxazoles PBO-M, PBO-Ad, and PBO-Si were successfully synthesized and well characterized. Their pore sizes, the ratios of microporous volume to total porous volume, the ratios of O/ C and N/C are effectively tuned through systematically varying the building blocks in the cross-linked networks. The comparative studies about the adsorptions of CO2, N2, and CH4 are conducted by means of dynamic breakthrough curves and static single-component gas adsorption isotherms. In comparison with the results obtained from the adsorption isotherms of the pure gases, at the same temperature and gas pressure, the breakthrough experiments under the flowing mixed gas conditions show the higher CO2 adsorption capacities and considerably lower uptakes of N2 and CH4. As a result, the three microporous polybenzoxazoles display excellent separation ability of CO2 over N2 and CH4. In addition, relative to PBO-Ad and PBO-Si, the synergistic effect of the smaller pore size, larger micropore surface area and the ratio of microporous volume to total porous volume, as well as more CO2-philic heteroatoms in PBO-M results in its largest CO2 uptake (11.6 wt %, 273 K/1 bar) and highest selectivity of CO2/N2 (96.9) and CO2/CH4 (12.4) among the three polymers, exhibiting potential application in CO2 capture from flue gas and stripping CO2 from natural gas or landfill gas.

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpcc.8b03031. F


Article


■

(13) Islamoglu, T.; Kim, T.; Kahveci, Z.; El-Kadri, O.; El-Kaderi, H. M. Systematic Postsynthetic Modification of Nanoporous Organic Frameworks for Enhanced CO2 Capture from Flue Gas and Landfill Gas. J. Phys. Chem. C 2016, 120, 2592−2599. (14) Alkordi, M. H.; Haikal, R. R.; Hassan, Y. S.; Emwas, A.; Belmabkhout, Y. Poly-functional Porous-Organic Polymers to Access Functionality-CO2 Sorption Energetic Relationships. J. Mater. Chem. A 2015, 3, 22584−22590. (15) Soliman, A. B.; Haikal, R. R.; Hassan, Y. S.; Alkordi, M. H. The Potential of a Graphene-Supported Porous-organic Polymer (POP) for CO2 Electrocatalytic Reduction. Chem. Commun. 2016, 52, 12032− 12035. (16) Lu, W.; Sculley, J. P.; Yuan, D.; Krishna, R.; Zhou, H. C. Carbon Dioxide Capture from Air Using Amine-Grafted Porous Polymer Networks. J. Phys. Chem. C 2013, 117, 4057−4061. (17) Yu, M.; Wang, X.; Yang, X.; Zhao, Y.; Jiang, J. X. Conjugated Microporous Copolymer Networks with Enhanced Gas Adsorption. Polym. Chem. 2015, 6, 3217−3223. (18) Yao, H.; Zhang, N.; Song, N.; Shen, K.; Huo, P.; Zhu, S.; Zhang, Y.; Guan, S. Microporous Polyimide Networks Constructed through a Two-Step Polymerization Approach, and Their Carbon Dioxide Adsorption Performance. Polym. Chem. 2017, 8, 1298−1305. (19) Suresh, V. M.; Bonakala, S.; Balasubramanian, S.; Maji, T. K.; et al. Amide Functionalized Microporous Organic Polymer (AmMOP) for Selective CO2 Sorption and Catalysis. ACS Appl. Mater. Interfaces 2014, 6, 4630−4637. (20) Ullah, R.; Atilhan, M.; Anaya, B.; Al-Muhtaseb, S.; Aparicio, S.; Patel, H.; Thirion, D.; Yavuz, C. T. Investigation of Ester- and AmideLinker-Based Porous Organic Polymers for Carbon Dioxide Capture and Separation at Wide Temperatures and Pressures. ACS Appl. Mater. Interfaces 2016, 8, 20772−20785. (21) Ding, L.; Gao, H.; Xie, F.; Li, W.; Bai, H.; Li, L. PorosityEnhanced Polymers from Hyper-Cross-Linked Polymer Precursors. Macromolecules 2017, 50, 956−962. (22) Rochelle, G. T. Amine Scrubbing for CO2 Capture. Science 2009, 325, 1652−1654. (23) Rabbani, M. G.; El-Kaderi, H. M. Synthesis and Characterization of Porous Benzimidazole-Linked Polymers and Their Performance in Small Gas Storage and Selective Uptake. Chem. Mater. 2012, 24, 1511−1517. (24) Luo, Y.; Li, B.; Wang, W.; Wu, K.; Tan, B. Hypercrosslinked Aromatic Heterocyclic Microporous Polymers: A New Class of Highly Selective CO2 Capturing Materials. Adv. Mater. 2012, 24, 5703−5707. (25) Song, W. C.; Xu, X. K.; Chen, Q.; Zhuang, Z. Z.; Bu, X. H. Nitrogen-Rich Diaminotriazine-Based Porous Organic Polymers for Small Gas Storage and Selective Uptake. Polym. Chem. 2013, 4, 4690− 4696. (26) Myers, A.; Prausnitz, J. M. Thermodynamics of Mixed-Gas Adsorption. AlChE J. 1965, 11, 121−127. (27) Bae, Y. S.; Lee, C. Y.; Kim, K. C.; Farha, O. K.; Nickias, P.; Hupp, J. T.; Nguyen, S. T.; Snurr, R. Q. High Propene/Propane Selectivity in Isostructural Metal-Organic Frameworks with High Densities of Open Metal Sites. Angew. Chem., Int. Ed. 2012, 51, 1857− 1860. (28) Zhao, Y.; Shen, Y.; Ma, G.; Hao, R. Adsorption Separation of Carbon Dioxide from Flue Gas by a Molecularly Imprinted Adsorbent. Environ. Sci. Technol. 2014, 48, 1601−1608. (29) Zhang, K.; Han, L.; Froimowicz, P.; Ishida, H. A Smart Latent Catalyst Containing o-Trifluoroacetamide Functional Benzoxazine: Precursor for Low Temperature Formation of Very High Performance Polybenzoxazole with Low Dielectric Constant and High Thermal Stability. Macromolecules 2017, 50, 6552−6560. (30) Park, H. B.; Jung, C. H.; Lee, Y. M.; Hill, A. J.; Pas, S. J.; Mudie, S. T.; Wagner, E.; Freeman, B. D.; Cookson, D. J. Polymers with Cavities Tuned for Fast Selective Transport of Small Molecules and Ions. Science 2007, 318, 254−258. (31) Patel, H. A.; Ko, D.; Yavuz, C. T. Nanoporous Benzoxazole Networks by Silylated Monomers, Their Exceptional Thermal

WAXD pattern, thermogravimetric analysis curves, FTIR spectra, single-component adsorption isotherms of three gases, breakthrough curves and adsorption capacity of CO2 at 0.15 bar and N2 at 0.85 bar of PBO-M for mixed gases of CO2/N2 (15/85) at three different rates, scheme and description of the dynamic breakthrough apparatus (PDF)

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Zhonggang Wang: 0000-0003-0451-1919 Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS The financial supports from the National Science Foundation of China (nos. 51473026 and U1462125) and the Fundamental Research Funds for the Central Universities (DUT18GF107) are acknowledged. We would like to thank Prof. Anhui Lu at School of Chemical Engineering, Dalian University of Technology for his kind help in the set up of the breakthrough apparatus.

■

REFERENCES

(1) McKeown, N. B.; Budd, P. M. Exploitation of Intrinsic Microporosity in Polymer-Based Materials. Macromolecules 2010, 43, 5163−5176. (2) Dawson, R.; Cooper, A. I.; Adams, D. J. Nanoporous Organic Polymer Networks. Prog. Polym. Sci. 2012, 37, 530−563. (3) Li, L.; Cai, K.; Wang, P.; Ren, H.; Zhu, G. Construction of Sole Benzene Ring Porous Aromatic Frameworks and Their High Adsorption Properties. ACS Appl. Mater. Interfaces 2015, 7, 201−208. (4) Thomas, A. Functional Materials: From Hard to Soft Porous Frameworks. Angew. Chem., Int. Ed. 2010, 49, 8328−8344. (5) Xu, Y.; Wang, T.; He, Z.; Zhong, A.; Yu, W.; Shi, B.; Huang, K. Synthesis of Triphenylphosphine-Based Microporous Organic Nanotube Framework Supported Pd Catalysts with Excellent Catalytic Activity. Polym. Chem. 2016, 7, 7408−7415. (6) Haikal, R. R.; Wang, X.; Hassan, Y. S.; Parida, M. R.; Murali, B.; Mohammed, O. F.; Pellechia, P. J.; Fontecave, M.; Alkordi, M. H. Porous-Hybrid Polymers as Platforms for Heterogeneous Photochemical Catalysis. ACS Appl. Mater. Interfaces 2016, 8, 19994−20002. (7) Deng, G. Y.; Wang, Z. G. Hierarchical Porous Phenolic Resin and Its Supported Pd-Catalyst for Suzuki-Miyaura Reactions in Water Medium. Macromol. Rapid Commun. 2018, 39, No. 1700618. (8) Xu, Y.; Jin, S.; Xu, H.; Nagai, A.; Jiang, D. Conjugated Microporous Polymers: Design, Synthesis and Application. Chem. Soc. Rev. 2013, 42, 8012−8031. (9) Bi, S. M.; Li, Y. K.; Wang, L. M.; Hu, J.; Liu, H. L. Constructing Diketopyrrolopyrrole-Based Fluorescent Porous Organic Polymer for Chromo Communication via Guest-to-Host Energy Transfer. J. Phys. Chem. C 2017, 121, 6685−6691. (10) Zhang, B.; Yan, J.; Shang, Y. Q.; Wang, Z. G. Synthesis of Fluorescent Micro- and Mesoporous Polyaminals for Detection of Toxic Pesticides. Macromolecules 2018, 51, 1769−1776. (11) Zhang, B. F.; Wang, Z. G. Microporous Thermosetting Film Constructed from Hyperbranched Polyarylate Precursors Containing Rigid Tetrahedral Core: Synthesis, Characterization, and Properties. Chem. Mater. 2010, 22, 2780−2789. (12) Islamoglu, T.; Behera, S.; Kahveci, Z.; Tessema, T. D.; Jena, P.; El-Kaderi, H. M. Enhanced Carbon Dioxide Capture from Landfill Gas Using Bifunctionalized Benzimidazole-Linked Polymers. ACS Appl. Mater. Interfaces 2016, 8, 14648−14655. G


Article

The Journal of Physical Chemistry C Stability, and Carbon Dioxide Capture Capacity. Chem. Mater. 2014, 26, 6729−6733. (32) Calle, M.; Lee, Y. M. Thermally Rearranged (TR) Poly(etherbenzoxazole) Membranes for Gas Separation. Macromolecules 2011, 44, 1156−1165. (33) Alghunaimi, F.; Ghanem, B.; Wang, Y.; Salinas, O.; Alaslai, N.; Pinnau, I. Synthesis and Gas Permeation Properties of a Novel Thermally-Rearranged Polybenzoxazole Made from an Intrinsically Microporous Hydroxyl-Functionalized Triptycene-Based Polyimide Precursor. Polymer 2017, 121, 9−16. (34) Luo, S.; Liu, J.; Lin, H.; Kazanowska, B. A.; Hunckler, M. D.; Roeder, R. K.; Guo, R. Preparation and Gas Transport Properties of Triptycene-Containing Polybenzoxazole (PBO)-Based Polymers Derived from Thermal Rearrangement (TR) and Thermal Cyclodehydration (TC) Processes. J. Mater. Chem. A 2016, 4, 17050− 17062. (35) Rabbani, M. G.; Islamoglu, T.; El-Kaderi, H. M. Benzothiazoleand Benzoxazole-Linked Porous Polymers for Carbon Dioxide Storage and Separation. J. Mater. Chem. A 2017, 5, 258−265. (36) Pyles, D. A.; Crowe, J. W.; Baldwin, L. A.; McGrier, P. L. Synthesis of Benzobisoxazole-Linked Two-Dimensional Covalent Organic Frameworks and Their Carbon Dioxide Capture Properties. ACS Macro Lett. 2016, 5, 1055−1058. (37) Zhao, Y.; Shen, Y.; Bai, L. Effect of Chemical Modification on Carbon Dioxide Adsorption Property of Mesoporous Silica. J. Colloid Interface Sci. 2012, 379, 94−100. (38) Zukal, A.; Jagiello, J.; Mayerová, J.; Č ejka, J. Thermodynamics of CO2 Adsorption on Functionalized SBA-15 Silica. NLDFT Analysis of Surface Energetic Heterogeneity. Phys. Chem. Chem. Phys. 2011, 13, 15468−15475. (39) Sayari, A.; Belmabkhout, Y. Stabilization of Amine-Containing CO2 Adsorbents: Dramatic Effect of Water Vapor. J. Am. Chem. Soc. 2010, 132, 6312−6314. (40) Fayaz, M.; Sayari, A. Long-Term Effect of Steam Exposure on CO2 Capture Performance of Amine-Grafted Silica. ACS Appl. Mater. Interfaces 2017, 9, 43747−43754. (41) Zukal, A.; Dominguez, I.; Mayerová, J.; Č ejka, J. Functionalization of Delaminated Zeolite ITQ-6 for the Adsorption of Carbon Dioxide. Langmuir 2009, 25, 10314−10321. (42) Grajciar, L.; Cejka, J.; Zukal, A.; Arean, C. O.; Palomino, G. T.; Nachtigall, P. Controlling the Adsorption Enthalpy of CO2 in Zeolites by Framework Topology and Composition. ChemSusChem 2012, 5, 2011−2022. (43) Vaidhyanathan, R.; Iremonger, S. S.; Dawson, K. W.; Shimizu, G. K. H. An Amine-Functionalized Metal Organic Framework for Preferential CO2 Adsorption at Low Pressures. Chem. Commun. 2009, 5230−5232. (44) Deng, G.; Wang, Z. G. Triptycene-Based Microporous Cyanate Resins for Adsorption/Separations of Benzene/Cyclohexane and Carbon Dioxide Gas. ACS Appl. Mater. Interfaces 2017, 9, 41618− 41627. (45) Gu, S.; Guo, J.; Huang, Q.; He, J.; Fu, Y.; Kuang, G.; Pan, C.; Yu, G. 1,3,5-Triazine-Based Microporous Polymers with Tunable Porosities for CO2 Capture and Fluorescent Sensing. Macromolecules 2017, 50, 8512−8520. (46) Liao, Y.; Cheng, Z.; Zuo, W.; Thomas, A.; Faul, C. F. NitrogenRich Conjugated Microporous Polymers: Facile Synthesis, Efficient Gas Storage, and Heterogeneous Catalysis. ACS Appl. Mater. Interfaces 2017, 9, 38390−38400. (47) Zeng, L.; Liao, P.; Liu, H.; Liu, L.; Liang, Z.; Zhang, J.; Chen, L.; Su, C. Y. Impregnation of Metal Ions into Porphyrin-Based Imine Gels to Modulate Guest Uptake and to Assemble a Catalytic Microfluidic Reactor. J. Mater. Chem. A 2016, 4, 8328−8336. (48) Zou, L.; Feng, D.; Liu, T. F.; Chen, Y. P.; Fordham, S.; Yuan, S.; Tian, J.; Zhou, H. C. Facile One-Pot Synthesis of Porphyrin Based Porous Polymer Networks (PPNs) as Biomimetic Catalysts. Chem. Commun. 2015, 51, 4005−4008. (49) Li, G.; Zhang, B.; Wang, Z. G. Microporous Poly(Schiff Base) Constructed from Tetraphenyladamantane Units for Adsorption of

Gases and Organic Vapors. Macromol. Rapid Commun. 2014, 35, 971− 975. (50) Yu, H.; Shen, C.; Tian, M.; Qu, J.; Wang, Z. G. Microporous Cyanate Resins: Synthesis, Porous Structure, and Correlations with Gas and Vapor Adsorptions. Macromolecules 2012, 45, 5140−5150. (51) Sing, K. S. W. Reporting Physisorption Data for Gas Solid Systems with Special Reference to the Determination of Surface-Area and Porosity. Pure Appl. Chem. 1985, 57, 603−619. (52) Almásǐ , M.; Zeleňaḱ , V.; Gyepes, R.; Bourrelly, S.; Opanasenko, M. V.; Llewellyn, P. L.; Č ejka, J. Microporous Lead-Organic Framework for Selective CO2 Adsorption and Heterogeneous Catalysis. Inorg. Chem. 2018, 57, 1774−1786. (53) Almásǐ , M.; Zeleňaḱ , V.; Zukal, A.; Kuchár, J.; Č ejka, J. A Novel Zinc(II) Metal-Organic Framework with a Diamond-Like Structure: Synthesis, Study of Thermal Robustness and Gas Adsorption Properties. Dalton Trans. 2016, 45, 1233−1242. (54) Yu, H.; Shen, C.; Wang, Z. G. Micro-and Mesoporous Polycyanurate Networks Based on Triangular Units. ChemPlusChem 2013, 78, 498−505. (55) Shen, C.; Yu, H.; Wang, Z. Synthesis of 1,3,5,7-Tetrakis(4Cyanatophenyl)-Adamantane and Its Microporous Polycyanurate Network for Adsorption of Organic Vapors, Hydrogen and Carbon Dioxide. Chem. Commun. 2014, 50, 11238−11241. (56) Li, G. Y.; Zhang, B.; Yan, J.; Wang, Z. G. Micro- and Mesoporous Poly(Schiff-Base)s Constructed from Different Building Blocks and Their Adsorption Behaviors towards Organic Vapors and CO2 Gas. J. Mater. Chem. A 2014, 2, 18881−18888. (57) Shen, C. J.; Wang, Z. G. Tetraphenyladamantane-Based Microporous Polyimide and Its Nitro-Functionalization for Highly Efficient CO2 Capture. J. Phys. Chem. C 2014, 118, 17585−17593. (58) Li, G. Y.; Wang, Z. G. Naphthalene-Based Microporous Polyimides: Adsorption Behavior of CO2 and Toxic Organic Vapors and Their Separation from Other Gases. J. Phys. Chem. C 2013, 117, 24428−24437. (59) Yuan, Y.; Sun, F.; Li, L.; Cui, P.; Zhu, G. Porous Aromatic Frameworks with Anion-Templated Pore Apertures Serving as Polymeric Sieves. Nat. Commun. 2014, 5, No. 4260. (60) Zhang, B.; Wang, Z. Building Ultramicropores within Organic Polymers Based on a Thermosetting Cyanate Ester Resin. Chem. Commun. 2009, 33, 5027−5029. (61) Yu, L.; Falco, C.; Weber, J.; White, R. J.; Howe, J. Y.; Titirici, M. M. Carbohydrate-Derived Hydrothermal Carbons: A Thorough Characterization Study. Langmuir 2012, 28, 12373−12383.

H


Microporous Polybenzoxazoles with Tunable Porosity and Heteroatom

Recommend Documents