11814 | Chem. Commun., 2015, 51, 11814--11817 This journal is©The Royal Society of Chemistry 2015

Cite this:Chem. Commun., 2015,

51, 11814

Hydrophobic zeolites coated with microporousorganic polymers: adsorption behavior ofammonia under humid conditions†

Sungah Kang,a Jiseul Chun,a Nojin Park,a Sang Moon Lee,a Hae Jin Kimb andSeung Uk Son*a

ZSM-5 nanoparticles coated with microporous organic polymers

showed 88% retention of ammonia adsorption capacity at 43% RH.

Zeolites are microporous aluminosilicate materials in which Al3+

and Si4+ form tetrahedral geometry by chemical bonding withoxygen.1 The resultant networks have a crystalline inner struc-ture. Among zeolites, ZSM-5 is the first entry of the pentasilzeolite family.2 Its discovery has been regarded as a milestone inzeolite chemistry.3 ZSM-5 has 5.6 Å sized pores surrounded by10 rings. Due to the microporosity with regular pore structureand surface activity, ZSM-5 has been applied as a powerfulcatalyst in petroleum industries and an efficient adsorbent forsmall molecules.4 In these applications, the hydrophilic or hydro-phobic properties of the zeolites are important factors in inter-action with guest molecules including solvents.4

Recently, chemical engineering of hydrophobic zeolites hasattracted significant attention of scientists.5 Hydrophobic zeo-lites showed much better catalytic performance for biofuelupgrading reactions in organic solvent/water interface, comparedwith conventional zeolites.5a It is also noteworthy that zeoliteshave been applied extensively as catalysts in organic media.6 Inaddition, hydrophobic zeolites showed promising adsorptionperformance toward target guests under humid conditions.5b–h

In these reports,5 hydrophobic zeolites showed not only enhancedstability in water but also selective interaction towards targetsubstrates. The common molecular method known in the litera-ture for obtaining the hydrophobic zeolites is the treatment ofzeolites with surfactants containing long alkyl chains.5a,b Thismethod has a limitation in the thickness control of hydrophobiccoating on the surface of zeolites. In addition, surfactants can bepotentially detached during chemical processes. Notwithstanding

the great potential in various applications, the chemicalapproaches for hydrophobic zeolites are quite limited andrequire further exploration.

Microporous organic polymers (MOPs) are a recent class ofporous materials.7 Various MOP materials have been preparedby coupling reactions of organic building blocks.7,8 Because oftheir organic nature, the MOP materials usually exhibit hydro-phobic nature, up to super-hydrophobicity (water contact angle41501).9 Our research group has studied functional MOPmaterials.10 Recently, we have shown that the MOP materialscan be engineered on various inorganic supports includingsilica, iron oxide, and metal organic frameworks.11 We specu-lated that the formation of MOP materials on the surface ofzeolites can be an efficient strategy for hydrophobic zeolites. Inthis work, we report the preparation of hydrophobic zeolites bycoating ZSM-5 with MOPs, the thickness control of MOPmaterials on ZSM-5, and their adsorption behavior of ammoniaunder humid conditions.

Fig. 1 shows a synthetic scheme for the preparation of ZSM-5@MOP materials.

ZSM-5 nanoparticles were prepared by literature methods.12

The ZSM-5 nanoparticles were coated with MOPs via Sonogashira

Fig. 1 Synthetic scheme of the ZSM-5@MOP and hollow MOP.

a Department of Chemistry and Department of Energy Science, Sungkyunkwan

University, Suwon 440-746, Korea. E-mail: sson@skku.edu; Fax: +82-031-290-4572b Korea Basic Science Institute, Daejeon 350-333, Korea

† Electronic supplementary information (ESI) available: Experimental details,SEM images of ZSM-5 and ZSM-5@MOP materials, solid phase 13C NMR spectraof ZSM-5@MOP materials, additional NH3 adsorption behavior of ZSM-5, ZSM-5@MOP, and hollow MOP materials. See DOI: 10.1039/c5cc03470a

Received 26th April 2015,Accepted 16th June 2015

DOI: 10.1039/c5cc03470a

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coupling of tetrakis(4-ethynylphenyl)methane and 1,4-diiodobenzene(see Experimental section in the ESI† for the detailed procedure).The white ZSM-5 powder became pale yellow after coating of MOPmaterials. The thickness of MOPs in the ZSM-5@MOP was con-trolled by changing the amount of building blocks. The materialsobtained using 0.20 g ZSM-5 and 10 mg, 20 mg, and 40 mg oftetrakis(4-ethynylphenyl)methane were denoted as ZSM-5@MOP-1,ZSM-5@MOP-2, and ZSM-5@MOP-3, respectively. The resultantmaterials were investigated by various analysis techniques.

According to transmission electron spectroscopy (TEM), theZSM-5 particles have B340 nm diameter (Fig. 2a and Fig. S1 inthe ESI†). When a water drop was loaded on the pellet of ZSM-5,it was absorbed completely into the pellet, indicating the hydro-philicity of materials (Fig. 2b and c). The thickness of MOPmaterials in ZSM-5@MOP materials increased gradually fromZSM-5@MOP-1 to ZSM-5@MOP-2, and ZSM-5@MOP-3 (Fig. 2d–fand Fig. S2 in the ESI†). The water contract angles for ZSM-5@MOP-1, ZSM-5@MOP-2, and ZSM-5@MOP-3 increased from1181 to 1361 and 1521, respectively, indicating the induction ofhydrophobicity by MOP coating (Fig. 2j–l). To confirm thehomogeneous coating of MOPs on the ZSM-5 materials, the innerZSM-5 was etched by treatment of HF solution. Based on TEManalysis, the thicknesses of MOP materials in ZSM-5@MOP-1,ZSM-5@MOP-2, and ZSM-5@MOP-3 were measured to beB10 nm, B20 nm, and B42 nm, respectively (Fig. 2g–i).

The N2 isotherm analysis based on the Brunauer–Emmett–Teller (BET) theory showed a surface area of 465 m2 g�1 of ZSM-5(Fig. 3a). The surface area increased gradually to 484 m2 g�1,588 m2 g�1, and 660 m2 g�1 for ZSM-5@MOP-1, ZSM-5@MOP-2,and ZSM-5@MOP-3, respectively. In the literature, the surface areasof common MOP materials prepared by Sonogashira coupling havebeen reported in the range of 500–1100 m2 g�1.13 Thus, theincreasing trend of the surface area by the introduction of MOPmaterials to ZSM-5 can be rationalized. The analysis of pore sizedistributions showed microporosity of all materials (inset ofFig. 3a). According to powder X-ray diffraction studies (PXRD),the crystallinity of ZSM-5 was retained completely in ZSM-5@MOP materials (Fig. 3b). MOP contents in ZSM-5@MOP-1,ZSM-5@MOP-2, and ZSM-5@MOP-3 were measured to be8.1 w%, 16 w% and 24 w%, respectively, based on combustionelemental analysis. The chemical structure of ZSM-5@MOPmaterials was analyzed by solid phase 13C nuclear magneticresonance (NMR) spectroscopy. As shown in Fig. S3 in the ESI,†13C peaks from benzylcarbon, and aromatic groups wereobserved at 66 ppm and 115–155 ppm, respectively.

Microporous materials (pore size o2 nm) are generally goodadsorbents for small molecules.14 Due to the regular porestructure and surface activity, microporous zeolites have beenused for the removal of small and polar molecules such asammonia.15 However, their adsorption capacities significantlydecrease under humid conditions due to the competitive adsorptionof water.16 Considering the hydrophobic coating in ZSM-5@MOPmaterials, we studied the adsorption behavior of ZSM-5@MOPmaterials toward ammonia under humid conditions, comparedwith that of ZSM-5 (see the Experimental section for details)Fig. 4 and Table 1 summarize the results.

As shown in breakthrough curves in Fig. 4a and entries 1–4in Table 1, ZSM-5 showed a breakthrough time of 124 seconds(5.7 mg NH3 per g breakthrough capacity)17 in 4500 ppm NH3

flow under dry conditions. When relative humidity (RH) was 10%,the breakthrough time dropped to 56 seconds. As RH increased

Fig. 2 TEM images of ZSM-5 (a), ZSM-5@MOP-1 (d), ZSM-5@MOP-2 (e),ZSM-5@MOP-3 (f), and hollow MOP materials obtained by chemicaletching of ZSM-5 in ZSM-5@MOP-1 (g), ZSM-5@MOP-2 (h), and ZSM-5@MOP-3 (i). Water contact angle of ZSM-5 (b and c), ZSM-5@MOP-1 (j),ZSM-5@MOP-2 (k), and ZSM-5@MOP-3 (l).

Fig. 3 (a) N2 isotherms at 77 K, pore size distribution diagrams (DFT method,inset), and (b) PXRD patterns of ZSM-5, ZSM-5@MOP-1, ZSM-5@MOP-2, andZSM-5@MOP-3.

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to 43% and 76%, the breakthrough time further decreased to39 seconds and 34 seconds, respectively. At 43% RH, the ammoniaadsorption capacity of ZSM-5 dropped to 31% of that under dryconditions. In comparison, ZSM-5@MOP-2 showed a breakthroughtime of 138 seconds (6.4 mg of NH3 per g breakthrough capacity)under dry conditions (Fig. 4b and entries 7–9, 12 in Table 1). WhenRH increased to 10%, 43%, and 76%, the breakthrough wasobserved at 130 seconds, 122 seconds, and 78 seconds, respectively.It is noteworthy that at 43% RH, ZSM-5@MOP-2 retained 88% ofammonia adsorption capacity of dry conditions.18

The retention degree of ammonia adsorption capacity underhumid conditions was dependent on the thickness of MOPmaterials (Fig. 4c and entries 5–7, 9, and 13–14 in Table 1).

At 43% RH, ZSM-5@MOP-1 (B10 nm MOP thickness)showed 73% retention of ammonia adsorption capacity under

dry conditions. At 43% RH, ZSM-5@MOP-3 (42 nm MOP thick-ness) showed nearly the same retention degree (B86%) ofammonia adsorption with ZSM-5@MOP-2 (20 nm MOP thick-ness), compared with adsorption under dry conditions. However,breakthrough time decreased significantly from 138 seconds(ZSM-5@MOP-2) to 92 seconds (ZSM-5@MOP-3) under dry con-ditions, which is attributed to the decreased amount of ZSM-5 inZSM-5@MOP-3. The hollow MOP materials obtained throughchemical etching of inner ZSM-5 showed very poor adsorptionability toward ammonia, possibly due to the non-polar natureof materials (Fig. S4 in the ESI†). Thus, the decreased retentionof ammonia adsorption capacity of ZSM-5@MOP-1, comparedwith that of ZSM-5@MOP-2 at 43% RH, is attributed to thethinner MOP coating which is less efficient for selective block-ing of water.

As the amount of MOPs in ZSM-5@MOPs increases, thematerials can block water adsorption more efficiently. However,it can result in the decrease of ammonia adsorption capacitydue to the decrease of the ZSM-5 content. Thus, the optimalcontent of MOP materials in ZSM-5@MOPs is important tomaximize the adsorption performance under humid condi-tions. The ZSM-5@MOP-2 recovered after adsorption at 43%RH showed the complete retention of adsorption capacitiesin successive two runs (entries 9–11 in Table 1 and Fig. S4 inthe ESI†).

In conclusion, this work shows that MOP chemistry can beapplied to the development of hydrophobic zeolite adsorbents.The coating of hydrophilic ZSM-5 with MOP materials resultedin the hydrophobic hybrid microporous materials whichshowed the promising retention of ammonia adsorption per-formance under humid conditions. We believe that the syn-thetic strategy in this work can be easily extended to variouszeolite materials.

Fig. 4 Breakthrough curves of ZSM-5 (a), ZSM-5@MOP-1 (c), ZSM-5@MOP-2 (b and c), and ZSM-5@MOP-3 (c) under dry and humid condi-tions (RH: 10%, 43%, and 76%) towards ammonia flow (inlet concentration:4500 ppm). The 50 mg of adsorbents were used. The upper detection limitof the ammonia sensor used in this work is 1000 ppm.

Table 1 Ammonia adsorption properties of materials in this worka

Entry Materials RHb (%)

Breakthrough

S.ABET

(m2 g�1)Time/capacityc

(s, mg g�1)

1 ZSM-5 0 124/5.7 4652 ZSM-5 10 56/2.6 —3 ZSM-5 43 39/1.8 —4 ZSM-5 76 34/1.6 —5 ZSM-5@MOP-1 0 123/5.7 4846 ZSM-5@MOP-1 43 90/4.1 —7 ZSM-5@MOP-2 0 138/6.4 5888 ZSM-5@MOP-2 10 130/6.0 —9 ZSM-5@MOP-2 43 122/5.6 —10 ZSM-5@MOP-2d 43 122/5.6 —11 ZSM-5@MOP-2e 43 122/5.6 —12 ZSM-5@MOP-2 76 78/3.6 —13 ZSM-5@MOP-3 0 92/4.2 66014 ZSM-5@MOP-3 43 79/3.6 —

a Experimental conditions: adsorbent (50 mg), ammonia flow (inletconcentration: 4500 ppm), and 20 1C. b Relative humidity (RH) wasadjusted by controlling the flow rate of wet N2 (see the Experimentalsection in the ESI). c Breakthrough time was measured at an outlet NH3

concentration of 450 ppm. Breakthrough capacity is calculated for theadsorbed ammonia during the breakthrough time. d ZSM-5@MOP-2recovered from entry 9 was used. e ZSM-5@MOP-2 recovered from entry10 was used.

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This work was supported by grants NRF-2012-R1A2A2A01045064(Midcareer Researcher Program) through the National ResearchFoundation of Korea.

Notes and references1 Recent reviews: (a) L. Tosheva and V. P. Valtchev, Chem. Mater.,

2005, 17, 2494; (b) Y. Tao, H. Kanoh, L. Abrams and K. Kaneko,Chem. Rev., 2006, 106, 896; (c) Y. Li and J. Yu, Chem. Rev., 2014,114, 7268.

2 (a) W. Holderich, M. Hesse and F. Naumann, Angew. Chem., Int.Ed. Engl., 1988, 27, 226; (b) H. van Koningsveld, J. C. Jansen andH. van Bekkum, Zeolites, 1990, 10, 235; (c) J. Dedecek, V. Balgova,V. Pashkova, P. Klein and B. Wichterlova, Chem. Mater., 2012,24, 3231.

3 R. J. Argauer and G. R. Landolt, US Pat., 3702886, Mobil Oil Corp.,1967.

4 (a) P. B. Weisz, Pure Appl. Chem., 1980, 52, 2091; (b) S. Namba,N. Hosonuma and T. Yashima, J. Catal., 1981, 72, 16; (c) M. Inaba,K. Murata, M. Saito and I. Takahara, Green Chem., 2007, 9, 638;(d) V. V. Krishna, M. Kandepi and N. Narender, Catal. Sci. Technol.,2012, 2, 471; (e) R. Gonzalez-Olmos, F.-D. Kopinke, K. Mackenzieand A. Georgi, Environ. Sci. Technol., 2013, 47, 2353.

5 Hydrophobic zeolites and adsorbents (a) P. A. Zapata, J. Faria, M. P.Ruiz, R. E. Jentoft and D. E. Resasco, J. Am. Chem. Soc., 2012,134, 8570; (b) M. Tomasevic-Canovic, A. Dakovic, G. Rottinghaus,S. Matijasevic and M. Ðuricic, Microporous Mesoporous Mater., 2003,61, 173; (c) M. V. Chandak and Y. S. Lin, Environ. Technol., 1998,19, 941; (d) J.-H. Yun, D.-K. Choi and S.-H. Kim, AIChE J., 1998,44, 1344; (e) X. S. Zhao, Q. Ma and G. Q. Lu, Energy Fuels, 1998,12, 1051; ( f ) M. Khalid, G. Joly, A. Renaud and P. Magnoux, Ind. Eng.Chem. Res., 2004, 43, 5275; (g) W.-T. Tsai, H.-C. Hsu, T.-Y. Su,K.-Y. Lin and C.-M. Lin, J. Colloid Interface Sci., 2006, 299, 513;(h) R. Gounder and M. E. Davis, AIChE J., 2013, 59, 3349.

6 G. Sartori and R. Maggi, Chem. Rev., 2006, 106, 1077.7 Reviews on microprous organic materials: (a) R. Dawson, A. I.

Cooper and D. J. Adams, Prog. Polym. Sci., 2012, 37, 530; (b) F. Vilela,K. Zhang and M. Antonietti, Energy Environ. Sci., 2012, 5, 7819;(c) A. Thomas, Angew. Chem., Int. Ed., 2010, 49, 8328; (d) A. I. Cooper,Adv. Mater., 2009, 21, 1291.

8 Recent examples of new synethetic approach for MOP materials:(a) A. Laybourn, R. Dawson, R. Clowes, J. A. Iggo, A. I. Cooper,Y. Z. Khimyak and D. J. Adams, Polym. Chem., 2012, 3, 533;(b) Y. Luo, S. Zhang, Y. Ma, W. Wang and B. Tan, Polym. Chem.,2013, 4, 1126; (c) J. Lu and J. Zhang, J. Mater. Chem. A, 2014, 2, 13831;(d) Y. Liao, J. Weber and C. F. J. Faul, Chem. Commun., 2014,50, 8002; (e) Y.-C. Zhao, L.-M. Zhang, T. Wang and B.-H. Han, Polym.Chem., 2014, 5, 614; ( f ) X. Zhu, C. Tian, T. Jin, J. Wang, S. M.Mahurin, W. Mei, Y. Xiong, J. Hu, X. Feng, H. Liu and S. Dai, Chem.Commun., 2014, 50, 15055; (g) M. Carta, M. Croad, K. Bugler,K. J. Msayib and N. B. McKeown, Polym. Chem., 2014, 5, 5262;(h) J. Dong, Y. Liu and Y. Cui, Chem. Commun., 2014, 50, 14949.

9 J. Jin, B. Kim, N. Park, S. Kang, J. H. Park, S. M. Lee, H. J. Kim andS. U. Son, Chem. Commun., 2014, 50, 14885.

10 (a) H. C. Cho, H. S. Lee, J. Chun, S. M. Lee, H. J. Kim and S. U. Son,Chem. Commun., 2011, 47, 917; (b) J. Chun, J. H. Park, J. Kim,S. M. Lee, H. J. Kim and S. U. Son, Chem. Mater., 2012, 24, 3458;(c) H. S. Lee, J. Choi, J. Jin, J. Chun, S. M. Lee, H. J. Kim andS. U. Son, Chem. Commun., 2012, 48, 94; (d) N. Kang, J. H. Park,

J. Choi, J. Jin, J. Chun, I. G. Jung, J. Jeong, J.-G. Park, S. M. Lee,H. J. Kim and S. U. Son, Angew. Chem., Int. Ed., 2012, 51, 6626;(e) J. Chun, S. Kang, N. Kang, S. M. Lee, H. J. Kim and S. U. Son,J. Mater. Chem. A, 2013, 1, 5517; ( f ) N. Kang, J. H. Park, K. C. Ko,J. Chun, E. Kim, H. W. Shin, S. M. Lee, H. J. Kim, T. K. Ahn, J. Y. Leeand S. U. Son, Angew. Chem., Int. Ed., 2013, 52, 6228; (g) J. H. Park,K. C. Ko, N. Park, H.-W. Shin, E. Kim, N. Kang, J. H. Ko, S. M. Lee,H. J. Kim, T. K. Ahn, J. Y. Lee and S. U. Son, J. Mater. Chem. A, 2014,2, 7656.

11 (a) N. Kang, J. H. Park, M. Jin, N. Park, S. M. Lee, H. J. Kim, J. M. Kimand S. U. Son, J. Am. Chem. Soc., 2013, 135, 19115; (b) J. Chun,S. Kang, N. Park, E. J. Park, X. Jin, K.-D. Kim, H. O. Seo, S. M. Lee,H. J. Kim, W. H. Kwon, Y.-K. Park, J. M. Kim, Y. D. Kim andS. U. Son, J. Am. Chem. Soc., 2014, 136, 6786; (c) B. H. Lim, J. Jin,S. Y. Han, K. Kim, S. Kang, N. Park, S. M. Lee, H. J. Kim andS. U. Son, Chem. Commun., 2014, 50, 7723; (d) J. Yoo, N. Park,J. H. Park, J. H. Park, S. Kang, S. M. Lee, H. J. Kim, H. Jo, J.-G. Parkand S. U. Son, ACS Catal., 2015, 5, 350.

12 Y.-P. Guo, T. Long, Z.-F. Song and Z.-A. Zhu, J. Biomed. Mater. Res.,Part B, 2014, 102, 583.

13 (a) J.-X. Jiang, F. Su, A. Trewin, C. D. Wood, N. L. Campbell, H. Niu,C. Dickinson, A. Y. Ganin, M. J. Rosseinsky, Y. Z. Khimyak andA. I. Cooper, Angew. Chem., Int. Ed., 2007, 46, 8574; (b) J.-X. Jiang,F. Su, A. Trewin, C. D. Wood, H. Niu, J. T. A. Jones, Y. Z. Khimyakand A. I. Cooper, J. Am. Chem. Soc., 2008, 130, 7710.

14 (a) L. M. Le Leuch and T. J. Bandosz, Carbon, 2007, 45, 568;(b) C.-C. Huang, H.-S. Li and C.-H. Chen, J. Hazard. Mater., 2008,159, 523; (c) C. Petit, B. Mendoza and T. J. Bandosz, Langmuir, 2010,26, 15302; (d) C. Petit and T. J. Bandosz, Adv. Funct. Mater., 2010,20, 111; (e) T. G. Glover, G. W. Peterson, B. J. Schindler, D. Britt andO. Yaghi, Chem. Eng. Sci., 2011, 66, 163; ( f ) C. Petit and T. J. Bandosz,Adv. Funct. Mater., 2011, 21, 2108; (g) A. M. B. Furtado, J. Liu, Y. Wangand M. D. LeVan, J. Mater. Chem., 2011, 21, 6698; (h) M. Goncalves,L. Sanchez-Garcıa, E. O. Jardim, J. Silvestre-Albero and F. Rodrıguez-Reinoso, Environ. Sci. Technol., 2011, 45, 10605.

15 (a) D. J. Parrillo, C. Lee and R. J. Gorte, Appl. Catal., A, 1994, 110, 67;(b) A. Kyrlidis, S. J. Cook, A. K. Chakraborty, A. T. Bell andD. N. Theodorou, J. Phys. Chem., 1995, 99, 1505; (c) J. Helminen,J. Helenius, E. Paatero and I. Turunen, AIChE J., 2000, 46, 1541;(d) D. R. Brown and A. J. Groszek, Langmuir, 2000, 16, 4207;(e) R. M. Burgess, M. M. Perron, M. G. Cantwell, K. T. Ho,J. R. Serbst and M. C. Pelletier, Arch. Environ. Contam. Toxicol.,2004, 47, 440.

16 In our own tests, ZSM-5 materials (50 mg or 300 mg loading) showeda dramatic decrease of NH3 adsorption capacity under humidconditions, 43% RH see Fig. S5 in the ESI.† Although a positiveeffect of water on NH3 adsorption was observed in carbon-basedadsorbents, the reduction of NH3 adsorption capacity of zeolitesunder humid conditions has been reported in the literature.(a) P. S. Chintawar and H. L. Greene, Appl. Catal., B, 1997, 14, 37;(b) T. J. Bandosz and C. Petit, J. Colloid Interface Sci., 2009, 338, 329.

17 The ammonia/ammonium breakthrough capacities of various zeo-lites were observed in the range of 2.4–8.3 mg g�1 in the literature.(a) J. Hlavay, G. Vigh, V. Olaszi and J. Inczedy, Water Res., 1982,16, 417; (b) N. A. Booker, E. L. Cooney and A. J. Priestley, Water Sci.Technol., 1996, 34, 17; (c) M. L. Nguyen and C. C. Tanner, N. Z. J. Agric.Res., 1998, 41, 427.

18 The analysis of water adsorption isotherm curves at 298 K showedB5 times more water adsorption of ZSM-5, compared with ZSM-5@MOP-2 (Fig. S6 in the ESI†).

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