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Zeolite Y deposition on aluminum substrate without structure directing agents (SDAs)
Materials Letters 71 (2012) 25–27
Contents lists available at SciVerse ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Zeolite Y deposition on aluminum substrate without structure directing agents (SDAs) Takamasa Onoki ⁎ Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
a r t i c l e
i n f o
Article history: Received 26 July 2011 Accepted 23 November 2011 Available online 29 November 2011 Keywords: Heat exchanger Antimicrobial coating Hydrophilic
a b s t r a c t Zeolite Y was deposited on an aluminum substrate without using structure directing agents (SDAs) (e. g. tetrapropyl-ammonium hydroxide: TPAOH). Zeolite Y powder that contained NaOH solution and an Al disk are pressed at 40 MPa uniaxially and heated up to 130 °C for 1 h through an autoclave for hydrothermal hot-pressing (HHP). Solidification of zeolite Y powder and deposition on Al substrate have been achieved simultaneously through the above shown treatment. The deposited zeolite Y has no secondary phase by pyrolytic decomposition and a dense structure. No other oxide layer generates at interface between the deposited zeolite Y and Al substrate. The interface has good adhesive property and high contact area. It is firstly demonstrated that the simple heat and pressing treatment is useful for zeolite Y deposition on Al substrate without using SDA. © 2011 Elsevier B.V. All rights reserved.
1. Introduction Zeolites are crystalline aluminosilicates with uniform molecular sized pores. Major commercial uses of zeolites include catalysts, separation media, and ion exchangers. For these applications they are used in powder composite form such as pellets and granules. Some kinds of zeolite powders composite forming in pellets and granules have proven useful in many industrial applications. As coating or deposition on porous substrates they form membranes capable of separating mixtures on the molecular level [1–6]. Examples include the separation of carbon dioxide from oxygen and saturated from unsaturated hydrocarbons. Their utilization as coatings on non-porous substrates can extend and improve adsorption applications over powder based adsorbents. For these adsorption applications, zeolite coatings are applied to structured substrates (e.g., monoliths), and the benefits are manifested as higher heat and mass transfer, lower pressure drop, and no attrition [7]. It has been interested in developing hydrophilic and antimicrobial zeolite coatings for use in manned spacecraft. Condensing heat exchangers (condensers) are a key component in the environmental control systems onboard manned spacecraft, and similar to their ubiquitous ground based counterparts for vehicles and building, their function is to regulate temperature and humidity [8,9]. Furthermore, the conventional zeolite coatings are highly porous and the pores are typically large (e.g. micrometer or subnanometer sized). Although this porosity helps to adsorb and wick water, it does not provide corrosion resistance to the metal substrate.
⁎ Corresponding author. Tel.: + 81 72 254 9395; fax: + 81 72 254 9912. E-mail address: [email protected]. 0167-577X/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2011.11.095
A corrosion-resistant coating would allow use of aluminum alloys in place of stainless steels in condensers. Since aluminum is lighter and has heat conductivity than steels, this switch would lead to significant weight and volume reduction. By combining the low weight and high thermal conductivity of aluminum (approximately 15 times that of stainless steel) with the ability of zeolite to remove contaminants and produce oxygen enriched air, desirable alternatives are offered for weight and size conscious environments. Much success has been made in synthesizing zeolite coatings on ceramic, steel and other corrosion resistant metal substrates [1–6,10–23]. Problems arise when attempting to synthesize zeolite coatings on aluminum substrates. Zeolite synthesis solutions are known to have a very high pH, often greater than 14. This high pH is very corrosive and dissolves the aluminum substrate during synthesis. Recently, several attempts of zeolite deposition or coating on metallic substrate were conducted [8,9,24]. Metallic substrates were immersed into solution using expensive structure directing agent (SDA), for example tetrapropyl-ammonium hydroxide (TPAOH) with great difficulty [8,9,24]. In this report, it has been firstly demonstrated that commercially available zeolites powder is deposited on an aluminum substrate by simple compression and heating treatments without SDA. 2. Experimental A commercially available pure aluminum (99%, Nilaco, Japan) rod in 10 mm diameter was cut into approximately 1.5 mm thickness. Surfaces of the Al disks were finished with # 1000 emery paper. After the finishing, the Al disks were immersed into ethanol at room temperature and washed with ultrasonic cleaner for 10 min. The Al substrates were then dried at room temperature. Zeolite Y powder
26
T. Onoki / Materials Letters 71 (2012) 25–27
(HSZ-320NAA, TOSOH, Japan, Average crystal size: 0.3 μm) was selected in this research. In order to dehydrate sorption water of the zeolite Y powder, pre-heat treatment was conducted by oven-dryer at 105 °C for 12 h. And then 2 mol/L sodium hydroxide (NaOH; WAKO Chemical, Japan) solution was added at 40 mass % of the zeolite Y powder and homogenized in a mortar. This mixed powder was prepared as a starting material for solidification and deposition of zeolite Y on the Al substrate. Simple and easy pressing and heating method, which was named hydrothermal hot-pressing (HHP) [25,26], was employed for depositing zeolite Y on the Al substrates in this research. Schematic illustration of the apparatus for HHP was shown in the previous literature [26]. It was expected that zeolite powder solidification and bonding to Al substrate occurred simultaneously by the HHP processing. The above described starting powder (approximately 300 mg) and the Al disk were located into the middle of the autoclave. The stainless steel (SUS304) autoclave has pistons within a cylindrical structure with an inside diameter of 10 mm. Pressure of 40 MPa was initially applied to the sample through the push rods from the top and bottom at room temperature. After initial loading the autoclave was heated to 130 °C at 10 °C/min with a sheath-type heater, and then the temperature was kept constant for 1 h. The axial pressure was kept at 40 MPa during the hydrothermal hotpressing treatment. After the HHP treatment, the autoclave was naturally cooled to room temperature, and the sample was removed from the autoclave. X-ray diffraction patterns (XRD: RIGAKU Miniflex2, Japan) using Cu Kα radiation in 30 kV and 15 mA were measured for verifying of crystal phase of the deposited and raw zeolite Y. Surface morphology of the deposited zeolite Y and structure near an interface between the deposited zeolite Y and the Al substrates were observed with a scanning electron microscopy (SEM: HITACHI S4800, Japan) operating at 15 kV.
Fig. 2. X-ray diffraction patterns of the deposited and raw zeolite materials.
3. Results and discussion Zeolite Y could be deposited on the Al disk at the 130 °C temperature and 40 MPa pressure of using the above-mentioned HHP treatment, as shown in Fig. 1. It was demonstrated that the deposited zeolite Y had good adhesive strength to the Al substrate. X-ray diffraction pattern analysis of the deposited and the raw zeolite Y materials was given in Fig. 2, respectively. Crystalline phase was assigned by the structure commission of the international zeolite association (IZA-SC). There is little crystalline difference between the deposited and raw zeolite Y materials. It has been indicated that no secondary phase was generated in the deposited zeolite Y through the HHP treatment. Peaks of secondary phases were appeared in the deposited zeolite Y prepared by the HHP treatment at higher temperature than 130 °C. In order keep crystalline structure of zeolite Y, excessively high temperature treatment should be avoided. The obtained samples were applied to 4 point bending
Fig. 1. Photograph of the zeolite Y deposited Al substrate by the HHP treatment.
Fig. 3. SEM micrographs near the interface between deposited zeolite and Al substrate in a cross sectional view (a), its high magnification (b) and surface morphology of deposited zeolite Y (c).
T. Onoki / Materials Letters 71 (2012) 25–27
tests in order to estimate adhesive properties of the interface. It was revealed that the zeolite Y was remaining on the Al substrates after the bending tests. The calculated bending strength was approximately 57.4 MPa. It was demonstrated that this desirable adhesive property was derived from chemical bonding between zeolite and Al. SEM micrographs in a cross sectional view of the interface between the deposited zeolite Y and the Al substrate were shown in Fig. 3(a) and (b). It is seemed that directly bonding zeolite Y and Al substrate is achieved. It was easily expected that some oxide layer (e. g., Al2O3) in several micro meter thickness could existed between the deposited zeolite Y and the Al substrate. It is difficult to distinguish the zeolite Y layer and the expected oxide layer due to zeolite Y that is typically an alumino-silicate compound. While slightly changing at the interface, there is no expected thick oxide layer at the interface, as shown in Fig. 3(b). From above shown results, it has been demonstrated that the deposited zeolite Y was tightly attached to the Al substrate, and that the interface between the deposited zeolite Y and the Al substrate had highly contacting area. As general, low heat transfer late of zeolite materials restricts for using zeolite materials in heat exchanging applications. It is well expected that much amount of heat can transfer from the Al substrate to the zeolite Y through the interface of the fabricated materials in this study. More precise investigation for interface structure is needed in order to elucidate the adhesive mechanism and to obtain higher heat transfer rate between zeolite Y and Al substrate. As shown in Fig. 3(c), surface morphology of the deposited zeolite Y was observed. The deposited zeolite Y was well solidified and had no defects. This surface morphology provides a possibility for hydrophilic and antimicrobial zeolite coatings on heat exchanger. Thickness of the deposited zeolite Y is approximately 1.5 mm in this study, as shown in Fig. 1. If it is needed the deposited zeolite Y to make more thinner, zeolite Y thin coating layer can be produced by employing double layered capsule hydrothermal hot-pressing (DC-HHP) method [27]. Without using expensive structure directing agent (SDA), zeolite Y coated Al materials getting above shown properties may be obtained. Therefore, hydrothermal hot-pressing techniques could be low cost and easy methods for zeolite coatings. 4. Conclusions A novel one-step synthesis method for zeolite Y deposition on an aluminum substrate was developed by employing a hydrothermal hot-pressing method. It is the first attempt of zeolite Y deposition without using structure directing agent (SDA). Zeolite Y could be deposited on the Al disk at the 130 °C temperature and 40 MPa pressure. It has been demonstrated that no secondary phase was existed in the
27
deposited zeolite Y through the HHP treatment, and that deposited zeolite Y ceramics has good adhesive properties to an aluminum substrate. The fabricated material has potentials for various applications (e. g. heat exchanger, environmental control systems onboard manned spacecraft).
Acknowledgments This work was partly supported by "A-STEP; Adaptable and Seamless Technology Transfer Program through target-driven R&D, Exploratory Research, AS231Z03430B" from Japan Science and Technology Agency and "Grant in Aid for Young Scientists (B), 23760702" from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
References [1] Nikolakis V, Xomeritakis G, Abibi A, Dickson M, Tsapatsis M, Vlachos D. J Membr Sci 2001;184:209–19. [2] Boudreau L, Tsapatsis M. Chem Mater 1997;9:1705–9. [3] Morooka S, Kuroda T, Kusakabe K. Stud Surf Sci Catal 1998;114:665–8. [4] Aoki K, Kusakabe K, Morooka S. J Membr Sci 1998;141:197–205. [5] Jeong B, Hasegawa Y, Sotowa K, Kusakabe K, Morooka S. Ind Eng Chem Res 2002;41:1768–73. [6] Jeong B, Hasegawa Y, Sotowa K, Kusakabe K, Morooka S. J Chem Eng Jpn 2004;35: 763–81. [7] Yan YS, Wang HT. Encycl Nanosci Nanotechnol 2004;7:763–81. [8] Chen G, Bedi RS, Yan YS, Walker SL. Langmuir 2010;26:12605–13. [9] McDonnell AMP, Beving DS, Wang A, Chen W, Yan Y. Adv Funct Mater 2005;15: 336–40. [10] Davis S, Borgstedt EVR, Suib SL. Chem Mater 1990;2:712–9. [11] Valtchev V, Mintova S, Vasilev I. J Chem Soc Chem Commun 1994:979–80. [12] Clet G, Peters J, van Bekkum H. Langmuir 2000;16:3993–4000. [13] Clet G, Peters J, van Bekkum H. Chem Mater 1999;11:1696–702. [14] Clet G, Gora L, Nishiyama N, Jansen J, van Bekkum H, Maschmeyer T. Chem Commun 2001:41–2. [15] Lee Y, Dutta P. J Phys Chem B 1904;106(2002):11898–904. [16] Kita H, Inoue T, Asanuma H, Tanaka K, Okamoto K. Chem Commun 1997:45–6. [17] Kusakabe K, Kuroda T, Morooka S. J Membr Sci 1998;148:13–23. [18] Kusakabe K, Kuroda T, Murata A, Morooka S. Ind Eng Chem Res 1997;36: 649–55. [19] Lassinantti M, Hedlund J, Sterte J. Microporous Mesoporous Mater 2000;38: 25–34. [20] Weh K, Noack M, Sieber I, Caro J. Microporous Mesoporous Mater 2002;54:27–36. [21] Bein T, Brown K, Frye G, Brinker C. J Am Chem Soc 1989;111:7640–1. [22] Mintova S, Radev D, Valtchev V. Metall 1998;52:447–50. [23] Valtchev V, Mintova S. Zeolite 1995;15:171–5. [24] Munoz R, Beving D, Mao Y, Yan Y. Microporous Mesoporous Mater 2005;86: 243–8. [25] Yamasaki N, Yanagisawa K, Nishioka M, Kanahara S. J Mater Sci Lett 1986;5: 355–65. [26] Onoki T, Hosoi K, Hashida T. Scr Mater 2005;52:767–70. [27] Onoki T, Hashida T. Surf Coat Technol 2006;200:6801–7.
Contents lists available at SciVerse ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Zeolite Y deposition on aluminum substrate without structure directing agents (SDAs) Takamasa Onoki ⁎ Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan
a r t i c l e
i n f o
Article history: Received 26 July 2011 Accepted 23 November 2011 Available online 29 November 2011 Keywords: Heat exchanger Antimicrobial coating Hydrophilic
a b s t r a c t Zeolite Y was deposited on an aluminum substrate without using structure directing agents (SDAs) (e. g. tetrapropyl-ammonium hydroxide: TPAOH). Zeolite Y powder that contained NaOH solution and an Al disk are pressed at 40 MPa uniaxially and heated up to 130 °C for 1 h through an autoclave for hydrothermal hot-pressing (HHP). Solidification of zeolite Y powder and deposition on Al substrate have been achieved simultaneously through the above shown treatment. The deposited zeolite Y has no secondary phase by pyrolytic decomposition and a dense structure. No other oxide layer generates at interface between the deposited zeolite Y and Al substrate. The interface has good adhesive property and high contact area. It is firstly demonstrated that the simple heat and pressing treatment is useful for zeolite Y deposition on Al substrate without using SDA. © 2011 Elsevier B.V. All rights reserved.
1. Introduction Zeolites are crystalline aluminosilicates with uniform molecular sized pores. Major commercial uses of zeolites include catalysts, separation media, and ion exchangers. For these applications they are used in powder composite form such as pellets and granules. Some kinds of zeolite powders composite forming in pellets and granules have proven useful in many industrial applications. As coating or deposition on porous substrates they form membranes capable of separating mixtures on the molecular level [1–6]. Examples include the separation of carbon dioxide from oxygen and saturated from unsaturated hydrocarbons. Their utilization as coatings on non-porous substrates can extend and improve adsorption applications over powder based adsorbents. For these adsorption applications, zeolite coatings are applied to structured substrates (e.g., monoliths), and the benefits are manifested as higher heat and mass transfer, lower pressure drop, and no attrition [7]. It has been interested in developing hydrophilic and antimicrobial zeolite coatings for use in manned spacecraft. Condensing heat exchangers (condensers) are a key component in the environmental control systems onboard manned spacecraft, and similar to their ubiquitous ground based counterparts for vehicles and building, their function is to regulate temperature and humidity [8,9]. Furthermore, the conventional zeolite coatings are highly porous and the pores are typically large (e.g. micrometer or subnanometer sized). Although this porosity helps to adsorb and wick water, it does not provide corrosion resistance to the metal substrate.
⁎ Corresponding author. Tel.: + 81 72 254 9395; fax: + 81 72 254 9912. E-mail address: [email protected]. 0167-577X/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2011.11.095
A corrosion-resistant coating would allow use of aluminum alloys in place of stainless steels in condensers. Since aluminum is lighter and has heat conductivity than steels, this switch would lead to significant weight and volume reduction. By combining the low weight and high thermal conductivity of aluminum (approximately 15 times that of stainless steel) with the ability of zeolite to remove contaminants and produce oxygen enriched air, desirable alternatives are offered for weight and size conscious environments. Much success has been made in synthesizing zeolite coatings on ceramic, steel and other corrosion resistant metal substrates [1–6,10–23]. Problems arise when attempting to synthesize zeolite coatings on aluminum substrates. Zeolite synthesis solutions are known to have a very high pH, often greater than 14. This high pH is very corrosive and dissolves the aluminum substrate during synthesis. Recently, several attempts of zeolite deposition or coating on metallic substrate were conducted [8,9,24]. Metallic substrates were immersed into solution using expensive structure directing agent (SDA), for example tetrapropyl-ammonium hydroxide (TPAOH) with great difficulty [8,9,24]. In this report, it has been firstly demonstrated that commercially available zeolites powder is deposited on an aluminum substrate by simple compression and heating treatments without SDA. 2. Experimental A commercially available pure aluminum (99%, Nilaco, Japan) rod in 10 mm diameter was cut into approximately 1.5 mm thickness. Surfaces of the Al disks were finished with # 1000 emery paper. After the finishing, the Al disks were immersed into ethanol at room temperature and washed with ultrasonic cleaner for 10 min. The Al substrates were then dried at room temperature. Zeolite Y powder
26
T. Onoki / Materials Letters 71 (2012) 25–27
(HSZ-320NAA, TOSOH, Japan, Average crystal size: 0.3 μm) was selected in this research. In order to dehydrate sorption water of the zeolite Y powder, pre-heat treatment was conducted by oven-dryer at 105 °C for 12 h. And then 2 mol/L sodium hydroxide (NaOH; WAKO Chemical, Japan) solution was added at 40 mass % of the zeolite Y powder and homogenized in a mortar. This mixed powder was prepared as a starting material for solidification and deposition of zeolite Y on the Al substrate. Simple and easy pressing and heating method, which was named hydrothermal hot-pressing (HHP) [25,26], was employed for depositing zeolite Y on the Al substrates in this research. Schematic illustration of the apparatus for HHP was shown in the previous literature [26]. It was expected that zeolite powder solidification and bonding to Al substrate occurred simultaneously by the HHP processing. The above described starting powder (approximately 300 mg) and the Al disk were located into the middle of the autoclave. The stainless steel (SUS304) autoclave has pistons within a cylindrical structure with an inside diameter of 10 mm. Pressure of 40 MPa was initially applied to the sample through the push rods from the top and bottom at room temperature. After initial loading the autoclave was heated to 130 °C at 10 °C/min with a sheath-type heater, and then the temperature was kept constant for 1 h. The axial pressure was kept at 40 MPa during the hydrothermal hotpressing treatment. After the HHP treatment, the autoclave was naturally cooled to room temperature, and the sample was removed from the autoclave. X-ray diffraction patterns (XRD: RIGAKU Miniflex2, Japan) using Cu Kα radiation in 30 kV and 15 mA were measured for verifying of crystal phase of the deposited and raw zeolite Y. Surface morphology of the deposited zeolite Y and structure near an interface between the deposited zeolite Y and the Al substrates were observed with a scanning electron microscopy (SEM: HITACHI S4800, Japan) operating at 15 kV.
Fig. 2. X-ray diffraction patterns of the deposited and raw zeolite materials.
3. Results and discussion Zeolite Y could be deposited on the Al disk at the 130 °C temperature and 40 MPa pressure of using the above-mentioned HHP treatment, as shown in Fig. 1. It was demonstrated that the deposited zeolite Y had good adhesive strength to the Al substrate. X-ray diffraction pattern analysis of the deposited and the raw zeolite Y materials was given in Fig. 2, respectively. Crystalline phase was assigned by the structure commission of the international zeolite association (IZA-SC). There is little crystalline difference between the deposited and raw zeolite Y materials. It has been indicated that no secondary phase was generated in the deposited zeolite Y through the HHP treatment. Peaks of secondary phases were appeared in the deposited zeolite Y prepared by the HHP treatment at higher temperature than 130 °C. In order keep crystalline structure of zeolite Y, excessively high temperature treatment should be avoided. The obtained samples were applied to 4 point bending
Fig. 1. Photograph of the zeolite Y deposited Al substrate by the HHP treatment.
Fig. 3. SEM micrographs near the interface between deposited zeolite and Al substrate in a cross sectional view (a), its high magnification (b) and surface morphology of deposited zeolite Y (c).
T. Onoki / Materials Letters 71 (2012) 25–27
tests in order to estimate adhesive properties of the interface. It was revealed that the zeolite Y was remaining on the Al substrates after the bending tests. The calculated bending strength was approximately 57.4 MPa. It was demonstrated that this desirable adhesive property was derived from chemical bonding between zeolite and Al. SEM micrographs in a cross sectional view of the interface between the deposited zeolite Y and the Al substrate were shown in Fig. 3(a) and (b). It is seemed that directly bonding zeolite Y and Al substrate is achieved. It was easily expected that some oxide layer (e. g., Al2O3) in several micro meter thickness could existed between the deposited zeolite Y and the Al substrate. It is difficult to distinguish the zeolite Y layer and the expected oxide layer due to zeolite Y that is typically an alumino-silicate compound. While slightly changing at the interface, there is no expected thick oxide layer at the interface, as shown in Fig. 3(b). From above shown results, it has been demonstrated that the deposited zeolite Y was tightly attached to the Al substrate, and that the interface between the deposited zeolite Y and the Al substrate had highly contacting area. As general, low heat transfer late of zeolite materials restricts for using zeolite materials in heat exchanging applications. It is well expected that much amount of heat can transfer from the Al substrate to the zeolite Y through the interface of the fabricated materials in this study. More precise investigation for interface structure is needed in order to elucidate the adhesive mechanism and to obtain higher heat transfer rate between zeolite Y and Al substrate. As shown in Fig. 3(c), surface morphology of the deposited zeolite Y was observed. The deposited zeolite Y was well solidified and had no defects. This surface morphology provides a possibility for hydrophilic and antimicrobial zeolite coatings on heat exchanger. Thickness of the deposited zeolite Y is approximately 1.5 mm in this study, as shown in Fig. 1. If it is needed the deposited zeolite Y to make more thinner, zeolite Y thin coating layer can be produced by employing double layered capsule hydrothermal hot-pressing (DC-HHP) method [27]. Without using expensive structure directing agent (SDA), zeolite Y coated Al materials getting above shown properties may be obtained. Therefore, hydrothermal hot-pressing techniques could be low cost and easy methods for zeolite coatings. 4. Conclusions A novel one-step synthesis method for zeolite Y deposition on an aluminum substrate was developed by employing a hydrothermal hot-pressing method. It is the first attempt of zeolite Y deposition without using structure directing agent (SDA). Zeolite Y could be deposited on the Al disk at the 130 °C temperature and 40 MPa pressure. It has been demonstrated that no secondary phase was existed in the
27
deposited zeolite Y through the HHP treatment, and that deposited zeolite Y ceramics has good adhesive properties to an aluminum substrate. The fabricated material has potentials for various applications (e. g. heat exchanger, environmental control systems onboard manned spacecraft).
Acknowledgments This work was partly supported by "A-STEP; Adaptable and Seamless Technology Transfer Program through target-driven R&D, Exploratory Research, AS231Z03430B" from Japan Science and Technology Agency and "Grant in Aid for Young Scientists (B), 23760702" from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
References [1] Nikolakis V, Xomeritakis G, Abibi A, Dickson M, Tsapatsis M, Vlachos D. J Membr Sci 2001;184:209–19. [2] Boudreau L, Tsapatsis M. Chem Mater 1997;9:1705–9. [3] Morooka S, Kuroda T, Kusakabe K. Stud Surf Sci Catal 1998;114:665–8. [4] Aoki K, Kusakabe K, Morooka S. J Membr Sci 1998;141:197–205. [5] Jeong B, Hasegawa Y, Sotowa K, Kusakabe K, Morooka S. Ind Eng Chem Res 2002;41:1768–73. [6] Jeong B, Hasegawa Y, Sotowa K, Kusakabe K, Morooka S. J Chem Eng Jpn 2004;35: 763–81. [7] Yan YS, Wang HT. Encycl Nanosci Nanotechnol 2004;7:763–81. [8] Chen G, Bedi RS, Yan YS, Walker SL. Langmuir 2010;26:12605–13. [9] McDonnell AMP, Beving DS, Wang A, Chen W, Yan Y. Adv Funct Mater 2005;15: 336–40. [10] Davis S, Borgstedt EVR, Suib SL. Chem Mater 1990;2:712–9. [11] Valtchev V, Mintova S, Vasilev I. J Chem Soc Chem Commun 1994:979–80. [12] Clet G, Peters J, van Bekkum H. Langmuir 2000;16:3993–4000. [13] Clet G, Peters J, van Bekkum H. Chem Mater 1999;11:1696–702. [14] Clet G, Gora L, Nishiyama N, Jansen J, van Bekkum H, Maschmeyer T. Chem Commun 2001:41–2. [15] Lee Y, Dutta P. J Phys Chem B 1904;106(2002):11898–904. [16] Kita H, Inoue T, Asanuma H, Tanaka K, Okamoto K. Chem Commun 1997:45–6. [17] Kusakabe K, Kuroda T, Morooka S. J Membr Sci 1998;148:13–23. [18] Kusakabe K, Kuroda T, Murata A, Morooka S. Ind Eng Chem Res 1997;36: 649–55. [19] Lassinantti M, Hedlund J, Sterte J. Microporous Mesoporous Mater 2000;38: 25–34. [20] Weh K, Noack M, Sieber I, Caro J. Microporous Mesoporous Mater 2002;54:27–36. [21] Bein T, Brown K, Frye G, Brinker C. J Am Chem Soc 1989;111:7640–1. [22] Mintova S, Radev D, Valtchev V. Metall 1998;52:447–50. [23] Valtchev V, Mintova S. Zeolite 1995;15:171–5. [24] Munoz R, Beving D, Mao Y, Yan Y. Microporous Mesoporous Mater 2005;86: 243–8. [25] Yamasaki N, Yanagisawa K, Nishioka M, Kanahara S. J Mater Sci Lett 1986;5: 355–65. [26] Onoki T, Hosoi K, Hashida T. Scr Mater 2005;52:767–70. [27] Onoki T, Hashida T. Surf Coat Technol 2006;200:6801–7.