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Synthesis and characterization of Fe–Ce–MCM-41
Materials Letters 60 (2006) 3221 – 3223 www.elsevier.com/locate/matlet
Synthesis and characterization of Fe–Ce–MCM-41 Ying Zheng a,⁎, Zhaohui Li b , Yong Zheng a , Xiaonv Shen a , Liangxu Lin a a
College of Chemistry and Material Science, Fujian Normal University, Fuzhou 350007, China b Research Institute of Photocatalysis, Fuzhou University, Fuzhou 350002, China Received 28 October 2005; accepted 23 February 2006 Available online 15 March 2006
Abstract The mesoporous molecular sieve Fe–Ce–MCM-41 was synthesized under hydrothermal condition and characterized by XRD, FT-IR, DRS, TG and low temperature N2 adsorption–desorption method. The results showed that with high BET surface area and narrow pore size distribution, the obtained Fe–Ce–MCM-41 has excellent thermal stability. © 2006 Elsevier B.V. All rights reserved. Keywords: Fe–Ce–MCM-41; Mesoporous molecular sieve; Synthesis; Characterization
1. Introduction
2. Experiment section
There has been a significant breakthrough in the science of molecular sieves since the M41S silicate sieves with diameters of 1.5–10 nm was successfully synthesized by Mobil corporation [1–3]. As a member of the M41S family, MCM-41 have attracted worldwide interest not only due to its high surface area (N 1000 m2/g), well-defined regular pore shape, narrow pore size distribution, large pore volume (N 0.7 ml/g) and tunable pore size in the range of 1.6–20 nm [1,4], but also its high thermal and chemical stability [5–9]. The MCM-41 molecular sieves containing transition metal (eg. Fe, V, Nb, etc.) [10–12] and rare earth (e.g. La, Ce, etc.) [13,14] have been synthesized under mild hydrothermal condition. Since rare earth metals not only possess peculiar electronic configuration but also variable valence state and the transition metals has redox ability, the incorporation of both the rare earth and transition metals into MCM-41 would bring forth a new type of catalyst for the decomposition of NOx and with higher oxygen store ability. In this study, we reported the synthesis of Fe and Ce adulterated MCM-41 and the obtained Fe– Ce–MCM-41 was characterized by XRD, FT-IR, DRS, TG and Low temperature N2 adsorption–desorption method.
2.1. Preparation of Fe–Ce–MCM-41 composites
⁎ Corresponding author. Tel.: +86 591 83465225; fax: +86 591 83465376. E-mail address: [email protected] (Y. Zheng). 0167-577X/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2006.02.075
0.24 g of NaOH and 2.19 g of CTAB was dissolved in 54 ml of distilled water. 6.25 g of TEOS (A.R.) was added dropwise under vigorous stirring to ensure the complete hydrolysis of TEOS. 0.25 g of Ce(NO3)3·6H2O and 0.24 g of Fe(NO3)3·9H2O (Si / Ce = 50 and Si / Fe = 50, respectively) were added slowly to the solution and the pH was adjusted to 8.5–9.0. After that, the solution was transferred to a 100 ml Teflon-lined autoclave and heated at 100 °C for 72 h. After cooling to room temperature, the solid product was obtained by filtration, washing and drying in air
Fig. 1. XRD patterns of MCM-41 (a) and Fe–Ce–MCM-41 (b).
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Y. Zheng et al. / Materials Letters 60 (2006) 3221–3223 Table 1 The comparison of the N2 absorption–desorption isotherms of the MCM-41 and Fe–Ce–MCM-41 Samples
BET surface (m2/g− 1)
Pore volume (ml/g− 1)
Average pore radius (nm)
MCM-41 Fe–Ce–MCM-41
987 507
0.72 0.56
1.8 1.6
by an OMNSORP 100CX gas absorb analyzer. The TG was analyzed by a FE TGA7 thermogravimetric analyzer. 3. Results and discussion Fig. 2. FT-IR spectra of MCM-41 (a) and Fe–Ce–MCM-41(b).
3.1. Powder X-ray diffraction XRD pattern of the obtained Fe–Ce–MCM-41 is in good agreement with MCM-41 in 2θ range of 1–10° (Fig. 1) and indicates that their structures are essentially the same. Three peaks at 2θ values of 2.3°, 3.97° and 4.60° can be indexed as the representative (100), (110) and (200) reflections of the P6m mesostructure of MCM-41 [1,2,15]. The intensity of the three peaks of Fe–Ce–MCM-41 decrease compared with those of MCM41. It suggests that the long-range order of the sample is not as good as that of MCM-41 and may be due to the incorporation of Fe and Ce into the framework of MCM-41. 3.2. FT-IR spectroscopy
Fig. 3. DRS spectra of MCM-41 (a) and Fe–Ce–MCM-41 (b).
at 60 °C. The sample was further treated at 540 °C for 10 h to remove the template.
2.2. Characterizations X-ray diffraction (XRD) patterns were recorded on a Bruker D8 Advance X-ray diffractometer with CuKα radiation. The IR spectra were recorded on a Nicolet Nexus 670 FT-IR Spectrometer. The DRS spectra were obtained on a Varian Carry 500 Spectrometer. The N2 absorption–desorption was analyzed
Fig. 4. Nitrogen adsorption–desorption isotherms of MCM-41 (a) and Fe–Ce– MCM-41 (b).
FT-IR spectrum of Fe–Ce–MCM-41 (Fig. 2) shows characteristic bands of Si–O–Si at 1090 cm− 1 for asymmetrical stretching and 801 cm− 1 for symmetrical stretching. The bands at 960 and 461 cm− 1 can be assigned to the Si–O stretching and twisting respectively [16]. Except that the positions of the bands shift a little, the IR spectra of MCM-41 before and after adulteration are essentially the same. It suggests that the framework of MCM-41 retained after Ce and Fe enter the framework. 3.3. DRS spectroscopy Fe–Ce–MCM-41 shows two absorptions at 258 and 296 nm while no absorption in the wavelength range of 190–350 nm for MCM-41 (Fig. 3). The absorption at 258 and 296 nm can be ascribed to isolated tetrahedral coordinated Fe3+ species and Ce4+ respectively. No significant absorption above 320 nm suggests the absence of Fe2O3 [10] and CeO2 [14].
Fig. 5. The pore size distributions of MCM-41 (a) and Fe–Ce–MCM-41 (b).
Y. Zheng et al. / Materials Letters 60 (2006) 3221–3223
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Ce are highly dispersed in the framework of the Fe–Ce–MCM41. The adulterated sample retains excellent thermal stability, high BET surface area and narrow pore size distribution of MCM-41. Acknowledgments The authors are grateful to financial support from Science Foundation of Fujian Province Education Commission of China (K04033, 2005K015) and Natural Science Foundation of Fujian Province (E0410009). References Fig. 6. TG curves of MCM-41 (a) and Fe–Ce–MCM-41 (b).
3.4. N2 adsorption–desorption analysis Both MCM-41 and Fe–Ce–MCM-41 display type IV nitrogen adsorption curve and suggest that they possess the mesoporous structure (Fig. 4) [17]. BET surface area and pore volume decreased after adulteration. (Table 1) The BJH pore distribution of both MCM41 and Fe–Ce–MCM-41 show sharp peaks in the range of 16–24 Å and suggest that both possess narrow pore size distribution (Fig. 5). The average pore radius for MCM-41 and Fe–Ce–MCM-41 is 18 and 16 Å respectively. Although the average pore radius decreases a little, the adulterated MCM-41 still shows a relatively large surface area and pore volume, indicating that the mesoporous structure are still retained. 3.5. TG analysis The weight loss observed at temperatures range from 30 to 120 °C corresponds to the desorption of the physically adsorbed water (Fig. 6). However no weight loss is observed in the temperature range of 120– 620 °C and suggests that the sample possesses a high thermal stability.
4. Conclusions The bimetallic mesoporous molecular sieve Fe–Ce–MCM41 has been synthesized under hydrothermal condition. Fe and
[1] C.T. Kresge, M.E. Leonowicz, W.J. Roth, J.C. Vartuli, J.S. Beck, Nature 359 (1992) 710. [2] J.S. Beck, J.C. Vartuli, W.J. Roth, M.E. Leonowicz, C.T. Kresge, K.D. Schmitt, C.T.-W. Chu, D.H. Olson, E.E. Sheppard, S.B. McCullen, J.B. Higgins, J.L. Schlenker, J. Am. Chem. Soc. 114 (1992) 10834. [3] K. Moller, T. Bein, Chem. Mater. 10 (1998) 2950. [4] Parasuraman Selvam, Suresh K. Bhatia, Chandrashekar G. Sonwane, Recent, Ind. Eng. Chem. Res. 40 (2001) 3237. [5] A. Corma, Chem. Rev. 97 (1997) 2373. [6] M. Gru¨n, K.K. Unger, A. Matsumoto, K. Tsutsumi, Microporous Mesoporous Mater. 27 (1999) 207. [7] B. Lindlar, A. Kogelbauer, P.J. Kooyman, R. Prins, Microporous Mesoporous Mater. 44–45 (2001) 89. [8] U. Ciesla, F. Schu¨th, Microporous Mesoporous Mater. 27 (1999) 131. [9] M. Jaroniec, M. Kruk, H.J. Shin, R. Ryoo, Y. Sakamoto, O. Terasaki, Microporous Mesoporous Mater. 48 (2001) 127. [10] B.A. Placidus, L. Sangyun, C. Dragos, Y. Yang, P. Lisa, L.H. Gary, J. Phys. Chem., B 109 (2005) 2645. [11] G. Yesim, D. Timur, B. Suna, Catal. Today 100 (2005) 473. [12] Z. Maria, N. Izabela, Zeolites 18 (1997) 356. [13] A.S. Araujo, M. Jaroniec, J. Colloid Interface Sci. 218 (1999) 462. [14] M.D. Kadgaonkar, S.C. Laha, R.K. Pandey, P. Kumar, S.P. Mirajkar, R. Kumar, Catal. Today 97 (2004) 225. [15] A.C. Wagner, B.V. Paula, W. Martin, S. Ulf, Zeolites 18 (1997) 408. [16] D.A. Maria, Z. Luan, K. Jacek, J. Phys. Chem. 100 (1996) 2178. [17] S. Shylesh, A.P. Singh, J. Catal. 228 (2004) 333.
Synthesis and characterization of Fe–Ce–MCM-41 Ying Zheng a,⁎, Zhaohui Li b , Yong Zheng a , Xiaonv Shen a , Liangxu Lin a a
College of Chemistry and Material Science, Fujian Normal University, Fuzhou 350007, China b Research Institute of Photocatalysis, Fuzhou University, Fuzhou 350002, China Received 28 October 2005; accepted 23 February 2006 Available online 15 March 2006
Abstract The mesoporous molecular sieve Fe–Ce–MCM-41 was synthesized under hydrothermal condition and characterized by XRD, FT-IR, DRS, TG and low temperature N2 adsorption–desorption method. The results showed that with high BET surface area and narrow pore size distribution, the obtained Fe–Ce–MCM-41 has excellent thermal stability. © 2006 Elsevier B.V. All rights reserved. Keywords: Fe–Ce–MCM-41; Mesoporous molecular sieve; Synthesis; Characterization
1. Introduction
2. Experiment section
There has been a significant breakthrough in the science of molecular sieves since the M41S silicate sieves with diameters of 1.5–10 nm was successfully synthesized by Mobil corporation [1–3]. As a member of the M41S family, MCM-41 have attracted worldwide interest not only due to its high surface area (N 1000 m2/g), well-defined regular pore shape, narrow pore size distribution, large pore volume (N 0.7 ml/g) and tunable pore size in the range of 1.6–20 nm [1,4], but also its high thermal and chemical stability [5–9]. The MCM-41 molecular sieves containing transition metal (eg. Fe, V, Nb, etc.) [10–12] and rare earth (e.g. La, Ce, etc.) [13,14] have been synthesized under mild hydrothermal condition. Since rare earth metals not only possess peculiar electronic configuration but also variable valence state and the transition metals has redox ability, the incorporation of both the rare earth and transition metals into MCM-41 would bring forth a new type of catalyst for the decomposition of NOx and with higher oxygen store ability. In this study, we reported the synthesis of Fe and Ce adulterated MCM-41 and the obtained Fe– Ce–MCM-41 was characterized by XRD, FT-IR, DRS, TG and Low temperature N2 adsorption–desorption method.
2.1. Preparation of Fe–Ce–MCM-41 composites
⁎ Corresponding author. Tel.: +86 591 83465225; fax: +86 591 83465376. E-mail address: [email protected] (Y. Zheng). 0167-577X/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2006.02.075
0.24 g of NaOH and 2.19 g of CTAB was dissolved in 54 ml of distilled water. 6.25 g of TEOS (A.R.) was added dropwise under vigorous stirring to ensure the complete hydrolysis of TEOS. 0.25 g of Ce(NO3)3·6H2O and 0.24 g of Fe(NO3)3·9H2O (Si / Ce = 50 and Si / Fe = 50, respectively) were added slowly to the solution and the pH was adjusted to 8.5–9.0. After that, the solution was transferred to a 100 ml Teflon-lined autoclave and heated at 100 °C for 72 h. After cooling to room temperature, the solid product was obtained by filtration, washing and drying in air
Fig. 1. XRD patterns of MCM-41 (a) and Fe–Ce–MCM-41 (b).
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Y. Zheng et al. / Materials Letters 60 (2006) 3221–3223 Table 1 The comparison of the N2 absorption–desorption isotherms of the MCM-41 and Fe–Ce–MCM-41 Samples
BET surface (m2/g− 1)
Pore volume (ml/g− 1)
Average pore radius (nm)
MCM-41 Fe–Ce–MCM-41
987 507
0.72 0.56
1.8 1.6
by an OMNSORP 100CX gas absorb analyzer. The TG was analyzed by a FE TGA7 thermogravimetric analyzer. 3. Results and discussion Fig. 2. FT-IR spectra of MCM-41 (a) and Fe–Ce–MCM-41(b).
3.1. Powder X-ray diffraction XRD pattern of the obtained Fe–Ce–MCM-41 is in good agreement with MCM-41 in 2θ range of 1–10° (Fig. 1) and indicates that their structures are essentially the same. Three peaks at 2θ values of 2.3°, 3.97° and 4.60° can be indexed as the representative (100), (110) and (200) reflections of the P6m mesostructure of MCM-41 [1,2,15]. The intensity of the three peaks of Fe–Ce–MCM-41 decrease compared with those of MCM41. It suggests that the long-range order of the sample is not as good as that of MCM-41 and may be due to the incorporation of Fe and Ce into the framework of MCM-41. 3.2. FT-IR spectroscopy
Fig. 3. DRS spectra of MCM-41 (a) and Fe–Ce–MCM-41 (b).
at 60 °C. The sample was further treated at 540 °C for 10 h to remove the template.
2.2. Characterizations X-ray diffraction (XRD) patterns were recorded on a Bruker D8 Advance X-ray diffractometer with CuKα radiation. The IR spectra were recorded on a Nicolet Nexus 670 FT-IR Spectrometer. The DRS spectra were obtained on a Varian Carry 500 Spectrometer. The N2 absorption–desorption was analyzed
Fig. 4. Nitrogen adsorption–desorption isotherms of MCM-41 (a) and Fe–Ce– MCM-41 (b).
FT-IR spectrum of Fe–Ce–MCM-41 (Fig. 2) shows characteristic bands of Si–O–Si at 1090 cm− 1 for asymmetrical stretching and 801 cm− 1 for symmetrical stretching. The bands at 960 and 461 cm− 1 can be assigned to the Si–O stretching and twisting respectively [16]. Except that the positions of the bands shift a little, the IR spectra of MCM-41 before and after adulteration are essentially the same. It suggests that the framework of MCM-41 retained after Ce and Fe enter the framework. 3.3. DRS spectroscopy Fe–Ce–MCM-41 shows two absorptions at 258 and 296 nm while no absorption in the wavelength range of 190–350 nm for MCM-41 (Fig. 3). The absorption at 258 and 296 nm can be ascribed to isolated tetrahedral coordinated Fe3+ species and Ce4+ respectively. No significant absorption above 320 nm suggests the absence of Fe2O3 [10] and CeO2 [14].
Fig. 5. The pore size distributions of MCM-41 (a) and Fe–Ce–MCM-41 (b).
Y. Zheng et al. / Materials Letters 60 (2006) 3221–3223
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Ce are highly dispersed in the framework of the Fe–Ce–MCM41. The adulterated sample retains excellent thermal stability, high BET surface area and narrow pore size distribution of MCM-41. Acknowledgments The authors are grateful to financial support from Science Foundation of Fujian Province Education Commission of China (K04033, 2005K015) and Natural Science Foundation of Fujian Province (E0410009). References Fig. 6. TG curves of MCM-41 (a) and Fe–Ce–MCM-41 (b).
3.4. N2 adsorption–desorption analysis Both MCM-41 and Fe–Ce–MCM-41 display type IV nitrogen adsorption curve and suggest that they possess the mesoporous structure (Fig. 4) [17]. BET surface area and pore volume decreased after adulteration. (Table 1) The BJH pore distribution of both MCM41 and Fe–Ce–MCM-41 show sharp peaks in the range of 16–24 Å and suggest that both possess narrow pore size distribution (Fig. 5). The average pore radius for MCM-41 and Fe–Ce–MCM-41 is 18 and 16 Å respectively. Although the average pore radius decreases a little, the adulterated MCM-41 still shows a relatively large surface area and pore volume, indicating that the mesoporous structure are still retained. 3.5. TG analysis The weight loss observed at temperatures range from 30 to 120 °C corresponds to the desorption of the physically adsorbed water (Fig. 6). However no weight loss is observed in the temperature range of 120– 620 °C and suggests that the sample possesses a high thermal stability.
4. Conclusions The bimetallic mesoporous molecular sieve Fe–Ce–MCM41 has been synthesized under hydrothermal condition. Fe and
[1] C.T. Kresge, M.E. Leonowicz, W.J. Roth, J.C. Vartuli, J.S. Beck, Nature 359 (1992) 710. [2] J.S. Beck, J.C. Vartuli, W.J. Roth, M.E. Leonowicz, C.T. Kresge, K.D. Schmitt, C.T.-W. Chu, D.H. Olson, E.E. Sheppard, S.B. McCullen, J.B. Higgins, J.L. Schlenker, J. Am. Chem. Soc. 114 (1992) 10834. [3] K. Moller, T. Bein, Chem. Mater. 10 (1998) 2950. [4] Parasuraman Selvam, Suresh K. Bhatia, Chandrashekar G. Sonwane, Recent, Ind. Eng. Chem. Res. 40 (2001) 3237. [5] A. Corma, Chem. Rev. 97 (1997) 2373. [6] M. Gru¨n, K.K. Unger, A. Matsumoto, K. Tsutsumi, Microporous Mesoporous Mater. 27 (1999) 207. [7] B. Lindlar, A. Kogelbauer, P.J. Kooyman, R. Prins, Microporous Mesoporous Mater. 44–45 (2001) 89. [8] U. Ciesla, F. Schu¨th, Microporous Mesoporous Mater. 27 (1999) 131. [9] M. Jaroniec, M. Kruk, H.J. Shin, R. Ryoo, Y. Sakamoto, O. Terasaki, Microporous Mesoporous Mater. 48 (2001) 127. [10] B.A. Placidus, L. Sangyun, C. Dragos, Y. Yang, P. Lisa, L.H. Gary, J. Phys. Chem., B 109 (2005) 2645. [11] G. Yesim, D. Timur, B. Suna, Catal. Today 100 (2005) 473. [12] Z. Maria, N. Izabela, Zeolites 18 (1997) 356. [13] A.S. Araujo, M. Jaroniec, J. Colloid Interface Sci. 218 (1999) 462. [14] M.D. Kadgaonkar, S.C. Laha, R.K. Pandey, P. Kumar, S.P. Mirajkar, R. Kumar, Catal. Today 97 (2004) 225. [15] A.C. Wagner, B.V. Paula, W. Martin, S. Ulf, Zeolites 18 (1997) 408. [16] D.A. Maria, Z. Luan, K. Jacek, J. Phys. Chem. 100 (1996) 2178. [17] S. Shylesh, A.P. Singh, J. Catal. 228 (2004) 333.