- Email: [email protected]
Catalytic performance of Mn3O4 and Co3O4 nanocrystals prepared by sonochemical method in epoxidation of styrene and cyclooctene
Applied Surface Science 256 (2010) 6678–6682
Contents lists available at ScienceDirect
Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc
Catalytic performance of Mn3 O4 and Co3 O4 nanocrystals prepared by sonochemical method in epoxidation of styrene and cyclooctene Azadeh Askarinejad a , Mojtaba Bagherzadeh b , Ali Morsali a,∗ a b
Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14155-4838, Tehran, Iran Department of Chemistry, Sharif University of Technology, Tehran, PO Box 11155-3615, Iran
a r t i c l e
i n f o
Article history: Received 4 December 2009 Received in revised form 11 April 2010 Accepted 20 April 2010 Available online 24 April 2010 Keywords: Epoxidation Styrene Cyclooctene Co3 O4 and Mn3 O4 nanocatalysts Sonochemistry
a b s t r a c t A simple sonochemical method was developed to synthesis uniform sphere-like Co3 O4 and Mn3 O4 nanocrystals. Epoxidation of styrene and cyclooctene by anhydrous tert-butyl hydroperoxide over the prepared Co3 O4 and Mn3 O4 nanocatalysts was investigated. The results of conversion activity were compared with bulk Co3 O4 and Mn3 O4 . Under optimized reaction conditions, the nanocatalysts showed a superior catalytic performance as compared to the bulk catalysts. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and BET surface area, were used to characterize and investigate the nanocatalysts. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Manganese oxide (Mn3 O4 , trimanganese tetroxide, Hausmannite) is been currently used in many industrial application domains as catalysis, magnetism, electrochemistry or air decontamination. For example, Mn3 O4 is a common catalyst for the oxidation of methane and carbon monoxide [1], the selective reduction of nitrobenzene [2], the decomposition of nitrogen oxides [3–5] and the oxydehydrogenation of alcohols [6]. Hausmannite powder is able to combust organic compounds at 100–500 ◦ C [7,8]. Spinel cobalt oxide (Co3 O4 ) is considered to be an important functional material, and has been widely used in electrochemistry, magnetism, catalysis and energy storage [9–17]. Co3 O4 and Mn3 O4 have significant promotion effect on the electrocatalytic activity and stability for electrooxidation of alcohols [18]. The properties of the metal oxides are influenced by the structure and morphologies including crystallite sizes, orientations, stacking manners and aspect ratios, which are sensitive to the preparation methodology used in their synthesis [19]. In order to offer better performances due to its size and/or its morphology toward these applications, Mn3 O4 has been prepared by various methods such as calcination of manganese oxides (MnO2 , Mn2 O3 , etc.), oxyhydroxide (g-MnOOH), carbonate (MnCO3 ) and nitrate (Mn(NO3 )2 ) at high temperature (1000 ◦ C) [20–22], solvothermal treatment of manganite (MnOOH)
∗ Corresponding author. Tel.: +98 2182884416; fax: +98 2188003455. E-mail address: morsali [email protected] (A. Morsali). 0169-4332/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2010.04.069
[23–28], sol–gel process with a post-treatment at higher temperature [29,30], precipitation coupled with oxidation of manganese hydroxide (Mn(OH)2 ) [31], electrospinning technique [32,33], gas condensation [34], chemical bath deposition to prepare thin films [35], gamma-ray irradiation of manganese sulfate (MnSO4 ·H2 O) [36], precipitation method from manganese nitrate (Mn(NO3 )2 ) at moderate temperature [37]. Also many methods have been attempted to prepare nanoscale cobalt oxide, including solid-state reaction [38], hydrothermal reaction [39], sodium nitrate-mediated synthesis [40,41], and microwave irradiation [42]. The ultrasound-activated reactions were recently employed in many areas of chemistry, one of them being the field of nanomaterials preparation [43,44]. The sonochemical process relies on the cavitation effects produced by collapsing bubbles in liquids. The extreme conditions of about 5000 ◦ C temperature and 500 atm pressure can drive chemical reactions such as oxidation, reduction, dissolution, and decomposition, which have been developed to fabricate a variety of metal, oxide, sulfide, and carbide nanoparticles [45–56]. The epoxidation of olefins is an extremely important class of catalytic reaction in the chemical industry because of the epoxides versatility in preparing many chemical intermediates. This type of reactions is generally carried out by using organic peracids and hydroperoxides as oxidants [57,58]. Generally, an epoxidation of terminal olefins, such as styrene, is difficult and requires long period (several hours) to achieve appreciate styrene oxide yield [59]. Up to now various transition metal ions, including Mo, Ti, V, W, Cu, Fe, Mn, and Co, have been used as suitable catalysts for epoxida-
A. Askarinejad et al. / Applied Surface Science 256 (2010) 6678–6682
tion reactions [60–63]. Cationic metalloporphyrins (MePs) [64–70], mesoporous nickel silicate [71] transition metal Schiff–base complexes [72] are some of the catalysts which have been used for styrene epoxidation. In a recent report, nano-size gold particles on a number of transition metal oxides (viz. TiO2 , Cr2 O3 , MnO2 , Fe2 O3 , Co3 O4 , NiO, CuO, ZnO, Y2 O3 , ZrO2 , La2 O3 and U3 O8 ), have been evaluated for their performance in the epoxidation of styrene [73]. Various catalysts such as Nb2 O5 –SiO2 nanocomposites [74], palladium catalyst on silica surface [75], molybdenum complexes [76,77] have been applied for cyclooctene epoxidation until now. In our previous work, nano-crystalline Mn3 O4 and Co3 O4 powders have been prepared via a one-step sonochemical method. Metal oxide particles with different crystallite sizes, morphologies and degree of crystallinity have been obtained at various conditions. The powders have been characterized by XRD, SEM, TEM and FTIR spectroscopy and the products with optimized purity, crystallinity, size and morphology have been characterized [78]. In the present work, the optimized obtained products of Mn3 O4 and Co3 O4 nanocrystals were used for catalytic epoxidation of styrene and cyclooctene by anhydrous tert-butyl hydroperoxide and the conversion activity of Mn3 O4 and Co3 O4 nanocatalysts were compared with these catalysts in bulk form. The results of catalytic performances were investigated by calculating the surface areas of the catalysts using the Brunauer–Emmett–Teller (BET) method. 2. Experimental
Fig. 1. X-ray powder diffraction pattern of (a) Co3 O4 and (b) Mn3 O4 nanocrystals.
power of 150–180W. These nanocrystals have shown the most crystallinity because of the existence of sharp peaks in the XRD pattern. The phase purity of the as-prepared Co3 O4 nanocrystals is completely obvious and all diffraction peaks are perfectly indexed to
Mn3 O4 and Co3 O4 nanocrystals were prepared by the reaction of Mn(CH3 COO)2 or Co(CH3 COO)2 precursors with tetramethylammonium hydroxide (TMAH) in a mixture of ethanol and water as solvents. The reactions were performed under ultrasound power. The optimized conditions used to obtain the products with the best size, dispersion, morphology and crystallinity were 25 ml Co(OAc)2 or Mn(OAc)2 (0.1 M), 50 ml TMAH (0.2 M), 1 h sonicating with the power of 150–180W. X-ray powder diffraction (XRD) measurements were performed using a X’pert diffractometer of Philips Company with monochromatized Cu K␣ radiation. The crystallite sizes of selected samples were estimated using the Scherrer formula. The samples were characterized with a scanning electron microscope (SEM) (Philips XL 30) with gold coating and a transmission electron microscope (TEM) [Philips CM 200 FEG (Field Emission Gun)]. BET surface area of the samples were determined by N2 adsorption–desorption isotherms using a Surface Area Analyzer (BET, Micromeretics Gemini 2375, USA), the nitrogen adsorption-desorption isotherms were measured at 77 K after degassing the samples at 150 ◦ C for 2 h. The styrene epoxidation reaction over the Mn3 O4 and Co3 O4 nanocatalysts was carried out at atmospheric pressure by contacting 0.005, 0.01 or 0.02 mmol catalyst with 0.2 mmol styrene or cyclooctene, 0.2 mmol chlorobenzene as an internal standard and 0.1 or 0.2 mmol t-butyl hydroperoxide [TBHP] in (1:1) CH2 Cl2 :CH3 OH (1 ml) in a magnetically stirred glass reactor, under reflux (at 70 ◦ C) for a period of 1 h. The reaction products and unconverted reactants were analyzed using gas chromatography (Agilent Technologies Instruments 6890N, equipped with a capillary column (19019 J-413 HP-5, 5% Phenyl Methyl Siloxane, Capillary 60.0 m × 250 m × 1.00 m) and a flame ionization detector). The conversion percent was calculated using the areas of substrate and internal standard peaks. 3. Results and discussion Fig. 1a shows the XRD pattern of Co3 O4 nanocrystals of the optimized product obtained by a direct sonochemical method with acetate salt/base molar ratio of 1:4 and 1 h sonicating with the
6679
Fig. 2. TEM images of (a) Co3 O4 and (b) Mn3 O4 .
6680
A. Askarinejad et al. / Applied Surface Science 256 (2010) 6678–6682
the cubic spinel structure with the lattice parameters of a = 8.0837 Å and Z = 8 and S.G = Fd3m which are in JCPDS card file No. 42-1467. No characteristic peaks of impurities are detected in the XRD pattern. The broadening of the peaks indicated that the particles were of nanometer scale. The average size of the particles calculated by the Scherrer formula was 19 nm, which is to some extent in agreement with that observed from SEM and TEM images. Fig. 1b shows the XRD pattern of Mn3 O4 nanocrystals of the optimized product. All the peaks are corresponding to a tetragonal structure of Mn3 O4 (Hausmannite) with lattice constants a = 5.7621 Å, c = 9.4696 Å, Z = 4 and S.G = 141 /amd (JCPDS card file No. 24-0734). As it can be seen in the XRD pattern of Mn3 O4 sample, it has a smaller signal to noise ratio due to the poorer crystallinity comparing with Co3 O4 nanocrystals which can be further confirmed by the TEM images (Fig. 2). The average size of the nanoparticles of this sample which is calculated from the Scherrer formula is 21.5 nm. The morphology and nanostructure of the as-prepared Co3 O4 and Mn3 O4 samples were further investigated using TEM. Fig. 2 shows the TEM images of Co3 O4 and Mn3 O4 samples. Fig. 2a shows the TEM image of optimized Co3 O4 NCs. It can be seen that these Co3 O4 nanocrystals have uniform fine cubic shapes that is corresponding to single crystals of Co3 O4 with cubic structure. The distances between the lattices planes can be obviously determined which results are in agreement with the XRD. The size of these cubic shapes is in the range of 16–24 nm which is in agreement with the XRD results. Fig. 2b shows the TEM images of Mn3 O4 nanostructures prepared with the same conditions as Co3 O4 NCs, which does not show the same morphology and crystallinity. The SEM micrographs of the as-prepared Co3 O4 and Mn3 O4 nanostructures are shown in Fig. 3. Fig. 3a shows the SEM image of Co3 O4 and Fig. 3b shows the SEM image of Mn3 O4 nanocrystals. Surface area of Mn3 O4 and Co3 O4 catalysts were confirmed with BET adsorption–desorption analysis. The results of BET surface area experiments, given in Table 1, show that Mn3 O4 and Co3 O4 catalysts in nanometer scale present higher surface areas than these catalysts in bulk form. These results confirm better catalytic performances of nanocatalysts. The catalytic performance of Co3 O4 and Mn3 O4 nanostructures was firstly studied in the epoxidation of styrene, as a model substrate, and tert-butyl hydrogen peroxide as the oxygen donor. In a series of experiments we evaluated the influence of several factors.
Fig. 3. SEM images of (a) Co3 O4 and (b) Mn3 O4 .
Table 1 BET surface area results of Mn3 O4 and Co3 O4 catalysts. Catalyst
Scale
BET surface area (m2 g−1 )
Mn3 O4 Mn3 O4 Co3 O4 Co3 O4
Bulk Nanometer Bulk Nanometer
67.3695 75.6792 7.6352 93.7138
Table 2 Conversion amounts in different catalytic epoxidation reaction conditions. Catalyst
Scale
Amount of catalyst
Amount of TBHP
Substrate
Time of reaction
Conversion (%)
Without catalyst Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Co3 O4 Co3 O4 Co3 O4 Co3 O4 Without catalyst Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Co3 O4 Co3 O4 Co3 O4 Co3 O4
– Nanometer Nanometer Nanometer Nanometer Nanometer Nanometer Nanometer Bulk Nanometer Nanometer Nanometer Bulk – Nanometer Nanometer Nanometer Bulk Nanometer Nanometer Nanometer Bulk
– 0.01 mmol 0.02 mmol 0.02 mmol 0.02 mmol 0.01 mmol 0.005 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol – 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol
0.2 mmol 0.1 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.1 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol
Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Cyclooctene Cyclooctene Cyclooctene Cyclooctene Cyclooctene Cyclooctene Cyclooctene Cyclooctene Cyclooctene
1h 15 min 15 min 30 min 1h 1h 1h 1h 1h 15 min 30 min 1h 1h 1h 15 min 30 min 1h 1h 15 min 30 min 1h 1h
10 2 32 96 100 100 43 24 20 14 19 98 14 25 21 55 92 43 15 40 85 40
A. Askarinejad et al. / Applied Surface Science 256 (2010) 6678–6682
Table 2 shows different reaction conditions and conversion results of the catalysts. Conversion percent was found to be dependent on the amount of catalyst. According to the results in Table 2, changing the catalyst amount from 0.05 mmol to 0.01 mmol and 0.02 mmol reflect increase of conversion percent. Changing the amount of TBHP from 0.1 mmol to 0.2 mmol has a positive effect on the catalytic activity, and also the results obtained after 1 h reaction are better than 30 min and 15 min in all cases. Optimum conditions for the catalytic system for styrene epoxidation at 70 ◦ C was obtained for 0.01 mmol Mn3 O4 nanoparticles, 0.2 mmol TBHP and time of 1 h which yielded 100% conversion of styrene to styrene oxide and benzaldehyde. The catalytic performance of Mn3 O4 in bulk form (micrometer scale) was compared with nano-sized Mn3 O4 by using bulk Mn3 O4 for catalyzing the reaction at the obtained optimized conditions. As it can be seen from Table 2, the result of 20% conversion was obtained for bulk Mn3 O4 which was comparable with the result obtained for the catalytic free reaction of styrene epoxidation. Co3 O4 nanocrystals were applied to catalyze the same reaction at the optimized conditions. An increase in the reaction time for epoxidation of styrene led to a significant increase in the conversion and in 1 h reaction 98% conversion was obtained. The reaction was redone by the existence of microparticles of Co3 O4 and 14% conversion was observed. In further experiments the optimized conditions of the catalytic reaction was performed with cyclooctene substrate and the results were compared with each other. In this case also the conversion amounts obtaining by use of nanometer and bulk form of Co3 O4 and Mn3 O4 had considerable differences. In general, the mechanisms proposed for t-BuOOH-based epoxidation of olefins with Co3 O4 and Mn3 O4 nanocatalysts are involving coordination of the oxidant to the metal centre. The Lewis acidity of the Co or Mn center increases the oxidizing power of the peroxo group and the olefin is subsequently deoxidized by nucleophilic attack on an electrophilic oxygen atom of the coordinated tert-butyl peroxide [79]. 4. Conclusion The synthesis procedure used in this work has allowed to obtain spinel Mn and Co oxides nanocrystals with high uniformity and crystallinity that are effective heterogeneous catalysts for cyclooctene and styrene epoxidation with TBHP. This study has shown that the size of the materials has a direct influence on their catalytic performances. Co3 O4 and Mn3 O4 nanomaterials appear very interesting and promising catalysts, having good activity for cyclooctene and styrene epoxidation in short times and rather low temperatures with the advantages of being prepared under direct and inexpensive conditions and they help to reach to considerably higher conversion activities than these materials in bulk form. Acknowledgement Supporting of this investigation by Tarbiat Modares University is gratefully acknowledged. References [1] E.R. Stobhe, B.A.D. Boer, J.W. Geus, Catal. Today 47 (1999) 161– 167. [2] E. Grootendorst, Y. Verbeck, V. Ponce, J. Catal. 157 (1995) 706– 712. [3] T. Yamashita, A. Vannice, J. Catal. 163 (1996) 158–168. [4] W.M. Wang, Y.N. Yang, Z. Jiayu, Appl. Catal. A 133 (1995) 81–93. [5] A. Maltha, H.F. Kist, B. Brunet, J. Ziolkowski, H. Onishi, Y. Iwasawa, V. Ponec, J. Catal. 149 (1995) 356–363. [6] M. Baldi, F. Milella, G. Ramis, V. Sanchez Escribano, G. Busca, Appl. Catal. A: Gen. 166 (1) (1998) 75–88.
6681
[7] M. Baldi, E. Finocchio, F. Milella, Appl. Catal. B: Environ. 16 (1998) 43–51. [8] M.F.M. Zwinkels, S.G. Jaras, P.G. Menon, Catal. Rev. Sci. Eng. 35 (1993) 319– 358. [9] T. Sugimoto, E. Matijevic, J. Inorg. Nucl. Chem. 41 (1979) 165–172. [10] Y. Okamoto, T. Imanaka, S. Teranishi, J. Catal. 65 (1998) 448–460. [11] S. Weichelm, P. Moller, J. Surf. Sci. 399 (1998) 219–237. [12] P. Nkeng, J. Koening, J. Gautier, P. Chartier, G. Poillerat, J. Electroanal. Chem. 402 (1996) 81–89. [13] H. Yamaura, J. Tamaki, K. Moriya, N. Miura, N. Yamazoe, J. Electrochem. Soc. 144 (1997) L158–L160. [14] M. Ando, T. Kobayashi, S. Lijima, M. Haruta, J. Mater. Chem. 7 (1997) 1779– 1783. [15] F. Svegl, B. Orel, M.G. Hutchins, K. Kalcher, J. Electrochem. Soc. 143 (1996) 1532–1539. [16] T. Maruyama, S. Arai, J. Electrochem. Soc. 143 (1996) 1383–1386. [17] M.G. Hutchins, P.J. Wright, P.D. Grebenik, Solar Energy Mater. 16 (1987) 113–131. [18] C. Xua, Z. Tian, P. Shen, S.P. Jiang, Electrochim. Acta 53 (2008) 2610–2618. [19] J. Jiang, L. Li, Mater. Lett. 61 (2007) 4894–4896. [20] C.H. Shomate, J. Am. Chem. Soc. 65 (1943) 786–789. [21] J.C. Southard, G.E. Moore, J. Am. Chem. Soc. 64 (1942) 1769–1770. [22] I. Ursu, R. Alexandrescu, I.N. Mihailescu, J. Phys. B 19 (1986) 825–830. [23] Y.C. Zhang, T. Qiao, X.Y. Hu, J. Solid State Chem. 177 (2004) 4093–4097. [24] G. Demazeau, J. Mater. Chem. 9 (1999) 15–18. [25] M. Yoshimura, MRS Bull. 25 (2000) 17–25 (special issue). [26] R.I. Walton, Chem. Soc. Rev. 31 (2002) 230–238. [27] Y.Q. Chang, X.Y. Xu, X.H. Luo, C.P. Chen, D.P. Yu, J. Cryst. Growth 264 (1–3) (2004) 232–236. [28] W. Zhang, Z. Yang, Y. Liu, S. Tang, X. Han, M. Chen, J. Cryst. Growth 263 (1–4) (2004) 394–399. [29] S. Ching, J.L. Roark, N. Duan, Chem. Mater. 9 (1997) 750–754. [30] F.A.A.L. Sagheer, M.A. Hasan, L. Pasupulety, J. Mater. Sci. Lett. 18 (1999) 209– 211. [31] Y.I. Jang, H. Wang, Y.M. Chiang, J. Mater. Chem. 8 (1998) 2761–2764. [32] C. Shao, H. Guan, Y. Liu, X. Li, X. Yang, J. Solid State Chem. 177 (2004) 2628– 2631. [33] C.L. Shao, H.Y. Guan, Y.S.B. Wen, B. Chen, X.H. Yang, J. Gong, Chin. Chem. Lett. 15 (2004) 471–488. [34] L. Dimesso, L. Heider, H. Hahn, Solid State Ionics 123 (1–4) (1999) 39–46. [35] H.Y. Xu, S.L. Xu, H. Wang, H. Yan, J. Electrochem. Soc. 152 (12) (2005) C803–C807. [36] Y. Hu, J. Chen, X. Xue, T. Li, Mater. Lett. 60 (2006) 383–385. [37] S. Rabiei, D.E. Miser, J.A. Lipscomb, K. Saoud, S. Gedevanishvili, F. Rasouli, J. Mater. Sci. 40 (2005) 4995–4998. [38] R. Xu, H.C. Zeng, Chem. Mater. 15 (2003) 2040–2048. [39] W.M. Zhang, X.Y. Song, D.Z. Li, H.Y. Yu, S.X. Sun, Chem. J. Chin. Univ. 25 (2004) 797–804. [40] J. Feng, H.C. Zeng, Chem. Mater. 15 (2003) 2829–2835. [41] R. Xu, H.C. Zeng, J. Phys. Chem. B 107 (2003) 926–930. [42] L. Li, J. Ren, Mater. Res. Bull. 41 (2006) 2286–2290. [43] K.S. Suslick, J.P. Price, Annu. Rev. Mater. Sci. 29 (1999) 295–326. [44] T.J. Mason, J.P. Lorimer, Applied Sonochemistry, Wiley–VCH, Weinheim, 2002. [45] V.G. Pol, A. Gedanken, J. Chem. Mater. 15 (2003) 1111–1118. [46] T. Gao, Q.H. Li, T.H. Wang, Chem. Mater. 17 (2005) 887–892. [47] N.A. Dhas, A. Zaban, A. Gedanken, Chem. Mater. 11 (1999) 806–813. [48] T. Gao, T.H. Wang, Chem. Commun. 22 (2004) 2558–2559. [49] N.A. Dhas, A. Gedanken, Appl. Phys. Lett. 72 (1998) 2514–2516. [50] M.A. Alavi, A. Morsali, Ultrason. Sonochem. 17 (2010) 132–138. [51] A. Askarinejad, A. Morsali, Chem. Eng. J. 153 (2009) 183–186. [52] M.A. Alavi, A. Morsali, Ultrason. Sonochem. 17 (2010) 441–446. [53] A. Askarinejad, A. Morsali, Chem. Eng. J. 150 (2009) 569–571. [54] H. Sadeghzadeh, A. Morsali, Cryst. Eng. Commun. 12 (2010) 370–372. [55] A. Askarinejad, A. Morsali, Mater. Lett. 62 (2008) 478–482. [56] M.A. Alavi, A. Morsali, Ultrason. Sonochem. 15 (2008) 833–838. [57] H. Shi, Z. Zhang, Y. Wang, J. Mol. Catal. A: Chem. 238 (2005) 13–25. [58] D.V. Deubel, G. Frenking, P. Gisdakis, W.A. Herrmann, N. Roesch, J. Sundermeyer, Acc. Chem. Res. 37 (2004) 645–652. [59] C. Coperet, H. Adolfsson, K.B. Sharpless, Chem. Commun. (1997) 1565– 1566. [60] D.E. De Vos, B.F. Sels, P.A. Jacobs, Adv. Synth. Catal. 345 (2003) 457–473. [61] R.A. Sheldon, M.C.A. van Vliet, in: R.A. Sheldon, H. van Bekkum (Eds.), Fine Chemicals through Heterogeneous Catalysis, Wiley–VCH, Weinheim, 2001, Chap. 9.1. [62] G. Grigoropoulou, J.H. Clark, J.A. Elings, Green Chem. 5 (2003) 1–7. [63] B.S. Lane, K. Burgess, Chem. Rev. 103 (2003) 2457–2473. [64] G. Olason, D.C. Sherrington, React. Funct. Polym. 42 (1999) 163–172. [65] B. Meunier, Chem. Rev. 92 (1992) 1411–1456. [66] J.R. Lindsay-Smith, R.A. Sheldon, Metaloporphyrin in Catalytic Oxidations, Marcel Dekker, New York, 1994, Chap. 11. [67] B. Meunier, in: F. Montanari, L. Casella (Eds.), Mettaloporphyrins Catalyzed Oxidations, Kluwer Academic Publishers, Dordrecht, 1994, Chap. 1. [68] D.R. Leanord, J.R.L. Smith, J. Chem. Soc.: Perkin Trans. 2 (1992) 2187–2196. [69] L. Barloy, J.P. Lallier, P. Battioni, D. Mansuy, Y. Piffard, M. Tournoux, J.B. Valim, W. Jones, New J. Chem. 16 (1992) 71–80. [70] Y. Iamamoto, Y.M. Idemori, S. Nakagaki, J. Mol. Catal. A: Chem. 99 (1995) 187–193.
6682
A. Askarinejad et al. / Applied Surface Science 256 (2010) 6678–6682
[71] V. Pârvulescu, C. Constantin, G. Popescu, B.L. Su, J. Mol. Catal. A 208 (2004) 253–256. [72] S.I. Mostafa, S. Ikeda, B. Ohtani, J. Mol. Catal. A 225 (2005) 181–188. [73] N.S. Patil, B.S. Uphade, D.G. McCulloh, S.K. Bhargava, V.R. Choudhary, Catal. Commun. 5 (2004) 681–685. [74] A. Aronne, M. Turco, G. Bagnasco, G. Ramis, E. Santacesaria, M. Di Serio, E. Marenna, M. Bevilacqua, C. Cammarano, E. Fanelli, Appl. Catal. A: Gen. 347 (2008) 179–185.
[75] J.H. Clark, D.J. Macquarrie, E.B. Mubofu, Green Chem. 2 (2000) 53–55. [76] M. Bagherzadeh, R. Latifi, L. Tahsini, V. Amani, A. Ellern, L. Keith Woo, Polyhedron 28 (2009) 2517–2521. [77] M. Bagherzadeh, L. Tahsini, R. Latifi, L. Keith Woob, Inorg. Chim. Acta. 262 (2009) 3698–3702. [78] A. Askarinejad, A. Morsali, Ultrason. Sonochem. 16 (2009) 124–131. [79] C.D. Nunes, A.A. Valente, M. Pillinger, J. Rocha, I.S. Goncualves, Chem. Eur. J. 9 (2003) 4380–4390.
Contents lists available at ScienceDirect
Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc
Catalytic performance of Mn3 O4 and Co3 O4 nanocrystals prepared by sonochemical method in epoxidation of styrene and cyclooctene Azadeh Askarinejad a , Mojtaba Bagherzadeh b , Ali Morsali a,∗ a b
Department of Chemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14155-4838, Tehran, Iran Department of Chemistry, Sharif University of Technology, Tehran, PO Box 11155-3615, Iran
a r t i c l e
i n f o
Article history: Received 4 December 2009 Received in revised form 11 April 2010 Accepted 20 April 2010 Available online 24 April 2010 Keywords: Epoxidation Styrene Cyclooctene Co3 O4 and Mn3 O4 nanocatalysts Sonochemistry
a b s t r a c t A simple sonochemical method was developed to synthesis uniform sphere-like Co3 O4 and Mn3 O4 nanocrystals. Epoxidation of styrene and cyclooctene by anhydrous tert-butyl hydroperoxide over the prepared Co3 O4 and Mn3 O4 nanocatalysts was investigated. The results of conversion activity were compared with bulk Co3 O4 and Mn3 O4 . Under optimized reaction conditions, the nanocatalysts showed a superior catalytic performance as compared to the bulk catalysts. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and BET surface area, were used to characterize and investigate the nanocatalysts. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Manganese oxide (Mn3 O4 , trimanganese tetroxide, Hausmannite) is been currently used in many industrial application domains as catalysis, magnetism, electrochemistry or air decontamination. For example, Mn3 O4 is a common catalyst for the oxidation of methane and carbon monoxide [1], the selective reduction of nitrobenzene [2], the decomposition of nitrogen oxides [3–5] and the oxydehydrogenation of alcohols [6]. Hausmannite powder is able to combust organic compounds at 100–500 ◦ C [7,8]. Spinel cobalt oxide (Co3 O4 ) is considered to be an important functional material, and has been widely used in electrochemistry, magnetism, catalysis and energy storage [9–17]. Co3 O4 and Mn3 O4 have significant promotion effect on the electrocatalytic activity and stability for electrooxidation of alcohols [18]. The properties of the metal oxides are influenced by the structure and morphologies including crystallite sizes, orientations, stacking manners and aspect ratios, which are sensitive to the preparation methodology used in their synthesis [19]. In order to offer better performances due to its size and/or its morphology toward these applications, Mn3 O4 has been prepared by various methods such as calcination of manganese oxides (MnO2 , Mn2 O3 , etc.), oxyhydroxide (g-MnOOH), carbonate (MnCO3 ) and nitrate (Mn(NO3 )2 ) at high temperature (1000 ◦ C) [20–22], solvothermal treatment of manganite (MnOOH)
∗ Corresponding author. Tel.: +98 2182884416; fax: +98 2188003455. E-mail address: morsali [email protected] (A. Morsali). 0169-4332/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2010.04.069
[23–28], sol–gel process with a post-treatment at higher temperature [29,30], precipitation coupled with oxidation of manganese hydroxide (Mn(OH)2 ) [31], electrospinning technique [32,33], gas condensation [34], chemical bath deposition to prepare thin films [35], gamma-ray irradiation of manganese sulfate (MnSO4 ·H2 O) [36], precipitation method from manganese nitrate (Mn(NO3 )2 ) at moderate temperature [37]. Also many methods have been attempted to prepare nanoscale cobalt oxide, including solid-state reaction [38], hydrothermal reaction [39], sodium nitrate-mediated synthesis [40,41], and microwave irradiation [42]. The ultrasound-activated reactions were recently employed in many areas of chemistry, one of them being the field of nanomaterials preparation [43,44]. The sonochemical process relies on the cavitation effects produced by collapsing bubbles in liquids. The extreme conditions of about 5000 ◦ C temperature and 500 atm pressure can drive chemical reactions such as oxidation, reduction, dissolution, and decomposition, which have been developed to fabricate a variety of metal, oxide, sulfide, and carbide nanoparticles [45–56]. The epoxidation of olefins is an extremely important class of catalytic reaction in the chemical industry because of the epoxides versatility in preparing many chemical intermediates. This type of reactions is generally carried out by using organic peracids and hydroperoxides as oxidants [57,58]. Generally, an epoxidation of terminal olefins, such as styrene, is difficult and requires long period (several hours) to achieve appreciate styrene oxide yield [59]. Up to now various transition metal ions, including Mo, Ti, V, W, Cu, Fe, Mn, and Co, have been used as suitable catalysts for epoxida-
A. Askarinejad et al. / Applied Surface Science 256 (2010) 6678–6682
tion reactions [60–63]. Cationic metalloporphyrins (MePs) [64–70], mesoporous nickel silicate [71] transition metal Schiff–base complexes [72] are some of the catalysts which have been used for styrene epoxidation. In a recent report, nano-size gold particles on a number of transition metal oxides (viz. TiO2 , Cr2 O3 , MnO2 , Fe2 O3 , Co3 O4 , NiO, CuO, ZnO, Y2 O3 , ZrO2 , La2 O3 and U3 O8 ), have been evaluated for their performance in the epoxidation of styrene [73]. Various catalysts such as Nb2 O5 –SiO2 nanocomposites [74], palladium catalyst on silica surface [75], molybdenum complexes [76,77] have been applied for cyclooctene epoxidation until now. In our previous work, nano-crystalline Mn3 O4 and Co3 O4 powders have been prepared via a one-step sonochemical method. Metal oxide particles with different crystallite sizes, morphologies and degree of crystallinity have been obtained at various conditions. The powders have been characterized by XRD, SEM, TEM and FTIR spectroscopy and the products with optimized purity, crystallinity, size and morphology have been characterized [78]. In the present work, the optimized obtained products of Mn3 O4 and Co3 O4 nanocrystals were used for catalytic epoxidation of styrene and cyclooctene by anhydrous tert-butyl hydroperoxide and the conversion activity of Mn3 O4 and Co3 O4 nanocatalysts were compared with these catalysts in bulk form. The results of catalytic performances were investigated by calculating the surface areas of the catalysts using the Brunauer–Emmett–Teller (BET) method. 2. Experimental
Fig. 1. X-ray powder diffraction pattern of (a) Co3 O4 and (b) Mn3 O4 nanocrystals.
power of 150–180W. These nanocrystals have shown the most crystallinity because of the existence of sharp peaks in the XRD pattern. The phase purity of the as-prepared Co3 O4 nanocrystals is completely obvious and all diffraction peaks are perfectly indexed to
Mn3 O4 and Co3 O4 nanocrystals were prepared by the reaction of Mn(CH3 COO)2 or Co(CH3 COO)2 precursors with tetramethylammonium hydroxide (TMAH) in a mixture of ethanol and water as solvents. The reactions were performed under ultrasound power. The optimized conditions used to obtain the products with the best size, dispersion, morphology and crystallinity were 25 ml Co(OAc)2 or Mn(OAc)2 (0.1 M), 50 ml TMAH (0.2 M), 1 h sonicating with the power of 150–180W. X-ray powder diffraction (XRD) measurements were performed using a X’pert diffractometer of Philips Company with monochromatized Cu K␣ radiation. The crystallite sizes of selected samples were estimated using the Scherrer formula. The samples were characterized with a scanning electron microscope (SEM) (Philips XL 30) with gold coating and a transmission electron microscope (TEM) [Philips CM 200 FEG (Field Emission Gun)]. BET surface area of the samples were determined by N2 adsorption–desorption isotherms using a Surface Area Analyzer (BET, Micromeretics Gemini 2375, USA), the nitrogen adsorption-desorption isotherms were measured at 77 K after degassing the samples at 150 ◦ C for 2 h. The styrene epoxidation reaction over the Mn3 O4 and Co3 O4 nanocatalysts was carried out at atmospheric pressure by contacting 0.005, 0.01 or 0.02 mmol catalyst with 0.2 mmol styrene or cyclooctene, 0.2 mmol chlorobenzene as an internal standard and 0.1 or 0.2 mmol t-butyl hydroperoxide [TBHP] in (1:1) CH2 Cl2 :CH3 OH (1 ml) in a magnetically stirred glass reactor, under reflux (at 70 ◦ C) for a period of 1 h. The reaction products and unconverted reactants were analyzed using gas chromatography (Agilent Technologies Instruments 6890N, equipped with a capillary column (19019 J-413 HP-5, 5% Phenyl Methyl Siloxane, Capillary 60.0 m × 250 m × 1.00 m) and a flame ionization detector). The conversion percent was calculated using the areas of substrate and internal standard peaks. 3. Results and discussion Fig. 1a shows the XRD pattern of Co3 O4 nanocrystals of the optimized product obtained by a direct sonochemical method with acetate salt/base molar ratio of 1:4 and 1 h sonicating with the
6679
Fig. 2. TEM images of (a) Co3 O4 and (b) Mn3 O4 .
6680
A. Askarinejad et al. / Applied Surface Science 256 (2010) 6678–6682
the cubic spinel structure with the lattice parameters of a = 8.0837 Å and Z = 8 and S.G = Fd3m which are in JCPDS card file No. 42-1467. No characteristic peaks of impurities are detected in the XRD pattern. The broadening of the peaks indicated that the particles were of nanometer scale. The average size of the particles calculated by the Scherrer formula was 19 nm, which is to some extent in agreement with that observed from SEM and TEM images. Fig. 1b shows the XRD pattern of Mn3 O4 nanocrystals of the optimized product. All the peaks are corresponding to a tetragonal structure of Mn3 O4 (Hausmannite) with lattice constants a = 5.7621 Å, c = 9.4696 Å, Z = 4 and S.G = 141 /amd (JCPDS card file No. 24-0734). As it can be seen in the XRD pattern of Mn3 O4 sample, it has a smaller signal to noise ratio due to the poorer crystallinity comparing with Co3 O4 nanocrystals which can be further confirmed by the TEM images (Fig. 2). The average size of the nanoparticles of this sample which is calculated from the Scherrer formula is 21.5 nm. The morphology and nanostructure of the as-prepared Co3 O4 and Mn3 O4 samples were further investigated using TEM. Fig. 2 shows the TEM images of Co3 O4 and Mn3 O4 samples. Fig. 2a shows the TEM image of optimized Co3 O4 NCs. It can be seen that these Co3 O4 nanocrystals have uniform fine cubic shapes that is corresponding to single crystals of Co3 O4 with cubic structure. The distances between the lattices planes can be obviously determined which results are in agreement with the XRD. The size of these cubic shapes is in the range of 16–24 nm which is in agreement with the XRD results. Fig. 2b shows the TEM images of Mn3 O4 nanostructures prepared with the same conditions as Co3 O4 NCs, which does not show the same morphology and crystallinity. The SEM micrographs of the as-prepared Co3 O4 and Mn3 O4 nanostructures are shown in Fig. 3. Fig. 3a shows the SEM image of Co3 O4 and Fig. 3b shows the SEM image of Mn3 O4 nanocrystals. Surface area of Mn3 O4 and Co3 O4 catalysts were confirmed with BET adsorption–desorption analysis. The results of BET surface area experiments, given in Table 1, show that Mn3 O4 and Co3 O4 catalysts in nanometer scale present higher surface areas than these catalysts in bulk form. These results confirm better catalytic performances of nanocatalysts. The catalytic performance of Co3 O4 and Mn3 O4 nanostructures was firstly studied in the epoxidation of styrene, as a model substrate, and tert-butyl hydrogen peroxide as the oxygen donor. In a series of experiments we evaluated the influence of several factors.
Fig. 3. SEM images of (a) Co3 O4 and (b) Mn3 O4 .
Table 1 BET surface area results of Mn3 O4 and Co3 O4 catalysts. Catalyst
Scale
BET surface area (m2 g−1 )
Mn3 O4 Mn3 O4 Co3 O4 Co3 O4
Bulk Nanometer Bulk Nanometer
67.3695 75.6792 7.6352 93.7138
Table 2 Conversion amounts in different catalytic epoxidation reaction conditions. Catalyst
Scale
Amount of catalyst
Amount of TBHP
Substrate
Time of reaction
Conversion (%)
Without catalyst Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Co3 O4 Co3 O4 Co3 O4 Co3 O4 Without catalyst Mn3 O4 Mn3 O4 Mn3 O4 Mn3 O4 Co3 O4 Co3 O4 Co3 O4 Co3 O4
– Nanometer Nanometer Nanometer Nanometer Nanometer Nanometer Nanometer Bulk Nanometer Nanometer Nanometer Bulk – Nanometer Nanometer Nanometer Bulk Nanometer Nanometer Nanometer Bulk
– 0.01 mmol 0.02 mmol 0.02 mmol 0.02 mmol 0.01 mmol 0.005 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol – 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol 0.01 mmol
0.2 mmol 0.1 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.1 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol 0.2 mmol
Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Styrene Cyclooctene Cyclooctene Cyclooctene Cyclooctene Cyclooctene Cyclooctene Cyclooctene Cyclooctene Cyclooctene
1h 15 min 15 min 30 min 1h 1h 1h 1h 1h 15 min 30 min 1h 1h 1h 15 min 30 min 1h 1h 15 min 30 min 1h 1h
10 2 32 96 100 100 43 24 20 14 19 98 14 25 21 55 92 43 15 40 85 40
A. Askarinejad et al. / Applied Surface Science 256 (2010) 6678–6682
Table 2 shows different reaction conditions and conversion results of the catalysts. Conversion percent was found to be dependent on the amount of catalyst. According to the results in Table 2, changing the catalyst amount from 0.05 mmol to 0.01 mmol and 0.02 mmol reflect increase of conversion percent. Changing the amount of TBHP from 0.1 mmol to 0.2 mmol has a positive effect on the catalytic activity, and also the results obtained after 1 h reaction are better than 30 min and 15 min in all cases. Optimum conditions for the catalytic system for styrene epoxidation at 70 ◦ C was obtained for 0.01 mmol Mn3 O4 nanoparticles, 0.2 mmol TBHP and time of 1 h which yielded 100% conversion of styrene to styrene oxide and benzaldehyde. The catalytic performance of Mn3 O4 in bulk form (micrometer scale) was compared with nano-sized Mn3 O4 by using bulk Mn3 O4 for catalyzing the reaction at the obtained optimized conditions. As it can be seen from Table 2, the result of 20% conversion was obtained for bulk Mn3 O4 which was comparable with the result obtained for the catalytic free reaction of styrene epoxidation. Co3 O4 nanocrystals were applied to catalyze the same reaction at the optimized conditions. An increase in the reaction time for epoxidation of styrene led to a significant increase in the conversion and in 1 h reaction 98% conversion was obtained. The reaction was redone by the existence of microparticles of Co3 O4 and 14% conversion was observed. In further experiments the optimized conditions of the catalytic reaction was performed with cyclooctene substrate and the results were compared with each other. In this case also the conversion amounts obtaining by use of nanometer and bulk form of Co3 O4 and Mn3 O4 had considerable differences. In general, the mechanisms proposed for t-BuOOH-based epoxidation of olefins with Co3 O4 and Mn3 O4 nanocatalysts are involving coordination of the oxidant to the metal centre. The Lewis acidity of the Co or Mn center increases the oxidizing power of the peroxo group and the olefin is subsequently deoxidized by nucleophilic attack on an electrophilic oxygen atom of the coordinated tert-butyl peroxide [79]. 4. Conclusion The synthesis procedure used in this work has allowed to obtain spinel Mn and Co oxides nanocrystals with high uniformity and crystallinity that are effective heterogeneous catalysts for cyclooctene and styrene epoxidation with TBHP. This study has shown that the size of the materials has a direct influence on their catalytic performances. Co3 O4 and Mn3 O4 nanomaterials appear very interesting and promising catalysts, having good activity for cyclooctene and styrene epoxidation in short times and rather low temperatures with the advantages of being prepared under direct and inexpensive conditions and they help to reach to considerably higher conversion activities than these materials in bulk form. Acknowledgement Supporting of this investigation by Tarbiat Modares University is gratefully acknowledged. References [1] E.R. Stobhe, B.A.D. Boer, J.W. Geus, Catal. Today 47 (1999) 161– 167. [2] E. Grootendorst, Y. Verbeck, V. Ponce, J. Catal. 157 (1995) 706– 712. [3] T. Yamashita, A. Vannice, J. Catal. 163 (1996) 158–168. [4] W.M. Wang, Y.N. Yang, Z. Jiayu, Appl. Catal. A 133 (1995) 81–93. [5] A. Maltha, H.F. Kist, B. Brunet, J. Ziolkowski, H. Onishi, Y. Iwasawa, V. Ponec, J. Catal. 149 (1995) 356–363. [6] M. Baldi, F. Milella, G. Ramis, V. Sanchez Escribano, G. Busca, Appl. Catal. A: Gen. 166 (1) (1998) 75–88.
6681
[7] M. Baldi, E. Finocchio, F. Milella, Appl. Catal. B: Environ. 16 (1998) 43–51. [8] M.F.M. Zwinkels, S.G. Jaras, P.G. Menon, Catal. Rev. Sci. Eng. 35 (1993) 319– 358. [9] T. Sugimoto, E. Matijevic, J. Inorg. Nucl. Chem. 41 (1979) 165–172. [10] Y. Okamoto, T. Imanaka, S. Teranishi, J. Catal. 65 (1998) 448–460. [11] S. Weichelm, P. Moller, J. Surf. Sci. 399 (1998) 219–237. [12] P. Nkeng, J. Koening, J. Gautier, P. Chartier, G. Poillerat, J. Electroanal. Chem. 402 (1996) 81–89. [13] H. Yamaura, J. Tamaki, K. Moriya, N. Miura, N. Yamazoe, J. Electrochem. Soc. 144 (1997) L158–L160. [14] M. Ando, T. Kobayashi, S. Lijima, M. Haruta, J. Mater. Chem. 7 (1997) 1779– 1783. [15] F. Svegl, B. Orel, M.G. Hutchins, K. Kalcher, J. Electrochem. Soc. 143 (1996) 1532–1539. [16] T. Maruyama, S. Arai, J. Electrochem. Soc. 143 (1996) 1383–1386. [17] M.G. Hutchins, P.J. Wright, P.D. Grebenik, Solar Energy Mater. 16 (1987) 113–131. [18] C. Xua, Z. Tian, P. Shen, S.P. Jiang, Electrochim. Acta 53 (2008) 2610–2618. [19] J. Jiang, L. Li, Mater. Lett. 61 (2007) 4894–4896. [20] C.H. Shomate, J. Am. Chem. Soc. 65 (1943) 786–789. [21] J.C. Southard, G.E. Moore, J. Am. Chem. Soc. 64 (1942) 1769–1770. [22] I. Ursu, R. Alexandrescu, I.N. Mihailescu, J. Phys. B 19 (1986) 825–830. [23] Y.C. Zhang, T. Qiao, X.Y. Hu, J. Solid State Chem. 177 (2004) 4093–4097. [24] G. Demazeau, J. Mater. Chem. 9 (1999) 15–18. [25] M. Yoshimura, MRS Bull. 25 (2000) 17–25 (special issue). [26] R.I. Walton, Chem. Soc. Rev. 31 (2002) 230–238. [27] Y.Q. Chang, X.Y. Xu, X.H. Luo, C.P. Chen, D.P. Yu, J. Cryst. Growth 264 (1–3) (2004) 232–236. [28] W. Zhang, Z. Yang, Y. Liu, S. Tang, X. Han, M. Chen, J. Cryst. Growth 263 (1–4) (2004) 394–399. [29] S. Ching, J.L. Roark, N. Duan, Chem. Mater. 9 (1997) 750–754. [30] F.A.A.L. Sagheer, M.A. Hasan, L. Pasupulety, J. Mater. Sci. Lett. 18 (1999) 209– 211. [31] Y.I. Jang, H. Wang, Y.M. Chiang, J. Mater. Chem. 8 (1998) 2761–2764. [32] C. Shao, H. Guan, Y. Liu, X. Li, X. Yang, J. Solid State Chem. 177 (2004) 2628– 2631. [33] C.L. Shao, H.Y. Guan, Y.S.B. Wen, B. Chen, X.H. Yang, J. Gong, Chin. Chem. Lett. 15 (2004) 471–488. [34] L. Dimesso, L. Heider, H. Hahn, Solid State Ionics 123 (1–4) (1999) 39–46. [35] H.Y. Xu, S.L. Xu, H. Wang, H. Yan, J. Electrochem. Soc. 152 (12) (2005) C803–C807. [36] Y. Hu, J. Chen, X. Xue, T. Li, Mater. Lett. 60 (2006) 383–385. [37] S. Rabiei, D.E. Miser, J.A. Lipscomb, K. Saoud, S. Gedevanishvili, F. Rasouli, J. Mater. Sci. 40 (2005) 4995–4998. [38] R. Xu, H.C. Zeng, Chem. Mater. 15 (2003) 2040–2048. [39] W.M. Zhang, X.Y. Song, D.Z. Li, H.Y. Yu, S.X. Sun, Chem. J. Chin. Univ. 25 (2004) 797–804. [40] J. Feng, H.C. Zeng, Chem. Mater. 15 (2003) 2829–2835. [41] R. Xu, H.C. Zeng, J. Phys. Chem. B 107 (2003) 926–930. [42] L. Li, J. Ren, Mater. Res. Bull. 41 (2006) 2286–2290. [43] K.S. Suslick, J.P. Price, Annu. Rev. Mater. Sci. 29 (1999) 295–326. [44] T.J. Mason, J.P. Lorimer, Applied Sonochemistry, Wiley–VCH, Weinheim, 2002. [45] V.G. Pol, A. Gedanken, J. Chem. Mater. 15 (2003) 1111–1118. [46] T. Gao, Q.H. Li, T.H. Wang, Chem. Mater. 17 (2005) 887–892. [47] N.A. Dhas, A. Zaban, A. Gedanken, Chem. Mater. 11 (1999) 806–813. [48] T. Gao, T.H. Wang, Chem. Commun. 22 (2004) 2558–2559. [49] N.A. Dhas, A. Gedanken, Appl. Phys. Lett. 72 (1998) 2514–2516. [50] M.A. Alavi, A. Morsali, Ultrason. Sonochem. 17 (2010) 132–138. [51] A. Askarinejad, A. Morsali, Chem. Eng. J. 153 (2009) 183–186. [52] M.A. Alavi, A. Morsali, Ultrason. Sonochem. 17 (2010) 441–446. [53] A. Askarinejad, A. Morsali, Chem. Eng. J. 150 (2009) 569–571. [54] H. Sadeghzadeh, A. Morsali, Cryst. Eng. Commun. 12 (2010) 370–372. [55] A. Askarinejad, A. Morsali, Mater. Lett. 62 (2008) 478–482. [56] M.A. Alavi, A. Morsali, Ultrason. Sonochem. 15 (2008) 833–838. [57] H. Shi, Z. Zhang, Y. Wang, J. Mol. Catal. A: Chem. 238 (2005) 13–25. [58] D.V. Deubel, G. Frenking, P. Gisdakis, W.A. Herrmann, N. Roesch, J. Sundermeyer, Acc. Chem. Res. 37 (2004) 645–652. [59] C. Coperet, H. Adolfsson, K.B. Sharpless, Chem. Commun. (1997) 1565– 1566. [60] D.E. De Vos, B.F. Sels, P.A. Jacobs, Adv. Synth. Catal. 345 (2003) 457–473. [61] R.A. Sheldon, M.C.A. van Vliet, in: R.A. Sheldon, H. van Bekkum (Eds.), Fine Chemicals through Heterogeneous Catalysis, Wiley–VCH, Weinheim, 2001, Chap. 9.1. [62] G. Grigoropoulou, J.H. Clark, J.A. Elings, Green Chem. 5 (2003) 1–7. [63] B.S. Lane, K. Burgess, Chem. Rev. 103 (2003) 2457–2473. [64] G. Olason, D.C. Sherrington, React. Funct. Polym. 42 (1999) 163–172. [65] B. Meunier, Chem. Rev. 92 (1992) 1411–1456. [66] J.R. Lindsay-Smith, R.A. Sheldon, Metaloporphyrin in Catalytic Oxidations, Marcel Dekker, New York, 1994, Chap. 11. [67] B. Meunier, in: F. Montanari, L. Casella (Eds.), Mettaloporphyrins Catalyzed Oxidations, Kluwer Academic Publishers, Dordrecht, 1994, Chap. 1. [68] D.R. Leanord, J.R.L. Smith, J. Chem. Soc.: Perkin Trans. 2 (1992) 2187–2196. [69] L. Barloy, J.P. Lallier, P. Battioni, D. Mansuy, Y. Piffard, M. Tournoux, J.B. Valim, W. Jones, New J. Chem. 16 (1992) 71–80. [70] Y. Iamamoto, Y.M. Idemori, S. Nakagaki, J. Mol. Catal. A: Chem. 99 (1995) 187–193.
6682
A. Askarinejad et al. / Applied Surface Science 256 (2010) 6678–6682
[71] V. Pârvulescu, C. Constantin, G. Popescu, B.L. Su, J. Mol. Catal. A 208 (2004) 253–256. [72] S.I. Mostafa, S. Ikeda, B. Ohtani, J. Mol. Catal. A 225 (2005) 181–188. [73] N.S. Patil, B.S. Uphade, D.G. McCulloh, S.K. Bhargava, V.R. Choudhary, Catal. Commun. 5 (2004) 681–685. [74] A. Aronne, M. Turco, G. Bagnasco, G. Ramis, E. Santacesaria, M. Di Serio, E. Marenna, M. Bevilacqua, C. Cammarano, E. Fanelli, Appl. Catal. A: Gen. 347 (2008) 179–185.
[75] J.H. Clark, D.J. Macquarrie, E.B. Mubofu, Green Chem. 2 (2000) 53–55. [76] M. Bagherzadeh, R. Latifi, L. Tahsini, V. Amani, A. Ellern, L. Keith Woo, Polyhedron 28 (2009) 2517–2521. [77] M. Bagherzadeh, L. Tahsini, R. Latifi, L. Keith Woob, Inorg. Chim. Acta. 262 (2009) 3698–3702. [78] A. Askarinejad, A. Morsali, Ultrason. Sonochem. 16 (2009) 124–131. [79] C.D. Nunes, A.A. Valente, M. Pillinger, J. Rocha, I.S. Goncualves, Chem. Eur. J. 9 (2003) 4380–4390.