Property and Activity of Molybdates Dispersed on Silica Obtained from Various Synthetic Procedures


The synthesis and characterization of several dispersed molybdena catalysts on silica support (MoO3-SiO2) prepared from a variety of precursors (Mo(VI)-acetylacetonate, oxo-peroxo Mo-species, hydrated ammonium heptamolybdate) and preparation methods (deposition of the Mo-phase on finite SiO2 support by aqueous and methanol impregnations, by adsorption, by oxo-peroxo route-like, and by one-step synthesis of MoO3-SiO2 system with molecular precursors) are presented. The molybdena concentration on silica was comprised in a large interval (1.5 - 14 wt%) depending on the preparation method which governed the Mo-loading on silica. Convenient comparisons among samples at similar Mo-concentration have been made discussing the morphologic-structural (XRD, XPS, UV-vis-DRS, and N2-adsorption) and physicochemical (TG-DTG, TPR, and n-butylamine-TPD) sample properties. Polymeric octahedral polymolybdate aggregates predominated in the samples prepared by aqueous and methanol impregnations, which were at high Mo-concentration. On the contrary, isolated Mo(VI) species in distorted Td symmetry predominated in the sample prepared by adsorption which was at very low Mo-concentration. The sample acidity was composed of a weak acidy site population, associated with the silica support, and a strong acid site population associated with the Mo-dispersed phase. Oxidation tests of formaldehyde, an oxygen-containing VOC (Volatile Organic Compound), were performed to determine the prevalent redox or acidic function of the Mo-species at the surface of the catalysts.

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A. Gervasini, L. Wahba, M. Finol and J. Lamonier, "Property and Activity of Molybdates Dispersed on Silica Obtained from Various Synthetic Procedures," Materials Sciences and Applications, Vol. 3 No. 4, 2012, pp. 195-212. doi: 10.4236/msa.2012.34030.

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The authors declare no conflicts of interest.


[1] H. H. Kung, “Transition Metal Oxides: Surface Chemis- try and Catalysis,” Elsevier, New York, 1989.
[2] G. Centi, Selective Oxidation by Heterogeneous Cataly- sis,” Kluwer Academic, New York, 2001.
[3] J. G. L. Fierro, “Metal Oxides: Chemistry and Applica- tions,” CRC Taylor & Francis: Boca Raton, 2006.
[4] H. Hair, M. J. Liszka, J. E. Gatt and D. Baertsch, “Effects of Metal Oxide Domain Size, Dispersion, and Interaction in Mixed WOx/MoOx Catalysts Supported on Al2O3 for the Partial Oxidation of Ethanol to Acetaldehyde,” The Journal of Physical Chemistry C, Vol. 112, No. 5, 2008, pp. 1612-1620. doi:10.1021/jp076300l
[5] A. Christodoulakis and S. Boghosian, “Molecular Struc- ture and Activity of Molybdena Catalysts Supported on Zirconia for Ethane Oxidative Dehydrogenation Studied by Operando Raman Spectroscopy,” Journal of Catalysis, Vol. 260, No. 1, 2008, pp. 178-187. doi:10.1016/j.jcat.2008.09.025
[6] N. Al-Yassir and R. Le Van Mao, “Catalysts for the Thermo-Catalytic Cracking (TCC) Process: Interactions between the Yttria in Yttria-Doped Alumina Aerogel and the Mono-Oxide MoO3, CeO2, and Bi-Oxide MoO3-CeO2 Species,” Applied Catalysis A: General, Vol. 332, No, 2, 2007, pp. 273-288. doi:10.1016/j.apcata.2007.08.023
[7] B. Solsona, A. Dejoz, T. García, P. Concepcíon, J. M. Lopez Nieto, M. J. Vázquez and M. T. Navarro, “Molyb- denum-Vanadium Supported on Mesoporous Alumina Catalysts for the Oxidative Dehydrogenation of Ethane,” Catalysis Today, Vol. 117, No. 1-3, 2006, pp. 228-233. doi:10.1016/j.cattod.2006.05.025
[8] L. Wang and W. K. Hall, “The Preparation and Genesis of Molybdena-Alumina and Related Catalytic Systems,” Journal of Catalysis, Vol. 77, No. 1, 1982, pp. 232-241. doi:10.1016/0021-9517(82)90163-4
[9] H. Jeziorowski and H. Knoezinger, “Raman and Ultra- violet Spectroscopic Characterization of Molybdena on Alumina Catalysts,” The Journal of Physical Chemistry, Vol. 83, No. 9, 1979. pp. 1166-1173. doi:10.1021/j100472a012
[10] J. M. Stencel, J. R. Diehl, J. R. D’Este, L. E. Makowsky, L. Rodrigo, K. Marcinkowska, A. Adnot, P. C. Roberge and S. Kaliaguine, “Characterization of Silica-Supported Mo(VI): The Effect of Calcination and Exposure to Water Vapor,” The Journal of Physical Chemistry, Vol. 90, No. 20, 1986, pp. 4739-4743. doi:10.1021/j100411a006
[11] D. G. H. Ballard, “Pi and Sigma Transition Metal Carbon Compounds as Catalysts for the Polymerization of Vinyl Monomers and Olefins,” Advanced in Catalysis, Vol. 23, 1973, pp. 263-325. doi:10.1016/S0360-0564(08)60303-X
[12] Y. I. Yermakov, “Supported Catalysts Obtained by Inter- action of Organometallic Compounds of Transition Ele- ments with Oxide Supports,” Catalysis Reviews: Science and Engineering, Vol. 13, No. 1, 1976, pp. 77-120. doi:10.1080/00087647608069935
[13] Y. Iwasawa and M. Yamagishi, “New SiO2-Attached ‘Mo-Pair’ Catalysts. Preparation, Surface Structure, and Chemical Nature,” Journal of Catalysis, Vol. 82, No.2, 1983, pp. 373-381. doi:10.1016/0021-9517(83)90204-X
[14] J.-Y. Piquemal, J.-M. Manoli, P. Beaunier, A. Ensuque, P. Tougne, A.-P. Legrand and J.-M. Brégeault, “Using In- organic Silicate Precursor/Molybdenum Peroxo Com- plexes/ Onium Salt Interfaces in Aqueous Acidic Media to Design Mesoporous Silica with High Molybdenum Content and High Dispersion,” Microporous and Meso- porous Materials, Vol. 29, No.3, 1999, pp. 291-304. doi:10.1016/S1387-1811(98)00342-4
[15] P. C. Bakala, E. Briot, L. Salles and J. M. Brégeault, “Comparison of Liquid-Phase Olefin Epoxidation over MoOx Inserted within Mesoporous Silica (MCM-41, SBA-15) and Grafted onto Silica,” Applied Catalysis A: General, Vol. 300, No. 2, 2006, pp. 91-99. doi:10.1016/j.apcata.2005.09.038
[16] Y. Wan and D. Zhao, “On the Controllable Soft-Tem- plating Approach to Mesoporous Silicates,” Chemical Reviews, Vol. 107, No. 7, 2007, pp. 2821-2860. doi:10.1021/cr068020s
[17] A. Bordoloi, A. Vinu and S. B. Halligudi, “One-Step Synthesis of SBA-15. Containing under Tungsten Oxide Nanoclustures: A Chemoselective Catalyst for Oxidation of Sulfides to Sulfoxides at Ambient Conditions,” Chemical Communication, Vol. 45, 2007, pp. 4806-4808. doi:10.1039/b709459k
[18] T. Salthammer, S. Mentese and R. Marutzky, “Formal- dehyde in the Indoor Environment,” Chemical Reviews, Vol. 110, No. 4, 2010, pp. 2536-2572. doi:10.1021/cr800399g
[19] S. Huh, J. W. Wiench, J.-C. Yoo, M. Pruski and V. S.-Y. Lin, “Organic Functionalization and Morphology Control of Mesoporous Silicas via a Co-Condensation Synthesis Method,” Chemistry of Materials, Vol. 15, No. 22, 2003, pp. 4247-4256. doi:10.1021/cm0210041
[20] A. Gervasini, C. Messi, P. Carniti, A. Ponti, N. Ravasio and F. Zaccheria, “Insight into the Properties of Fe Oxide Present in High Concentrations on Mesoporous Silica,” Journal of Catalysis, Vol. 262, No. 2, 2009, pp. 224-234. doi:10.1016/j.jcat.2008.12.016
[21] P. C. Bakala, E. Briot, J.-Y. Piquemal, J.-M. Brégeault and P. Beaunier, “Comparison of the Conventional Im- pregnation Method Using Ammonium Heptamolybdate with a Simple Route to Silica-Supported Molybdenum(VI) Materials,” Catalysis Communications, Vol. 8, No. 10, 2007, pp. 1447-1451. doi:10.1016/j.catcom.2006.12.015
[22] A. Gervasini, “Characterization of the Textural Properties of Metal Loaded Zsm-5 Zeolites,” Applied Catalysis A: General, Vol. 180, No. 1-2, 1999, pp. 71-82. doi:10.1016/S0926-860X(98)00333-0
[23] E. P. Barrett, L. G. Joyner and P. Halenda, “The Deter- mination of Pore Volume and Area Distributions in Po- rous Substances. I. Computations from Nitrogen Iso- therms,” Journal of the American Chemical Society, Vol. 73, No. 1, 1951, pp. 373-380. doi:10.1021/ja01145a126
[24] P. Malet and A. Caballero, “The Selection of Experimen- tal Conditions in Temperature-Programmed Reduction Experiments,” Journal of the Chemical Society, Faraday Transactions 1, Vol. 84, No.7, 1988, pp. 2369-2375. doi:10.1039/f19888402369
[25] D. A. M. Monti and A. Baiker, “Temperature-Programmed Reduction. Parametric Sensitivity and Estimation of Ki- netic Parameters,” Journal of Catalysis, Vol. 83, No. 2, 1983, pp. 323-335. doi:10.1016/0021-9517(83)90058-1
[26] P. Carniti, A. Gervasini and S. Bennici, “Experimental and Modelization Approach in the Study of Acid-Site Energy Distribution by Base Desorption. Part I: Modified Silica Surfaces,” Journal of Physical Chemistry B, Vol. 109, No. 4, 2005, pp. 1528-1536. doi:10.1021/jp047889g
[27] A. Gervasini, C. Messi, D. Flahaut and C. Guimon, “Acid Properties of Iron Oxide Catalysts Dispersed on Silica- Zirconia Supports with Different Zr Content,” Applied Catalysis A: General, Vol. 367, No. 1-2, 2009, pp. 113- 121. doi:10.1016/j.apcata.2009.07.044
[28] A. W. Miller, W. Atkinson, M. Barber and P. Swift, “The High Energy Photoelectron Spectra of Molybdenum in Some Mo/Al2O3 Systems,” Journal of Catalysis, Vol. 22, No. 1, 1971, pp. 140-142. doi:10.1016/0021-9517(71)90274-0
[29] G. Muralidhar, B. E. Concha, G. I. Bartholomew and C. H. Bartholomew, “Characterization of Reduced and Sul- fided, Supported Molybdenum Catalysts by O2 Chemi- sorption, X-Ray Diffraction, and ESCA,” Journal of Ca- talysis, Vol. 89, No. 2, 1984, pp. 274-284. doi:10.1016/0021-9517(84)90305-1
[30] N. K. Nag, “A Comparative Study on the Dispersion and Carrier-Catalyst Interaction of Molybdenum Oxides Sup- ported on Various Oxides by Electron Spectroscopy for Chemical Analysis,” The Journal of Physical Chemistry, Vol. 91, No. 9, 1987, pp. 2324-2327. doi:10.1021/j100293a023
[31] C. V. Cáceres, J. L. G. Fierro, J. Lázaro, A. López Agudo and J. Soria, “Effect of Support on the Surface Character- istics of Supported Molybdena Catalysts,” Journal of Catalysis, Vol. 122, No. 1, 1990, pp. 113-125. doi:10.1016/0021-9517(90)90265-L
[32] Y. V. Plyuto, I. V. Babich, I. V. Plyuto, A. D. Van Lan- geveld and J. A. Moulijn, “XPS Studies of MoO3/A12O3 and MoO3/SiO2 Systems,” Applied Surface Science, Vol. 119, No. 1-2, 1997, pp. 11-18. doi:10.1016/S0169-4332(97)00185-2
[33] M. A. Ba?ares, J. L.G Fierro and J. B. Moffat, “The Par- tial Oxidation of Methane on MoO3/SiO2 Catalyst: Influence on the Molybdenum Content and Type of Oxidant,” Journal of Catalysis, Vol. 142, No. 2, 1993, pp. 406-417. doi:10.1006/jcat.1993.1218
[34] T.-J. Yang and J. H. Lunsford, “Partial Oxidation of Methanol to Formaldehyde over Molybdenum Oxide on Silica,” Journal of Catalysis, Vol. 103, No. 1, 1987, pp. 55-64. doi:10.1016/0021-9517(87)90092-3
[35] F. Solymosi, A. Erd?helyi and A. Sz?ke, “Dehydrogena- tion of Methane on Supported Molybdenum Oxides. For- mation of Benzene from Methane,” Catalysis Letters, Vol. 32, No. 1-2, 1995, pp. 43-53. doi:10.1007/BF00806100
[36] F. E. Massoth, G. Muralidhar and J. Shabtai, “Catalytic Functionalities of Supported Sulfides: II. Effect of Sup- port on Mo Dispersion,” Journal of Catalysis, Vol. 85, No. 1, 1984, pp. 53-62. doi:10.1016/0021-9517(84)90109-X
[37] R. D. Roark, S. D. Kohler and J. G. Ekerdt, “Role of Si- lanol Groups in Dispersing Mo(VI) on Silica,” Catalysis Letters, Vol. 16, No. 1-2, 1992, pp. 71-76. doi:10.1007/BF00764356
[38] P. Maksimowski and W. Skupinski, “Catalytic of Sup- ported Tungsten and Molybdenum Complexes in Olefin Methatesis,” Journal of Molecular Catalysis, Vol. 65, No. 1-2, 1991, pp. 187-192. doi:10.1016/0304-5102(91)85095-J
[39] S. O. Grim and L. J. Matienzo, “X-Ray Photoelectron Spectroscopy of Inorganic and Organometallic Com- pounds of Molybdenum,” Inorganic Chemistry, Vol. 14, No. 5, 1975, pp. 1014-1018. doi:10.1021/ic50147a013
[40] H. Al-Kandari, F. Al-Kandari and A. Katrib, “Surface Electronic Structure-Catalytic Activity of Different Mo Oxidation States for Olefins and Saturated Hydrocarbon Molecules,” Catalysis Letters, Vol. 139, No. 3-4, 2010, pp. 134-140. doi:10.1007/s10562-010-0414-0
[41] M. Mieterle, G. Weinberg and G. Mestl, “Raman Spec- troscopy of Molybdenum Oxides Part I. Structural Char- acterization of Oxygen Defects in MoO3?x by DR UV/ VIS, Raman Spectroscopy and X-Ray Diffraction,” Physi- cal Chemistry Chemical Physics, Vol. 4, No. 5, 2002, pp. 812-821.
[42] M. A. Larrubia and G. Busca, “An Ultraviolet-Visible- Near Infrared Study of the Electronic Structure of Oxide Supported Vanadia-Tungsta and Vanadia-Molybdena,” Materials Chemistry and Physics, Vol. 72, No. 3, 2001, pp. 337-346. doi:10.1016/S0254-0584(01)00329-7
[43] C. C. Williams, J. G. Ekerdt, J.-M. Jehng, F. D. Hard- castle, A. M. Turek and I. E. Wachs, “A Raman and Ul- traviolet Diffuse Reflectance Spectroscopic Investigation of Silica-Supported Molybdenum Oxide,” The Journal of Physical Chemistry, Vol. 95, No. 22, 1991, pp. 8781- 8791. doi:10.1021/j100175a068
[44] J. Fournier, C. Louis, M. Che, P. Chaquin and D. Masure, “Polyoxometallates as Models for Oxide Catalysts: Part I. An UV-Visible Reflectance Study of Polyoxomolybdates: Influence of Polyhedra Arrangement on the Electronic Transitions and Comparison with Supported Molybde- num Catalysts,” Journal of Catalysis, Vol. 119, No. 2, 1989, pp. 400-414. doi:10.1016/0021-9517(89)90170-X
[45] M. A. Ba?ares and J. L. G. Fierro, “Selective Oxidation of Methane to Formaldehyde on Supported Molybdate Catalysts,” Catalysis Letters, Vol. 17, No. 3-4, 1993, pp. 205-211. doi:10.1007/BF00766143
[46] P. Gajardo, P. Grange and B. Delmon, “Physicochemical Characterization of the Interaction between Cobalt Mo- lybdenum Oxide and Silicon Dioxide. 1. Influence of the Cobalt-Molybdenum Ratio,” The Journal of Physical Chemistry, Vol. 83, No. 13, 1979, pp. 1771-1779. doi:10.1021/j100476a018
[47] K. Marcinkowska, L. Rodrigo, S. Kaliaguine and P. C. Roberge, “Characterization of Supported Mo(VI)/SiO2: The Effects of Water Leaching and Support Dehydroxy- lation,” Journal of Catalysis, Vol. 97, No. 1, 1986, pp. 75-84. doi:10.1016/0021-9517(86)90039-4
[48] J. P. Thielemann, T. Ressler, A. Walter, G. Tzolova- Müller and C. Hess, “Structure of Molybdenum Oxide Supported on Silica SBA-15 Studied by Raman, UV-Vis and X-Ray Absorption Spectroscopy,” Applied Catalysis A: Genera., Vol. 399, No. 1-2, 2011, pp. 28-34. doi:10.1016/j.apcata.2011.03.032
[49] F. Arena and A. Parmaliana, “Silica-Supported Molybdena Catalysts. Surface Structures, Reduction Pattern, and Oxy- gen Chemisorption,” The Journal of Physical Chemistry, Vol. 100, No. 51, 1996, pp. 19994-20005. doi:10.1021/jp9618587
[50] H. M. Ismail, M. I. Zaki, G. C. Bond and R. Shukri, “Temperature-Programmed Reduction of MoOx/SiOx and MoOx/Al2O3 Catalysts. Surface Structural Consequences of Impregnation Acidity,” Applied Catalysis A General, Vol. 72, No. 1, 1991, pp. L1-L12.
[51] R. L. Cordero, F. J. G. Lambias and A. L. Agudo, “Tem- perature Programmed Reduction and Zeta Potential Stud- ies of Structure of MoO3/Al2O3 and MoO3/SiO2 Catalysts. Effect of the Impregnation pH and Molybdenum Load- ing,” Applied Catalysis A: General, Vol. 74, No. 1, 1991, pp. 125-136. doi:10.1016/0166-9834(91)90013-X
[52] M. De Boer, A. J. van Dillen, D. C. Koninsberger, J. W. Geus, M. A. Vuurman and I. E. Wachs, “Remarkable Spreading Behavior of Molybdena on Silica Catalysts. An in Situ EXAFS-Raman Study,” Catalysis Letters, Vol. 11, No. 2, 1991, pp. 227-239. doi:10.1007/BF00764089
[53] H. Tian, C. A. Roberts and I. E. Wachs, “Molecular Struc- tural Determination of Molybdena in Different Environ- ments: Aqueous Solutions, Bulk Mixed Oxides, and Sup- ported MoO3 Catalysts,” The Journal of Physical Chem- istry C, Vol. 114, No. 33, 2010, p. 14110. doi:10.1021/jp103269w
[54] M. A. Baňares, H. Hu and I. E. Wachs, “Molybdena on Silica Catalysts: Role of Preparation Methods on the Structure-Selectivity Properties for the Oxidation of Me- thano,” Journal of Catalysis, Vol. 150, No. 2, 1994, pp. 407-420. doi:10.1006/jcat.1994.1359
[55] S. R. Seyedmonir and R. F. Howe, “Redox Chemistry of Molybdena-Silica Catalysts: 1. Characterization and Ther- mal Reduction,” Journal of Catalysis, Vol. 110, No. 2, 1988, pp. 216-228. doi:10.1016/0021-9517(88)90314-4
[56] J. C. Vedrine, “The Role of Redox, Acid-Base and Col- lective Properties and of Cristalline State of Heterogene- ous Catalysts in the Selective Oxidation of Hydrocar- bons,” Topics in Catalysis, Vol. 21, No. 1-3, 2002, pp. 97-106. doi:10.1023/A:1020560200125
[57] T. Kataoka and J. A. Dumesic, “Acidity of Unsupported and Silica-Supported Vanadia, Molybdena, and Titania as Studied by Pyridine Adsorption,” Journal of Catalysis, Vol. 112, No. 1, 1988, pp. 66-79. doi:10.1016/0021-9517(88)90121-2
[58] S. Rajagopal, J. A. Marzari and R. Miranda, “Silica-Alu- mina-Supported Mo Oxide Catalysts: Genesis and De- mise of Br?nsted-Lewis Acidity,” Journal of Catalysis, Vol. 151, No. 1, 1995, pp. 192-203. doi:10.1006/jcat.1995.1021
[59] C. F. Mao and M. A. Vannice, “Formaldehyde Oxidation over Ag Catalysts,” Journal of Catalysis, Vol. 154, No. 2, 1995, pp. 230-244. doi:10.1006/jcat.1995.1165
[60] W.-H. Cheng, “Methanol and Formaldehyde Oxidation Study over Molybdenum Oxide,” Journal of Catalysis, Vol. 158, No. 2, 1996, pp. 477-485. doi:10.1006/jcat.1996.0047
[61] R. L. McCormick, M. B. Al-Sahali and G. O. Alptekin, “Partial Oxidation of Methane, Methanol, Formaldehyde, and Carbon Monoxide over Silica: Global Reaction Ki- netics,” Applied Catalysis A: General, Vol. 226, No. 1-2, 2002, pp. 129-138. doi:10.1016/S0926-860X(01)00894-8

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