Abstract
Molybdenum supported on silica was prepared by the sol-gel method by hydrolysis of tetraethylortosilicate (TEOS) using oxalic acid (OA) or citric acid (CA) as a template through a chelating effect. The effect of the type of template and the molybdenum loading on the structural properties was studied. The relationship between the structure of materials and physical and chemical properties was identified by XRD, FTIR, Raman spectroscopy, H2-TPR, SEM-EDX, and N2 adsorption/desorption techniques. The XRD patterns illustrate that materials prepared varying the type of template and molybdenum loading are in different MoOx species. TPR-H2 analysis shows three different regions attributed to the process of reducing the molybdenum oxide (VI) to molybdenum metal. N2 adsorption/desorption studies reveal the influence of the metal loading and the type of template in the surface area and pore diameter obtained in all the cases values greater when oxalic acid was used. SEM-EDX studies show the similar morphological structures related to silica materials. Finally, the oxalic acid carbonyl groups are less separated which orientates the structure of the silicon oxide towards smaller pores and therefore, larger surface-specific areas with respect to citric acid.
Highlights
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Molybdenum supported on silica was prepared by the sol-gel method modifying the type of template.
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Amorphous silica structures were obtained and MoO3 species were observed when the molybdenum load was 6 wt%.
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The increase of molybdenum loading produces a decrease in the surface area by the formation of Mo–O–Si or Mo=O–Si bonds.
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Oxalic acid allows obtaining materials with higher surface area relative to citric acid.
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The larger size of the molecule of citric acid plays an important role as a chelating agent of molybdenum.
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References
Khoabane K, Mokoena EM, Coville NJ (2005) Synthesis and study of ammonium oxalate sol-gel templated silica gels. Microporous Mesoporous Mater 83(1–3):67–75
Alinauskas L, Brooke E, Regoutz A, Katelnikovas A, Raudonis R, Yitzchaik S, Payne DJ, Garskaite E (2017) Nanostructuring of SnO2 via solution-based and hard template assisted method. Thin Solid Films 626:38–45
Wang Y, Huang S, Kang S, Zhang C, Li X (2012) Low-cost route for synthesis of mesoporous silica materials with high silanol groups and their application for Cu(II) removal. Mater Chem Phys 132(2–3):1053–1059
Wang X, Wang X, Huang W, Sebastian PJ, Gamboa S (2005) Sol-gel template synthesis of highly ordered MnO2 nanowire arrays. J Power Sources 140(1):211–215
Papynov EK, Palamarchuk MS, Mayorov VY, Modin EB, Portnyagin AS, Sokol’nitskaya TA, Belov AA, Tananaev IG, Avramenko VA (2017) Sol-gel (template) synthesis of macroporous Mo-based catalysts for hydrothermal oxidation of radionuclide-organic complexes. Solid State Sci 69:31–37
Cortés Ortiz WG, Fajardo CAGuerrero (2018) Selective catalytic oxidation for methane conversion to methanol: a review. Cienc e Ing Neogranadina 28:45–71
Anderson JA, Hu H, Wachs IE, Faraldos M, Ba MA, Fierro G (1996) Comparison of silica-supported MoO3 and V2O5 catalysts in the selective partial oxidation of methane. J Catal 160:214–221
Bañares MA, Fierro JLG (1993) Selective oxidation of methane to formaldehyde on supported molybdate catalysts. Catal Lett 17(3–4):205–211
Bañares MA, Fierro JLG, Moffat JB (1993) The partial oxidation of methane on MoO3/SiO2 catalysts: influence of the molybdenum content and type of oxidant. J Catal 142:406–417
Jia PY, Liu XM, Li GZ, Yu M, Fang J, Lin J (2006) Sol – gel synthesis and characterization of molybdenum oxide gels. J Mater Sci Mater Electron 734(0):0
Standard Test Method for Determination of Nitrogen Adsorption and Desorption Isotherms of Catalysts and Catalyst Carriers by Static Volumetric Measurements. ASTM-D4222−03, 2008
Standard Practice for Calculation of Pore Size Distributions of Catalysts and Catalyst Carriers from Nitrogen Desorption Isotherms. ASTM-D4641−12, 2012
Adam F, Iqbal A (2011) Silica supported amorphous molybdenum catalysts prepared via sol-gel method and its catalytic activity. Microporous Mesoporous Mater 141(1–3):119–127
Guerrero Fajardo CA, N’Guyen Y, Courson C, Roger A-C (2006) Fe/SiO2 catalysts for the selective oxidation of methane to formaldehyde. Ing e Investig 26(2):37–44
Maheswari N, Muralidharan G (2017) Controlled synthesis of nanostructured molybdenum oxide electrodes for high performance supercapacitor devices. Appl S 416:461–469
Teimouri A, Mahmoudsalehi M, Salavati H (2018) Catalytic oxidative desulfurization of dibenzothiophene utilizing molybdenum and vanadium oxides supported on MCM-41. Int J Hydrog Energy 43:14816–14833
Vyas V, ali AKA, Prasad S, Srivastava P, Mallick S, Ershad M, Singh S, Pyare R (2016) Assessment of nickel oxide substituted bioactive glass-ceramic on in vitro bioactivity and mechanical properties. Boletín la Soc. Española Cerámica y Vidr. 55(6):228–238
Brinker CJ, Scherer G (1990) Structural evolution during consolidation. in Sol-Gel Science, San Diego: Academic Press, pp. 514–615
Mahmood T, Din SU, Naeem A, Mustafa S, WAseem M, Hamayun M (2012) Adsorption of arsenate from aqueous solution on binary mixed oxide of iron and silicon. Chem Eng J 192:90–98
Khalil K, Makhlouf S (2008) High surface area thermally stabilized porous iron oxide/silica nanocompositesvia a formamide modified sol–gel process. Appl. Surf. Sci. 254(13):3767–3773
Pudukudy M, Yaakob Z (2015) Methane decomposition over Ni, Co and Fe based monometallic catalysts. Chem Eng J 262:1009–1021
Zhan Z, Zeng HC (1999) A catalyst-free approach for sol–gel synthesis of highly mixed ZrO2–SiO2 oxides. J Non Cryst Solids 243:26–38
Neumann R, Levin-Elad M (1997) Metal oxide (TiO2, MoO3, WO3) substituted silicate xerogels as catalysts for the oxidation of hydrocarbons with hydrogen peroxide. J Catal 166(2):206–217
Bañares M, Fierro JLG (1993) Methane-Selective Oxidation of Silica-Supported Molybdenum (VI) Catalysts Structure and Catalytic Performance. in Catalytic selective oxidation, no. Vi, Washington, DC: American Chemical Society, pp. 354–367
Banares MA, Hu H, Wachs IE (1994) Molybdena on silica catalysts: role of preparation methods on the structure-selvtivity properties fo the oxidation of methanol. J Catal 150:407–420
Ibrahim AA, Fakeeha AH, Al-Fatesh AS, Abasaeed AE, Khan WU (2015) Methane decomposition over iron catalyst for hydrogen production. Int J Hydrog Energy 40(24):7593–7600
Feng L, Li X, Dadyburjor DB, Kugler EL (2000) A temperature-programmed-reduction study on alkali-promoted, carbon-supported molybdenum catalysts. J Catal 190(1):1–13
Rajagopal S, Marini H, Marzari A, Miranda R (1994) Silica-alumina-supported acidic molybdenum catalysts - TPR and XRD characterization. J Catal 147:417–428
Cuesta Zapata PM, Nazzarro MS, Parentis ML, Gonzo EE, Bonini NA (2013) Effect of hydrothermal treatment on Cr-SiO2mesoporous materials. Chem Eng Sci 101:374–381
Sing KSW (1982) Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Provisional). Pure Appl Chem 54:11
Zhu J, Tay BY, Ma J (2007) Hydrothermal synthesis and characterization of mesoporous SnO2/SnO2-SiO2 on neutral template. J Mater Process Technol 192–193:561–566
Sing KSW (1985) Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984). Pure Appl Chem 57(4):603–619
Pang JB, Qiu KY, Wei Y (2001) Preparation of mesoporous silica materials with non-surfactant hydroxy-carboxylic acid compounds as templates via sol ± gel process. J Non-Cryst Solids 283:101–108
Heinrichs B, Lambert S, Job N, Pirard JP. Sol-Gel Synthesis of Supported Metals. in Catalyst Preparation Science and Engineering, Taylor & Francis Group, 2007, pp 163–208
Pudukudy M, Yaakob Z (2015) Methane decomposition over Ni, Co and Fe based monometallic catalysts supported on sol gel derived SiO2 microflakes. Chem Eng J 262:1009–1021
Del Río JD, Durán GA, Londoño Orjuela Á, Sánchez FJ, Guerrero Fajardo CA (2007) Partial oxidation of methane to formaldehyde on MoO3, Fe2O3 and ferromolybdenum catalysts. Ing e Investig 27(1):19–24
Guerrero Fajardo CA Oxidación selectiva de metano hasta formaldehído. Universidad Nacional de Colombia y Laboratoire Des Matériaux, Surfaces Et Procédés Pour La Catalyse, 2008
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This research was accomplished with financial support from Universidad Nacional de Colombia under 37174 and 40814 projects.
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Cortés-Ortiz, W.G., Baena-Novoa, A. & Guerrero-Fajardo, C.A. Structuring-agent role in physical and chemical properties of Mo/SiO2 catalysts by sol-gel method. J Sol-Gel Sci Technol 89, 416–425 (2019). https://doi.org/10.1007/s10971-018-4892-7
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DOI: https://doi.org/10.1007/s10971-018-4892-7