PMo or PW heteropoly acids supported on MCM-41 silica nanoparticles: Characterisation and FT-IR study of the adsorption of 2-butanol
- GIR-QUESCAT, Dpto. de Quimica Inorganica, Universidad de Salamanca, 37008-Salamanca (Spain)
- Instituto de Estructura de la Materia, C.S.I.C., Serrano, 123, 28006-Madrid (Spain)
Mesoporous silica, prepared in basic conditions, has been loaded (20% weight) with 12-molybdophosphoric (PMo) or 12-tungstophosphoric (PW) acid and calcined at different temperatures ranging between 250 and 550 deg. C. The samples have been characterised by N{sub 2} adsorption-desorption at -196 deg. C, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), UV-visible diffuse reflectance, Raman spectroscopy and temperature programmed reduction (TPR). The acidity and catalytic activity have been, respectively, examined by monitoring the adsorption of pyridine and 2-butanol by FT-IR spectroscopy. The results indicate that PW and PMo acids are highly dispersed on mesoporous silica MCM-41 spherical nanoparticles. While PMo retains its Keggin structure up to 550 deg. C, PW decomposes at this temperature into crystalline WO{sub 3} and phosphorous oxides. In both cases, the morphology, hexagonal symmetry and long-range order observed for the support are preserved with calcination up to 450 deg. C. The Broensted-type acid sites found in all samples, whose surface concentration decreases as the calcination temperature increases, are responsible for the selective formation of cis-butene detected upon adsorption of 2-butanol. The sample containing PW calcined at 450 deg. C also shows selectivity to methyl ethyl ketone. - Graphical abstract: Samples based in MCM-41 nanoparticles loaded with tungstophosphoric and molybdophosphoric acids have been synthesised. The uncalcined solids and that derived upon their calcination in the temperature range 250-550 deg. C have been characterised and evaluated in the decomposition of 2-butanol monitored by FT-IR spectroscopy.
- OSTI ID:
- 21128409
- Journal Information:
- Journal of Solid State Chemistry, Vol. 181, Issue 8; Other Information: DOI: 10.1016/j.jssc.2008.05.004; PII: S0022-4596(08)00237-5; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ADSORPTION
BUTANOLS
BUTENES
CALCINATION
DESORPTION
INFRARED SPECTRA
KETONES
MOLYBDOPHOSPHORIC ACID
MONITORING
MORPHOLOGY
NANOSTRUCTURES
PARTICLES
RAMAN SPECTROSCOPY
SILICA
SURFACES
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TRANSMISSION ELECTRON MICROSCOPY
TUNGSTEN OXIDES
X-RAY DIFFRACTION