کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1332190 979032 2008 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
PMo or PW heteropoly acids supported on MCM-41 silica nanoparticles: Characterisation and FT-IR study of the adsorption of 2-butanol
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی معدنی
پیش نمایش صفحه اول مقاله
PMo or PW heteropoly acids supported on MCM-41 silica nanoparticles: Characterisation and FT-IR study of the adsorption of 2-butanol
چکیده انگلیسی

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 °C. The samples have been characterised by N2 adsorption–desorption at −196 °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 °C, PW decomposes at this temperature into crystalline WO3 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 °C. The Brönsted-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 °C also shows selectivity to methyl ethyl ketone.

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 °C have been characterised and evaluated in the decomposition of 2-butanol monitored by FT-IR spectroscopy.Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Solid State Chemistry - Volume 181, Issue 8, August 2008, Pages 2046–2057
نویسندگان
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