کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
158391 | 457006 | 2008 | 7 صفحه PDF | دانلود رایگان |
In order to fully exploit the green characteristics of solid base catalysts they should be fabricated into macrostructured rather than powder form. Magnesia-rich magnesium aluminate spinel (MgO·MgAl2O4)(MgO·MgAl2O4) framework catalysts with tunable basicity have been prepared by using γ‐Al2O3γ‐Al2O3 macrospheres (0.5–1.0 mm in diameter) as a hard template. The process involves in situ growth of magnesium–aluminum layered double hydroxides (MgAl-LDHs) in the channels of the γ‐Al2O3γ‐Al2O3 macrospheres by the urea hydrolysis method, followed by calcination, tuning of the basicity through etching of excess aluminum with aqueous alkali and a final calcination step. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), elemental analysis and low temperature N2 adsorption–desorption studies demonstrate that the composite MgO·MgAl2O4MgO·MgAl2O4 materials are composed of nanosized rod-like particles aggregated into a spherical framework. Catalytic reactivity was investigated by using methanolysis of soybean oil as probe reaction. The MgO·MgAl2O4MgO·MgAl2O4 composite shows a higher biodiesel yield compared to an MgO/MgAl2O4/γ‐Al2O3MgO/MgAl2O4/γ‐Al2O3 material with the same loading of magnesium prepared by a conventional impregnation method. The enhanced catalytic activity of the former material can be ascribed to its higher basicity, specific surface area, pore volume and pore size.
Journal: Chemical Engineering Science - Volume 63, Issue 17, 1 September 2008, Pages 4306–4312