Ultra-High Dispersion Of Mgo/Cao In Mesoporous Sba-15 And Macroporous Sba-15 Using A One-Pot Method: Novel Material Preparation And Application As A Base Catalyst For Transesterification

ABSTRACT

Global uncertainty over fossil fuels security provides the impetus for the development of fuels from renewable feedstocks. A promising route to diesel is available through transesterification of vegetable oils. In this work, there is a novel development of the true liquid crystal templating approach to the synthesis of uniformly dispersed ordered porous mixed oxides. Via this route, a family of mesoporous and mesomacroporous MgO/SBA-15 and CaO/SBA-15 catalysts with metal loading in the range of 1.00-9.00 wt.% and 3.00-18.00 wt.% have been prepared respectively. Textural characterization of the materials shows surface areas > 500 and 600 m2. g-1 for magnesium functionalised mesoporous and macroporous series. Surface areas recorded for calcium functionalized mesoporous and macroporous areas > 200 and 400 m2. g-1. Pore diameters were determined by the N2 porosimetry and are found to be in the order of 3.0 nm and 4.0 nm for both meso- and macrofamilies. Elemental (ICP-OES) and XPS analysis for magnesium and calcium functionalized species suggest that majority of MgO is preferentially located within the pore network of all catalyst. TGA chromatogram showed desorption of gases evolved for magnesium species but showed desorption of surfaces carbonates for calcium species around 500 oC to 800 oC. Meso – calcium series (CaO/(TLCT) SBA-15) were further recalcined at 800 oC to remove all the surface carbonates. TEM and SEM-EDX images show the uniform dispersion of metal oxide in long channel SBA-15 materials for meso- and interconnected macropores for macro- materials. Catalytic studies have been conducted in stirred batch reactors with pressure flasks at 60 oC and 90 oC. Optimization studies revealed that most favorable conditions are 10 mmol: excess tributyrin/tricaprylin, 50 mg catalyst and reaction time 24 h. Under these conditions, 3.59 wt.% CaO/(TLCT) SBA-15 was found to be most active providing > 99% of FAME in 24 h. Overall

trend in conversion showed that macropore materials are suitable as compared to mesopore material and this is much more evident in higher triglyceride molecule where 15.78 wt.% CaO/MM – (TLCT) SBA-15 proved to be the best catalyst.