Green biodiesel production through enhanced adsorption using bifunctional ethoxy amine modified silica catalysts

This study explored a silica catalyst impregnated with APTES [(3-aminopropyl) triethoxy silane] for the transesterification of vegetable oil to biodiesel. Its aim was to enhance the activity of silica by adding various concentrations of APTES as a modifier, which would impart basic amine functional groups to the silica surface. Synthesis and functionalization of the silica were confirmed through the use of various characterization methods such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Spectroscopy), XRD (X-ray Diffraction), and BET (Brunauer-Emmett-Teller) surface area analysis. Of the four synthesized catalysts, the highest yield of biodiesel (62.2%) was obtained using the catalyst containing 0.75 g of APTES, used at 65 °C for 5 h with 0.3 g of catalyst. GC (Gas chromatography) showed a promising FAME (fatty acid methyl esters) profile, which suggests the FAME would have good properties essential to low temperatures, as well as aiding in the biodiesel cold flow properties. The catalyst retained over 90% of its catalytic activity after three cycles, demonstrating excellent reusability. Although the maximum biodiesel yield achieved was 62.2%, the consistent activity over multiple runs confirms the material's stability and operational potential.