Effect of Synthesis Method on the Catalytic Performance of Ca-Mg-Al Mixed Metal Oxide Nanocatalyst for Biodiesel Production from Waste Cooking Oil

Abstract

The synthesized nanomaterials by two different methods were used as a catalyst in the transesterification of waste cooking oil to produce biodiesel. For both environmental and economic reasons, it is beneficial to produce biodiesel from waste cooking oils. It is desirable to help solve waste oil disposal by utilizing its oils as an inexpensive starting material in biodiesel synthesis. The structure, morphology, and surface properties of resulting nanocatalysts were characterized by X-ray Fluorescence Spectroscopy (XRF), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Energy Dispersive X-ray Spectroscopy (EDX) and N₂ adsorption-desorption isotherms. The synthesized nanocatalysts' efficiency in the production of biodiesel was studied by Gas Chromatography (GC) as well as leaching amounts of surface active components of each catalyst investigated by the EDX technique. The reactions were performed at 65°C using a 9:1 methanol to oil ratio for 3 h. The results indicate that the impregnated mixed metal oxide catalyst ( Ca-MgAl) shows a higher surface area and better mechanical strength than the totally co-precipitated mixed metal oxide catalyst (CaMgAl(O)). Although both of the fully co-precipitated and impregnated catalysts represented about 90% of fatty acid methyl esters (FAME) yield the leaching of active calcium component was significantly reduced from 45.8% in precipitated CaMgAl(O) to 8% for the impregnated Ca-MgAl catalyst. This improved structure represents the advantage of the impregnation technique to co-precipitation procedure for fabrication of robust nanostructures.