One-Step conversion of high FFA Crude Karanja oil (Pongamia pinnata) to Bio-diesel Using Portland cement as excellent heterogeneous catalyst

Abstract

Heterogeneous catalyst was prepared from Portland cement. The prepared heterogeneous catalyst was tested for catalytic activity in the transesterification of non-edible, high free fatty acid feedstock, such as crude karanja oil (CKO), for biodiesel production, at methanol reflux temperature. Gas chromatographic (Gc) analysis technique was used to determine the fatty acid methyl ester yield. The preparation of heterogeneous catalyst from low-cost sources, and the use of non-edible feedstock, only at methanol reflux temperature, were all aimed at reducing the cost of biodiesel production. Insight into the catalytic activities of catalyst was obtained by characterizations for their textural properties, using Brunnear-Emmet-Teller (BET) analysis technique, surface scanning electron microscopy (SEM) and electron dispersive x-ray (EDX) for microstructure, surface morphology and chemical composition; x-ray diffraction (XRD) and Fourier-Transform Infra-Red (FTIR) spectroscopy for structural and functional groups analyses, respectively. Differential thermal and thermogavimetric (DTA/TGA) analyses were performed to determine the proper temperature ranges for the dehydration, decomposition, desorption and oxidation of sample via the TGA curves and their melting points and changes in crystal structures via the DTA curves, for effective determination of calcination temperature. The application of Portland Cement-derived heterogeneous catalyst in the transesterification reaction revealed excellent activity in the transesterification of crude karanja oil, with excellent fatty acid methyl ester yield of over 97.87 %. Operational conditions such as methanol/oil mole ratio (1:3 - 18), catalyst loading (3 - 9 % by wt) and reaction time (0.5 – 7 hours), were investigated to obtain the optimum reaction conditions for the feedstock, while the reaction temperature was kept constant at methanol reflux temperature, to minimise cost of production, in line with the objective of this investigation. Calcined heterogeneous catalysts gave over 80% fatty acid methyl ester yields than the raw counterpart, which were attributed to changes in crystal structures and phases of catalysts, observed in the characterization of catalysts, after calcination. Keywords: Portland cement, heterogeneous catalyst, Crude Karanja oil, transesterification reaction, Feedstock