Fatty acid methyl esters from waste beef tallow using supercritical methanol transesterification

The aim of this work is to perform synthesis of fatty acid methyl esters by means of one-step supercritical methanol transesterification from waste beef tallow without pre-treatment. Animal waste samples were collected from local markets and the experiments were carried out in a 170 cm(3) batch reactor made of Inconel 625 alloy. On the first set of experiments, the fatty acid methyl esters were obtained by varying methanol:waste beef tallow (M:WBT) molar ratios from 25:1 to 47:1, at 613 K, 60 min of synthesis and pressures up to 27 MPa. Due to the high yield, a second set of transesterification reactions was carried out in order to assess the temperature effect in the interval of (578-693) K while keeping the molar ratio of 45:1. The fatty acid methyl esters were characterized by Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), gas chromatography coupled to mass spectrometry (GC-MS), high performance liquid chromatography coupled to mass spectrometry (HPLC-MS), cryoscopy, Gardner color, water content, free fatty acids and cloud point; calculations of the global yield from NMR and predicted cetane number were also performed.

Automated summary

The aim of this study was to synthesize fatty acid methyl esters from waste beef tallow using one-step supercritical methanol transesterification without pre-treatment. Animal waste samples were collected from local markets and experiments were conducted in a batch reactor made of Inconel 625 alloy. Various parameters such as methanol:waste beef tallow molar ratio, temperature, and pressure were investigated to obtain the fatty acid methyl esters, which were then characterized and the overall yield was calculated.