*3.1. General*

Nitrates of Mn, Fe, Co, Cu, Ni, Zn, and Cd; zinc acetate; CaO; methanol (99.8%); methyl laurate (99%); and diethanolamine (99%) were purchased from Sigma-Aldrich, USA, and were used as such without further purification. Waste soybean oil was collected from local restaurants located in Jeonju. Scanning electron microscopy (SEM) was performed on a JEOL JSM 6510LV (JEOL Ltd., Akishima, Tokyo, Japan) to collect the SEM images, and transmission electron microscopy (TEM) was performed on a HITACHI 7500 to record TEM images. Scanning microscopy-energy-dispersive X-ray analysis (SEM-EDX) was performed for the qualitative analysis of the catalysts. Fourier-transform–nuclear magnetic resonance (FT–NMR) spectra of vegetable oils, fatty acid methyl esters (FAMEs), and fatty acid amides were recorded on a Bruker Avance-II (400 MHz) spectrophotometer (Bruker Corporation, Billerica, MA, USA). The presence of amide functional groups was supported with the help of FTIR spectra recorded on a Thermo Scientific Nicolet iS10 spectrometer (Thermo Fisher Scientific, Waltham, MA, USA). Mass spectra of methyl laurate and the amide derivative of methyl laurate were recorded on a Waters Micromass Q-ToF Micro mass spectrophotometer (Waters Corporation, Milford, MA, USA) equipped with electrospray ionization (ESI) and atmospheric pressure chemical ionization (APcI) sources with a mass range of 4000 amu in quadruple and 20,000 amu in ToF (Time-Of-Flight). The free fatty acids (FFA), saponification, iodine values, and moisture content of the virgin soybean oil (VSO), animal fat (AF), waste soybean oil (WSO), Karanja oil (KO), and jatropha oil (JO) were determined by following methods reported in the literature [34] (Table S1).
