Methyl Esters Production from Degummed Soybean Oil Catalyzed by Niobium Phosphate

The present study aimed a significant investigation of interesterification reaction to produce fatty acid methyl esters (FAME) from degummed soybean oil (DSO) in pressurized methyl acetate (MeA) catalyzed by niobium phosphate (NbOPO₄). It investigated a glycerol-free route for biodiesel production from a low-cost feedstock concerning the problem of high cost and surplus glycerol production. NbOPO₄ was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and nitrogen adsorption/desorption. Important factors in FAME production including temperature, catalyst content, and DSO:MeA molar ratio (MR) were investigated through an experimental design in two reaction times (60 min and 180 min). Response surface methodology was used to optimize important reaction variables. It was possible to obtain an FAME yield of 87.48% at 345 °C, 8 wt% of catalyst, and an MR of 1:35 in 60 min of reaction. The decomposition phenomenon was evident, achieving 64.14% at 345 °C and 8 wt% of catalyst, mainly due to prolonged exposure to large amounts of catalyst and high temperatures. The catalyst was shown to be active in the experimental conditions investigated. The reuse test pointed out a decrease in activity of up to 34.59%, which may be related to the adsorption of contaminants and mass loss.