Hydrolysis of soybean oil over solid acid catalysts

The hydrolysis reaction to produce free fatty acids is of great importance to the oleochemical industry. The process is can performed thermally as a liquid-liquid (or gas-liquid) reaction or using a catalyst. The reaction proceeds in three stages (simultaneously), but with different rates. Initially, triacylglycerides (TG) are converted to diacylglycerides (DG) and free fatty acids (FFA), followed by monoacylglycerides (MG) and AGL and finally, AGL and glycerol. The present study evaluated the performance of solid acids as the -Al2O3 (G-250), niobium oxide (Nb2O5), niobium phosphate (NbOPO4), ZSM-5 and -zeolite in the hydrolysis reaction of degummed soybean oil. The textural properties (BET surface area, diameter and pore volume) were determined by N2- physisorption and acidic sites were characterized by temperature programmed desorption of isopropyl amine (IPA-TPD). Typical reactions tests were performed in a 500 mL-stirrer batch reactor at 25 bar and 250 oC during 3h by using Oil/H2O/catalyst mass ratio of 50/50/10. The catalytic performances (TG conversions and MG and DG yields) of some catalysts are exhibited in the figures below. The best catalytic activity exhibited by the -Al2O3, which may be associated with its high specific area and the presence of strong Lewis acid sites.