Soybean oil and beef tallow alcoholysis by acid heterogeneous catalysis

Abstract

Sulfonated polystyrene compounds (SPS) were synthesized from linear polystyrene (PS), leading to catalytically active polymeric materials with sulfonation degrees between 5.0 and 6.2 mmol SO 3H/g of dry polymer. Catalyst performance was evaluated in beef tallow and soybean oil transesterification with ethanol and methanol. The SPS were used at 20 mol% of –SO 3H groups in relation to the oil mass. Methanol:oil molar ratios of 3:1, 6:1, 9:1, and 100:1 were employed, and the reactions lasted between 3 and 18 h. The SPS samples were insoluble in the reaction media and led to conversions of 85 and 75% of refined soybean oil and beef tallow with a 53 mg KOH/g acid number, respectively. There was an increase in ester production for reactions carried out at higher methanol:oil molar ratio and, in some cases, products with as much as 94% methyl ester content were obtained. Therefore, sulfonated polymeric compounds obtained from linear polystyrene are efficient catalysts for the alcoholysis of refined vegetable oils and raw materials containing high acid numbers.