Hydrolysis of palm oil was studied using four types of commercial H + -exchanged resin with acidity in the region of 5 ×10 −3 eq g −1 but with different pore volumes, specific surface areas, and pore diameters. The reaction was carried out in a stirred batch reactor in the liquid phase with continuous steam injection for up to 14 h. The rate of hydrolysis did not depend on total pore volume and specific surface area but did depend on pore diameter. On exchanging H + with La 3+ , Co 2+ , and Na + , the rate of reaction decreased markedly and was dependent on the degree of exchange, demonstrating that hydrolysis was catalyzed by H + sites. The activation energy for the hydrolysis of the triglycerides was estimated to be 240 kJ mol −1 . A procedure to estimate the rates of the different stages of hydrolysis and hence the individual rate constants of the forward and reverse reactions is described. The procedure yielded reasonable parameters for the reaction at 155°C up to 6 h of reaction time, when about 75 mol% of triglycerides was hydrolyzed.Paper no. J8946 in JAOCS 76, 529-533 (April 1999).Continuous high-pressure fat splitting with superheated steam is still the preferred technology for fatty acid production since its invention in the 1930s. Hydrolysis is usually carried out at 250°C and 3000-5000 kN/m 2 pressure with countercurrent flow of water and oil. About 96-98% of hydrolysis takes place within 2 h (1). The process involves high capital cost because of the corrosive nature of the acid produced at such high temperatures and pressures; high steam pressure also requires high energy input and costs. Due to rising energy and capital costs, renewed interest in ambient temperature enzymatic fat splitting using lipase as catalyst emerged around 1980 (1,2). The lipase process is suitable for small-scale production of fatty acids from heat-sensitive oils. The problems of catalyst recovery and the low rate of attaining equilibrium prevent commercialization of the process for large-scale production, although efforts to immobilize the enzyme on solid supports and to carry out the reaction at temperatures above ambient have resulted in some success (3).Catalyzed hydrolysis of fats and oils in batchwise fatty acid production was used even before steam splitting. The Twitchell process, which uses a sulfonic acid as catalyst, was first patented in 1898 (4). Other catalysts involving solid acids and bases, such as supported alkylbenzene sulfonic acid, ZnO, and lime, have also been used (5). Cation-exchanged resins have been used for hydrolysis of esters (6-8), and the hydrolysis kinetics of triglycerides catalyzed by cation-exchanged resins has also been reported (6). It is well established that the hydrolysis of triglycerides is a stepwise process catalyzed by acid/base; however, there are insufficient kinetic data on the process in current literature. This report aims to fill the gap. EXPERIMENTAL PROCEDURESFour samples of polystyrene sulfonic acid cation-exchanged resins, CT-110, CT-151, CT-165, and CT-175, were gifts fro...

The hydrolysis activity of superacids on palm olein, including tungstophosphoric acid and molybdophosphoric acid and their partially ion-exchanged cesium (Cs) salt, were investigated and compared with macroporous cation-exchanged resin and aluminum-incorporated mesoporous molecular sieve. The activities of the superacids supported on the resin and silica were also determined. The reactions were carried out in a stirred batch reactor with continuous steam injection at temperatures from 140 to 180°C. The reaction kinetics, obtained by regression, are first order with respect to TG of the superacids and Cs salts. Of the catalysts studied, the superacids loaded onto cation-exchanged resins were the most active on a weight basis. However, in terms of the turnover number per acid site, the Cs salt of tungstophosphoric acid had 13 times the activity of the cation-exchanged resin. The original superacids had lower activities than the Cs salts in terms of their turnover number. The observations are qualitatively in line with the higher acid strengths of the catalysts, as confirmed by the low activity of the aluminum silicate mesoporous molecular sieve, which is known to have a high concentration of low-to moderate-strength acid sites. The activation energy of the reaction with the Cs salts was ~49 kJ mol −1 . This is rather low as compared to that catalyzed by the cation-exchanged resin.