(563a) Catalyst Performance of the Ion-Exchange Resin in the Continuous Production Process of Biodiesel Fuel

Fatty acid esters, used as biodiesel fuel (BDF), are produced by transesterification of triglyceride and alcohol. We have reported that the anion-exchange resin gives a high transesterification rate and high conversion to BDF at 50 °C under atmospheric pressure without the saponification¹⁾.  The catalytic activity of the resin gradually decreased during the reaction, but it was easily recovered by a three-step regeneration method.  In this research, the continuous BDF production was performed using a column reactor packed with the various resins, and the effect of physical property of the resin on the overall catalytic activity of BDF was discussed.

Triolein with a purity of about 65 % and ethanol, which is miscible with triolein, was used, and the molar ratio of triolein to ethanol was set at 1:15.  The physical property of the resin is shown in Table 1.  The feed solution was supplied to the bottom of the column at a constant flow rate of 0.16 cm³/min (residence time of 60 min).  The up-flow leads to bed expansion toward the top of the column.  The reaction temperature was kept constant at 50 °C.  The effluent solution from the column was collected and the concentrations of reactants and products in the collected fractions were determined using the HPLC system.  Each continuous experiment was stopped when the product concentration in the effluent was zero, which meant that the catalytic activity of the resin disappeared.

Figure 1(a) shows the results for the continuous transesterification using the various resins.  The abscissa is the operating time from the start of supplying the feed solution to the column and the ordinate is the BDF concentration in the effluent.  In order to compare the overall catalytic activity, the total amounts of BDF produced in each experiment were calculated by integrating the variation of the BDF concentration with operating time.  Table 2 shows the total amounts of BDF produced in each experiment, and the second experiments were performed using the resins treated by the regeneration process.  Using the resin of type I with a lower crosslinking density, XPA306, the total amount of BDF was the largest and 20 times as much as its ion-exchange capacity.  Figure 1(b) shows the variation of the triglyceride concentrations in the effluent.  The triglyceride concentration was kept at zero until 8h using XPA306.  During this period, the intermediates, diglyceride and monoglyceride, were also not detected and the conversion of triglyceride was attained to be 100 %.  The period was longer than that required for the regeneration process (about 3 h).   Therefore, the continuous production process of BDF can be constructed by alternately switching two columns between transesterification and regeneration.

[Reference] ¹⁾ N. Shibasaki-Kitakawa et al., Bioresour. Technol., 98, 416 (2007)