| Biodiesel has considerable production potential as a renewable source of energy. The conventional processes use soluble alkali catalysts that contaminate the biodiesel and glycerol products, and present separation problems. An efficient and clean process is crucial for large scale commercial production. Solid catalysts have the potential to eliminate these problems.;A method has been developed to produce biodiesel using a solid catalyst. The reaction is carried out at high temperature and pressure conditions (260°C, 70 atm). The high temperature is not a problem since the solid catalyst is part of a continuous process in which heat energy can be recovered. The reaction time is short (15 minutes) compared to that of the conventional processes (∼ 100 minutes). Promising catalysts were identified from batch tests; and MnO was found to be the most effective catalyst from the lab-scale packed-bed reactor tests. The reaction conditions allow for this mild solid base which can have a long life. The conventional process conditions (60∼70°C, 70 atm) need specially prepared strong bases that lose their activity quickly. The kinetics of the MnO-catalyzed reaction has been studied. External mass transfer limited effects have been identified. MnO was not the strongest of the bases tested, but it was the most effective. The reasons have been evaluated. MnO has a long catalyst life (more than 500 hours). Also, the amphoteric nature of MnO aids in the conversion of free fatty acids. This means used vegetable oil can be converted to biodiesel efficiently. MnO can sustain high water content in the feedstock without diminishing efficiency. The method has been found to be favourable in terms of low pressure drop.;Lastly, the MnO solid catalyst process has been compared with other processes and was found to be favourable in terms of reaction rate, catalyst life, pressure, temperature, side reactions and maintenance. |
