Continuous biodiesel production using a fixed-bed Lewis-based catalytic system

• Tubular continuous reactor packed with mixed oxide to produce biodiesel.
• Continuous flux of soybean oil and methanol or ethanol with retention time of 5 h.
• The system was more active for Soybean oil methanolysis than ethanolysis.
• The activity of the system increased with the increase in the temperature.

It was developed a fixed bed tubular continuous reactor to produce biodiesel, using pellets of aluminum oxide doped with zinc oxide. The pellets were placed into a tubular reactor as a 30 cm long column (2.65 kg). The reactor was feed with soybean oil (168 g h−1) and methanol or ethanol (89 g h−1) with the temperature fixed at 100 °C. Under these conditions it was possible to convert soybean oil into biodiesel in up to 75% yield in the case of methanol and 35% for ethanol. Increasing the temperature to 180 °C, it was possible to ethanolise soybean oil with yields up to 78%. It is important to note that after a steady state is achieved the conversions remained approximately constant with time. It is also worth to mention that the fixed bed remained active for more than 120 h, showing no catalyst leaching or deactivation, and so far it was not possible to determine its overall productivity.