Purpose

The purpose of this project is to produce biodiesel using a microreactor. The primary objective of this project is to optimize biodiesel yield by altering physical parameters of the reaction. Supporting objectives include design and construction of the microreactor. Next settings and operation of system components such as reactants, syringe pump, microreactor, water bath, and product collection will be worked with until reliable and replicable operation is obtained. Finally, the effect of temperature and flow rate on yield of biodiesel will be determined following a full 3-factorial test. Other supporting objectives include design of a mathematical model of the microreactor using FEMLAB. We will also be compiling a data collection system to automatically transfer GC readings to a computer.

Microreactor

The microreactor was designed, with the help of Goran Jovanovic, by this student team. The micro reactor was designed to be a plug flow reactor where two separate phase fluids react by diffusion. The reaction between the two fluids occurs at the interface. The microreactor is favorable over a traditional batch reactor because the small microchannels require significantly less time for diffusion.

The two reactants are an oil (canola, soy, cottonseed, etc) and methanol solution containing sodium hydroxide. The sodium hydroxide is a catalyst for the reaction. Each reactant is held in separate syringes (Figure 1.). The syringes connect to tubing that feed into connectors on the microreactor. The microreactor is immersed in a water bath for a constant temperature system. The reactants are fed through the connector into a microchannel that is 100 microns deep and 125 microns wide. The two reactants are fed through the microchannels as incompressible laminar flow and make contact in the reaction section of the microreactor. The reaction section has a depth of 100 microns and a width of 250 microns. The reaction section of the microreactor is 3 inches long.

Figure 1. Microreactor Setup

At the end of the reaction section the products are removed from the microreactor through another connector into a product collection vessel. The product collection vessel will contain an acidic brine solution to aid in the separation between the biodiesel and glycerin phases.

Gas Chromatograph

The composition of reactants and products will be determined using an HP 5890 Series II gas chromatograph with a high temperature column. The programmed GC temperature profile will match the recommended American Society for Testing and Materials (ASTM) settings as closely as possible. Readings will be collected on computer following design and installation of a computerized data collection system. Component peak readings will be calibrated using standards obtained from Dr. Jovanovic’s lab. The exact procedure for the operation will be a deliverable and determined during the course of the experiment.