(57k) Design Studies of Heterogeneous Catalysis in Microchannels

This is a numerical study of the fluid flow and catalytic behavior in microreactors to produce biodiesel fuel. Vegetable oil and alcohol feed flows into a very small channel about the size of a human hair. The microchannel cross dimensions are 200 microns or smaller. The channel walls contain obstructions to add reactive surface area and to redistribute the fluid. These microreactors have a metal oxide catalyst coated on all surfaces. Due to the micro scale and heterogeneous catalysis, processing time is reduced from hours to seconds, and product purity is greatly increased relative to conventional approaches. A computer simulation study was conducted to understand how changes in the cross sectional area, flow rate, and reaction rate affect conversion. The microreactors were simulated using CFD-ACE+ software. The arrangement of obstructions was the result of a previous study. The focus of this study is to optimize the cross sectional area and flow rate to more efficiently meet conversion goals, taking into account micro fabrication and operational constraints, such as pressure drop. Simulations show that high levels of conversion are obtained in seconds.