An effective modular process for biodiesel manufacturing using heterogeneous catalysis

We present an innovative reaction set-up and process for biodiesel manufacturing by heterogeneous catalysis. This process has two key advantages over the state-of-the-art process: it enables a variable reaction time and easy catalyst switching/replacement. The process principle presented here is generic for liquid-phase reactions requiring long residence times, where conventional fixed-bed column reactors offer little flexibility. This is especially important when one switches between feedstocks or when the catalyst activity declines over time. Biodiesel manufacturing is a highly relevant example, because the reactor performance depends on the feedstock nature and composition. The concept is demonstrated in a scaled-down continuous laboratory reactor, keeping a similar reaction time and comparable heat and mass transfer to a large-scale process by optimising the reactor dimensions, fluid velocity and catalyst pellet size. We then provide the design of the large-scale process, which consists of serpentine-type plug flow reactors assembled as vertical tubes filled with catalysts. The reactor productivity can increase significantly by reducing the catalyst pellet size. A switching system allows connecting/bypassing the tubes and easy catalyst replacement. The reactor can be employed in a two-stage reaction technology, or in a one-stage reaction combined with membrane separation. Production capacity can be scaled-up simply by adding parallel modules. The versatility and ease of application make this catalytic process concept suitable for low-cost mobile biodiesel production plants.