Biodiesel Production Technologies and Processes

With abundant research and many evolutions, biodiesel has come a long way. It continues to prove its worth as a biodegradable, renewable, and sustainable form of fuel. Fundamentally, biodiesel is manufactured from animal fats, vegetable oils, etc. But how do you prepare biodiesel? Of course, it is through a biodiesel plant. But what are the various techniques that biodiesel manufacturers use? Let’s look at a few in this blog.

Downstream Processing

Downstream processing is a popular technique to create biodiesel. Biodiesel will be in a mixture of catalyst, excess methanol, and glycerin after completing the oil conversion reaction. In a specific gravity of 0.1 in a mixture of compounds, phase separation takes place by gravity. But feedstock impurities may lead to the formation of emulsion that intervenes in the phase separation process. Sodium chloride or centrifugation breaks the emulsion and accelerates the phase separation process.

Enzymatic Conversion

Many biodiesel plants also use lipases for enzymatic catalysts of oils to manufacture biodiesel. They can use the enzymes in solution or immobilize them onto a support material that enables using fixed-bed reactors. The reaction can be done at 35 to 45 degrees Celsius. But it is very slow and requires from four to 40 hours. This process is usually not commercially viable, as the expensive enzymes increase the overall manufacturing cost.

Solid Catalyst

Some biodiesel manufacturers also use solid catalysts. The process is called heterogeneous catalysis and uses fixed-bed reactors. The catalyst remains in the reactor and is used for an extended time. Sulfonic resins such as Nafion® NR50, sulfated zirconia (SZ), and tungstate zirconia (WZ) are adequately strong in terms of acid site to catalyze biodiesel-forming transesterification reactions.

Heterogenous catalysis systems ensure continuous operation and produce highly pure glycerin. The fatty acid esters and products do not require a water wash. In addition, the yields are usually high. The catalyst needs per ton of biodiesel for heterogeneous catalysis is significantly lower compared to other processes. But these systems operate under high pressure and temperature.

Non-Catalytic Conversion

Oil converts to biodiesel very slowly due to meager methanol and oil miscibility. But using a soluble co-solvent in methanol and oil may help enhance the reaction rate. It helps complete the reaction by 95 percent in merely 10 minutes at ambient temperatures and does not need a catalyst. Tetrahydrofuran (THF), which is used as a co-solvent, is recovered in a single step after the reaction is complete.

There’s another non-catalytic process, which uses methanol at extreme temperatures (350 to 400 degrees Celsius) and pressure (higher than 80 atm or 1200 psi) to enable the conversion of oil to biodiesel. The process needs a high alcohol-to-oil ratio (42:1 mole ratio). The reaction gets completed in about three to five minutes.

But the process has a downside that includes the use of expensive high-pressure vessels and high energy consumption than age-old processes. In addition, the reaction should be completed quickly to prevent the decomposition of the products.

Want to know more or looking for a biodiesel plant for your company, connect with S-Cube. We are comprehensive biodiesel plant solution providers. Please write to us at chetan@s3dist.in to learn more about our solutions.