Sustainable biodiesel production through heterogeneous catalysis

Most of today’s biodiesel processes employ homogeneous catalysts, such as sulphuric acid, sodium hydroxide, potassium hydroxides or alkali methoxides. This requires costly neutralisation, washing, separation and recovery operations. It also results in salt waste streams, with severe ecological and economical penalties.

In contrast, the Yellow Diesel approach uses only heterogeneous (solid) acid/base catalysts. This eliminates the salt waste streams, and simplifies the downstream processing. The solid acid catalyst is used in the esterification of free fatty acids, while the solid base catalyses the main trans-esterification step of the triglycerides. The simpler and more robust process means reduces both capital investment and operating costs. Moreover, suppressing the by-products and waste water at the source creates an intrinsically waste-free process.

Note that this approach is particularly suitable for treating waste oil feedstocks, including triglycerides with up to 90% free fatty acids (FFA), such as frying oils, animal tallow, tall oil from paper manufacturing and various types of organic waste.

We provide a customised catalyst + process solution for each client, depending on the feedstock and product requirements. Moreover, we offer the possibility of producing samples of the future product in a continuous laboratory plant operating in conditions close to those of the actual process. The process flowsheet development is performed in close co-operation with the client, based customised experiments and reactor design.

A typical process design of the chemical reaction section may include a fixed bed reactor, a reactive distillation column, or a combination of both. We develop several process alternatives for each client, selecting together the optimal one for the detailed plant design. This gives both the best process flowsheet and the optimal operation window, that match the characteristics of raw materials and the required product specifications.