A new catalyst to produce the biodiesel of the future

FGUSAL/DICYT Researchers at the University of Salamanca have designed a new type of catalyst to obtain biodiesel. The requirements established by the regulations for coming years make the current biodiesel production processes both expensive and inefficient, while this new proposal has many advantages. Through a proof of concept, scientists are demonstrating that the idea can be developed on an industrial scale.

Biodiesel is a biofuel, which means that is a renewable energy source. It can be used on current diesel engines. It is obtained from animal or vegetable fats or oils that are combined with other elements, usually with methanol. Current regulations impose the use of biodiesel mixed with diesel in an increasing percentage each year, up to reach an 8.5% in 2020.

However, the problem is that nowadays it is only possible to use a 7% of edible oils to obtain biodiesel which results in a problem, as non-edible oils contain a large proportions of fatty acids for which the current technology is no longer valid, explains to DiCYT Jorge Cuéllar, researcher of the Department of Chemical and Textile Engineering of the University of Salamanca.

Catalysts that are currently being used during the manufacturing process form foams in the presence of these fatty acids, another product that arises from the reaction. . That makes very difficult to separate biodiesel from glycerin, and necessary requires the use of a second catalyst, summarized the researcher. So far the alternative is inefficient, because it involves two types of catalyses -sulfuric acid and a basic hydroxide -in two different steps, making the whole process complex and expensive and calls into question if biodiesel production is profitable at all.

The project from the scientists of the University of Salamanca goes on to manufacture biodiesel in a single stage thanks to a new catalyst, dodecylbenzenesulfonic acid. "We have tried and successfully used it to make biodiesel when we have large proportions of fatty acids," says Cuéllar. The reaction catalysed with dodecylbenzenesulfonic acid is "up to 20 times faster" than with sulfuric acid, which simplifies the process and greatly reduces costs.

Another significant improvement of the new catalyst would be in the separation of the reaction products, the biodiesel itself and the glycerin. In contrast to the conventional method, "foams are not formed and the separation is much simpler, which also means lower costs in this part", says the expert.

Scaling up the Project

Until now the studies of the Department of Chemical Engineering and Textile had already demonstrated all these advantages, but to be able to implement the new catalyst it is necessary to scale the project, that is, to move from the laboratory to the industrial stage. This requires the use of much bigger equipment which has been carried out thanks to the Proof of Concept of the General Foundation of the University of Salamanca and within the TCUE program of the Junta de Castilla y León, co-financed with FEDER funds. On this industrial scale it is necessary to demonstrate the efficiency of the catalyst in the two processes, both the reaction and the product separation.

"We have carried out the synthesis of biodiesel using equipment of very different sizes. Results show no significant problems that is, the reaction behaves in the same way regardless of the size of the reactor, explains the researcher.

Demonstrating significant improvements in the separation stage is somewhat more complex. "We have developed the separation and purification process on a laboratory scale which is simpler than the industrial one. Therefore it cannot be proven valid in industrial facilities as they are configured nowadays. Some changes and new testing are necessary. For this, the researchers already have some contacts with companies.

When these last actions are completed, "we will have developed a product that complies with specific regulations and that can be used in actual engines," says Jorge Cuellar.