Researchers at the KU Leuven Centre for Surface Chemistry and Catalysis (Leuven, Belgium) have developed a process that eliminates a step in the production of polylactic acid (PLA) and reduces waste. The patent on the technology was recently sold to a chemical company that intends to apply the production process on an industrial scale.

PLA is derived from renewable sources, such as corn, and is industrially compostable and recyclable, if it is appropriately collected and sorted. Because it is biocompatible, the material has medical applications, and it is also one of the few materials that is suitable for 3D printing. Despite these desirable properties, uptake of the material as an alternative to traditional petroleum-based plastics has been hampered because of the steep production costs.

The production process for PLA is expensive because of the intermediary steps, as Professor Bert Sels from the Centre for Surface Chemistry and Catalysis explains in a news release from the university. "First, lactic acid is fed into a reactor and converted into a type of pre-plastic under high temperature and in a vacuum. This is an expensive process. The pre-plastic—a low-quality plastic—is then broken down into  building blocks for PLA. Even though PLA is considered a green plastic, the various intermediary steps in the production process still require metals and produce waste," says Sels.

KU Leuven researchers developed a new technique that involves applying a petrochemical concept to biomass. "We speed up and guide the chemical process in the reactor with zeolite as a catalyst," explains postdoctoral researcher Michiel Dusselier. "Zeolites are porous minerals. By selecting a specific type on the basis of its pore shape, we were able to convert lactic acid directly into the building blocks for PLA without making the larger by-products that do not fit into the zeolite pores," says Dusselier. Compared with conventional techniques, the technology produces more PLA with less waste and without using metals. And by eliminating a step in the production process, the cost of the material is reduced.

Our intention is not to promote the use of disposable plastics, stresses Sels. "But products made of PLA can now become cheaper and greener. Our method is a great example of how the chemical industry and biotechnology can join forces," he adds.

The university did not disclose the name of the company that has purchased the patent.

A paper on the technology has been published in Science under the title, "Shape-selective zeolite catalysis for bioplastics production."