In a development that could eventually put a large swathe of the polymers world on a low-carbon footing, Bayer spinoff Covestro has demonstrated in the lab a process for making the polyurethane precursor aniline from sugar instead of petrochemical raw materials.
Aniline is one of the most important chemical building blocks. Nearly 5 million metric tons of it is used globally, mostly to make the polyurethane raw material methylene diphenyl diisocyanate. Aniline is also used to manufacture dyes, pigments, rubber processing chemicals, and agricultural chemicals.
In the conventional route to aniline, benzene is nitrated with nitric acid and then hydrogenated into aniline. Historically, aniline has also been made by reacting phenol and ammonia.
Covestro hasn’t completely taken the wraps off its process. The company tells C&EN that a microorganism combines sugar and ammonia into an unnamed intermediate. A chemical catalyst then converts this molecule into aniline, resulting in a product with entirely biobased carbon content.
Covestro has been working on the process for about five years, collaborating with the University of Stuttgart, the CAT Catalytic Center at RWTH Aachen University, and Bayer.
The next steps will be to hone the process in the laboratory while gathering the information needed for scale-up. The company might begin pilot-scale production in 2020, followed by commercialization in the middle of the next decade.
Covestro is no stranger to low-carbon polyurethane raw materials. Last year, the company started up a plant in Dormagen, Germany, for making polyols that derive 20% of their carbon from carbon dioxide. In 2015, it unveiled a biobased polyurethane coatings hardener, pentamethylene diisocyanate.
Aniline is one of the largest-volume chemicals for which a biobased route is being sought. Similarly, companies such as Avantium, Virent, Gevo and Anellotech, are trying to develop biobased routes to the polyester raw material purified terephthalic acid.