Researchers Develop a Method to Produce Bio-based Nylon Using Microorganisms

Until now, nylon has been produced from petroleum-based raw materials. However, this is quite harmful to the environment because non-renewable fossil resources are used, a great deal of energy is required, and climate-damaging nitrous oxide is emitted during production.

A research team from the Helmholtz Centre for Environmental Research (UFZ) and the Leipzig University has now developed a process that can produce adipic acid, one of two building blocks of nylon, from phenol through electrochemical synthesis and the use of microorganisms.

The team also showed that phenol can be replaced by waste materials from the wood industry. This could then be used to produce bio-based nylon. The research work was published in Green Chemistry.

Electrochemical Synthesis Replaces Hydrogen Gas with Electric Energy:

In T-shirts, stockings, shirts, and ropes -or as a component of parachutes and car tires - polyamides are used everywhere as synthetic fibers. At the end of the 1930s, the name Nylon was coined for such synthetic polyamides. Nylon6 and Nylon6.6 are two polyamides that account for around 95% of the global nylon market. Until now, they have been produced from fossil-based raw materials.

However, this petrochemical process is harmful to the environment because it emits around 10% of the climate-damaging nitrous oxide (laughing gas) worldwide and requires a great deal of energy. Our goal is to make the entire nylon production chain environmentally friendly. This is possible if we access bio-based waste as feedstock and make the synthesis process sustainable".

For example nylon consists of about 50% adipic acid, which has so far been industrially extracted from petroleum. In a first step, phenol is converted to cyclohexanol, which is then converted to adipic acid. This energy intensive process requires high temperatures, high gas pressure, and a large amount of organic solvents. It also releases a lot of nitrous oxide and carbon dioxide. The researchers have now developed a process in which they can convert phenol into cyclohexanol using an electrochemical process.

"The chemical transformation behind it is the same as in the established processes. However, electrochemical synthesis replaces the hydrogen gas with electric energy which takes place in an aqueous solution and requires only ambient pressure and temperature explains Harnisch. For this reaction to run as quickly and efficiently as possible, a suitable catalyst is needed. This would maximize the yield of electrons needed for the reaction and the efficiency of the conversion of phenol to cyclohexanol. In laboratory experiments, the best yields (almost 70% electrons and just over 70% cyclohexanol) were shown with a carbon-based rhodium catalyst.

Source: Helmholtz Centre for Environmental Research (UFZ)/specialchem

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