GREEN CHEMISTRY
The manufacture of batteries requires large quantities of solvents such as N-methyl pyrrolidone( NMP) for coating the electrodes. Conventionally, NMP recovery has been impractical due to the complexities and costs arising from metal contamination.
However, recent research by Indaver Solvents and the Flemish Institute for Technological Research has shown that an advanced separation technology can effectively remove these metals at a level that satisfies the strict purity standards of the battery and microelectronics industries. In fact, the recovered solvents are so pure they can even be used in the pharmaceutical industry.
This new approach not only allows for the sustainable recovery and re-use of solvents used in battery manufacture but also reduces costs and CO 2 emissions. The practical, complete and safe re-use of critical substances like NMP is an important step towards full circular recycling, in which materials are not just reused but even given higher value.
Solutions at all scales
The goal is to provide solutions that are available, affordable and reliable. To this end, another important factor is scalability. The ability to recover solvents from even small volumes of contaminated mixtures is important, if this approach is to bring value throughout industry. In order to achieve full circular recycling, it must be possible to leverage processes that can be scaled from small quantities to full-scale manufacture.
As well as enabling companies recycle their own solvents on-site, independent solvent recovery sites facilitate the collection of even low volumes of used solvents for processing at a central point. Modern distillation and cooling columns can provide improvements in efficiencies and capacity, as well as better recovery from a wide variety of very complex industrial streams. In addition, the implementation of boiler systems that run on used lower grade, recycled solvents can significantly reduce reliance on fossil fuels and lead to a lower CO 2 footprint.
Solvent recovery is usually based on multi-stage fractionation and distillation( Figure 1). Both of these processes separate components based on differences in their boiling points, with fractionation offering a more refined separation by using a fractionating column to achieve multiple vapour-liquid equilibrium stages.
These are both efficient and sustainable approaches that achieve high-purity solvent recovery. However, recent developments in available technologies are allowing companies to raise the efficiency, capacity and sustainability of their solvent recycling processes even further.
For example, a new pressure swing plant will come into commission at Indaver Solvents’ UK site in the summer of 2025. This bespoke technology is a niche offering that enables the management of highly complex mixtures, as it can break azeotropes that conventional distillation plants struggle to manage.
Pressure swing plant technology is generally more economical than the conventional methods like extractive distillation and no extra solvent is required to achieve the separation of solvent mixtures. Therefore, day-today use of pressure swing distillation for the separation of azeotropic mixture adds another solution to the solvent recovery sector that drive us further towards a fully circular economy.
Calculating environmental impact
The EU Green Deal highlights the need for Europe to work towards economic growth without increasing the
67