(470b) An Electrochemical Engineering Journey Towards Sustainable Nylon Precursors

The chemical industry accounts for ~5% of the US energy utilization and >30% of the US energy-derived industrial CO₂ emissions. Amongst these processes, the production of organic chemical commodities accounts for most of the energy utilization. The electrification of these processes via the implementation of electro-organic reactions could accelerate the decarbonization of the chemical industry. In this presentation, I will discuss how these reactions can help improve the sustainability of the production of one of the most important polymers in society, Nylon 6,6.

The production of Nylon 6,6 involves the step-growth polymerization of 1,6-hexanediamine (HMDA) with adipidic acid. HMDA is currently produced by the hydrogenation of adiponitrile (ADN). The beginning of our journey starts by understanding and controlling the electrohydrodimerization of acrylonitrile (AN) to Adiponitrile (ADN). Our investigations on ADN are aimed at uncovering the relationship between the microenvironment at and near the electrical double layer (EDL) and reaction performance metrics. I will discuss general guidelines for electrolyte formulation and provide insights into the role of different electrolyte species in achieving conversions of AN to ADN with selectivity as high as 83%. Using in situ attenuated total reflectance Fourier-transform Infrared (ATR-FTIR) spectroscopy, we demonstrate how supporting cations modulate the concentration of concentration species at the electrode/electrolyte interfaces, and ultimately impact selectivity. I will also show how carefully controlling pulsed electrosynthesis conditions guided by active machine learning can help circumvent mass transport limitations, control the concentration of AN near the EDL and enhance the production rate of ADN. Our learnings on ADN electrosynthesis helped us to also engineer the electrocatalytic hydrogenation of ADN to HMDA, achieving the highest reported selectivity to date for this reaction (>95%). More recently, we have started to explore electrochemical routes to produce AN from glutamic acid, an abundant and inexpensive bio-based feedstock.