Understanding Electrochemically Induced Olefin Complexation: Towards Electrochemical Olefin-Paraffin Separations

React Chem Eng. 2024 Aug 1;9(8):2171-2179. doi: 10.1039/d4re00145a. Epub 2024 May 13.

Abstract

Olefin-paraffin separation is a critical yet energy-intensive process in the chemical industry, accounting for over 250 trillion BTU/year of global energy consumption. This work explores the use of redox-active nickel maleonitriledithiolate complex for olefin-paraffin separations. Key performance factors, namely the electrochemical oxidation of the complex and the olefin capture utilization fraction, were systematically quantified. Electrochemical studies revealed near-complete oxidation of Ni(II) to Ni(IV) species, suggesting that the electrochemical oxidation step is not a limiting factor in olefin capture. The utilization fraction was found to be strongly dependent on the complexation equilibrium behavior between olefin-bound and unbound state of the complex. Time-resolved kinetic measurements unveiled a sluggish complexation rate, requiring over 36 hours to approach equilibrium. These insights highlight the importance of driving the complexation equilibrium and improving the kinetics to enhance the performance of Ni-based electrochemical swing absorbers for energy-efficient olefin-paraffin separations. The findings lay the groundwork for future optimization strategies and industrial implementation of this sustainable separation technology.