Our main achievements include the improved design of ionic liquids and porous ionic liquids with controlled reactivity through both the cation and the anion, as well as the control of the viscosity of the solution after CO2 sorption. In addition, we paved the way for integrated carbon utilization or storage by providing strategies to control sorption reversibility, porosity, and the reaction pathways governing the chemical transformation of CO2 after sorption.
The scientific investigation focused on sorption thermodynamics, a critical first step towards real-world implementation, particularly with regard to the energy requirements for sorbent regeneration, gas sorption capacity, and uptake kinetics. To this end, we experimentally measured gas sorption in a range of ionic liquids, including porous ionic liquids, and established a mechanistic understanding of the sorption process in terms of both equilibrium and kinetics. We also investigated the interactions between the ionic liquids and porous solids, with particular emphasis on porosity retention and the stability of the porous framework.
Overall, our materials exhibit a combination of physical and chemical sorption pathways through the anion and the cation of the ionic liquid resulting in complex chemical speciation within the bulk sorbent. We developed the appropriate experimental and modelling tools to analyse these systems while accounting for chemical speciation and reactivity. This development was supported by theoretical studies of basicity, speciation, and reaction mechanisms, complemented by detailed NMR investigations.
Synthetic accessibility was explicitly considered throughout the material design process. The ionic liquids can be prepared in only a few synthetic steps from commercially available starting materials, while the porous ionic liquids were formulated using readily available porous solids. Within these practical constraints, we successfully designed a range of new materials with tailored chemical reactivity and gas sorption properties.
