A life cycle approach to solvent design: challenges and opportunities for ionic liquids – application to CO₂ capture

Abstract

CO2 capture and storage is widely anticipated to play a key role in combatting climate change, however the solvents proposed for use have embedded environmental concerns.

Combined Superbase Ionic Liquid Approach to Separate CO2 from Flue Gas

“…In the development of such task-specific ILs for gas separation processes, the toxicology and environmental impact of the chosen ILs require evaluation alongside the energy consumption and techno-economic calculations/modeling of the desired process. 4 , 46 …”

“…In situ utilization of gases absorbed (and activated) by ILs is also a continually developing research area. − However, barriers to the deployment of IL systems for gas capture include their high viscosity (with consideration to viscosity changes upon gas absorption required) and the cost of IL production on an industrial scale. In the development of such task-specific ILs for gas separation processes, the toxicology and environmental impact of the chosen ILs require evaluation alongside the energy consumption and techno-economic calculations/modeling of the desired process. , …”

The green solvent: a critical perspective

“…Such methods use life cycle inventory approaches, in which (at the very least) an inventory is made of the materials used and emitted, and the energy consumed, in the production, use and ultimate disposal of an ionic liquid beginning with the primary raw materials from which ionic liquids are made. Cuéllar-Franca et al ( 2021 ) have recently examined the environmental burden of a practical process for post-combustion carbon dioxide capture using life cycle methods. The conventional absorption solvent, 30 wt% monoethanolamine, was found to generate significantly less impact than the ionic liquid 1-butyl-3-methylimidazolium acetate (RN 28409-75-8) despite the better CO 2 -uptake characteristics of the latter.…”

Sustainability Assessment of Alternative Synthesis Routes to Aprotic Ionic Liquids: The Case of 1-Butyl-3-methylimidazolium Tetrafluoroborate for Fuel Desulfurization

“…Ionic liquids (ILs) comprise salts with melting temperatures below 100 °C. Over the last decades, they have emerged as potential sustainable chemicals, owing to their low melting point, high chemical and thermal stability, high solvating power and tunability, negligible vapor pressure, and ease of recycling. , These properties are appealing in a range of applications, including fuel desulfurization, − biomass pretreatment, , CO 2 capture, electrocatalysis, separation of organic mixtures, and even explosives. , …”

“…Although LCA has been conducted for a wide range of chemicals, it has been scarcely applied to ILs . Most LCA studies furthermore rely on simple models, such as stoichiometric and heat of formation calculations or approximations, rather than detailed first-principles process models, and their main focus is on conventional synthesis routes. ,− In contrast, alternative synthesis procedures such as halide-free synthesis have remained largely unexplored. A recent comparative LCA of two PILs using detailed process modeling has also highlighted the need to include the use phase of solvents in analysis to ensure a meaningful comparison …”