A comprehensive database on physical properties of ionic liquids (ILs), which was collected from 109 kinds of literature sources in the period from 1984 through 2004, has been presented. There are 1680 pieces of data on the physical properties for 588 available ILs, from which 276 kinds of cations and 55 kinds of anions were extracted. In terms of the collected database, the structure-property relationship was evaluated. The correlation of melting points of two most common systems, disubstituted imidazolium tetrafluoroborate and disubstituted imidazolium hexafluorophosphate, was carried out using a quantitative structure-property relationship method.

As an emerging carbon dioxide (CO₂) capture technology, separating CO₂ from industrial gases with ionic liquids is increasingly attracting remarkable interests. In this paper, the research progress on CO₂ capture with ionic liquids is reviewed with particular attention on the viewpoint of potential industrial applications. We investigate and compare the CO₂ capture capacities of pure ionic liquids, including conventional and task-specific ionic liquids, and ionic liquid-based mixtures. The mechanisms of chemisorption and physisorption are explained with experimental characteristics and molecular simulation, which show more and more important roles for screening suitable ionic liquids from tremendous candidates. Considering the scaling up of novel units for ionic liquid-based fluids, the studies on the transport properties and hydrodynamics of ionic liquid fluids are presented. The process design and assessment of ionic liquid processes are discussed, including the research progress on thermodynamic properties and prediction models. Besides giving an overview of research for each issue above, we also provide discussions for future work to try to identify the gap between the current work and the demand by real industrial applications. Finally, we present some perspectives of ionic liquid-based novel technologies, and the challenges which will be faced while developing industrially available technologies.