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Ionic liquids (ILs) present a new alternative for postcombustion CO2 capture because their properties can be tuned by means of different cation−anion combinations in order to obtain the most suitable properties for a specific task. This work is a novel study that investigates the absorption kinetics and evolution of the chemical transformations produced by CO2 absorption in ILs at different temperatures. A large range of pure ILs was tested with a screening process based on the pKa anion for efficient and reversible CO2 capture. CO2 uptake by selected ILs was determined for a wide range of pressures between atmospheric pressure and 2000 kPa at room temperature. Results show that CO2 absorption capacities of [bmim][Ac] and [bmim][Phen] at 100 kPa are close to those obtained at higher pressures, suggesting the existence of two solvation regimes. This was confirmed by IR analysis. The kinetics were significantly affected by the temperature and were shown to increase sharply with it. The optimum temperature for CO2 capture in [bmim][Ac] and [bmim][Phen] was found to be 323.15 and 348.15 K, respectively., M.P. Gimeno acknowledges the support of the Spanish National Research Council (CSIC) through their JAE-Doc program.

A novel method for the chemical liquefaction of low-rank coals in relatively moderate conditions and short reaction times is presented. Using concentrated hydriodic acid as the reaction medium, microwaves as the energy source, and reaction times of 20 min at 230 °C, up to 50% of the organic carbon of coal can be extracted with THF. The study of the process shows that temperature of the reaction and time are the main factors affecting the desulfurization process. The redox potential and the nucleophilicity of the concentrated hydriodic acid were the driving force of the reaction as experiments with other acids or lower acid concentrations gave worse results., This work was funded by the European Coal and Steel Community (ref. 9220-EC/759) and Spanish CICYT (ref. AMB92-1221-CE).

A novel method for the chemical desulfurization of coal in relatively moderate conditions and short times is presented. Using concentrated hydroiodic acid as a desulfurizing agent and microwaves as the energy source, sulfate and pyritic sulfur are completely removed in 10 min. Moreover, for the low-rank coals studied, variable amounts of organic sulfur, up to 70% in 20 min, can be removed, for a total sulfur (organic + pyritic) elimination greater than 80%. The study of the process shows that time and temperature of the reaction are the main factors affecting the desulfurization process. Experiments with other acids and lower concentrations showed low yields, the special characteristics of the concentrated hydroiodic acid being the driving force of the reaction. Experiments carried out at different microwave power did not show any singular effect of the microwave irradiation on the removal of sulfur., The work shown here was funded by the European Coal and Steel Community (ref. 9220-EC/759) and Spanish CICYT (ref. AMB92-1221-CE). A patent has been applied for the treatment described in the paper.