(401d) Performance Evaluation of Long Chain Alkyl Ionic Liquids and Their Mixtures for CO2 Solubility at Elevated Temperature and Pressure

Technological Development worldwide has significantly intensify the energy demand and per capita energy consumption for last two decades which has subsequently threatened the globe with the biggest environmental issue of global warming associated with greenhouse gas emissions from numerous industries including energy and cement sectors[1]. On the other hand aqueous mono-ethanol amine (MEA) scrubbing techniques have technological issues of corrosion, degradation and economically penalizing the energy sector to mitigate CO₂ emission[2]. To overcome the issues of multiple applications and material degradation other compounds like large number of solid sorbents (such as metal organic framework, covalent organic polymers, silica, activated carbon and nanoclays) and other liquids such as ionic liquid and deep eutectic solvents (DES) have been under investigation since long for pre- and post-combustion CO₂ capture and separation. Although various solid sorbents such as covalent organic polymers and polybenzimidazole have shown promising results as long as capturing capacity and repeatability of the sorbent are concerns[3, 4]. However, chemisorption, lower selectivity, porosity dependent adsorption and slow adsorption kinetics are among the major issues which hinder the large scale applications of solid sorbents. Alternatively, studies have shown that ionic liquids are very promising [5, 6] capture solvents for CO₂ and other toxic gases since; their physical and chemical properties at various temperatures could be tailored through modifying their cationic and anionic moieties[7]. Additionally, extremely low vapor pressures, high thermal and chemical stability, non-flammable nature, high solvation capacity, and promising gas solubility features, ionic liquids have emerged as attractive compounds since the last decade. Moreover, modifying solvent properties at room temperature through hydrogen bond donors, ionic liquids mixtures may have great potential for efficient CO₂ absorption.

Since, mixing two or three components capable of intermolecular interactions through the hydrogen bonding may generate channels to absorb more CO₂. Thus, there is a possibility of designing specific ionic combinations which possess suitable properties and can be tested for high pressure CO₂ capture at various temperatures. Based on the advantageous features ionic liquids, we report testing and preparation of novel mixtures of ionic liquids based on their long alkyl chain. CO₂ capture of three ionic liquids and their mixtures were obtained with the state of art equipment magnetic suspension balance (MSB). Mole fraction CO2 solubility of three different ionic liquids at 25 °C and maximum of 50 bars clearly shows differences in the absorption capaity indicating effect of alkyl chain. The initial findings have indicated that, the novel mixtures have favorable strong thermo physical stability and appreciable CO₂ capturing capacity. TGA, FTIR, viscosity, density, pH, and thermal conductivity analysis have also indicated the suitability of these ionic mixtures for CO2 and other gases solubility. Moreover, the repeated use of material at various temperature and pressure without any decrease in CO₂ capturing capacity make these compounds capable to be considered for further investigation on larger scale applications.

 

References

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