(173a) Identification of Non-Aqueous Solvents for Pairing with Amine-Type CO? Capture Systems

The Industrial Revolution of the 19th century unlocked the formidable potential of fossil fuels, establishing their enduring dominance as the primary energy source up to the present day. Since 1950, the consumption of fossil energy, harnessed from the combustion of oil, gas, and coal, has grown eightfold, constituting nearly 84% of the global energy mix in 2019. Although these fossil fuel-based energy feed stocks have consistently driven economic prosperity across nations by energizing diverse industries and elevating living standards for an expanding population, a noteworthy drawback lies in the substantial increase in the atmospheric carbon dioxide (COâ‚‚) emissions resulting from the combustion of these fuels. Elevated atmospheric COâ‚‚ levels pose a dual threat: a) contributing to the greenhouse effect with potential long-term climatic repercussions and b) posing direct health risks due to increased air pollution.

In view of these challenges, carbon capture and storage (CCS) has positioned itself as the most sought out technology to abate COâ‚‚ emission from large point sources. Particularly for post combustion processes, amine absorption is the preferred method for capturing waste COâ‚‚. Current amine absorption technology typically uses 30 wt% monoethanolamine aqueous solution. This solvent is considered as the most mature amine scrubbing solvent available for COâ‚‚ capture due to its advanced technological readiness, ease of operation, impressive COâ‚‚ absorption rates, and recyclability. However, COâ‚‚ capture via aqueous MEA imposes a substantial energy burden during solvent regeneration, thereby driving up the overall cost to capture COâ‚‚.

The desorption of captured CO₂ during the solvent regeneration phase necessities heating the CO₂-rich aqueous solvent to near boiling temperatures (80-120 °C). Given that water accounts for ~ 70 wt% of the aqueous amine solvent, the majority of the heat being supplied by the reboiler of the regeneration column is associated with the heating and vaporization enthalpy of water. Therefore, adopting of non-aqueous solvents with lower heating and vaporization enthalpies would result in reduced heat requirements in the regeneration column, thereby making the CO₂ capture process a potentially compelling, low-energy, and cost-effective technology.

This work endeavors the development of a multi-parametric framework using Aspen simulations and optimization tools, to screen and identify potential non-aqueous absorbents that are compatible with amine-type solvent while also being suitable for post-combustion flue gas conditions. Some of the potential non aqueous solvents discussed in this work include ethanol, triethylene glycol, and polyethylene glycol. These solvents were screened based on parameters such as normal boiling point, viscosity, COâ‚‚ loading, relative volatility, enthalpy of vaporization, enthalpy of COâ‚‚ absorption, MEA and Hâ‚‚O compatibility, regeneration efficiency and thermal stability.