Aqueous amine technologies have long been the benchmark for solvent-based CO2 separations from mixed gas streams to help DOE's office of Fossil Energy (FE) decrease greenhouse gas emissions from fossil fuel utilization.  Due to the maturity of the technology amine solvents are considered the most likely �first generation� carbon capture technology for treating global flue gas sources, even though the energy requirements are prohibitively costly by FE estimates.  In order to reduce energy penalties to acceptable levels DOE R&D investments are being made towards developing lower energy �transformational� solvent systems, which include nano-material organic hybrids (NOHMs), task-specific, protic and reversible ionic liquids, phase change solvents and binding organic liquids. Although the chemistries of each of these solvents are vastly different, they are physically similar in that they offer the ability to operate, with little or no water as a solute.  Anhydrous operation offers considerable reductions in the heat loads compared to aqueous solvents since the energy required to boil and condense water is lessened.  This shift can result in energy reductions of more than 40% compared to aqueous amine options. Despite this primary advantage, transformational solvents face significant technical challenges (high viscosity, expensive materials costs and unknown process compatibility) before commercial adoption is possible. To address this grand challenge and meet DOE's carbon capture goals, PNNL has taken a comprehensive approach to identify key solvent system advantages, limitations and unknowns of the chemistries and engineering principles needed to enhance transformational solvent system performance. We present here an approach using a combination of molecular design, thermodynamic and physical property simulations, synthesis, materials testing and engineering principles to gather knowledge and provide an understanding of performance of several transformational solvent systems that are currently under development in DOE's portfolio. Initial results will be presented supporting improved formulations of transformational solvent systems with the goal of aiding DOE in advancing these solvents through the technology readiness scales and priming them for commercialization.

Evaluating transformational solvent systems for post-combustion CO<sub>2</sub> separations

248th National Meeting (2014)

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Evaluating transformational solvent systems for post-combustion CO2 separations

Evaluating transformational solvent systems for post-combustion CO₂ separations