(41a) Biphasic Solvents for Point-Source CO2 capture from Simulated Natural-Gas Flue Gas

Despite growing concerns over the substantial environmental impacts of anthropogenic climate change, fossil fuel fired power plants will likely remain a significant component of the world’s energy infrastructure for many years to come. Steps must, consequently, be taken to limit or, ideally, eliminate the release of greenhouse gases from these carbon emitting energy sources. This may be achieved using various methods for carbon capture and sequestration. Amongst the methods for carbon capture, solvent-based CO₂ absorption is currently considered the most promising. The considerable capital costs and high regeneration energy demands of the most well-established solvents used in this application (e.g., aqueous 30 wt. % MEA) are, nevertheless, a sizable obstacle to their implementation. Biphasic solvents, which split into distinct CO₂ rich and CO₂ lean liquid phases after CO₂ absorption, can appreciably reduce both the cost of the absorbent system and its energy demand. This is largely because only the rich phase needs to be regenerated after loading but can also be partially attributed to the relatively water lean nature of biphasic solvents. As a result, a potential biphasic solvent based system could match or even exceed the CO₂ capture rate of a more traditional solvent system with a much smaller footprint and with energy costs that are both lower overall and per unit volume regenerated. Despite these potential advantages and considerable interest in the literature, reliable separation of the two phases at scale remains an obstacle to the full implementation of biphasic solvents. This work, therefore, investigates both the development of a novel biphasic solvent formulation for cost effective carbon capture and a continuous-flow phase-separation system for process intensification. Additionally, this work focuses on the recovery of CO₂ from natural gas flue gas (5-10 % CO₂) which is an application typically neglected in the literature despite the relative ubiquity of natural gas fired power plants (~72 % of all utility scale energy generated using fossil fuels in the US).