Direct Air Capture Of CO2 Using Low Regeneration Temparature Sorbents


University of Wyoming



Direct Air Capture (DAC) of CO2 is a potentially scalable negative CO2 emissions technology to meet the 2C rise in temperature to mitigate climate change. Beyond negative emissions, DAC technologies can be placed ubiquitously to utilize CO2 for wide variety of applications, ranging from CO2 utilization for value-added products, to enhanced oil recovery, to geological sequestration without expensive pipelines. Current estimates for DAC suggest that it can cost between $300 to $1,500/tonne of CO2 captured. The key to lower the cost of DAC rests on two factors: 1) the energy required for releasing CO2 from the capture agents, and 2) the pressure required to move the air through the capture device. This project is aimed at developing solid sorbent materials which can be regenerated at much lower temperatures than the current state-of-the-art materials and can be made into structured sorbent beds for low pressure drop operation to significantly lower the overall cost of DAC.


To achieve this objective, Susteon is developing amine doped solid sorbents catalyzed by ionic liquids. Ionic liquids are salts in liquid state. Typical ionic liquid structures combine organic cations with inorganic or organic anions. They have capability to dissolve compounds with various polarity. Advantages of using ionic liquids for CO2 capture are high thermal stability, low vapor pressure, inflammability, recyclability, high CO2 selectivity, no nitrosamine emissions, low corrosivity, and low heat capacity. Our tests have demonstrated that ionic liquids have the potential to increase the CO2 desorption rate by several orders of magnitude at desorption temperatures of 80 to 90°C. In laboratory tests, the proprietary ionic liquid catalysts used in ppm levels as catalysts in MEA solvent increased the CO2 desorption rate by 60 times at 85°C. This transformational discovery enables solvent regeneration at much lower temperatures to dramatically reduce energy consumption, amine degradation, and solvent emissions, this enabling lower CO2 capture costs for DAC application.


Lower regeneration temperatures (~85ºC) will open a new pathway to use waste heat to regenerate the sorbent, reduce the amount of water evaporated from the sorbent, and consequently reduce the overall cost of CO2 capture. These catalysts can be easily added in ppm quantities to current state-of-art amine doped solid sorbents. The combination of a well-studied/industrially utilized solid CO2 capture sorbent with our proprietary catalyst to form a new class of materials for DAC presents a low technology risk option with high potential for success. The development of these materials provides a clear pathway for reducing the cost of CO2 capture for DAC applications to less than $100/tonne of CO2.