Direct Air CO2 Capture via Hot Water Cycling of Poly(ethyleneimine)/Silica Hollow Fiber Sorbents

Hollow fiber sorbents containing amine-infused mesoporous silicas are promising materials for CO2 capture from ambient air due to their ease of heat integration and low pressure drops. This advanced sorbent design permits a wide range of heat source integration options, though limited experimental insights are found in the literature. In this study, hot water is utilized as the heat source for regenerating poly(sulfone)-silica-poly(ethyleneimine) fibers prepared with a hybrid poly(vinylidene chloride)/styrene-butadiene lumen barrier. Fiber sorbents with this novel polymer and lumen formulation are characterized and tested using breakthrough and desorption measurements to evaluate the optimal adsorption and desorption times. Rapid temperature swing adsorption cycles are completed to evaluate the stability, productivity, and swing capacities of the fiber sorbents. In the final cycle, a swing capacity of 0.72 mmol gfiber-1 under 400 ppm CO2 flow at 22 °C and 45% relative humidity was reached, with a CO2 recovery of 68%.