Ultra-low volatility solid polyamine CO2 capture materials for greenhouse CO2 enrichment

Yields from agriculture can be enhanced by maintaining elevated CO2 environments typically in the range of 1000 ppm CO2. Technologies that have the potential to supply these elevated CO2 levels in a carbon neutral manner can improve agricultural yields whilst mitigating further CO2 emissions. Direct air capture (DAC) is one such technology that captures and concentrates CO2 from the atmosphere. Most current DAC research focuses on producing high concentrations of CO2 which typically requires high temperature/pressure swings in order to achieve high purity CO2 streams. These conditions complicate plant design and affect the longevity of the material. This study explores the possibility of producing CO2 at suitable concentrations for agricultural yield enhancement using mild desorption conditions (50 degrees C and no pressure swing). A novel crosslinked polyamine formula utilising non-hazardous liquid components was developed in order to be more aligned to agricultural exposure limits. 1000 ppm CO2 could be maintained during desorption with air flow at 50 degrees C (with no vacuum) for up to 70 % of the materials working capacity of 3.8 wt% CO2. The longevity of the material was enhanced due to the lower desorption temperature as evidenced by no reduction in working capacity after 30 days exposure to desorption conditions (equivalent to 205 cycles). Compared to a previous work utilising the commercially available Lewatit VP OC 1065, the Lewatit resin had a repeated cyclic uptake of 4.1% wt. % CO2 compared to 3.8 wt% for the polymer used in this study.