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

• DAC CO 2 capture under ambient conditions with desorption at low temperature (50 °C) and no vacuum. • CA-E crosslinked polyamine maintained 70% working capacity for multiple cycles at desorption conditions. • Stability maintained after 30 days of ageing at desorption conditions (5.3 % difference in uptake after 205 cycles). • Desorption produces lower CO 2 concentrations (1000 ppm) suitable for agricultural use. • Polymer is easy to synthesize using non-hazardous liquid components in the final product. Yields from agriculture can be enhanced by maintaining elevated CO 2 environments typically in the range of 1000 ppm CO 2 . Technologies that have the potential to supply these elevated CO 2 levels in a carbon neutral manner can improve agricultural yields whilst mitigating further CO 2 emissions. Direct air capture (DAC) is one such technology that captures and concentrates CO 2 from the atmosphere. Most current DAC research focuses on producing high concentrations of CO 2 which typically requires high temperature/pressure swings in order to achieve high purity CO 2 streams. These conditions complicate plant design and affect the longevity of the material. This study explores the possibility of producing CO 2 at suitable concentrations for agricultural yield enhancement using mild desorption conditions (50 °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 CO 2 could be maintained during desorption with air flow at 50 °C (with no vacuum) for up to 70 % of the materials working capacity of 3.8 wt% CO 2 . 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. % CO 2 compared to 3.8 wt% for the polymer used in this study.