Influence of adsorption time and temperature using cross linked polymers for CO2 capture

https://doi.org/10.1039/D1MA01072G

“The CO₂ adsorption behaviour of 10 : 1 (R) is superior to that of the other PEI-4BMFPT adsorbents at 30 °C, with a maximum capacity after 120 minutes of 2.31 mmol g⁻¹, as shown in Fig. 10 (and against all PEI-4BMFPT adsorbents in Fig. S10, ESI†). This is 1 mmol higher than that reported by Huang et al. for their high surface area functionalised co-polymers,⁴⁸ and 0.1 mmol higher than reported by Mane et al. for alkyl chloride cross-linked PEI,⁵⁰ both analysed at 25 °C, and under 1 bar pure CO₂. Compared to 10 : 1 (V) and 25 : 1 (V), CO₂ uptake by 10 : 1 (R) is faster, adsorbing 59.51% of its final capacity after 10 minutes, reaching 1.38 mmol g⁻¹ uptake. In common with all other adsorbents, its adsorption kinetics is improved by increasing temperature, and like the more cross-linked adsorbents, 1 : 1 (V), 3 : 1 (V) and 5 : 1 (V), 10 : 1 (R) shows its highest adsorption at the lowest temperature of 30 °C. Its final capacity reduces to 2.09 mmol g⁻¹ and 1.45 mmol g⁻¹ at 60 °C and 90 °C, respectively, therefore it is less effective than 25 : 1 (V) at higher temperatures, Fig. S10 (ESI†). The adsorption behaviour of 10 : 1 (R) may be linked with its morphology: the clear pathway through the bulk of the material formed between the distinct spherical particles likely allows good contact between the amine groups and CO₂, enabling higher adsorption at 30 °C. Increasing temperature may aid diffusion, but any benefit is outweighed by the greater promotion of CO₂ desorption, leading to reduced capacity.”

“Fig. 10 TGA–CO₂ sorption (mmol g⁻¹) of 10 : 1 (R) at: (a) 30 °C; (b) 60 °C; (c) 90 °C, under 90% CO₂.”