Cryo-compressed CO2 sorption and diffusion in elastomers for the CO2 transport chain: Examples of FKM, EPDM and HNBR

Abstract

• CO 2 solubility and diffusivity in elastomers is inspected in wide ranges of temperature and pressure. • The suitability of representative FKM, HNBR and EPDM for CO 2 transport applications is assessed. • Prediction of key parameters is obtained through thermodynamic and transport models. Carbon capture and storage (CCS) is critical for achieving net-zero CO 2 emissions by 2050, necessitating efficient and reliable CO 2 transport solutions. The present study investigates the suitability of typical various elastomers for sealing applications in CCS infrastructure, focusing on fluoro-elastomers (FKM), nitrile rubbers (HNBR), and hydrocarbon-based rubbers (EPDM). These materials were tested to evaluate CO 2 solubility and diffusivity under temperature and pressure conditions relevant to CO 2 transport. Six different grades of elastomeric materials, characterized by different filler content (carbon black − CB), were inspected by means of a pressure decay method, spanning from room to cryogenic temperatures. The results indicated that of the materials tested in this research, the FKM tested exhibited a relatively large CO 2 uptake, which was attributed to fluorinated structure, while EPDM showed a rather low affinity for CO 2, attributed to its nonpolar nature. The solubility and diffusivity of CO 2 in the materials investigated were analyzed using the Lattice Fluid equation of state and diffusivity models, extending the understanding of CO 2 behavior in elastomers beyond the tested conditions, including both vapor and liquid CO 2 . The study highlights the critical role of CO 2 -induced swelling of the polymer matrix, and the resulting plasticization, crucial features for the sealing performance of elastomers in CCS applications, providing valuable insights for the development of a robust and safe CO 2 transport infrastructure.

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