Microscopic simulation study on the penetration property of pure hydrogen sulfide gas in polyethylene and polyvinylidene fluoride

The H2S penetration in the nonmetallic biogas pipelines and reinforced thermoplastic composite pipelines can lead to severe environmental pollution and disrupt the regular operations of oil and gas fields. Thus, delving into and comprehending the H2S penetration in polyethylene (PE) or polyvinylidene fluoride (PVF2) holds immense significance for both environmental preservation and industrial progress. In this study, Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) are employed to investigate and contrast the H2S penetration property within PE and PVF2 at 300-360 K and 0.1-1.5 MPa. The results indicate the diffusion and penetration coefficients decrease with decreasing temperature and pressure, while the solubility coefficient increases with decreasing temperature. Compared to PE, PVF2 demonstrates stronger resistance to H2S penetration, mainly due to H2S is difficult to diffuse in PVF2. The relationship between penetration coefficient and temperature is consistent with Arrhenius law. In 0.1 MPa, the activation energy of H2S in PE and PVF2 are 31911 and 42247 J/mol, respectively. Moreover, the relationship between activation energy and pressure is power function. The study also reveals the H2S diffusion in both PE and PVF2 follows the leap mechanism. These research findings can offer valuable guidance for reducing environmental pollution and ensuring industrial development.