Department of Chemistry, Norwegian University of Science and Technology Trondheim, Norway.
Department of Process and Energy, Delft University of Technology Delft, Netherlands.
Front Chem. 2013 Dec 24;1:38. doi: 10.3389/fchem.2013.00038. eCollection 2013.
We performed classical molecular dynamics (MD) simulations to understand the mechanism of adsorption from a gas mixture of CO2 and H2 (mole fraction of CO2 = 0.30) and diffusion along a graphite surface, with the aim to help enrich industrial off-gases in CO2, separating out H2. The temperature of the system in the simulation covered typical industrial conditions for off-gas treatment (250-550 K). The interaction energy of single molecules CO2 or H2 on graphite surface was calculated with classical force fields (FFs) and with Density Functional Theory (DFT). The results were in good agreement. The binding energy of CO2 on graphite surface is three times larger than that of H2. At lower temperatures, the selectivity of CO2 over H2 is five times larger than at higher temperatures. The position of the dividing surface was used to explain how the adsorption varies with pore size. In the temperature range studied, the self-diffusion coefficient of CO2 is always smaller than of H2. The temperature variation of the selectivities and the self-diffusion coefficient imply that the carbon molecular sieve membrane can be used for gas enrichment of CO2.
我们进行了经典分子动力学（MD）模拟，以了解从 CO2 和 H2（CO2 摩尔分数为 0.30）的混合气体中吸附以及沿石墨表面扩散的机制，旨在帮助从工业废气中富集 CO2，分离出 H2。模拟中系统的温度涵盖了工业废气处理的典型条件（250-550 K）。使用经典力场（FF）和密度泛函理论（DFT）计算了单个 CO2 或 H2 分子在石墨表面上的相互作用能。结果吻合良好。CO2 在石墨表面上的结合能是 H2 的三倍。在较低的温度下，CO2 对 H2 的选择性是在较高温度下的五倍。分界面的位置用于解释吸附如何随孔径而变化。在所研究的温度范围内，CO2 的自扩散系数始终小于 H2。选择性和自扩散系数随温度的变化表明，碳分子筛膜可用于 CO2 的气体富集。
