Co-adsorption of H2+nCO+mO2 on α-Fe (110): Effect on hydrogen adsorption, dissociation and diffusion

Hydrogen enriched compressed natural gas contains CO and O2 impurities, which have a coupling effect on hydrogen adsorption, dissociation and diffusion. First principles plane wave calculations have been used to study the co-adsorption and mutual interaction of H2+nCO + mO2 on Fe (110) plane. The results show that it’s easier for pre-adsorbed nCO + mO2 to form high surface coverage compared with pre-adsorbed nCO or mO2. The CO and O2 increased H2 dissociation barrier (Edis−b), and high coverage of nCO, mO2 and nCO + mO2 increased the hydrogen dissociation activation energy (Edis). With the coverage increased, the diffusion barrier (Edif) of H atom into Fe (110) decreased from 1.01eV to 0 by nCO and increased from 1.01eV to 2.14eV by mO2. The Edif was controlled by CO under low coverage and was controlled by O2 under high coverage when nCO + mO2 pre-adsorbed: the deformation charge density and state density analysis show that in H2+nCO + mO2 system, H atom is in an electron gain state at low coverage, which is similar to H in pre-adsorbed nCO, and H is in an electron loss state at high coverage, which is similar to H in pre-adsorbed mO2.The Edif probably related to the charge interaction of Hx− and Hy+ with Fez+.The C, O and H formant peaks from density of states show the influence of C and O on hydrogen invasion in orbital energy.