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

Hydrogen enriched compressed natural gas contains CO and O-2 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 H-2+nCO + mO(2) on Fe (110) plane. The results show that it's easier for pre-adsorbed nCO + mO(2) to form high surface coverage compared with pre-adsorbed nCO or mO(2). The CO and O-2 increased H-2 dissociation barrier (Edis-b), and high coverage of nCO, mO(2) and nCO + mO(2) increased the hydrogen dissociation activation energy (E-dis). 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 mO(2). The Edif was controlled by CO under low coverage and was controlled by O-2 under high coverage when nCO + mO(2) pre-adsorbed: the deformation charge density and state density analysis show that in H-2 + nCO + mO(2) system, H atom is in an electron gain state at low coverage, which is similar to H in preadsorbed nCO, and H is in an electron loss state at high coverage, which is similar to H in pre-adsorbed mO(2.)The E-dif 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. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.