Theoretical insights of catalytic oxidation of Hg0 on g-C3N4-supported Fe/Co/Ni-based bi-metallic catalysts using O2 in coal-fired flue gas as the oxidant

Shuai LIU, Mengxia Xu, Chengheng Pang, Edward Lester, Tao Wu

Research output: Journal PublicationArticlepeer-review

5 Citations (Scopus)

Abstract

In this work, density functional theory (DFT) calculations were conducted to investigate the adsorption and oxidation of Hg0 with O2 as the oxidant on pristine and O-adsorbed dimers of Fe, Co and Ni supported on the buckled g-C3N4 surface. The calculation reveals that all the dimers supported on the buckled g-C3N4 surface (Fe2/Co2/Ni2@g-C3N4) are stable at 700 K. It is found that Hg0 oxidation starts from the adsorption of O2 and its subsequent dissociation, followed by the formation of OHgO and the desorption of HgO from the surface. However, after desorption of the first HgO, the active site of the dimer becomes an O-adsorbed dimer, which affects - Hg0 oxidation reaction although the reaction pathway is similar. DFT calculations demonstrate that both the pristine dimer and O-adsorbed dimer are effective in O2 dissociation and are relatively easy for the metal-O bond to break, which is associated with a low energy barrier for these two processes. However, the interactions between O2/Hg0 and the pristine surface are significantly stronger than those between O2/Hg0 and the O-adsorbed dimer site. Rate-determining step of catalytic oxidation process on the pristine and O-adsorbed Fe2@g-C3N4 and Co2@g-C3N4 is the cleavage of the metal-O bond, while the HgO desorption dominates the pristine and O-adsorbed Ni2@g-C3N4 with an energy barrier of 2.04 eV and 1.62 eV, respectively. It is found that among the dimers studied, the Ni2@g-C3N4 exhibites the highest efficiency in the catalytic oxidation of Hg0.

Original languageEnglish
Article number121593
JournalFuel
Volume306
DOIs
Publication statusPublished - 15 Dec 2021

Keywords

  • Catalytic oxidation
  • Density functional theory
  • Dimer
  • G-CN
  • Hg removal

ASJC Scopus subject areas

  • Chemical Engineering (all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Organic Chemistry

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