An Experimental and Density Functional Theory Simulation Study of NO Reduction Mechanisms over Fe0 Supported on Graphene with and without CO

Huanran Wang; Xianchun Li; Junzhi Wu; Dongke Zhang

doi:10.1021/acs.langmuir.3c02461

An Experimental and Density Functional Theory Simulation Study of NO Reduction Mechanisms over Fe⁰ Supported on Graphene with and without CO

Langmuir. 2023 Oct 31;39(43):15369-15379. doi: 10.1021/acs.langmuir.3c02461. Epub 2023 Oct 20.

Authors

Huanran Wang^{1

2

3}, Xianchun Li^{1

2}, Junzhi Wu^{3

4}, Dongke Zhang³

Affiliations

¹ Liaoning Provincial Engineering Research Centre for Advanced Coking and Coal Utilization, University of Science and Technology Liaoning, Anshan 114051, China.
² School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China.
³ Centre for Energy (M473), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
⁴ Shanxi Institute of Energy, Taiyuan, Shanxi 030006, China.

PMID: 37862119
DOI: 10.1021/acs.langmuir.3c02461

Abstract

NO reduction over highly dispersed zerovalent iron (Fe⁰) supported on graphene (G), with and without the presence of CO in the reacting stream, was systematically studied using a fixed-bed reactor, and the reaction mechanism was examined with the aid of in situ Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations. The in situ FTIR results showed that NO adsorbed on the Fe⁰ site is reduced to form active surface oxygen species (O*), which is then reduced by carbon in graphene to form CO₂. The presence of CO in the reacting stream helps to reduce the oxidized Fe(O) sites to regenerate Fe⁰ sites, making NO reduction easier. It was revealed that NO and CO₂ are easily adsorbed on the active surface oxygen species (O*) to form nitrate and carbonate, inhibiting their reduction by CO and deactivating the catalyst. The DFT calculations results suggest that the role of Fe is to reduce the energy barrier of the NO adsorption and decomposition, which controls the formation of active surface oxygen species and N₂. The combined FTIR and DFT results offer new insights into the possible mechanism of catalytic NO reduction over graphene loaded with Fe, with and without CO.