Surface reaction mechanisms of CO with Fe-based oxygen carrier supported by CaO and K2CO3 in chemical looping combustion: Case study. (5th May 2023)

• Record Type: Journal Article
• Authors: Mu, Lin; Zhang, Bin; Huang, Xiankun; Wang, Zhen; Yin, Hongchao; Shang, Yan; Huo, Zhaoyi
• Is Part Of: Chemical engineering science. Volume 271(2023)
• Publication Date: 2023-05-05
• Subjects: Chemical looping combustion -- Density functional theory -- Fe-based oxygen carrier -- Supporting carrier -- CO adsorption -- Surface reaction mechanism; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; Chemical engineering; Periodicals; Electronic journals; 660
• DOI: 10.1016/j.ces.2023.118564
• Languages: English
• ISSNs: 0009-2509

Abstract

Highlights: Reaction mechanism of CO with CaO and K2 CO3 supported Fe2 O3 was studied by DFT. CaO and K2 CO3 supporting benefited Fe2 O3 cluster to capture more free CO molecule. CaO had more improvement of adsorption of CO on the Fe2 O3 cluster that K2 CO3 . Energy barriers of CaO and K2 CO3 supported Fe2 O3 reacting with the CO were reduced. Two reaction paths that CaO and K2 CO3 activated the Fe2 O3 cluster was concluded. Abstract: The density functional theory was used to explore the CO adsorption mechanisms of pure and CaO (1 0 0)- and K2 CO3 (0 0 1) -supported Fe2 O3 clusters. The supporting carriers, CaO (1 0 0) and K2 CO3 (0 0 1), had a strong bond with the Fe2 O3 cluster and the binding energies were −3.50 eV and −5.54 eV, respectively. The interaction between the Fe2 O3 cluster and supporting carriers lengthened the chemical bonds of the cluster. Compared with the pure and K2 CO3 - supported Fe2 O3 clusters, the adsorption performance of the CaO- supported Fe2 O3 cluster was improved, and the adsorption energies at the three adsorption sites were greater than 1 eV. The Fe2 O3 cluster was activated by CaO and K2 CO3, which extended and weakened the bonds, causing the bonds to easily break. Furthermore, CO was adsorbed on the Fe2 O3 cluster surface as carbonates. Therefore, the atoms on the Fe2 O3 cluster surface required less energy to overcome the potential migration resistance and traveled shorter distances to form new chemical bonds with CO.