Mechanistic Study on the Possibility of Converting Dissociated Oxygen into Formic Acid on χ-Fe<sub>5</sub>C<sub>2</sub>(510) for Resource Recovery in Fischer–Tropsch Synthesis
During Fischer–Tropsch synthesis, O atoms are dissociated on the surface of Fe-based catalysts. However, most of the dissociated O would be removed as H<sub>2</sub>O or CO<sub>2</sub>, which results in a low atom economy. Hence, a comprehensive study of the O removal pathway...
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MDPI AG
2023-12-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/28/24/8117 |
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| author | Ning Ai Changyi Lai Wanpeng Hu Qining Wang Jie Ren |
| author_facet | Ning Ai Changyi Lai Wanpeng Hu Qining Wang Jie Ren |
| author_sort | Ning Ai |
| collection | DOAJ |
| description | During Fischer–Tropsch synthesis, O atoms are dissociated on the surface of Fe-based catalysts. However, most of the dissociated O would be removed as H<sub>2</sub>O or CO<sub>2</sub>, which results in a low atom economy. Hence, a comprehensive study of the O removal pathway as formic acid has been investigated using the combination of density functional theory (DFT) and kinetic Monte Carlo (kMC) to improve the economics of Fischer–Tropsch synthesis on Fe-based catalysts. The results show that the optimal pathway for the removal of dissociated O as formic acid is the OH pathway, of which the effective barrier energy (0.936 eV) is close to that of the CO activation pathway (0.730 eV), meaning that the removal of dissociated O as formic acid is possible. The main factor in an inability to form formic acid is the competition between the formic acid formation pathway and other oxygenated compound formation pathways (H<sub>2</sub>O, CO<sub>2</sub>, methanol-formaldehyde); the details are as follows: 1. If the CO is hydrogenated first, then the subsequent reaction would be impossible due to its high effective Gibbs barrier energy. 2. If CO reacts first with O to become CO<sub>2</sub>, it is difficult for it to be hydrogenated further to become HCOOH because of the low adsorption energy of CO<sub>2</sub>. 3. When the CO + OH pathway is considered, OH would react easily with H atoms to form H<sub>2</sub>O due to the hydrogen coverage effect. Finally, the removal of dissociated O to formic acid is proposed via improving the catalyst to increase the CO<sub>2</sub> adsorption energy or CO coverage. |
| first_indexed | 2024-03-08T20:29:44Z |
| format | Article |
| id | doaj.art-31eea8c77cca479bb0a7bf3f1fed4aba |
| institution | Directory Open Access Journal |
| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-08T20:29:44Z |
| publishDate | 2023-12-01 |
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| series | Molecules |
| spelling | doaj.art-31eea8c77cca479bb0a7bf3f1fed4aba2023-12-22T14:27:51ZengMDPI AGMolecules1420-30492023-12-012824811710.3390/molecules28248117Mechanistic Study on the Possibility of Converting Dissociated Oxygen into Formic Acid on χ-Fe<sub>5</sub>C<sub>2</sub>(510) for Resource Recovery in Fischer–Tropsch SynthesisNing Ai0Changyi Lai1Wanpeng Hu2Qining Wang3Jie Ren4College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, ChinaCollege of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, ChinaCollege of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, ChinaNational Demonstration Center for Experimental Chemistry and Chemical Engineering Education, Zhejiang University of Technology, Hangzhou 310014, ChinaCollege of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, ChinaDuring Fischer–Tropsch synthesis, O atoms are dissociated on the surface of Fe-based catalysts. However, most of the dissociated O would be removed as H<sub>2</sub>O or CO<sub>2</sub>, which results in a low atom economy. Hence, a comprehensive study of the O removal pathway as formic acid has been investigated using the combination of density functional theory (DFT) and kinetic Monte Carlo (kMC) to improve the economics of Fischer–Tropsch synthesis on Fe-based catalysts. The results show that the optimal pathway for the removal of dissociated O as formic acid is the OH pathway, of which the effective barrier energy (0.936 eV) is close to that of the CO activation pathway (0.730 eV), meaning that the removal of dissociated O as formic acid is possible. The main factor in an inability to form formic acid is the competition between the formic acid formation pathway and other oxygenated compound formation pathways (H<sub>2</sub>O, CO<sub>2</sub>, methanol-formaldehyde); the details are as follows: 1. If the CO is hydrogenated first, then the subsequent reaction would be impossible due to its high effective Gibbs barrier energy. 2. If CO reacts first with O to become CO<sub>2</sub>, it is difficult for it to be hydrogenated further to become HCOOH because of the low adsorption energy of CO<sub>2</sub>. 3. When the CO + OH pathway is considered, OH would react easily with H atoms to form H<sub>2</sub>O due to the hydrogen coverage effect. Finally, the removal of dissociated O to formic acid is proposed via improving the catalyst to increase the CO<sub>2</sub> adsorption energy or CO coverage.https://www.mdpi.com/1420-3049/28/24/8117χ-Fe<sub>5</sub>C<sub>2</sub>Fischer–Tropsch synthesishydrogen coverage effectformic aciddissociated oxygen |
| spellingShingle | Ning Ai Changyi Lai Wanpeng Hu Qining Wang Jie Ren Mechanistic Study on the Possibility of Converting Dissociated Oxygen into Formic Acid on χ-Fe<sub>5</sub>C<sub>2</sub>(510) for Resource Recovery in Fischer–Tropsch Synthesis Molecules χ-Fe<sub>5</sub>C<sub>2</sub> Fischer–Tropsch synthesis hydrogen coverage effect formic acid dissociated oxygen |
| title | Mechanistic Study on the Possibility of Converting Dissociated Oxygen into Formic Acid on χ-Fe<sub>5</sub>C<sub>2</sub>(510) for Resource Recovery in Fischer–Tropsch Synthesis |
| title_full | Mechanistic Study on the Possibility of Converting Dissociated Oxygen into Formic Acid on χ-Fe<sub>5</sub>C<sub>2</sub>(510) for Resource Recovery in Fischer–Tropsch Synthesis |
| title_fullStr | Mechanistic Study on the Possibility of Converting Dissociated Oxygen into Formic Acid on χ-Fe<sub>5</sub>C<sub>2</sub>(510) for Resource Recovery in Fischer–Tropsch Synthesis |
| title_full_unstemmed | Mechanistic Study on the Possibility of Converting Dissociated Oxygen into Formic Acid on χ-Fe<sub>5</sub>C<sub>2</sub>(510) for Resource Recovery in Fischer–Tropsch Synthesis |
| title_short | Mechanistic Study on the Possibility of Converting Dissociated Oxygen into Formic Acid on χ-Fe<sub>5</sub>C<sub>2</sub>(510) for Resource Recovery in Fischer–Tropsch Synthesis |
| title_sort | mechanistic study on the possibility of converting dissociated oxygen into formic acid on χ fe sub 5 sub c sub 2 sub 510 for resource recovery in fischer tropsch synthesis |
| topic | χ-Fe<sub>5</sub>C<sub>2</sub> Fischer–Tropsch synthesis hydrogen coverage effect formic acid dissociated oxygen |
| url | https://www.mdpi.com/1420-3049/28/24/8117 |
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