Catalytic Performance of Nitrogen-Doped Activated Carbon Supported Pd Catalyst for Hydrodechlorination of 2,4-Dichlorophenol or Chloropentafluoroethane
Nitrogen-doped activated carbon (N-AC) obtained through the thermal treatment of a mixture of HNO<sub>3</sub>-pretreated activated carbon (AC) and urea under N<sub>2</sub> atmosphere at 600 °C was used as the carrier of Pd catalyst for both liquid-phase hydrodechlori...
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MDPI AG
2019-02-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/24/4/674 |
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| author | Haodong Tang Bin Xu Meng Xiang Xinxin Chen Yao Wang Zongjian Liu |
| author_facet | Haodong Tang Bin Xu Meng Xiang Xinxin Chen Yao Wang Zongjian Liu |
| author_sort | Haodong Tang |
| collection | DOAJ |
| description | Nitrogen-doped activated carbon (N-AC) obtained through the thermal treatment of a mixture of HNO<sub>3</sub>-pretreated activated carbon (AC) and urea under N<sub>2</sub> atmosphere at 600 °C was used as the carrier of Pd catalyst for both liquid-phase hydrodechlorination of 2,4-dichlorophenol (2,4-DCP) and gas-phase hydrodechlorination of chloropentafluoroethane (R-115). The effects of nitrogen doping on the dispersion and stability of Pd, atomic ratio of Pd/Pd<sup>2+</sup> on the surface of the catalyzer, the catalyst’s hydrodechlorination activity, as well as the stability of N species in two different reaction systems were investigated. Our results suggest that, despite no improvement in the dispersion of Pd, nitrogen doping may significantly raise the atomic ratio of Pd/Pd<sup>2+</sup> on the catalyst surface, with a value of 1.2 on Pd/AC but 2.2 on Pd/N-AC. Three types of N species, namely graphitic, pyridinic, and pyrrolic nitrogen, were observed on the surface of Pd/N-AC, and graphitic nitrogen was stable in both liquid-phase hydrodechlorination of 2,4-DCP and gas-phase hydrodechlorination of R-115, with pyridinic and pyrrolic nitrogen being unstable during gas-phase hydrodechlorination of R-115. As a result, the average size of Pd nanocrystals on Pd/N-AC was almost kept unchanged after liquid-phase hydrodechlorination of 2,4-DCP, whereas crystal growth of Pd was clearly observed on Pd/N-AC after gas-phase hydrodechlorination of R-115. The activity test revealed that Pd/N-AC exhibited a much better performance than Pd/AC in liquid-phase hydrodechlorination of 2,4-DCP, probably due to the enhanced stability of Pd exposed to the environment resulting from nitrogen doping as suggested by the higher atomic ratio of Pd/Pd<sup>2+</sup> on the catalyst surface. In the gas-phase hydrodechlorination of R-115, however, a more rapid deactivation phenomenon occurred on Pd/N-AC than on Pd/AC despite a higher activity initially observed on Pd/N-AC, hinting that the stability of pyridinic and pyrrolic nitrogen plays an important role in the determination of catalytic performance of Pd/N-AC. |
| first_indexed | 2024-12-18T08:10:44Z |
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| spelling | doaj.art-aa9b6d16cbee454f847509ab3b4084102022-12-21T21:14:54ZengMDPI AGMolecules1420-30492019-02-0124467410.3390/molecules24040674molecules24040674Catalytic Performance of Nitrogen-Doped Activated Carbon Supported Pd Catalyst for Hydrodechlorination of 2,4-Dichlorophenol or ChloropentafluoroethaneHaodong Tang0Bin Xu1Meng Xiang2Xinxin Chen3Yao Wang4Zongjian Liu5Institute of Industrial Catalysis, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 300014, ChinaInstitute of Industrial Catalysis, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 300014, ChinaInstitute of Industrial Catalysis, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 300014, ChinaInstitute of Industrial Catalysis, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 300014, ChinaInstitute of Industrial Catalysis, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 300014, ChinaInstitute of Industrial Catalysis, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 300014, ChinaNitrogen-doped activated carbon (N-AC) obtained through the thermal treatment of a mixture of HNO<sub>3</sub>-pretreated activated carbon (AC) and urea under N<sub>2</sub> atmosphere at 600 °C was used as the carrier of Pd catalyst for both liquid-phase hydrodechlorination of 2,4-dichlorophenol (2,4-DCP) and gas-phase hydrodechlorination of chloropentafluoroethane (R-115). The effects of nitrogen doping on the dispersion and stability of Pd, atomic ratio of Pd/Pd<sup>2+</sup> on the surface of the catalyzer, the catalyst’s hydrodechlorination activity, as well as the stability of N species in two different reaction systems were investigated. Our results suggest that, despite no improvement in the dispersion of Pd, nitrogen doping may significantly raise the atomic ratio of Pd/Pd<sup>2+</sup> on the catalyst surface, with a value of 1.2 on Pd/AC but 2.2 on Pd/N-AC. Three types of N species, namely graphitic, pyridinic, and pyrrolic nitrogen, were observed on the surface of Pd/N-AC, and graphitic nitrogen was stable in both liquid-phase hydrodechlorination of 2,4-DCP and gas-phase hydrodechlorination of R-115, with pyridinic and pyrrolic nitrogen being unstable during gas-phase hydrodechlorination of R-115. As a result, the average size of Pd nanocrystals on Pd/N-AC was almost kept unchanged after liquid-phase hydrodechlorination of 2,4-DCP, whereas crystal growth of Pd was clearly observed on Pd/N-AC after gas-phase hydrodechlorination of R-115. The activity test revealed that Pd/N-AC exhibited a much better performance than Pd/AC in liquid-phase hydrodechlorination of 2,4-DCP, probably due to the enhanced stability of Pd exposed to the environment resulting from nitrogen doping as suggested by the higher atomic ratio of Pd/Pd<sup>2+</sup> on the catalyst surface. In the gas-phase hydrodechlorination of R-115, however, a more rapid deactivation phenomenon occurred on Pd/N-AC than on Pd/AC despite a higher activity initially observed on Pd/N-AC, hinting that the stability of pyridinic and pyrrolic nitrogen plays an important role in the determination of catalytic performance of Pd/N-AC.https://www.mdpi.com/1420-3049/24/4/674activated carbonhydrodechlorinationnitrogen dopingPd |
| spellingShingle | Haodong Tang Bin Xu Meng Xiang Xinxin Chen Yao Wang Zongjian Liu Catalytic Performance of Nitrogen-Doped Activated Carbon Supported Pd Catalyst for Hydrodechlorination of 2,4-Dichlorophenol or Chloropentafluoroethane Molecules activated carbon hydrodechlorination nitrogen doping Pd |
| title | Catalytic Performance of Nitrogen-Doped Activated Carbon Supported Pd Catalyst for Hydrodechlorination of 2,4-Dichlorophenol or Chloropentafluoroethane |
| title_full | Catalytic Performance of Nitrogen-Doped Activated Carbon Supported Pd Catalyst for Hydrodechlorination of 2,4-Dichlorophenol or Chloropentafluoroethane |
| title_fullStr | Catalytic Performance of Nitrogen-Doped Activated Carbon Supported Pd Catalyst for Hydrodechlorination of 2,4-Dichlorophenol or Chloropentafluoroethane |
| title_full_unstemmed | Catalytic Performance of Nitrogen-Doped Activated Carbon Supported Pd Catalyst for Hydrodechlorination of 2,4-Dichlorophenol or Chloropentafluoroethane |
| title_short | Catalytic Performance of Nitrogen-Doped Activated Carbon Supported Pd Catalyst for Hydrodechlorination of 2,4-Dichlorophenol or Chloropentafluoroethane |
| title_sort | catalytic performance of nitrogen doped activated carbon supported pd catalyst for hydrodechlorination of 2 4 dichlorophenol or chloropentafluoroethane |
| topic | activated carbon hydrodechlorination nitrogen doping Pd |
| url | https://www.mdpi.com/1420-3049/24/4/674 |
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