Highly Dispersed Metal Carbide on ZIF-Derived Pyridinic-N-Doped Carbon for CO2 Enrichment and Selective Hydrogenation
| Autor: | Dong‐Hau Kuo, Jinqing Hong, Hua Zhang, Binghui Chen, Xiaohu Cai, Chen Sijing, Wenju Wang, Yunhua Li, Kevin H. L. Zhang |
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| Rok vydání: | 2018 |
| Předmět: |
Reaction mechanism
Materials science General Chemical Engineering Inorganic chemistry 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Dissociation (chemistry) 0104 chemical sciences Catalysis Carbide Metal chemistry.chemical_compound General Energy Adsorption chemistry Desorption visual_art Imidazolate visual_art.visual_art_medium Environmental Chemistry General Materials Science 0210 nano-technology |
| Zdroj: | ChemSusChem. 11:1040-1047 |
| ISSN: | 1864-5631 |
| DOI: | 10.1002/cssc.201800016 |
| Popis: | Catalytic conversion of CO2 into chemicals is a critical issue for energy and environmental research. Among such reactions, converting CO2 into CO has been regarded as a significant foundation to generate a liquid fuels and chemicals on a large scale. In this work, zeolitic imidazolate framework-derived N-doped carbon-supported metal carbide catalysts (M/ZIF-8-C; M=Ni, Fe, Co and Cu) with highly dispersed metal carbide were prepared for selective CO2 hydrogenation. Under the same metal loadings, catalytic activity for CO2 hydrogenation to CO follows the order: Ni/ZIF-8-C≈Fe/ZIF-8-C>Co/ZIF-8-C>Cu/ZIF-8-C. These catalysts are composed of carbide or metal supported on pyridinic N sites within the N-doped carbon structure. ZIF-8-derived pyridinic nitrogen and carbide effect CO2 adsorption, whereas dispersed Ni or Fe carbide and metal species serve as an active site for CO2 hydrogenation. The supported Ni catalyst exhibits extraordinary catalytic performance, which results from high dispersion of the metal and exposure of the carbide. Based on high-sensitivity low-energy ion scattering (HS-LEIS) and line scan results, density functional theory (DFT) was used to understand reaction mechanism of selective CO2 hydrogenation over Ni/ZIF-8-C. The product CO is derived mainly from the direct cleavage of C-O bonds in CO2 * rather than decomposition of COOH*. The CO* desorption energy on Ni/ZIF-8-C is lower than that for further hydrogenation and dissociation. Comparison of Ni/ZIF-8-C with ZIF-8-C indicates that the combined effects of the highly dispersed metal or carbide and weak CO adsorption result in high CO selectivity for CO2 hydrogenation. |
| Databáze: | OpenAIRE |
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