Effect of the nanostructure and the surface composition of bimetallic Ni-Ru nanoparticles on the performance of CO methanation
| Autor: | Xiaonian Li, Changkun Yuan, Jing Wang, Nan Yao |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Nanostructure
Materials science General Physics and Astronomy chemistry.chemical_element Nanoparticle 02 engineering and technology Surfaces and Interfaces General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films Catalysis Electron transfer Chemical engineering chemistry Methanation Particle 0210 nano-technology Bimetallic strip Carbon |
| Zdroj: | Applied Surface Science. 441:816-823 |
| ISSN: | 0169-4332 |
| Popis: | The Ni/SiO2 catalysts with trace Ru promoter were prepared by either polyethylene glycol (PEG)-assisted or PEG-free impregnation method and were used in CO methanation reaction. The presence of PEG molecules was beneficial to form bimetallic Ni-Ru particles with smaller size, better anti-sintering property and low-temperature reducibility on SiO2 support than the conventional PEG-free derived NiRu/SiO2 catalyst. Moreover, it was found that the low-temperature reduction at 573 K was favorable to form bimetallic Ni-Ru particles with more surface Ru atoms. This nanostructure not only allowed the electron transfer happening from Ru0 to Ni0 which led to its higher electron cloud density, but also could reduce the deposition of less reactive carbon on the catalyst. Therefore, the low-temperature reduction enhanced the reaction stability of NiRu/SiO2 catalyst. The increase of reduction temperature from 573 K to 693 K did not change the size of metallic particles, but decreased the amount of surface Ru atoms. It deactivated the catalyst due to the deposition of more less reactive carbon. Although the higher reduction temperature (e.g. 693 and 793 K) was unfavorable to the reaction stability, it created more surface defects. The amount of defects showed a volcano-shaped correlation with the reduction temperature which was consistent with the variation tendency of turnover frequency of CO conversion. Consequently, it evidenced that the amount of surface Ru atoms and defects on the bimetallic Ni-Ru particle played the critical roles on the stability and the intrinsic activity of methanation, respectively. |
| Databáze: | OpenAIRE |
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