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Indexed by:期刊论文

Date of Publication:2014-01-01

Journal:CATALYSIS SCIENCE & TECHNOLOGY

Included Journals:SCIE、EI、Scopus

Volume:4

Issue:1

Page Number:53-61

ISSN No.:2044-4753

Abstract:Silicon-nickel intermetallic compounds (IMCs) supported on silica (Si-Ni/SiO2), as a highly efficient catalyst for CO methanation, have been prepared by direct silicification of Ni/SiO2 with silane at relatively low temperature in a fluidized bed reactor. The as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, in situ FT-IR of CO adsorption, and H-2-temperature programmed reduction-mass spectrometry (TPR-MS) of CO. The results indicate that uniform NiSix nanoparticles with about 3-4 nm are evenly dispersed on silica. The combined in situ FTIR and TPR-MS results suggest that the Si-Ni/SiO2 catalysts afforded high activity in CO methanation, promoting the formation of CH4 at ca. 240 degrees C. The catalytic hydrogenation of CO on Si-Ni/SiO2 was investigated in a fixed-bed reactor at GHSVs 48 000 mL h(-1) g(-1) under 1 atm in the temperature interval 200-600 degrees C. In the higher temperature reaction region (500-600 degrees C), it is notable that the Si-Ni/SiO2 catalysts present high activity for CO methanation as compared to the Ni/SiO2 catalyst. More importantly, the Si-Ni/SiO2-350 catalyst containing thermally stabile Si-Ni IMCs shows significantly higher resistance to the sintering of Ni particles. Raman characterization of the spent materials qualitatively shows that carbon deposition observed on the conventional Ni/SiO2 catalyst is much higher than that of the used Si-Ni/SiO2-350. It is proposed that small amounts of silicon interacting with Ni atoms selectively prevent the adsorption of resilient carbon species.