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Bimetallic Fe-Ni/SiO2 catalysts for furfural hydrogenation: Identification of the interplay between Fe and Ni during deposition-precipitation and thermal treatments.
- Source :
-
Catalysis Today . Aug2019, Vol. 334, p162-172. 11p. - Publication Year :
- 2019
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Abstract
- • Co-deposition of Ni(II) and Fe(II) by DPU requires the absence of oxidizing species. • The result is an ill-crystallized Fe-containing Ni(II) 1:1 phyllosilicate phase. • Fe reduction is triggered by Ni reduction but needs high temperatures to be complete. • fcc Fe-Ni particles are formed with a standard deviation in composition of 8 at %. • A surface enrichment in Fe is evidenced by Mössbauer spectroscopy. Supported Fe-Ni catalysts have been reported for their activity and selectivity in the hydrogenation of unsaturated organic molecules. However, the control of the size and composition of the bimetallic nanoparticles remains a bottleneck when oxide-supported catalysts are prepared by impregnation, and alternative procedures should be investigated. Starting with Ni(II) and Fe(II) sulfates as precursor salts, deposition-precipitation with urea (DPU) on SiO 2 in an inert atmosphere initially leads to the formation of an ill-crystallized Fe-containing Ni(II) 1:1 phyllosilicate, which reduces under hydrogen at 700 °C into bimetallic fcc Fe-Ni nanoparticles of 5.4 nm in average. Compared with the composition of the DPU solution (50 Fe at %, 50 Ni at %), an excess of Ni is detected on the catalyst (38 Fe at %, 62 Ni at %), due to the preferential reaction of Ni2+ ions with silica. In situ X-ray absorption spectroscopy and 57Fe Mössbauer spectroscopy show that the reduction of Fe ions to the metallic state is triggered by the formation of reduced Ni centers above 350 °C, and, from then, proceeds progressively, resulting in an excess of Fe in the outer shells of the bimetallic particles. The composition of individual Fe-Ni particles evidences a standard deviation of 8%. The bimetallic Fe-Ni/SiO 2 catalyst gives high yields in furfuryl alcohol in the hydrogenation of furfural, in contrast with an analog Ni/SiO 2 catalyst that favours side-reactions of etherification, hydrogenolysis and hydrogenation of the furan ring. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09205861
- Volume :
- 334
- Database :
- Academic Search Index
- Journal :
- Catalysis Today
- Publication Type :
- Academic Journal
- Accession number :
- 137093234
- Full Text :
- https://doi.org/10.1016/j.cattod.2018.11.041