Please use this identifier to cite or link to this item: http://nopr.niscair.res.in/handle/123456789/11014
Title: Influence of promoter and Fe<sup>2+</sup>/Fe<sup>3+</sup> ratio on microstructure of fused iron catalysts for ammonia synthesis
Authors: Pu, Zhi-ying
Zheng, Yi-fan
Liu, Hua-zhang
Li, Xiao-nian
Keywords: Catalysts
Fused iron catalysts
X-ray diffraction
Iron
Ammonia
Issue Date: Feb-2011
Publisher: NISCAIR-CSIR, India
Abstract: Fused iron catalysts have been prepared by melting a mixture of magnetite powder, reducing agent (iron) and promoters (K, Ca and Al). The effects of the Fe<sup>2+</sup>/Fe<sup>3+</sup> ratio and addition of promoters on the microstructure of the catalysts have been investigated by X-ray diffraction, high-resolution scanning electron microscopy and energy disperse spectroscopy techniques. The XRD results indicate that the addition of the promoters restrains the occurrence of disproportionation reaction and favors the formation of wustite. SEM and EDS measurements show that the Fe<sup>2+</sup>/Fe<sup>3+</sup> ratio significantly influences the microstructure of the catalyst as well as the distribution of the promoters K and Ca. The catalyst with high Fe<sup>2+</sup>/Fe<sup>3+</sup> ratio is reduced more easily than that with low Fe<sup>2+</sup>/Fe<sup>3+</sup> ratio. The promoter in the sample with high Fe<sup>2+</sup>/Fe<sup>3+</sup> ratio is distributed homogeneously on the surface of particles as needle-like films. After being reduced, the sample with low Fe<sup>2+</sup>/Fe<sup>3+</sup> ratio has a compact structure with the promoter being distributing heterogeneous on the catalyst surface in an amorphous state, while the sample with high Fe<sup>2+</sup>/Fe<sup>3+</sup> ratio had a porous structure and on the surface of particles the promoter is crystalline.
Description: 156-162
URI: http://hdl.handle.net/123456789/11014
ISSN: 0975-0975(Online); 0376-4710(Print)
Appears in Collections:IJC-A Vol.50A(02) [February 2011]

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