Synthesis and surface properties of zinc ferrite species in supported sorbents for coal gas desulphurisation

• Published in: Fuel processing technology Vol. 86; no. 2; pp. 191 - 203
• Main Authors: Tomás-Alonso, F., Palacios Latasa, J.M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.11.2004; Elsevier Science
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fuels; Hot coal gas desulphurisation; Supported sorbents characterisation; Zinc ferrites; Zinc ferrites; Hot coal gas desulphurisation; Supported sorbents characterisation; Pellet; Desulfurization; Iron oxide; In situ; Ions; High temperature; Zeolite; Molecular sieve; Zinc; Ferrite; Substitution; Preparation; Surface properties; Coal gas; Hot gas; Performance; Sorbent; Catalyst; Strength
• ISSN: 0378-3820; 1873-7188
• DOI: 10.1016/j.fuproc.2004.03.004

The paper explores several alternative ways for improving the performance of zinc ferrites, which are common high-throughput sorbents used in hot gas desulphurisation processes (IGCC). The catalysts have been prepared by supporting the pure oxides (zinc and iron oxides) in porous supports (sepiolite, ZrO 2 and zeolite) that provides the necessary strength. The active phase (zinc ferrite) is “in situ” synthesized as combined mixed oxides with a spinel structure, produced after calcination at high temperature. It has been found that the preparation method has a strong influence on the spatial distribution of the chemical species inside the pellet. In some cases, it is even possible to produce a profile where metallic oxides concentrate near the outer edge of the particle. According to XRD, it is found a preferential formation of enstatite phase rather than franklinite, due to substitution of interstitial ions in the framework of supports for Fe 2+ and Zn 2+. These conclusions set up strong requirements for the synthesis of specific sorbents in FGD reactions. This can be achieved by means of a combination of different preparation methodologies, which allow selecting the metallic ions and the supports in order to build the active spinels required for the FGD reaction.