Preparation And Characterization Of Cufe2O4 Bulk

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Ceramics International 37 (2011) 803–812 www.elsevier.com/locate/ceramint

Preparation and characterization of CuFe2O4 bulk catalysts
´ Julia E. Tasca a, Claudia E. Quincoces b, Araceli Lavat a,*, Ana M. Alvarez b, M. Gloria Gonzalez b
b a ´ Fac Ing. (UNCPBA), Av del Valle 5737, B7400JWI Olavarrıa, Argentina ´ Centro de investigacion Desarrollo enCiencias Aplicadas Dr. J.J. Ronco (CINDECA) (CONICET-UNLP), 47 Nro 257, 1900 La Plata, Argentina

Received 14 May 2010; received in revised form 9 August 2010; accepted 8 October 2010 Available online 19 November 2010

Abstract This work is devoted to the investigation of the influence of the preparation process on the physical–chemical properties of a copper spinel applied as catalyst forhydrocarbon (HC) oxidation. Samples of CuFe2O4 mixed oxide belonging to the inverted spinel type structure have been obtained by high temperature solid state reaction and by wet chemical synthesis methods, applying nitrate and citrate precursor procedures, within the thermal range from 150 to 700 8C. ¨ The bulk catalysts were characterized by XRD, TPR, FTIR, SEM-EDX, TEM and Mossbauer spectroscopy.Propane combustion was performed as a reaction test. In this work it is demonstrated that the calcination temperature and chemical synthesis affect the crystal properties and cation distribution in the spinel structure, microstructure, surface area and reducibility; which are among the most relevant physical chemical properties for the catalytic activity. The materials obtained by wet chemicalprocedure, through nitrate and citrate routes, are better suited for propane combustion. This feature is assigned to the microstructure, to the presence of nanometric size particles and also to the cation distributions in the spinel sublattices of these materials. # 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
Keywords: Cu–Fe spinel; Bulk catalyst; Synthesis; Characterization;Structure–properties correlation; Catalytic propane combustion

1. Introduction The catalytic combustion of light alkanes, especially propane, is of great interest as a promising process for environmentally benign energy generation and emission control [1]. The most important advantages of this process are the low production of contaminant by products, i.e. NOx, CO, etc. and the improvement of theenergy efficiency. A large number of metallic oxides belonging to different structural types, as spinels, perovskites, and K2NiF4, among others, have been reported for HC (hydrocarbon) combustion [2–4]. These groups of materials exhibit high electronic and oxygen ion conductivity, properties that are believed to be important for high activity in complete HC oxidation [5]. In addition to this, metallicoxides are less expensive and often thermally more stable than the noble metals, traditionally used for this purpose.

* Corresponding author. Tel.: +54 02284 451055; fax: +54 02284 451055. E-mail address: alavat@fio.unicen.edu.ar (A. Lavat).

The ferrites with the formula MFe2O4, belonging to the spinel structural type, have received attention because of their unique properties and multipleapplications in many fields, including ferrofluids, magnetic drug delivery and information storage [6]. Furthermore the catalysts based on ferrites MIIFeIII2O4, (M = Cu, Co and Cr) are of great importance for catalytic processes, and particularly total oxidation of light HC [7,8]. The interaction between metallic cations results in the key factor for the catalytic process, mainly by preventing orinhibiting oxides sintering. Copper is one of the most used metals in several catalytic reactions. The distribution of Cu in the two different crystal sites in this structure is so far believed to keep the active sites separated, prolonging the activity and stability of catalysts [9]. Due to the practical reasons mentioned above, magnetic ferrite particles must have the reduced size and uniform...