Preferential Oxidation of CO over CoFe2O4 and M/CoFe2O4 (M = Ce, Co, Cu or Zr) Catalysts

Abstract

CoFe2O4 prepared by sol-gel has been examined with respect to its catalytic performance for preferential CO oxidation in a H2-rich stream. In turn, the promoting effects of incorporation of Ce, Co, Cu, and Zr by impregnation on the surface of CoFe2O4 on the process are examined as well. The catalysts have been characterized by N2 adsorption, X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), temperature programmed reduction (TPR), and X-ray photoelectron spectra (XPS), as well as diffuse reflectance infrared DRIFTS under reaction conditions with the aim of establishing structure/activity relationships for the mentioned catalyst/process. It is shown that while the presence of the various metals on CoFe2O4 hinders a low temperature CO oxidation process, it appreciably enhances the activity above 125 °C. This is basically attributed to the surface modifications, i.e. cobalt oxidation, induced in CoFe2O4 upon introduction of the metals. In turn, no methanation activity is observed in any case except for the copper-containing catalyst, in which achievement of reduced states of cobalt appears most favored.

Innovative Methodology for the Synthesis of CoFe2O4 Encapsulated La2Fe2O6 Nanoparticles for their Use in Various Applications.

“…The peaks with high B.E. >530 eV can be due to surface oxygen species of lattice defects [31,32]. According to ZHAO Kun et.al [33], those peaks are attributed to the adsorbed oxygen (O 2 2− , O 2 1− ) which is interrelated to the oxygen vacancies.…”

“…The high-resolution Co 2p spectrum, depicted in Fig. 5:c, consists of two spin-orbit doublets Co 2p3/2 characterized for Co 2+ , and Co 3+ in B-sites [31,32]. While the detected Co 2p1/2 peak is categorized for Co 2+ in B sites.…”

Tuning the Structural and Magnetic Properties of the Stuffed Framework Structures MeFe2O4 (Me = Ni, Ca, and Sr)

“…The low binding energy < 530 eV was owing to the Fe/ Ca-O and Fe/Sr-O bonds [53]. Higher binding energy peaks > 530 eV can be attributed to the surface oxygen species of lattice defects [53,54]. According to ZHAO Kun et al [55], the observed peaks can be due to the adsorbed oxygen (O 2 2− , O 2 1− ), which is interrelated to the oxygen vacancies.…”

Effects of Metal Promoters (M = Fe, Co, and Cu) in Pt/MxZryOz Catalysts and Influence of CO2 and H2O on the CO Oxidation Activity (PROX): Analysis of Surface Properties After Reaction

“…11−16 More specifically, the performance of iron-zirconia solid solutions has been investigated in these systems 17−21 although the use of CoFe 2 O 4 mixed oxide resulted in high CO conversions (about 80%) and good stability (during 30 h) at 250 °C in the CO-PROX reaction. 22 The use of dual metal Fe−Co single sites on N-doped carbon supports has also been investigated by Wang, 17 concluded that CO adsorption occurs on the Co sites and that oxygen dissociation takes place on the Fe sites.…”

“…The Fe and Cu were found to be incorporated into a Cu−Fe supersaturated solid solution, which improved the CO oxidation activity, with carbon dioxide and water produced selectively with high catalytic activity in depleted hydrogen streams. The preferential oxidation of CO over CoFe 2 O 4 promoted with M/CoFe 2 O 4 (M = Ce, Co, Cu, or Zr) was studied by Bejaoui et al 22 Indeed, the mixed oxides have structures and morphologies that are active in the PROX reaction and other oxidation processes. The vacancies within mixed oxide compounds favor the oxidation process, depending upon the specific metal oxides or materials utilized to increase oxygen storage within the lattice framework of the oxide.…”