Supported LaCoO

Nguyen, S.V., Szabo, V., Trong-On, D., and Kaliaguine, S. (2002) Mesoporous silica supported LaCoOs perovskites as catalysts for methane oxidation. Microporous Mesoporous Mater., 54 (1-2), 51-61. 

R.N.S.H., and Schmal, M. (2012) Alumina-supported LaCoOs perovskite for selective CO oxidation (SELOX). Int. J. Hydrogen Energy, SI, 5022-5031. 

It is well known that the major limitation of the application of perovskites as combustion catalysts is their lower surface area and their increased tendency to sinter. One solution to increase the contact surface between the VOC and the perovskite is to disperse it on a large surface area and thermally stable support. Thus, supported LaCoOs perovskites on CeZr02 have been studied recently. The use of a CeZr02 support for lanthanum cobalt perovskites promoted the catalytic activity with respect to the corresponding bulk perovskites, decreasing the temperature for complete toluene oxidation by more than 50 C. The increased activity was related to two factors (i) the larger exposed surface and (ii) the composition of the support which provided the increased oxygen mobility of the catalyst. 

The cobalt metal area of the reduced perovskites was determined by hydrogen chemisorption experiments. The results are shown in Table 1. The chemisorption measurements revealed that the cobalt metallic surface area was similar for all the perovskites. This is supported by the Co/Ln surface ratio (Table I) obtained by XPS which also suggests similar metallic dispersion. The XPS analyses of the reduced perovskites showed the presence of Co" (778.6 eV) but also a doublet at approximately 780.5 and 796.2 eV which correspond to Co 2p, and Co 2p , peaks respectively, for the Co ion. Shake-up satellite lines with 4.7 eV over the Co lines were also detected indicating the presence of Co [12]. These oxidised species of cobalt are probably formed by air oxidation during the transference of the reduced sample from the reactor to the XPS spectrometer. Also, Marcos el al. [15] have shown that the reduction of the perovskite LaCoO, produced a La,0, oxide covered by hydroxyl groups which upon heating and evacuation in the XPS pretreatment chamber partly reoxidises the cobalt crystallites. 

Seldne et al. [78] investigated the WGS reaction at low temperature (300 °C) over Pt and Pd catalysts supported on several LaBOs (B = Cr, Mn, Fe, Co, and Ni) perovskite oxides prepared using the Pechini method. They observed that perovsldte oxides without active metal showed no activity for the WGS reaction, while those loaded with Pt and Pd exhibited good WGS activity. Interaction between Pt or Pd and the support promotes the WGS reaction. They found that both Pt/LaCoOs and Pd/LaCoOs catalysts have high catalytic activity, although Pt/LaCoOs catalyst deactivated immediately, and Pd/LaCoOs, although initially less active, exhibited superior stability. The cause of deactivation of Pt/LaCoOs was attributed to the reduction of Co and Pt cations. 

Colonna S. Rossi De S. Faticanti M. et al. Zirconia supported La, Co oxides and LaCoOs perovskite structural characterization and catalytic CO oxidation. JMol. Catal. A Chem. 2002, 180, 161-168. 

Another cathode material development work is carried out in the consortium of Ris0-DTU and TOFC. LaCoi jjNix03 (LCN) has been reported to possess beneficial materials properties for SOFC cathode application [17]. The thermal expansion of the LaCoo 6Nio 403 (LCN60) is better matched to the SOFC anode support as compared to other cathode materials such as LSCF, and especially LSC. Electronic conductivities of about 1,400 S/cm at SOFC operating temperatures have been reported. Symmetrical cell tests at 750 °C and OCV demonstrated no... 

---