LaCoO material

From XPS analyses, the coexistence of Mn and Mn species was evidenced in LaMnOs material, while the LaCoOs one showed the presence of Co and Co " at the same time. Additionally, these authors established a higher Oads/Oiatt molar ratio on LaCoOs perovskite than that observed for the LaMnOs one. This phenomenon, observed at the surface of the material, improved the low-temperature reducibility of LaCoOs material, where the catalyst s properties claimed to be responsible for the remarkable catalytic performance of the cobalt-based perovskite in the CO oxidation reaction. Other authors have also remarked the importance of the presence of Co " species as active sites for the adsorption of CO [37-39]. For instance, by using DRIFT spectroscopy, Natile et al. [37]... 

While high temperatures do not severely limit fabrication of Ni—YSZ cermets, they can impact the way in which other composite electrodes are made. This is well-known for cathodes, where the most commonly used material is a composite of YSZ and Sr-doped LaMnOs (LSM). The primary reason for using LSM, rather than materials such as Sr-doped LaFeOs (LSF) or LaCoOs (LSC) that exhibit a better performance, is that LSM—YSZ mixtures can be... 

R.H.E. Van Doom, H. Kruidhof, H.J.M. Bouwmeester and A.J. Burggraaf, Oxygen permeability of strontium-doped LaCoOs-s perovskites, in G.-A. Nazri, J.-M. Taracson and M.S. Schreiber (Eds.), Materials Research Society Symposium Proceedings, Vol 369 Solid State Ionics IV. Materials Research Society, Pittsburgh, PA, 1995, pp. 377-382. 

In case of La(Sr)Mn03 the formation of spinel MnCr204 takes place at the interface with the contact paste. Some chromium was detected on the surface of the contact layer. The use of LaCoOs as contacting material might reduce the chromium diffusion through the contact paste because no enrichment of this element was observed. This effect may be due to the formation of a dense interaction layer which consists of a mixture of spinel and perovskite compounds which are virtually free of Cr. 

Figure 3.5 Temperature dependence of methane combustion on (a) mesoporous LaCoOs after removal of silica, (b) mesoporous LaCoOs-silica hybrid material, and (c) conventional LaCoOs and (d) used mesoporous LaCoOs catalyst [23].

In terms of application, the high specific surface area and the nano-size obtained from FH provide catalytic materials with improved resistance to high temperature treatment As an example, the methane combustion was used as a probe reaction. Although LaMnOs and LaCoOs+g prepared by the amorphous citrate method had lower temperature of methane oxidation, the corresponding catalysts prepared by FH demonstrated higher resistance to sintering after forced exposiu-e to reaction conditions at 800 °C for 24 h [76]. The catalysts prepared by the citrate method possess small particles obtained at low calcination temperature, for example, 600-700 °C. Thermal resistance is obtained only after calcination at 850-900 °C but at the expense of the specific surface area, whereas an ideal compromise is obtained by FH. 

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