Abstract
The effect of the preparation method on the properties of LaMnO3 and La0.8Sr0.2MnO3 perovskite was studied. Materials were prepared by four methods: sol-gel, chemical combustion, solvothermal and spray pyrolysis and characterized. The effect of the synthesis method on the texture, acid-base character of the surface, reducibility with hydrogen, oxygen desorption, surface composition and catalytic activity for combustion of lean methane was studied. It was found that synthesis method affects physicochemical properties of obtained materials-solvothermally produced materials exhibit well-developed surface area, presence of reactive oxygen species on surface and high catalytic activity for CH4 combustion. Generally, LaMnO3 and La0.8Sr0.2MnO3 perovskites show catalytic activity for lean CH4 combustion comparable or higher than the activity of 0.5 wt.% Pt/Al2O3 but lower than 1 wt.% Pd/Al2O3.
Highlights
Huge amounts of methane are emitted into atmosphere every year from numerous sources like coal mines, animal waste or landfill
This paper reports results of comparative investigation of the physicochemical properties of the LaMnO3 and La0.8Sr0.2MnO3 perovskites prepared by different synthesis routes
The LSM samples crystallized in regular system in the space group Pm-3m, except of LSM-chemical combustion (CC), which crystallized in a trigonal system (Table 1)
Summary
Huge amounts of methane are emitted into atmosphere every year from numerous sources like coal mines, animal waste or landfill. Concentration of methane in the atmosphere has been increasing strongly since beginning of XX century. Up to 350 bln m3 of methane is released from Polish coal mines and only a part of this gas is used, the majority goes into the atmosphere as VAM with a methane concentration of 0.1% - 1.0% [2]. Conventional flame burners possess insufficient efficiency to oxidize diluted methane in VAM and catalytic oxidation is often proposed for this purpose. Catalytic oxidation of methane needs higher temperature than in the case of VOC oxidation catalyst activity and its thermal stability is a crucial problem. Various catalytic systems were proposed for methane oxidation. Metal oxides seem to be more suitable for such applications than noble metals because they combine low volatility and reactivity with relatively high activity in oxidation reactions and low price [5]
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