Structural Features of Mixed La–Al Oxides and Their Catalytic Properties in the Oxidation of Methane

The authors study the effect the means of synthesis and preliminary treatment have on the structural features of samples of mixed lanthanum and aluminum oxides with constant atomic ratio La : Al = 1 : 1, along with their catalytic properties during the oxidation of methane. Using organic substances (filter paper or starch) as structuring agents in synthesizing the samples and subjecting them to an aqueous or aqueous–ammonia fluid environment with high-temperature treatment at different stages allows the phase composition, structural characteristics, and morphology of the resulting systems to be varied. It is shown there is no direct correlation between the structural characteristics, morphology, and catalytic properties of La–Al oxides. It is suggested that the efficiency of systems during the oxidation of methane is associated exclusively with the type and concentration of point defects, primarily the state of surface oxygen anions. At the same time, the phase composition and morphology influence the number and type of active centers, and their accessibility to reagents.