Key words: mixed oxides, synthesis, water fluid, lanthanum, group IIA elements, aluminates, catalytic oxidation, oxidative coupling of methane
The formation of mixed oxides in La2O3/MO—Al2O3 systems (M is a group IIA element: Mg, Ca, Sr or Ba) during high-temperature treatment and treatment with water fluids (WF) has been studied. It has been shown that high-temperature treatment of the corresponding group IIA metal aluminate with supported lanthanum nitrate leads to the formation of LaAlO3 only in the case of the Mg-containing system. In other cases, there is no transformation of the initial aluminates, and lanthanum oxide is formed. When treating La/M—Al ternary systems with WF, the formation of LaAlO3 is observed in all cases. Also, in all samples, except for Ba-containing, phases of free metal oxides of group IIA elements appear. The increase in activity and selectivity in the OCM process in La/M—Al ternary oxide systems compared to double M—Al systems is associated with the presence of a separate La2O3 oxide phase.
doi:10.34984/SCFTP.2024.19.3.005