Synthesis of La‐hexaaluminate catalyst for methane combustion by a reverse SDS microemulsion

La‐hexaaluminate catalyst for methane catalytic combustion was synthesized by a reverse microemulsion. Pseudo‐ternary phase diagrams of a quaternary microemulsion system of sodium dodecyl sulfate (SDS), n ‐pentanol, n ‐octane, and water (or Al(NO 3 ) 3 solution) were presented. The effects of alcohol chain length, cosurfactant‐to‐surfactant ratio, and salt concentration on the formation and stability of the microemulsion system were studied. The phenomenon that the conductivity changed with water supported the phase behavior of the microemulsion system. La(Mn x /Fe x )Al 12− x O 19− δ catalysts, applied in methane combustion and with high‐temperature stability, were synthesized within the stable areas of the phase diagram of the microemulsion system, when SDS was chosen as surfactant, n ‐pentanol as cosurfactant, and n ‐octane as oil phase. The physical properties and structure of the catalysts were characterized by BET method, transmission electron microscope (TEM), and X‐ray diffraction (XRD). A micro‐fixed‐bed reactor was used to measure the catalytic activity of hexaaluminates in methane combustion. The results show that the reverse microemulsions can be used to produce discrete La‐hexaaluminate nanoparticles that display excellent methane combustion activity owing to their high surface area and high thermal stability.