The catalytic activity and surface characterization of Ln2B2O7 (Ln=Sm, Eu, Gd and Tb; B=Ti or Zr) with pyrochlore structure as novel CH4 combustion catalyst

Ln₂B₂O₇ (Ln=Sm, Eu, Gd and Tb; B=Zr or Ti) with pyrochlore structure was prepared by sol–gel method for the high-temperature catalytic combustion. The crystal structure of Ln₂B₂O₇ was identified by XRD and their surface area was about 4 m²/g after calcinations at 1200 °C. Catalytic activity of methane combustion was observed for Ln₂Zr₂O₇ series and the best catalyst was Sm₂Zr₂O₇. Its relative reaction rate per unit surface area at 600 °C was 2 cm³/m² min, which was twice higher than that of Mn-substituted Sr hexaaluminate. From surface analysis by XPS, the low binding energy of each Ln element of Ln₂Zr₂O₇ compared to that of Ln₂Ti₂O₇, gave the catalytic activity of methane combustion.