The catalytic activity and surface characterization of Ln(2)B(2)O(7) (Ln = Sm, Eu, Gd and Tb; B = Ti or Zr) with pyrochlore structure as novel CH4 combustion catalyst

Abstract

Ln(2)B(2)O(7) (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 Ln(2)B(2)O(7) was identified by XRD and their surface area was about 4 m(2)/g after calcinations at 1200degreesC. Catalytic activity of methane combustion was observed for Ln(2)Zr(2)O(7) series and the best catalyst was Sm2Zr2O7. Its relative reaction rate per unit surface area at 600degreesC was 2 cm(3)/m(2) 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 Ln(2)Zr(2)O(7) compared to that of Ln(2)Ti(2)O(7), gave the catalytic activity of methane combustion. (C) 2003 Elsevier B.V. All rights reserved.