Catalysis Today, Vol.245, 28-36, 2015
Three-dimensionally ordered macroporous Pr6O11 and Tb4O7 with mesoporous walls: Preparation, characterization, and catalytic activity for CO oxidation
Three-dimensionally ordered macroporous (3DOM) praseodymium oxide and terbium oxide with mesoporous walls and cubic crystal structures have been successfully fabricated with polymethyl methacrylate (PMMA) as hard template and F127, sucrose, and L-lysine as surfactant. Physicochemical properties of the materials were characterized by means of numerous techniques. It is shown that the Pr6O11 and Tb4O7 samples displayed a 3DOM architecture with polycrystalline wormhole-like mesoporous walls. The nature of surfactant and solvent and calcination condition had important effects on the pore structure and surface area of the final product. The introduction of surfactant and the partial carbonization of sucrose or L-lysine favored the enhancement in surface area of the 3DOM-structured materials, with the 3DOM Pr6O11 and Tb4O7 samples derived with F127 showing the highest surface areas of 32.0 and 25.2 m(2)/g, respectively. The low-temperature reducibility of the Pr6O11 and Tb4O7 samples decreased according to the sequences of Pr6O11-F127 > Pr6O11-Sucrose > Pr6O11-Lysine and Tb4O7-F127 > Tb4O7-Sucrose > Tb4O7-Lysine, coinciding with the order in surface oxygen vacancy density. The improved physicochemical properties associated with the generation of 3DOM skeletons and wormhole-like mesoporous walls rendered the Pr6O11-F127 and Tb4O7-F127 samples to perform the best in the oxidation of CO. (C) 2014 Elsevier B.V. All rights reserved.