title: Mesoporous chromia with ordered three-dimensional structures for the complete oxidation of toluene and ethyl acetate.
abstract: Mesoporous chromia with ordered three-dimensional (3D) hexagonal polycrystalline structures were fabricated at 130, 180, 240, 280, and 350 degrees C in an autoclave through a novel solvent-free route using KIT-6 as the hard template. The as-obtained materials were characterized (by means of X-ray diffraction, transmission electron microscopy, N(2) adsorption-desorption, temperature-programmed reduction, and X-ray photoelectron spectroscopy techniques) and tested as a catalyst for the complete oxidation of toluene and ethyl acetate. We found that with a high surface area of 106 m(2)/g and being multivalent (Cr(3+), Cr(5+), and Cr(6+)), the chromia (meso-Cr-240) fabricated at 240 degrees C is the best among the five in catalytic performance. According to the results of the temperature-programmed reduction and X-ray photoelectron spectroscopy investigations, it is apparent that the coexistence of multiple chromium species promotes the low-temperature reducibility of chromia. The excellent performance of meso-Cr-240 is because of good 3D mesoporosity and low-temperature reducibility as well as the high surface area of the chromia. The combustion follows a first-order reaction with respect to toluene or ethyl acetate in the presence of excess oxygen, and the corresponding average activation energy is 79.8 and 51.9 kJ/mol, respectively, over the best-performing catalyst.
authors.affiliation: Laboratory of Catalysis Chemistry and Nanoscience, Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China.
authors.forename: Yunsheng
authors.initials: Y
authors.lastname: Xia
authors.forename: Hongxing
authors.initials: H
authors.lastname: Dai
authors.forename: Haiyan
authors.initials: H
authors.lastname: Jiang
authors.forename: Jiguang
authors.initials: J
authors.lastname: Deng
authors.forename: Hong
authors.initials: H
authors.lastname: He
authors.forename: Chak Tong
authors.initials: CT
authors.lastname: Au
mesh_terms: D000085:Acetates / Q000737:chemistry*; D002384:Catalysis; D002857:Chromium / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006859:Hydrogen / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D016062:Porosity; D013499:Surface Properties; D014050:Toluene / Q000737:chemistry*
chemical_list: D000085:Acetates; D002857:Chromium; D014050:Toluene; C007650:ethyl acetate; D006859:Hydrogen; D010100:Oxygen