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A layered perovskite-type oxide K2La2Ti3O10 was prepared with high-temperature solid-state reaction, and characterized with X-ray diffraction (XRD) and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). Platinum was loaded onto K2La2Ti3O10 as a co-catalyst with different methods. The dispersion of platinum on K2La2Ti3O10 was determined with HOT method. The photocatalytic activity of Pt/K2La2Ti3O10 was studied. This catalyst showed much higher activity in hydrogen evolution reaction than Ni/K2La2Ti3O10. The effects of different amounts of loaded platinum and several preparation methods were evaluated. The best achieved hydrogen evolution rate was 233.88 μmol·h−1 by Pt(2%)/K2La2Ti3O10. A possible band structure and mechanism were discussed based on the results. [ABSTRACT FROM AUTHOR]

The present work synthesizes La-Cu4FeAICO3 catalyst under microwave irradiation and characterizes its structure using XRD and IR techniques. The results show that the obtained La-Cu4FeAICO3 has a hydrotalcite structure. In the phenol hydroxylation with H2O2 catalyzed by La-Cu4FeAICO3, the effects of reaction time and phenol/H2O2 molar ratio on the phenol hydroxylation, and relationships between the initial hydroxylation rate with concentration of the catalyst, phenol, H2O2 and reaction temperature are also investigated in details. It is shown the phenol conversion can reach 50.09% (mol percent) in the phenol hydroxylation catalyzed by La-Cu4FeAICO3, under the reaction conditions of the molar ratio of phenol/H2O21/2, the amount ratio of phenol/catalyst 20, reaction temperature 343 K, reaction time 120 min, 10 ml_ distilled water as solvent. Moreover, a kinetic equation of v = k[La-Cu4FeAlCO3][C6H5OH][H2O2]. and the activation energy of E a=58.37 kJ/mol are obtained according to the kinetic studies. Due to the fact that the HO-Cu+-OH species are detected in La-Cu4FeAICO3/H2O2 system by XPS, the new mechanism about the generation of hydroxyl free radicals in the phenol hydroxylation is proposed, which is supposed that HO-Cu+-OH species are transition state in this reaction. [ABSTRACT FROM AUTHOR]

The coating process of a nano-scale SiO2 film on the nanocrystalline Mg-Al layered double hydroxides via a sol-gel process was investigated. The uniform and dense SiO2film with a thickness of about 5 nm on the nano-LDHs particles was characterized by the solubility test in the dilute HNO3 or HCl acid, TEM and FT-IR, XRD, TG and DSC. The chemical shifts of binding energies of Al 2p, Mg 2p, Si 2s and O 1s on the coated particles indicate that the coating of the SiO2 nano-film on the surface of the nano-LDHs proceeds through the formation of Mg-O-Si and Al-O-Si bonds. The thermal analysis shows that both the SiO2-coated nano-LDHs and the nano-LDHs have a similar mass loss process, in which there are three obvious stages of mass loss in the temperature range of 40-700°C. Furthermore, the more the coated amount of SiO2 on the surface of the nano-LDHs is, the less the mass loss of the samples is at 700°C.The nano LDHs have two obvious endothermic peaks at 244.67°C and 430.13°C, whose corresponding heat absorption capacities are 412.28 J/g and 336.30 J/g, respectively. In contrast, the coated nano-LDHs have only one endothermic peak at 243.60°C with a heat absorption capacity of 221.25 J/g. [ABSTRACT FROM AUTHOR]

In the reaction of catalytic oxidation of CH4, CO2 with O2 to synthesis gas, carbon-deposition is an important factor for deactivation. By adding different oxides to Ni/Al2O3 catalyst, its resistance to carbon-deposition was improved. The experimental results indicate that the order of resistance to carbon-deposition is as follows: Ni/CaO-Al2O3>Ni/MgO-Al2O3>Ni/ TiO2-Al2O3 > Ni/CeO2-Al2O3>Ni/La2O3-Al2O3>Ni/Y2O3-Al2O3>Ni/Fe2O3-Al2O3>Ni/Al2O3. The catalysts were characterized by CO2-TPD, O2-TPD and XPS methods. Here the relation between the order of resistance to carbon-deposition and performance of catalyst is discussed. [ABSTRACT FROM AUTHOR]

Pt/TiO2 nano-film was prepared by Pt deposition on TiO2 nano-film which synthesized by sol–gel method. The characterization of TiO2 nano-film showed 20 nm of average crystal size and about 77 nm of the thickness determined by XRD and SEM, respectively. Photocatalytic decomposition of gaseous methanol on Pt/TiO2 nano-film was carried out in a continuous-flow reactor. The effect of varied factors on photocatalysis process, such as space velocity, reaction time and methanol concentration, was investigated. And photocatalytic activities of Pt/TiO2 nano-film were also compared with that of TiO2 nano-film. The mechanism was deduced according to the detected products. [Copyright &y& Elsevier]