Effects of carrier and Mn loading on supported manganese oxide catalysts for catalytic combustion of methane

Supported manganese oxide catalysts were prepared by incipient wetness impregnation method for methane catalytic combustion, and effects of the support （Al2O3, SiO2 and TiO2） and Mn loading were investigated. These catalysts were characterized with N2 adsorption, X-ray diffraction, X-ray photoelectron spectroscopy and temperature-programmed reduction techniques. Methane conversion varied in a large range depending on supports or Mn loading. Al2O3 supported 15% Mn catalyst exhibited better activity toward methane catalytic oxidation. The manganese state and oxygen species played an important role in the catalytic performance,

Effect of Fe_2O_3 Loading Amount on Catalytic Properties of Monolithic Fe_2O_3/Ce_(0.67)Zr_(0.33)O_2-Al_2O_3 Catalyst for Methane Combustion

Ce0.67Zr0.33O2-Al2O3 solid solution was prepared by the co-precipitation method. Fe2O3-based catalysts supported on the solid solution were obtained by the impregnation method. The article revealed that the optimal loading amount of Fe2O3 on Ce0.67Zr0.33 O2-Al2O3 in our experimental condition for catalytic combustion of methane was 8% （ mass fraction）. The prepared catalysts were characterized by BET, TPR, XRD analyses, and their catalytic activity was investigated after being calcined at 873 K and after being aged in water gas at 1273 K. When the loading amount of Fe203 was 8% （ mass fraction）, the catalyst held the highest activity, and the best temperature speciality and thermal stability. The complete-conversion temperature of methane for fresh and aged sample was 788 and 838 K, respectively. The range between the light-off temperature and the complete-conversion temperature was only 15 K. The characterization results of XRD indicated that Fe2O3 was well dispersed on the Ce0.67Zr0.33O2-Al2O3 matrix. The results of BET and TPR were in good harmony with the catalytic activity results.

Surface density of synthetically tuned spinel oxides of Co^(3+) and Ni^(3+) with enhanced catalytic activity for methane oxidation

Spinel oxides containing Co and Ni are a promising substitute as a noble metal catalyst for methane combustion.Achieving a complete oxidation of methane under 400°C remains challenging,andhydrothermal 60 h NiClittle impact on activity,especially at high space velocities due to the long hydrothermal time with less absorbed oxygen species and crystal defects.Overall,these results help clarify methane activa-tion mechanisms and aid the development of more efficient low-cost catalysts.

Surface structure and catalytic performance of Sr-doped La_2NiAlO_6 double perovskite catalysts for methane combustion

A species of novel St-doped rare earth double perovskite catalysts （La2 xSrxNiA106, x=0, 0.1） were prepared by the sol-gel method using citric acid as a complexing agent and calcined at 1100 ℃ for 3 h, then investigated for methane catalytic combustion. The as-prepared catalysts were characterized by X-ray diffraction patterns （XRD）, H2-temperature-programmed reduction （H2-TPR）, specific surface area （BET）, magnetic property measurement technology （M-H）, scanning electron microscopy （SEM）, and X-ray photoelectron spectroscopy （XPS）. Experimental results showed that Lal.9Sr0.1NiA106 catalyst exhibited significantly improved catalytic activity （T10=378.7 ℃, T90=602.9 ℃） compared with that of La2NiAIO6, whose T10 decreased by 74.4 ℃ and T90 decreased by 66.8 ℃, respectively. The excellent catalytic activity of Lal.9Sr0.tNiA106 caused by Sr-doping could be explained by the larger number of adsorption oxygen on the catalyst surface, which could be proven by XPS analysis.

Nanostructured perovskite oxides as promising substitutes of noble metals catalysts for catalytic combustion of methane

Heterogeneous catalytic combustion provides a feasible technique for high efficient methane utilization.Perovskites ABO_3-type materials have received renewed attention as a potential alternative for noble metals supported catalysts in catalytic methane combustion due to excellent hydrothermal stability and sulfur resistance. Recently, the emergence of nanostructured perovskite oxides（such as threedimensional ordered nanostructure, nano-array structure） with outstanding catalytic activity has further driven methane catalytic combustion research into spotlight. In this review, we summarize the recent development of nanostructured perovskite oxide catalysts for methane combustion, and shed some light on the rational design of high efficient nanostructured perovskite catalysts via lattice oxygen activation,lattice oxygen mobility and materials morphology engineering. The emergent issues needed to be addressed on perovskite catalysts were also proposed.