Axial density profile of the gas-liquid-solid mixture in a slurry bubble column was measured by gamma-ray attenuation technology.Several measures for improving measurement precision were presented based on the discuss...Axial density profile of the gas-liquid-solid mixture in a slurry bubble column was measured by gamma-ray attenuation technology.Several measures for improving measurement precision were presented based on the discussion on attenuation law.It was found that the response frequency and the ray intensity should be as high as possible to improve the measurement precision.The mass absorption coefficient depended on not the object’s thickness but the location where the object was placed between the ray source and the detector.The results showed that the density in the column decreases with the increase of column height,which indicates that the measurement by gamma-ray attenuation is reasonable.展开更多
Most of TiO_(2) particles can be used as a photocatalyst for the selective oxidation of cyclohexane under ultraviolet light illumination.In this paper,Ti^(3+) self-doped TiO_(2) submicron-sized particles(i.e.,Ti^(3+)/...Most of TiO_(2) particles can be used as a photocatalyst for the selective oxidation of cyclohexane under ultraviolet light illumination.In this paper,Ti^(3+) self-doped TiO_(2) submicron-sized particles(i.e.,Ti^(3+)/TiO_(2) SMP)were used as a catalyst for visible-light driven photocatalytic cyclohexane oxidation.The microstructure and properties of the Ti^(3+)/TiO_(2) SMP were characterized by X-ray diffraction(XRD),UVevisible diffuse reflection(UVeVis DRS),scanning electron microscopy(SEM),electron paramagnetic resonance(EPR),solid-state photoluminescence spectroscopy(PLS)and X-ray photoelectron spectroscopy(XPS).The Ti^(3+)/TiO_(2) SMP exhibits good visible-light driven photocatalytic performances for cyclohexane oxidation with cyclohexanone as a dominate product.Effects of solvent,reaction temperature,reaction time and oxygen pressure on the formation of cyclohexanone were investigated.The cyclohexane oxidation over the Ti^(3+)/TiO_(2) SMP photocatalyst using carbon tetrachloride as a solvent under the optimal conditions presents a greater selectivity to cyclohexane(i.e.,95.1%).Based on the controlled experimental results with different radical scavengers,the hole(h^(+))is critical for the activation of cyclohexane.展开更多
基金support from Major State Basic Research Development Program of China(973 Program,2005CB221205)is gratefully acknowledged.
文摘Axial density profile of the gas-liquid-solid mixture in a slurry bubble column was measured by gamma-ray attenuation technology.Several measures for improving measurement precision were presented based on the discussion on attenuation law.It was found that the response frequency and the ray intensity should be as high as possible to improve the measurement precision.The mass absorption coefficient depended on not the object’s thickness but the location where the object was placed between the ray source and the detector.The results showed that the density in the column decreases with the increase of column height,which indicates that the measurement by gamma-ray attenuation is reasonable.
基金the support of this work by National Key Research and Development Plan(Grant No.2016YFC0303704)the National Natural Science Foundation of China(Grant No.21676296).
文摘Most of TiO_(2) particles can be used as a photocatalyst for the selective oxidation of cyclohexane under ultraviolet light illumination.In this paper,Ti^(3+) self-doped TiO_(2) submicron-sized particles(i.e.,Ti^(3+)/TiO_(2) SMP)were used as a catalyst for visible-light driven photocatalytic cyclohexane oxidation.The microstructure and properties of the Ti^(3+)/TiO_(2) SMP were characterized by X-ray diffraction(XRD),UVevisible diffuse reflection(UVeVis DRS),scanning electron microscopy(SEM),electron paramagnetic resonance(EPR),solid-state photoluminescence spectroscopy(PLS)and X-ray photoelectron spectroscopy(XPS).The Ti^(3+)/TiO_(2) SMP exhibits good visible-light driven photocatalytic performances for cyclohexane oxidation with cyclohexanone as a dominate product.Effects of solvent,reaction temperature,reaction time and oxygen pressure on the formation of cyclohexanone were investigated.The cyclohexane oxidation over the Ti^(3+)/TiO_(2) SMP photocatalyst using carbon tetrachloride as a solvent under the optimal conditions presents a greater selectivity to cyclohexane(i.e.,95.1%).Based on the controlled experimental results with different radical scavengers,the hole(h^(+))is critical for the activation of cyclohexane.
