Nano-sized γ-alumina （γ-Al2O3） was first prepared by a precipitation method. Then, active component of cobalt and a series of alkaline- earth metal promoters or nickel （Ni） with different contents were loaded on...Nano-sized γ-alumina （γ-Al2O3） was first prepared by a precipitation method. Then, active component of cobalt and a series of alkaline- earth metal promoters or nickel （Ni） with different contents were loaded on the γ-Al2O3 support. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction （XRD） and thermogravimetry analysis （TGA）. The activity and selectivity of the catalysts in catalytic partial oxidation （CPO） of methane have been compared with Co/γ-Al2O3, and it is found that the catalytic activity, selectivity, and stability are enhanced by the addition of alkaline-earth metals and nickel. The optimal loadings of strontium （Sr） and Ni were 6 and 4 wt%, respectively. This finding will be helpful in designing the trimetallic Co-Ni-Sr/γ-Al2O3 catalysts with high performance in CPO of methane展开更多
The Ru/Al2O3 catalysts modified with metal oxide （K20 and La2O3） were prepared v/a incipient wetness impregnation method from RuCl3.nH2O mixed with nitrate loading on Al2O3 support. The activity of catalysts was eva...The Ru/Al2O3 catalysts modified with metal oxide （K20 and La2O3） were prepared v/a incipient wetness impregnation method from RuCl3.nH2O mixed with nitrate loading on Al2O3 support. The activity of catalysts was evaluated under simulative conditions for the preferential oxidation of CO （CO-PROX） from the hydrogen-rich gas streams produced by reforming gas, and the performances of catalysts were investigated by XRD and TPR. The results showed that the activity temperature of the modified catalysts Ru-K20/Al2O3 and Ru-La2O3/Al2O3 were lowered approximately 30℃ compared with pure Ru/Al2O3, and the activity temperature range was widened. The conversion of CO on Ru-K20/Al2O3 and Ru-La2O3/Al2O3 was above 99% at 140-160℃, suitable to remove CO in a hydrogen-rich gas and the selectivity of Ru-La2O3/Al2O3 was higher than that of Ru-K2O/Al2O3in the active temperature range. Slight methanation reaction was detected at 220℃ and above.展开更多
This study investigates the temperature inversion phenomenon in the Zhujiang(Pearl) River Estuary(ZRE) using hydrological data collected in a summer cruise during July 6–17, 2015. The results suggest that temperature...This study investigates the temperature inversion phenomenon in the Zhujiang(Pearl) River Estuary(ZRE) using hydrological data collected in a summer cruise during July 6–17, 2015. The results suggest that temperature inversion occurred primarily near the salinity front, with an average temperature difference(ΔT) of 0.42°C between the inversion layer and the underlying water. The inversion layer was approximately 4 m thick on average, with an upper boundary at a depth of 1–6 m and a lower boundary at a depth of 3–10 m. Different mechanisms and dynamic processes were responsible for temperature inversion in different parts of the study area.(1) At the salinity front in the west of the ZRE, the measurements collected by CTD(conductivity,temperature, and depth) showed that the low-salinity water mass on the inner side of the front was approximately2°C cooler than the high-salinity water mass on the outer side. Temperature inversion occurred when the cooler low-salinity water overlapped the warmer high-salinity water near the front due to the driving force of the background flow.(2) Inversion layers occurred at the mouth of the Taiping waterway as a result of varying horizontal flow between two different water masses under the effects of tides and runoff.(3) To the southwest of Hong Kong, temperature inversion occurred due to the interaction of upwelling and the salinity front.展开更多
In the process of extracting ion-absorbed rare earth ore(IREO),the production of radioactive waste is a major environmental concern.To address this issue,MoS_(2) was used to modify ion-absorbed rare earth tailings(RET...In the process of extracting ion-absorbed rare earth ore(IREO),the production of radioactive waste is a major environmental concern.To address this issue,MoS_(2) was used to modify ion-absorbed rare earth tailings(RET) to synthesize a novel MoS_(2)@RET composite material for the effective handling of radioactive waste generated in IREO separation industry.The composite material was thoroughly characterized using various analytical techniques,including X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),thermogravimetry(TG),Fourier-transform infrared(FTIR),scanning electron microscopy(SEM),Brunaue r-Emmett-Teller(BET) and energy dispersive spectroscopy(EDS).By optimizing the operating parameters,the optimal experimental conditions were determined to be pH=3,contact time=60 min,liquid-solid ratio=6 g/L,and initial concentration=150 mg/L.The adsorption data fitted well with the pseudo second-order rate model.The thermodynamic parameters concerning the adsorption of Th(Ⅳ) were analyzed and computed.Langmuir isotherm model is a more fitting choice for the adsorption process compared to the Freundlich isotherm model.MoS_(2)@RET was used in the acid leachate of IREO waste residue,achieving the separation of Th and rare earth successfully.The mechanism of Th(Ⅳ) adsorption by MoS_(2)@RET was investigated,revealing that the adsorption process involves electrostatic interactions,chemical bonding,and redox reactions.The above research results indicate that MoS_(2)@RET composite materials have application potential in the sustainable treatment of IREO radioactive waste.展开更多
基金supported by the Open Foundation of State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University (No.200906)the Natural Science Foundation of Jiangxi Province (No.2010GZH0048)+1 种基金the National Natural Science Foundation of China (No. 21067004)the Young Science Foundation of Jiangxi Province Education Office (No. GJJ10150)
文摘Nano-sized γ-alumina （γ-Al2O3） was first prepared by a precipitation method. Then, active component of cobalt and a series of alkaline- earth metal promoters or nickel （Ni） with different contents were loaded on the γ-Al2O3 support. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction （XRD） and thermogravimetry analysis （TGA）. The activity and selectivity of the catalysts in catalytic partial oxidation （CPO） of methane have been compared with Co/γ-Al2O3, and it is found that the catalytic activity, selectivity, and stability are enhanced by the addition of alkaline-earth metals and nickel. The optimal loadings of strontium （Sr） and Ni were 6 and 4 wt%, respectively. This finding will be helpful in designing the trimetallic Co-Ni-Sr/γ-Al2O3 catalysts with high performance in CPO of methane
基金the National Natural Science Foundation of China(20576023)the Guangdong Province Natural Science Foundation (06025660)
文摘The Ru/Al2O3 catalysts modified with metal oxide （K20 and La2O3） were prepared v/a incipient wetness impregnation method from RuCl3.nH2O mixed with nitrate loading on Al2O3 support. The activity of catalysts was evaluated under simulative conditions for the preferential oxidation of CO （CO-PROX） from the hydrogen-rich gas streams produced by reforming gas, and the performances of catalysts were investigated by XRD and TPR. The results showed that the activity temperature of the modified catalysts Ru-K20/Al2O3 and Ru-La2O3/Al2O3 were lowered approximately 30℃ compared with pure Ru/Al2O3, and the activity temperature range was widened. The conversion of CO on Ru-K20/Al2O3 and Ru-La2O3/Al2O3 was above 99% at 140-160℃, suitable to remove CO in a hydrogen-rich gas and the selectivity of Ru-La2O3/Al2O3 was higher than that of Ru-K2O/Al2O3in the active temperature range. Slight methanation reaction was detected at 220℃ and above.
基金The National Basic Research Program of China under contract No.2015CB954004the National Natural Science Foundation of China under contract Nos 41776027,41606009 and U1405233
文摘This study investigates the temperature inversion phenomenon in the Zhujiang(Pearl) River Estuary(ZRE) using hydrological data collected in a summer cruise during July 6–17, 2015. The results suggest that temperature inversion occurred primarily near the salinity front, with an average temperature difference(ΔT) of 0.42°C between the inversion layer and the underlying water. The inversion layer was approximately 4 m thick on average, with an upper boundary at a depth of 1–6 m and a lower boundary at a depth of 3–10 m. Different mechanisms and dynamic processes were responsible for temperature inversion in different parts of the study area.(1) At the salinity front in the west of the ZRE, the measurements collected by CTD(conductivity,temperature, and depth) showed that the low-salinity water mass on the inner side of the front was approximately2°C cooler than the high-salinity water mass on the outer side. Temperature inversion occurred when the cooler low-salinity water overlapped the warmer high-salinity water near the front due to the driving force of the background flow.(2) Inversion layers occurred at the mouth of the Taiping waterway as a result of varying horizontal flow between two different water masses under the effects of tides and runoff.(3) To the southwest of Hong Kong, temperature inversion occurred due to the interaction of upwelling and the salinity front.
基金Project supported by the National Key R&D Program of China (2017YFE0106900)Key R&D Program of Jiangxi Province(20203BBG72W013)Fujian Program for High-Level Entrepreneurial and Innovative Talents Introduction。
文摘In the process of extracting ion-absorbed rare earth ore(IREO),the production of radioactive waste is a major environmental concern.To address this issue,MoS_(2) was used to modify ion-absorbed rare earth tailings(RET) to synthesize a novel MoS_(2)@RET composite material for the effective handling of radioactive waste generated in IREO separation industry.The composite material was thoroughly characterized using various analytical techniques,including X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),thermogravimetry(TG),Fourier-transform infrared(FTIR),scanning electron microscopy(SEM),Brunaue r-Emmett-Teller(BET) and energy dispersive spectroscopy(EDS).By optimizing the operating parameters,the optimal experimental conditions were determined to be pH=3,contact time=60 min,liquid-solid ratio=6 g/L,and initial concentration=150 mg/L.The adsorption data fitted well with the pseudo second-order rate model.The thermodynamic parameters concerning the adsorption of Th(Ⅳ) were analyzed and computed.Langmuir isotherm model is a more fitting choice for the adsorption process compared to the Freundlich isotherm model.MoS_(2)@RET was used in the acid leachate of IREO waste residue,achieving the separation of Th and rare earth successfully.The mechanism of Th(Ⅳ) adsorption by MoS_(2)@RET was investigated,revealing that the adsorption process involves electrostatic interactions,chemical bonding,and redox reactions.The above research results indicate that MoS_(2)@RET composite materials have application potential in the sustainable treatment of IREO radioactive waste.
