A new kind of materials La 2O 3-Gd 2O 3-Mo has been produced by powder metallurgy method. The composition and microstructure of the material were studied by XRD and SEM. It shows that no chemical reaction takes place ...A new kind of materials La 2O 3-Gd 2O 3-Mo has been produced by powder metallurgy method. The composition and microstructure of the material were studied by XRD and SEM. It shows that no chemical reaction takes place among La 2O 3, Gd 2O 3, Mo and the rare earth oxides exist along molybdenum grain boundaries and in the pores. The emission property measurement results of this material show that adding rare earth oxide into molybdenum can improve the secondary emission coefficient of the emitter, and the emission property depends on the activating temperature. After La 2O 3-Gd 2O 3-Mo was activated at 1 360 ℃, the maximum secondary emission coefficient can be high to 2.62, which has exceeded that for practical uses(2.0).展开更多
Developing efficient electrocatalysts for hydrogen evolution reaction(HER) is of great importance in contemporary water electrolysis technology. Here, a novel hierarchically sea urchin-like electrocatalyst(Mo_(4)O_(11...Developing efficient electrocatalysts for hydrogen evolution reaction(HER) is of great importance in contemporary water electrolysis technology. Here, a novel hierarchically sea urchin-like electrocatalyst(Mo_(4)O_(11)-MoS_(2)-VO_(2)) is synthesized by hydrothermal deposition and post-annealing strategy. The optimized electrocatalyst behaves as a high active hydrogen evolution electrode in 0.5 mol/L H_(2)SO_(4). This electrode needs overpotential of only 43 m V to achieve 10 m A/cm^(2)with a Tafel slope of 37 m V/dec and maintains its catalytic activity for at least 36 h. Better than most previously reported non-noble metal electrocatalysts anchored on carbon cloth. It is worth mentioning that the hierarchical sea urchin-like structure promotes the redistribution of electrons and provides more catalytic active sites. This strategy shows a way for the construction of inexpensive non-noble metal electrocatalysts in the future.展开更多
This work reports the enhancing effect of a highly cost effective and efficient metal, Fe, incorporation to Co or Ni based Mo/Al2O3 catalysts in the oxidative desulfurization （ODS） of dibenzothiophene （DBT） using ...This work reports the enhancing effect of a highly cost effective and efficient metal, Fe, incorporation to Co or Ni based Mo/Al2O3 catalysts in the oxidative desulfurization （ODS） of dibenzothiophene （DBT） using H2O2 and formic acid as oxidants. The influence of operating parameters i.e. reaction time, catalyst dose, reaction temperature and oxidant amount on oxidation process was investigated. Results revealed that 99% DBT conversion was achieved at 60℃ and 150 min reaction time over Fe-Ni-Mo/Al2O3. Fe tremendously enhanced the ODS activity of Co or Ni based Mo/Al2O3 catalysts following the activity order：Fe-Ni-Mo/Al2O3 〉 Fe-Co-Mo/Al2O3 〉 Ni-Mo/Al2O3 〉 Co-Mo/Al2O3, while H2O2 exhibited higher oxidation activity than formic acid over all catalyst systems. Insight about the surface morphology and textural properties of fresh and spent catalysts were achieved using scanning electron microscopy （SEM）, X-ray diffraction （XRD）, energy dispersive X-ray （EDX） analysis, Atomic Absorption Spectroscopy （AAS） and BET surface area analysis, which helped in the interpretation of experimental data. The present study can be deemed as an effective approach on industrial level for ODS of fuel oils crediting to its high efficiency, low process/catalyst cost, safety and mild operating condition.展开更多
At three critical temperatures which were obtained by thermo-gravimetry-differential thermal analysis–differential scanning calorimetry（TG/DTG/DSC）curves of lanthanum nitrate crystal, the air thermal decomposition ...At three critical temperatures which were obtained by thermo-gravimetry-differential thermal analysis–differential scanning calorimetry（TG/DTG/DSC）curves of lanthanum nitrate crystal, the air thermal decomposition experiments and solid–liquid spray doping simulation procedures of lanthanum nitrate crystal were carried out, and their products were analyzed by X-ray diffraction（XRD）. Meanwhile, the spray doping processing of Mo O2–50 wt% La（NO3）3composite powder was undergone with lanthanum nitrate solution as the dopant,and doped Mo O2powder was analyzed by XRD. The results demonstrate that during the traditional solid–liquid spray doping processing, lanthanum nitrate, in the form of either crystal or aqueous solution, would be converted into La（NO3）3á4H2O by the dehydration reaction, rather than be decomposed to La2O3and NO or NO2. Therefore, it is inferred that the oxynitride gas produced from the process is attributed to the decomposition of residual HNO3in lanthanum nitrate crystal. The source of HNO3is supported by the chemical composition of lanthanum nitrate crystal.展开更多
文摘A new kind of materials La 2O 3-Gd 2O 3-Mo has been produced by powder metallurgy method. The composition and microstructure of the material were studied by XRD and SEM. It shows that no chemical reaction takes place among La 2O 3, Gd 2O 3, Mo and the rare earth oxides exist along molybdenum grain boundaries and in the pores. The emission property measurement results of this material show that adding rare earth oxide into molybdenum can improve the secondary emission coefficient of the emitter, and the emission property depends on the activating temperature. After La 2O 3-Gd 2O 3-Mo was activated at 1 360 ℃, the maximum secondary emission coefficient can be high to 2.62, which has exceeded that for practical uses(2.0).
基金supported by the National Natural Science Foundation of China (No. 51802177)Independent Cultivation Program of Innovation Team of Ji nan City (No. 2019GXRC011)Introduction and Cultivation Plan of Young Innovative Talents in Colleges and Universities of Shandong Province,Shandong Provincial Natural Science Foundation (No. ZR^(2)020ME052)。
文摘Developing efficient electrocatalysts for hydrogen evolution reaction(HER) is of great importance in contemporary water electrolysis technology. Here, a novel hierarchically sea urchin-like electrocatalyst(Mo_(4)O_(11)-MoS_(2)-VO_(2)) is synthesized by hydrothermal deposition and post-annealing strategy. The optimized electrocatalyst behaves as a high active hydrogen evolution electrode in 0.5 mol/L H_(2)SO_(4). This electrode needs overpotential of only 43 m V to achieve 10 m A/cm^(2)with a Tafel slope of 37 m V/dec and maintains its catalytic activity for at least 36 h. Better than most previously reported non-noble metal electrocatalysts anchored on carbon cloth. It is worth mentioning that the hierarchical sea urchin-like structure promotes the redistribution of electrons and provides more catalytic active sites. This strategy shows a way for the construction of inexpensive non-noble metal electrocatalysts in the future.
文摘This work reports the enhancing effect of a highly cost effective and efficient metal, Fe, incorporation to Co or Ni based Mo/Al2O3 catalysts in the oxidative desulfurization （ODS） of dibenzothiophene （DBT） using H2O2 and formic acid as oxidants. The influence of operating parameters i.e. reaction time, catalyst dose, reaction temperature and oxidant amount on oxidation process was investigated. Results revealed that 99% DBT conversion was achieved at 60℃ and 150 min reaction time over Fe-Ni-Mo/Al2O3. Fe tremendously enhanced the ODS activity of Co or Ni based Mo/Al2O3 catalysts following the activity order：Fe-Ni-Mo/Al2O3 〉 Fe-Co-Mo/Al2O3 〉 Ni-Mo/Al2O3 〉 Co-Mo/Al2O3, while H2O2 exhibited higher oxidation activity than formic acid over all catalyst systems. Insight about the surface morphology and textural properties of fresh and spent catalysts were achieved using scanning electron microscopy （SEM）, X-ray diffraction （XRD）, energy dispersive X-ray （EDX） analysis, Atomic Absorption Spectroscopy （AAS） and BET surface area analysis, which helped in the interpretation of experimental data. The present study can be deemed as an effective approach on industrial level for ODS of fuel oils crediting to its high efficiency, low process/catalyst cost, safety and mild operating condition.
基金financially supported by the National Science and Technology Support Program of China (No. 2012BAE06B02)
文摘At three critical temperatures which were obtained by thermo-gravimetry-differential thermal analysis–differential scanning calorimetry（TG/DTG/DSC）curves of lanthanum nitrate crystal, the air thermal decomposition experiments and solid–liquid spray doping simulation procedures of lanthanum nitrate crystal were carried out, and their products were analyzed by X-ray diffraction（XRD）. Meanwhile, the spray doping processing of Mo O2–50 wt% La（NO3）3composite powder was undergone with lanthanum nitrate solution as the dopant,and doped Mo O2powder was analyzed by XRD. The results demonstrate that during the traditional solid–liquid spray doping processing, lanthanum nitrate, in the form of either crystal or aqueous solution, would be converted into La（NO3）3á4H2O by the dehydration reaction, rather than be decomposed to La2O3and NO or NO2. Therefore, it is inferred that the oxynitride gas produced from the process is attributed to the decomposition of residual HNO3in lanthanum nitrate crystal. The source of HNO3is supported by the chemical composition of lanthanum nitrate crystal.
