Mo/ZSM 5 catalysts with different Mo content were prepared by impregnation method. The effect of Mo content on the property of Mo/ZSM 5 catalysts and their performance for selective catalytic reduction(SCR) of NO with...Mo/ZSM 5 catalysts with different Mo content were prepared by impregnation method. The effect of Mo content on the property of Mo/ZSM 5 catalysts and their performance for selective catalytic reduction(SCR) of NO with ammonia was investigated by XRD, ICP, XPS and NO TPD respectively. The results showed that the catalytic activity of Mo/ZSM 5 for SCR of NO is strongly influenced by the Mo loading in HZSM 5 zeolites. The NOx conversion reached the highest value of 64.2% at 375℃ when Mo content is about 10 9%, and the temperatures at which the maximum of NOx conversion obtained were declined with the increase of Mo content. From XRD results, it can be seen that it exhibits the distinct interaction between Mo and HZSM 5 when Mo content is about 10 9%. This may result in a suitable phase structure in Mo/ZSM 5 catalyst, which is advantageous for NO reduction. XPS and NO TPD results also showed that the catalytic activity of Mo/ZSM 5 may be related to the Mo percent on the surface.展开更多
The effect of Mo on nano-scaled particles,prior austenite grains and impact toughness of coarse-grained heat-affected zone(CGHAZ)in offshore engineering steels with Ca deoxidation was studied.The heat-affected zone(HA...The effect of Mo on nano-scaled particles,prior austenite grains and impact toughness of coarse-grained heat-affected zone(CGHAZ)in offshore engineering steels with Ca deoxidation was studied.The heat-affected zone(HAZ)toughness of Mo16 steel is obviously higher than that of Mo8 steel at all the heat inputs of 50,100,150 and 200 kJ/cm,with HAZ toughness of both steels decreased with increasing the welding heat input.When the Mo content is increased from 0.08 to 0.16%,the size of nano-scaled particles in HAZ is decreased from 18 to 15 nm,and their number density is increased from 0.7 to 0.9μm^(−2).Thus,the Zener pinning force is increased,and the prior austenite grain size(PAGS)is decreased,leading to the improved HAZ toughness.Microstructural characterizations show that the nano-scaled particles in both steels are Ti(C,N)with the solute elements of Nb and Mo.The calculated critical particle size of TiN is 10.2 and 8.4 nm in Mo8 and Mo16 steels at 1350℃,and the particles larger than the critical size are stable during the welding process.From the Zener pinning force calculation,Ti(C,N)particles play the more important role in the pinning effect on the prior austenite grain growth.Based on the regression analysis by the MATLAB results,the predicted values of PAGS at different heat inputs are well fitted with the experimental data.展开更多
The effects of Mo on the microstructure and mechanical properties of Ti（C,N）-based cermets with low Ni have been studied systematically. Different contents of Mo （4-12 wt.%） were added into Tl（C,N）-based cermets...The effects of Mo on the microstructure and mechanical properties of Ti（C,N）-based cermets with low Ni have been studied systematically. Different contents of Mo （4-12 wt.%） were added into Tl（C,N）-based cermets. Specimens were fabricated by conventional powder metallurgy and vacuum sintered at temperatures of 1440, 1450, and 1460℃ individually. The microstructure and fracture morphology were investigated by scanning electron microscope, and the mechanical properties such as transverse strength and hardness were measured. The results show that the microstructure is uniform and the thickness of rim phase is moderate when the content of Mo is 8 wt.%; the mechanical properties of the specimens sintered at 1450℃ are better than those sintered at 1440 and 1460℃. The integrated properties of transverse strength and hardness are the best when the content of Mo is 8 wt.% and the sintering temperature is 1450℃.展开更多
文摘Mo/ZSM 5 catalysts with different Mo content were prepared by impregnation method. The effect of Mo content on the property of Mo/ZSM 5 catalysts and their performance for selective catalytic reduction(SCR) of NO with ammonia was investigated by XRD, ICP, XPS and NO TPD respectively. The results showed that the catalytic activity of Mo/ZSM 5 for SCR of NO is strongly influenced by the Mo loading in HZSM 5 zeolites. The NOx conversion reached the highest value of 64.2% at 375℃ when Mo content is about 10 9%, and the temperatures at which the maximum of NOx conversion obtained were declined with the increase of Mo content. From XRD results, it can be seen that it exhibits the distinct interaction between Mo and HZSM 5 when Mo content is about 10 9%. This may result in a suitable phase structure in Mo/ZSM 5 catalyst, which is advantageous for NO reduction. XPS and NO TPD results also showed that the catalytic activity of Mo/ZSM 5 may be related to the Mo percent on the surface.
基金supported by the National Natural Science Foundation of China(U1960202).
文摘The effect of Mo on nano-scaled particles,prior austenite grains and impact toughness of coarse-grained heat-affected zone(CGHAZ)in offshore engineering steels with Ca deoxidation was studied.The heat-affected zone(HAZ)toughness of Mo16 steel is obviously higher than that of Mo8 steel at all the heat inputs of 50,100,150 and 200 kJ/cm,with HAZ toughness of both steels decreased with increasing the welding heat input.When the Mo content is increased from 0.08 to 0.16%,the size of nano-scaled particles in HAZ is decreased from 18 to 15 nm,and their number density is increased from 0.7 to 0.9μm^(−2).Thus,the Zener pinning force is increased,and the prior austenite grain size(PAGS)is decreased,leading to the improved HAZ toughness.Microstructural characterizations show that the nano-scaled particles in both steels are Ti(C,N)with the solute elements of Nb and Mo.The calculated critical particle size of TiN is 10.2 and 8.4 nm in Mo8 and Mo16 steels at 1350℃,and the particles larger than the critical size are stable during the welding process.From the Zener pinning force calculation,Ti(C,N)particles play the more important role in the pinning effect on the prior austenite grain growth.Based on the regression analysis by the MATLAB results,the predicted values of PAGS at different heat inputs are well fitted with the experimental data.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50074017) the Natural Science Foundation of Hubei Province, China (No. 2003ABA092).
文摘The effects of Mo on the microstructure and mechanical properties of Ti（C,N）-based cermets with low Ni have been studied systematically. Different contents of Mo （4-12 wt.%） were added into Tl（C,N）-based cermets. Specimens were fabricated by conventional powder metallurgy and vacuum sintered at temperatures of 1440, 1450, and 1460℃ individually. The microstructure and fracture morphology were investigated by scanning electron microscope, and the mechanical properties such as transverse strength and hardness were measured. The results show that the microstructure is uniform and the thickness of rim phase is moderate when the content of Mo is 8 wt.%; the mechanical properties of the specimens sintered at 1450℃ are better than those sintered at 1440 and 1460℃. The integrated properties of transverse strength and hardness are the best when the content of Mo is 8 wt.% and the sintering temperature is 1450℃.
