A series of layered mixed oxides La 4BaCu 5-x Mn x O 13+λ ( x =0—5) was prepared, characterized and used as catalysts for NO+CO reaction. It was found that all the samples were single phase having a structure with f...A series of layered mixed oxides La 4BaCu 5-x Mn x O 13+λ ( x =0—5) was prepared, characterized and used as catalysts for NO+CO reaction. It was found that all the samples were single phase having a structure with five layered perovskite. La 4BaCu 2Mn 3O 13+λ showed the highest activity in the title reaction, this could be attributed to the synergetic effect between Cu and Mn. The results of TPR, TPD and excess oxygen investigations confirmed that the Cu ion would be the active center. The displacement of the Cu ion by Mn caused the Cu ion to be more easily reducible and more content of excess oxygen, and it was beneficial to the activity of the catalyst. The reaction mechanism was also proposed.展开更多
The crystal structure of 5-{[(4′-heptoxy-biphenylyl-4-yl)oxy]carbonyl}-1-pentyne({A3E′O7}) was investigated by wide angle X-ray diffraction(WAXD), transmission electron microscope(TEM) and atom force microscope(AFM)...The crystal structure of 5-{[(4′-heptoxy-biphenylyl-4-yl)oxy]carbonyl}-1-pentyne({A3E′O7}) was investigated by wide angle X-ray diffraction(WAXD), transmission electron microscope(TEM) and atom force microscope(AFM). The structures of A3E′O7 solution-crystal and melt-crystal are the same. The crystals belong to the monoclinic P112/m space group, the cell parameters are {a0.589 nm}, b0^771 nm, c4.75 nm, αβ90° and γ93.8°, the calculated cell density is {1.167 g/cm+3}.展开更多
Based on monolayer dispersion theory,Co_(3)O_(4)/ZSM-5 catalysts with different loadings have been prepared for selective catalytic reduction of nitrogen oxides by ammonia.Co_(3)O_(4)can spontaneously disperse on HZSM...Based on monolayer dispersion theory,Co_(3)O_(4)/ZSM-5 catalysts with different loadings have been prepared for selective catalytic reduction of nitrogen oxides by ammonia.Co_(3)O_(4)can spontaneously disperse on HZSM-5 support with a monolayer dispersion threshold of 0.061 mmol 100 m^(-2),equaling to a weight percentage around 4.5%.It has been revealed that the quantities of surface active oxygen(O_(2)^(-))and acid sites are crucial for the reaction,which can adsorb and activate NO_(x)and NH_(3)reactants effectively.Below the monolayer dispersion threshold,Co_(3)O_(4)is finely dispersed as sub-monolayers or monolayers and in an amorphous state,which is favorable to generate the two kinds of active sites,hence promoting the performance of ammonia selective catalytic reduction of nitrogen oxide.However,the formation of crystalline Co_(3)O_(4)above the capacity is harmful to the reaction performance.4%Co_(3)O_(4)/ZSM-5,the catalyst close to the monolayer dispersion capacity,possesses the most abundant active O_(2)^(-)species and acidic sites,thereby demonstrating the best reaction performance in all the samples.It is proposed the optimal Co_(3)O_(4)/ZSM-5 catalyst can be prepared by loading the capacity amount of Co_(3)O_(4)onto HZSM-5 support.展开更多
The conditions of heating and cooling of piercing mandrels made of 4X5MFS steel of a three-roll screw mill 30-80 in the production of a closed cavity of steel vessels of small volume are determined.It is established t...The conditions of heating and cooling of piercing mandrels made of 4X5MFS steel of a three-roll screw mill 30-80 in the production of a closed cavity of steel vessels of small volume are determined.It is established that multiple cycles of heating up to 600℃ and cooling with water up to 80℃ for about 7 seconds/1 cycle lead to the formation of ridges,shells and cracks on the surface and in the volume of the tool.The loss of structural strength of the material leads to the breakdown of the mandrel during the stitching process.The technique and equipment of magnetic powder control have been developed to establish the dynamics of the growth of internal and external defects of mandrels.An equation is obtained that allows determining the increase in the number of defects in the sewing tool of a screw rolling mill.The technology of non-destructive testing made it possible to develop a rational plan for replacing the sewing mandrels,which allows for predicting the appearance of defects leading to a complex breakdown of the deforming tool at the NPO Pribor machine-building enterprise.展开更多
文摘A series of layered mixed oxides La 4BaCu 5-x Mn x O 13+λ ( x =0—5) was prepared, characterized and used as catalysts for NO+CO reaction. It was found that all the samples were single phase having a structure with five layered perovskite. La 4BaCu 2Mn 3O 13+λ showed the highest activity in the title reaction, this could be attributed to the synergetic effect between Cu and Mn. The results of TPR, TPD and excess oxygen investigations confirmed that the Cu ion would be the active center. The displacement of the Cu ion by Mn caused the Cu ion to be more easily reducible and more content of excess oxygen, and it was beneficial to the activity of the catalyst. The reaction mechanism was also proposed.
文摘The crystal structure of 5-{[(4′-heptoxy-biphenylyl-4-yl)oxy]carbonyl}-1-pentyne({A3E′O7}) was investigated by wide angle X-ray diffraction(WAXD), transmission electron microscope(TEM) and atom force microscope(AFM). The structures of A3E′O7 solution-crystal and melt-crystal are the same. The crystals belong to the monoclinic P112/m space group, the cell parameters are {a0.589 nm}, b0^771 nm, c4.75 nm, αβ90° and γ93.8°, the calculated cell density is {1.167 g/cm+3}.
基金the financial supporting by the National Natural Science Foundation of China(Grant Nos.21962009,22172071,22102069,22062013)the Natural Science Foundation of Jiangxi Province(Grant Nos.20202BAB203006,20181ACB20005)the Key Laboratory Foundation of Jiangxi Province for Environment and Energy Catalysis(Grant No.20181BCD40004).
文摘Based on monolayer dispersion theory,Co_(3)O_(4)/ZSM-5 catalysts with different loadings have been prepared for selective catalytic reduction of nitrogen oxides by ammonia.Co_(3)O_(4)can spontaneously disperse on HZSM-5 support with a monolayer dispersion threshold of 0.061 mmol 100 m^(-2),equaling to a weight percentage around 4.5%.It has been revealed that the quantities of surface active oxygen(O_(2)^(-))and acid sites are crucial for the reaction,which can adsorb and activate NO_(x)and NH_(3)reactants effectively.Below the monolayer dispersion threshold,Co_(3)O_(4)is finely dispersed as sub-monolayers or monolayers and in an amorphous state,which is favorable to generate the two kinds of active sites,hence promoting the performance of ammonia selective catalytic reduction of nitrogen oxide.However,the formation of crystalline Co_(3)O_(4)above the capacity is harmful to the reaction performance.4%Co_(3)O_(4)/ZSM-5,the catalyst close to the monolayer dispersion capacity,possesses the most abundant active O_(2)^(-)species and acidic sites,thereby demonstrating the best reaction performance in all the samples.It is proposed the optimal Co_(3)O_(4)/ZSM-5 catalyst can be prepared by loading the capacity amount of Co_(3)O_(4)onto HZSM-5 support.
文摘The conditions of heating and cooling of piercing mandrels made of 4X5MFS steel of a three-roll screw mill 30-80 in the production of a closed cavity of steel vessels of small volume are determined.It is established that multiple cycles of heating up to 600℃ and cooling with water up to 80℃ for about 7 seconds/1 cycle lead to the formation of ridges,shells and cracks on the surface and in the volume of the tool.The loss of structural strength of the material leads to the breakdown of the mandrel during the stitching process.The technique and equipment of magnetic powder control have been developed to establish the dynamics of the growth of internal and external defects of mandrels.An equation is obtained that allows determining the increase in the number of defects in the sewing tool of a screw rolling mill.The technology of non-destructive testing made it possible to develop a rational plan for replacing the sewing mandrels,which allows for predicting the appearance of defects leading to a complex breakdown of the deforming tool at the NPO Pribor machine-building enterprise.
