A modified two-sphere model of sintering neck has been proposed, wherein three diffusion mechanisms including surface diffusion, grain-boundary diffusion and coupled surface and grain-boundary diffusion are assumed. S...A modified two-sphere model of sintering neck has been proposed, wherein three diffusion mechanisms including surface diffusion, grain-boundary diffusion and coupled surface and grain-boundary diffusion are assumed. Sintering neck is appropriately simulated using the modified model. The dynamic change of sintering neck is presented using the simulation. The variational shape of sintering neck in surface diffusion mechanism is continuous, whereas in grain-boundary diffusion mechanism, besides the variational shape of sintering neck being continuous, the center distance between the particles is also assumed to contract. However, the variational shape of sintering neck in coupling diffusion mechanism is integrated using the two diffusion mechanisms mentioned above.展开更多
Pure Cu nanowires as catalyst were prepared by electrochemical deposition and were used in CO2 hydrogenation to methanol.The active sites of the Cu based catalyst were discussed.The performance and structural developm...Pure Cu nanowires as catalyst were prepared by electrochemical deposition and were used in CO2 hydrogenation to methanol.The active sites of the Cu based catalyst were discussed.The performance and structural development of the catalyst were observed during CO2 hydrogenation.A mechanism for the deactivation of the catalyst was discussed.The key factors that affect the deactivation of the catalyst were found.Cu nanowire sample was characterized by SEM,EDS,XRD,and BET.The results show that Cu nanowires have very high sintering resistance and catalytic stability.This helps to develop high performance catalysts.The changes in the grain size,SEM morphology and catalytic properties of the sample during CO2 hydrogenation show that the migration of the Cu atoms on the surface of the Cu nanowires can occur.Continuous migration of Cu atoms and sintering of Cu grains can lead to flow blockage in gas channels.The gas channel flow blockage or the sintering of Cu grains can lead to deactivation of the catalyst.However,the shape of catalytic performance curve indicates that the main reason for the deactivation of the catalyst is the gas channel flow blockage.展开更多
文摘A modified two-sphere model of sintering neck has been proposed, wherein three diffusion mechanisms including surface diffusion, grain-boundary diffusion and coupled surface and grain-boundary diffusion are assumed. Sintering neck is appropriately simulated using the modified model. The dynamic change of sintering neck is presented using the simulation. The variational shape of sintering neck in surface diffusion mechanism is continuous, whereas in grain-boundary diffusion mechanism, besides the variational shape of sintering neck being continuous, the center distance between the particles is also assumed to contract. However, the variational shape of sintering neck in coupling diffusion mechanism is integrated using the two diffusion mechanisms mentioned above.
基金Project(51074205)supported by the National Natural Science Foundation of China
文摘Pure Cu nanowires as catalyst were prepared by electrochemical deposition and were used in CO2 hydrogenation to methanol.The active sites of the Cu based catalyst were discussed.The performance and structural development of the catalyst were observed during CO2 hydrogenation.A mechanism for the deactivation of the catalyst was discussed.The key factors that affect the deactivation of the catalyst were found.Cu nanowire sample was characterized by SEM,EDS,XRD,and BET.The results show that Cu nanowires have very high sintering resistance and catalytic stability.This helps to develop high performance catalysts.The changes in the grain size,SEM morphology and catalytic properties of the sample during CO2 hydrogenation show that the migration of the Cu atoms on the surface of the Cu nanowires can occur.Continuous migration of Cu atoms and sintering of Cu grains can lead to flow blockage in gas channels.The gas channel flow blockage or the sintering of Cu grains can lead to deactivation of the catalyst.However,the shape of catalytic performance curve indicates that the main reason for the deactivation of the catalyst is the gas channel flow blockage.
