Ru nanoparticles with fcc and hcp crystal phases were obtained by chemical reduction method using different precursors and reducing agents,and their catalytic properties in ammonia synthesis were compared.The catalyti...Ru nanoparticles with fcc and hcp crystal phases were obtained by chemical reduction method using different precursors and reducing agents,and their catalytic properties in ammonia synthesis were compared.The catalytic reaction rate(666.4μmol·h^(−1)·g^(−1))of fcc Ru catalyst is higher than that of hcp Ru(378.9μmol·h^(−1)·g^(−1))at the reaction temperature(400℃)and pressure(1 MPa).The results indicate that the exposed crystal faces have a certain impact on the catalytic activity.The dissociation ability to N_(2) of fcc Ru exposed(111)and(200)is better than that of hcp Ru exposed(100).When the ruthenium catalyst was loaded on rod-like CeO_(2) support,the ammonia synthesis activity was further improved.The ammonia synthesis activity of fcc Ru/CeO_(2) is 1.4 times higher than that of hcp Ru/CeO_(2) under the test conditions.展开更多
Spherical cobalt carbonate with high tap density, good crystallization and uniform particle size was prepared by controlled chemical crystal method using cobalt chloride and ammonium bicarbonate as cobalt source and p...Spherical cobalt carbonate with high tap density, good crystallization and uniform particle size was prepared by controlled chemical crystal method using cobalt chloride and ammonium bicarbonate as cobalt source and precipitator. The effects of pH value and reaction time on crystallization and physical properties of cobalt carbonate were studied. The results show that the key factors influencing the preparation process of spherical cobalt carbonate with high tap density and good crystallization are how to control pH value (7.25±0.05) and keep some reaction time (about 10 h). Co4O3 was prepared by sintering spherical morphology CoCO3 samples at varied temperatures. The results show that as the decomposition temperature increases, the as-obtained Co4O3 products with porous structure transform into polyhedral structure with glazed surface, and simultaneously the cobalt content and tap density increase. However, the specific surface area shows a trend of decrease.展开更多
基金The National Natural Science Foundation of China(22102194)The Science and Technology Plan of Gansu Province(24JRRA067,23ZDFA016)The Youth Innovation Promotion Association of CAS(2022427).
文摘Ru nanoparticles with fcc and hcp crystal phases were obtained by chemical reduction method using different precursors and reducing agents,and their catalytic properties in ammonia synthesis were compared.The catalytic reaction rate(666.4μmol·h^(−1)·g^(−1))of fcc Ru catalyst is higher than that of hcp Ru(378.9μmol·h^(−1)·g^(−1))at the reaction temperature(400℃)and pressure(1 MPa).The results indicate that the exposed crystal faces have a certain impact on the catalytic activity.The dissociation ability to N_(2) of fcc Ru exposed(111)and(200)is better than that of hcp Ru exposed(100).When the ruthenium catalyst was loaded on rod-like CeO_(2) support,the ammonia synthesis activity was further improved.The ammonia synthesis activity of fcc Ru/CeO_(2) is 1.4 times higher than that of hcp Ru/CeO_(2) under the test conditions.
文摘Spherical cobalt carbonate with high tap density, good crystallization and uniform particle size was prepared by controlled chemical crystal method using cobalt chloride and ammonium bicarbonate as cobalt source and precipitator. The effects of pH value and reaction time on crystallization and physical properties of cobalt carbonate were studied. The results show that the key factors influencing the preparation process of spherical cobalt carbonate with high tap density and good crystallization are how to control pH value (7.25±0.05) and keep some reaction time (about 10 h). Co4O3 was prepared by sintering spherical morphology CoCO3 samples at varied temperatures. The results show that as the decomposition temperature increases, the as-obtained Co4O3 products with porous structure transform into polyhedral structure with glazed surface, and simultaneously the cobalt content and tap density increase. However, the specific surface area shows a trend of decrease.
