In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The ...In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The DFT results showed that Ru-N_(x)SACs had the best catalytic performance among the four catalysts,and Ru-N_(x)SACs could effectively inhibit the reduction of ruthenium cation.To verify the DFT results,Ru-N_(x)SACs were fabricated by pyrolyzing MOFs in-situ spatially confined metal precursors.The N coordination environment could be controlled by changing the pyrolysis temperature.Catalytic performance tests indicated that low N coordination number(Ru-N_(2),Ru-N_(3))exhibited excellent catalytic activity and stability compared to RuCl_(3)catalyst.DFT calculations further revealed that Ru-N_(2)and Ru-N_(3)had a tendency to activate HCl at the first step of reaction,whereas Ru-N4tended to activate C_(2)H_(2).These findings will serve as a reference for the design and control of metal active sites.展开更多
A novel NiB deposited layered double hydroxide （LDH） coated ferroferric oxide （Fe304@LDH@NiB） magnet- ic core-shell nanocomposite was successfully fabricated by the combination of coprecipitation and impregna- tio...A novel NiB deposited layered double hydroxide （LDH） coated ferroferric oxide （Fe304@LDH@NiB） magnet- ic core-shell nanocomposite was successfully fabricated by the combination of coprecipitation and impregna- tion-reduction. During the Fe304@LDH preparation, a facile template-free approach was employed to introduce the LDH shell, which was more efficient than the conventional method for the preparation of mesoporous materials that always needs to introduce and remove templates. The resulted Fe304@LDH has a relatively high surface area and abundant surface hydroxyl group, which can adsorb metal ions, making it favorable to disperse and stabilize the ac- tive Ni species, as demonstraed by TEM, XPS, FT-IR and BET characterizations. Therefore, it exhibited good activ- ity in the selective hydrogenation of cinnamic acid to hydrocinnamic acid with the conversion and selectivity both approaching to 100%. Notably, the obtained Fe304@LDH@NiB can be easily separated by an external magnetic field and recycled eleven times without appreciable loss of its initial catalytic activity.展开更多
基金supported by the National Natural Science Foundation of China (NSFC,22172082,21978137,22102074,and 21878162)Natural Science Foundation of Tianjin (20JCZDJC00770)+1 种基金Postdoctoral Research Foundation of China (2021M701776)NCC Fund (NCC2020FH05)。
文摘In this work,DFT calculations were used firstly to simulate the nitrogen coordinated metal single-atom catalysts(M-N_(x)SACs,M=Hg,Cu,Au,and Ru) to predict their catalytic activities in acetylene hydrochlorination.The DFT results showed that Ru-N_(x)SACs had the best catalytic performance among the four catalysts,and Ru-N_(x)SACs could effectively inhibit the reduction of ruthenium cation.To verify the DFT results,Ru-N_(x)SACs were fabricated by pyrolyzing MOFs in-situ spatially confined metal precursors.The N coordination environment could be controlled by changing the pyrolysis temperature.Catalytic performance tests indicated that low N coordination number(Ru-N_(2),Ru-N_(3))exhibited excellent catalytic activity and stability compared to RuCl_(3)catalyst.DFT calculations further revealed that Ru-N_(2)and Ru-N_(3)had a tendency to activate HCl at the first step of reaction,whereas Ru-N4tended to activate C_(2)H_(2).These findings will serve as a reference for the design and control of metal active sites.
基金This work was supported by the National Natural Science Foundation of China （Nos. 21376060 and 21676068） and the Natural Science Foundation of Hebei Province （No. B2014201024）.
文摘A novel NiB deposited layered double hydroxide （LDH） coated ferroferric oxide （Fe304@LDH@NiB） magnet- ic core-shell nanocomposite was successfully fabricated by the combination of coprecipitation and impregna- tion-reduction. During the Fe304@LDH preparation, a facile template-free approach was employed to introduce the LDH shell, which was more efficient than the conventional method for the preparation of mesoporous materials that always needs to introduce and remove templates. The resulted Fe304@LDH has a relatively high surface area and abundant surface hydroxyl group, which can adsorb metal ions, making it favorable to disperse and stabilize the ac- tive Ni species, as demonstraed by TEM, XPS, FT-IR and BET characterizations. Therefore, it exhibited good activ- ity in the selective hydrogenation of cinnamic acid to hydrocinnamic acid with the conversion and selectivity both approaching to 100%. Notably, the obtained Fe304@LDH@NiB can be easily separated by an external magnetic field and recycled eleven times without appreciable loss of its initial catalytic activity.
