In this work,the solidification of liquid iron with or without external magnetic field was investigated by using two molecular dynamics methods,namely direct cooling and two-phase simulation.The influence of external ...In this work,the solidification of liquid iron with or without external magnetic field was investigated by using two molecular dynamics methods,namely direct cooling and two-phase simulation.The influence of external magnetic field on the solidification is characterized by the critical temperature and radial distribution functions.Our computational results show that under external magnetic field,the solidification point tends to decrease significantly.By further analyzing the diffusion coefficients and viscosity,we attribute the effect to the stronger fluctuation of liquid iron atoms driven by the external magnetic field.展开更多
Selective semi-hydrogenation of phenylacetylene to styrene is a crucial step in the polystyrene industry.Although Pd-based catalysts are widely used in this reaction due to their excellent hydrogenation activity,the s...Selective semi-hydrogenation of phenylacetylene to styrene is a crucial step in the polystyrene industry.Although Pd-based catalysts are widely used in this reaction due to their excellent hydrogenation activity,the selectivity for styrene remains a great challenge.Herein,we designed a mesoporous silica stabilized Pd-Ru@ZIF-8(MS Pd-Ru@ZIF-8)nanoreactor with novel Pd and Ru single site synergistic catalytical system for semi-hydrogenation of phenylacetylene.The nanoreactor exhibited a superior performance,achieving 98%conversion of phenylacetylene and 96%selectivity to styrene.Turnover frequency(TOF)of nanoreactor was up to as high as 2,188 h^(−1),which was 25 times and 5 times more than the single metal species catalysts,mesoporous silica stabilized Pd@ZIF-8 nanoreactor(MS Pd@ZIF-8),and mesoporous silica stabilized Ru@ZIF-8 nanoreactor(MS Ru@ZIF-8).This catalytic activity was attributed to the synergistic effect of Pd and Ru single site anchored strongly into the framework of ZIF-8,which reduced the desorption energy of styrene and increased the hydrogenation energy barrier of styrene.Importantly,since the ordered mesoporous silica was introduced into the nanoreactor shell to stabilize ZIF-8,MS Pd-Ru@ZIF-8 showed excellent reusability and stability.After the five cycles,the catalytical activity and selectivity still remained.This work provides insights for a synergistic catalytic system based on single-site active sites for selective hydrogenation reactions.展开更多
基金funded by the National Natural Science Foundation of China(No.22173057 for Yongle Li and No.51690164 for Xi Li)the Foundation of Shanghai Science and Technology Commission(No.21JC1402700 and No.21DZ2304900 for Yongle Li)supported by Open Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University。
文摘In this work,the solidification of liquid iron with or without external magnetic field was investigated by using two molecular dynamics methods,namely direct cooling and two-phase simulation.The influence of external magnetic field on the solidification is characterized by the critical temperature and radial distribution functions.Our computational results show that under external magnetic field,the solidification point tends to decrease significantly.By further analyzing the diffusion coefficients and viscosity,we attribute the effect to the stronger fluctuation of liquid iron atoms driven by the external magnetic field.
基金the financial support from the Beijing Natural Science Foundation(No.2182061)Science Foundation of China University of Petroleum,Beijing(No.2462019BJRC001)。
文摘Selective semi-hydrogenation of phenylacetylene to styrene is a crucial step in the polystyrene industry.Although Pd-based catalysts are widely used in this reaction due to their excellent hydrogenation activity,the selectivity for styrene remains a great challenge.Herein,we designed a mesoporous silica stabilized Pd-Ru@ZIF-8(MS Pd-Ru@ZIF-8)nanoreactor with novel Pd and Ru single site synergistic catalytical system for semi-hydrogenation of phenylacetylene.The nanoreactor exhibited a superior performance,achieving 98%conversion of phenylacetylene and 96%selectivity to styrene.Turnover frequency(TOF)of nanoreactor was up to as high as 2,188 h^(−1),which was 25 times and 5 times more than the single metal species catalysts,mesoporous silica stabilized Pd@ZIF-8 nanoreactor(MS Pd@ZIF-8),and mesoporous silica stabilized Ru@ZIF-8 nanoreactor(MS Ru@ZIF-8).This catalytic activity was attributed to the synergistic effect of Pd and Ru single site anchored strongly into the framework of ZIF-8,which reduced the desorption energy of styrene and increased the hydrogenation energy barrier of styrene.Importantly,since the ordered mesoporous silica was introduced into the nanoreactor shell to stabilize ZIF-8,MS Pd-Ru@ZIF-8 showed excellent reusability and stability.After the five cycles,the catalytical activity and selectivity still remained.This work provides insights for a synergistic catalytic system based on single-site active sites for selective hydrogenation reactions.
