ZSM-5 zeolite microparticles(MPs)were synthesized under hydrothermal condition using a low crystal seed addition approach without template.The synthesis parameters such as the seed addition amount,the SiO2/Al2O3ratio,...ZSM-5 zeolite microparticles(MPs)were synthesized under hydrothermal condition using a low crystal seed addition approach without template.The synthesis parameters such as the seed addition amount,the SiO2/Al2O3ratio,the aluminum source,the feeding addition method,aging,and crystallization were investigated.The structure,morphology and composition of the as-synthesized ZSM-5 zeolite MPs were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),laser particle size distribution(PSD)measurements,and inductively coupled plasma-atomic emission spectrometry(ICP-AES).The SiO2/Al2O3ratio of ZSM-5 zeolite MPs was in the range of 20—80.The low seed addition was beneficial to improving the crystallinity and shortening the crystallization time,and the suitable amount of seed was 0.25%(SiO2).The ZSM-5 zeolite MPs synthesized with aluminium nitrate nonahydrate used as the aluminum source exhibited a relatively high crystallinity.An appropriate aging time could eliminate the effect of feeding addition method and effectively adjust particle size.The particle size of ZSM-5 zeolite obtained at an aging time of 20 h was around 2.0μm.Prolonging the aging time appropriately could also shorten the high-temperature crystallization time.The suitable aging time was 24 h,and the relative crystallinity of ZSM-5 zeolite could reach up to 99%after crystallization for 24 h at 180℃.展开更多
The 5-parameter Morse pntential（5-MP） of the interaction between oxygen atoms and iron surfaces was constructed. The adsorption and diffusion of O atoms on Fe low-index and Fe（211 ） high-index surfaces were invest...The 5-parameter Morse pntential（5-MP） of the interaction between oxygen atoms and iron surfaces was constructed. The adsorption and diffusion of O atoms on Fe low-index and Fe（211 ） high-index surfaces were investigated by using 5-MP. All the critical characteristics of the system, such as adsorption site, adsorption geometry, binding energy, and eigenvalues for vibration, were calculated. The calculation results show that O atoms are located at the fourfold hollow site of the Fe（100） surface with an eigenvibration at437 cm^-1. These results are in good agreement with the experimental and theoretical results obtained previously. With regard to the adsorption site of O-Fe（110） system, the authors of this study assume that the preferential adsorption state is the H3 site and not the LB site, which is not in agreement with the experimental inferences obtained earlier. However, on the Fe（ 111 ） and Fe（211 ） surfaces, O atoms predominantly occupy the quasi-3-fold site.展开更多
The 5-parameter Morse potential （5-MP） of interaction between an adatom and metal surface cluster is put forward and performed on O-Pt stepped surface systems. We have primarily studied O/Pt（331）, O/Pt（221） and ...The 5-parameter Morse potential （5-MP） of interaction between an adatom and metal surface cluster is put forward and performed on O-Pt stepped surface systems. We have primarily studied O/Pt（331）, O/Pt（221） and O/Pt（553） systems and drawn some conclusions from the calculated results in good agreement with experimental and theoretical information. The O atom adsorbs stably near the step, so the step is the active place in the reaction. There are two types of atomic states, β1 and β2, in the adsorbed systems, corresponding to the three-fold states and four-fold long-bridged state behind the step respectively. Moreover, the length of （Ⅲ） terrace affects weakly the properties of all critical points in these systems.展开更多
The O-Ag（210） surface adsorption system was studied via the five-parameter Morse potential theory. Mean- while, the 20-Ag （ 210） system was investigated v/a the extended London-Eyring-Polanyi-Sato （LEPS） potenti...The O-Ag（210） surface adsorption system was studied via the five-parameter Morse potential theory. Mean- while, the 20-Ag （ 210） system was investigated v/a the extended London-Eyring-Polanyi-Sato （LEPS） potential theo- ry to learn the interaction between the adsorption states. Calculated results demonstrate that there are two stable on- surface adsorption sites（B and H） for 0 atoms on Ag（210） stepped surface. And the perpendicular vibrations are 30. 3 and 42.9 meV, which are close to that observed in high resolution electron energy loss spectroscopy （HREELS）. Also, there exists an octabedral subsurface adsorption state with a high vibrational frequency, and the interaction between the on-surface and subsurface 0 species is slight. The mode at 54.6 meV, which is close to that observed in HREELS（54-56 meV）, is because of the vibration of the 0 atom on B site under the influence of that on H site.展开更多
The 5-parameter Morse potential （5-MP） of the interaction between H atom and Ag surfaces has been constructed. The adsorption and diffusion of H on Ag low-index surfaces are investigated with 5-MP in detail. The cha...The 5-parameter Morse potential （5-MP） of the interaction between H atom and Ag surfaces has been constructed. The adsorption and diffusion of H on Ag low-index surfaces are investigated with 5-MP in detail. The characteristics of critical points are obtained. The theoretical results show that H atom can only adsorb at the three-fold site on Ag（111 ）; the quasi-3-fold site and long-bridge site are stable adsorption sites on Ag（110） surface for the H atom, and at low coverage hydrogen predominantly occupies the quasi-3-fold site. This work predicts that the four-fold hollow site is the most stable adsorption state for H atom on Ag（100）. The results of this work are approved by the experimental and theoretical results.展开更多
基金Financial support from the Innovation Fund for Elitists of Henan Province,China(No.0221001200)the Talent Training Joint Fund of NSFC-Henan(No.U1204203)the China Postdoctoral Science Foundation(No.2012M511121)
文摘ZSM-5 zeolite microparticles(MPs)were synthesized under hydrothermal condition using a low crystal seed addition approach without template.The synthesis parameters such as the seed addition amount,the SiO2/Al2O3ratio,the aluminum source,the feeding addition method,aging,and crystallization were investigated.The structure,morphology and composition of the as-synthesized ZSM-5 zeolite MPs were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),laser particle size distribution(PSD)measurements,and inductively coupled plasma-atomic emission spectrometry(ICP-AES).The SiO2/Al2O3ratio of ZSM-5 zeolite MPs was in the range of 20—80.The low seed addition was beneficial to improving the crystallinity and shortening the crystallization time,and the suitable amount of seed was 0.25%(SiO2).The ZSM-5 zeolite MPs synthesized with aluminium nitrate nonahydrate used as the aluminum source exhibited a relatively high crystallinity.An appropriate aging time could eliminate the effect of feeding addition method and effectively adjust particle size.The particle size of ZSM-5 zeolite obtained at an aging time of 20 h was around 2.0μm.Prolonging the aging time appropriately could also shorten the high-temperature crystallization time.The suitable aging time was 24 h,and the relative crystallinity of ZSM-5 zeolite could reach up to 99%after crystallization for 24 h at 180℃.
基金the Natural Science Foundation of Shandong Province(No Y2002B09)
文摘The 5-parameter Morse pntential（5-MP） of the interaction between oxygen atoms and iron surfaces was constructed. The adsorption and diffusion of O atoms on Fe low-index and Fe（211 ） high-index surfaces were investigated by using 5-MP. All the critical characteristics of the system, such as adsorption site, adsorption geometry, binding energy, and eigenvalues for vibration, were calculated. The calculation results show that O atoms are located at the fourfold hollow site of the Fe（100） surface with an eigenvibration at437 cm^-1. These results are in good agreement with the experimental and theoretical results obtained previously. With regard to the adsorption site of O-Fe（110） system, the authors of this study assume that the preferential adsorption state is the H3 site and not the LB site, which is not in agreement with the experimental inferences obtained earlier. However, on the Fe（ 111 ） and Fe（211 ） surfaces, O atoms predominantly occupy the quasi-3-fold site.
基金The project was supported by NSF of Shandong Province (Y2002B09)
文摘The 5-parameter Morse potential （5-MP） of interaction between an adatom and metal surface cluster is put forward and performed on O-Pt stepped surface systems. We have primarily studied O/Pt（331）, O/Pt（221） and O/Pt（553） systems and drawn some conclusions from the calculated results in good agreement with experimental and theoretical information. The O atom adsorbs stably near the step, so the step is the active place in the reaction. There are two types of atomic states, β1 and β2, in the adsorbed systems, corresponding to the three-fold states and four-fold long-bridged state behind the step respectively. Moreover, the length of （Ⅲ） terrace affects weakly the properties of all critical points in these systems.
基金Supported by the Natural Science Foundation of Shandong Province,China(No.Y2002B09).
文摘The O-Ag（210） surface adsorption system was studied via the five-parameter Morse potential theory. Mean- while, the 20-Ag （ 210） system was investigated v/a the extended London-Eyring-Polanyi-Sato （LEPS） potential theo- ry to learn the interaction between the adsorption states. Calculated results demonstrate that there are two stable on- surface adsorption sites（B and H） for 0 atoms on Ag（210） stepped surface. And the perpendicular vibrations are 30. 3 and 42.9 meV, which are close to that observed in high resolution electron energy loss spectroscopy （HREELS）. Also, there exists an octabedral subsurface adsorption state with a high vibrational frequency, and the interaction between the on-surface and subsurface 0 species is slight. The mode at 54.6 meV, which is close to that observed in HREELS（54-56 meV）, is because of the vibration of the 0 atom on B site under the influence of that on H site.
基金The project was supported by NSF of Shandong Province (Y2002B09)
文摘The 5-parameter Morse potential （5-MP） of the interaction between H atom and Ag surfaces has been constructed. The adsorption and diffusion of H on Ag low-index surfaces are investigated with 5-MP in detail. The characteristics of critical points are obtained. The theoretical results show that H atom can only adsorb at the three-fold site on Ag（111 ）; the quasi-3-fold site and long-bridge site are stable adsorption sites on Ag（110） surface for the H atom, and at low coverage hydrogen predominantly occupies the quasi-3-fold site. This work predicts that the four-fold hollow site is the most stable adsorption state for H atom on Ag（100）. The results of this work are approved by the experimental and theoretical results.
