A series of Fe‐Mn/Al2O3 catalysts were prepared and studied for low temperature selective catalytic reduction （SCR） of NO with NH3 in a fixed‐bed reactor. The effects of Fe and Mn on NO conversion and the deactiva...A series of Fe‐Mn/Al2O3 catalysts were prepared and studied for low temperature selective catalytic reduction （SCR） of NO with NH3 in a fixed‐bed reactor. The effects of Fe and Mn on NO conversion and the deactivation of the catalysts were studied. N2 adsorption‐desorption, X‐ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, H2 temperature‐programmed reduction, NH3 temperature‐programmed desorption, X‐ray photoelectron spectroscopy （XPS）, thermal gravimetric analysis and Fourier transform infrared spectroscopy were used to character‐ize the catalysts. The 8Fe‐8Mn/Al2O3 catalyst gave 99%of NO conversion at 150？？ and more than 92.6%NO conversion was obtained in a wide low temperature range of 90–210？？. XPS analysis demonstrated that the Fe3＋was the main iron valence state on the catalyst surface and the addition of Mn increased the accumulation of Fe on the surface. The higher specific surface area, enhanced dispersion of amorphous Fe and Mn, improved reduction properties and surface acidity, lower binding energy, higher Mn4＋/Mn3＋ratio and more adsorbed oxygen species resulted in higher NO conversion for the 8Fe‐8Mn/Al2O3 catalyst. In addition, the SCR activity of the 8Fe‐8Mn/Al2O3 cata‐lyst was only slightly decreased in the presence of H2O and SO2, which indicated that the catalyst had better tolerance to H2O and SO2. The reaction temperature was crucial for the SO2 resistance of catalyst and the decrease of catalytic activity caused by SO2 was mainly due to the sulfate salts formed on the catalyst.展开更多
We have studied the quasiparticle transport in quantum-wire /ferromagnetic-insulator/d wave super- conductor Junction （q/FI/d） in the framework of the Blonder-Tinkham-Klapwijk model. We calculate the tunneling condu...We have studied the quasiparticle transport in quantum-wire /ferromagnetic-insulator/d wave super- conductor Junction （q/FI/d） in the framework of the Blonder-Tinkham-Klapwijk model. We calculate the tunneling conductance in q/FI/d as a function of the bias voltage at zero temperature and finite temperature based on Bogoliubov- de Gennes equations. Different from the case in normal-metal/insulator/d wave superconductor Junctions, the zero-bias conductance peaks vanish for the single-mode case. The tunneling conductance spectra depend on the magnitude of the exchange interaction at the ferromagnetic-insulator.展开更多
A styryl phosphonate ester(SPE) collector was used to improve the flotation performance of ilmenite, and the adsorption mechanism and model were revealed and established, respectively. Microflotation tests showed that...A styryl phosphonate ester(SPE) collector was used to improve the flotation performance of ilmenite, and the adsorption mechanism and model were revealed and established, respectively. Microflotation tests showed that SPE exhibited a stronger collecting ability for ilmenite than the traditional collector styrene phosphonic acid(SPA). Zeta potential measurements revealed that both SPE and SPA could negatively shift the zeta potential of ilmenite, while SPE had more effects than SPA, suggesting the stronger adsorption of SPE. The analysis of X-ray photoelectron spectroscopy confirmed the chemisorption of SPA and SPE onto the Fe/Ti sites of ilmenite. According to frontier orbital theory, the chemical activities of SPE are greater than those of SPA. The partial densities of states analysis indicated that the PO—H groups of the collectors could interact with the Ti/Fe atoms of the ilmenite surface to generate a stable four-membered ring. The bonding model of the collector and(104) ilmenite surface showed that the adsorption energy of SPE was higher than that of SPA. Overall, SPE presented a better collecting ability and interaction effect for ilmenite flotation than SPA, and had the potential to replace SPA in the industry.展开更多
The metastable phase 3c-Fe7S8 with the hexagonal platelet morphology has been prepared by using solvothermal route. The product was characterized by means of X-ray powder diffraction (XRD) and transmission electron mi...The metastable phase 3c-Fe7S8 with the hexagonal platelet morphology has been prepared by using solvothermal route. The product was characterized by means of X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS). The experiment results show that the as-prepared Fe7S8 is a metastable phase with the hexagonal platelet morphology.展开更多
Single-molecule magnets （SMMs） are regarded as promising candidates for ultrahigh-density storage, quantum information processing and molecular spintronics. It is a crucial challenge for chemists to modulate magneti...Single-molecule magnets （SMMs） are regarded as promising candidates for ultrahigh-density storage, quantum information processing and molecular spintronics. It is a crucial challenge for chemists to modulate magnetic dynamics of SMMs. Here, we successfully synthesized two 3d-4f polynuclear compounds [Co2Dy（TTTTCl）2（MeOH）]NO3.3MeOH （1） and [Co2Dy（TTTTCl）2 （MeOH）][Co（HTTTTCl）]（NO3）z-2.5MeOH＇2H20 （2）, where H3TTTTCl=2,2＇,2＂-（（（nitrilotris（ethane-2,1-diyl）） tris（azanediyl）） tris（methylene））tris-（4-chlorophenol）. On applying the approach by co-crystallization of bulky diamagnetic moiety, the effective energy barrier enhances from 401 K （1） to 536 K （2）, which are both among the highest d-f heterometallic SMMs.展开更多
Technetium-99(~99Tc),largely produced by nuclear fission of ~235U or ~239Pu,is a component of radioactive waste.This study focused on a remediation strategy for the reduction of pertechnetate(Tc O_4^-)by studying its ...Technetium-99(~99Tc),largely produced by nuclear fission of ~235U or ~239Pu,is a component of radioactive waste.This study focused on a remediation strategy for the reduction of pertechnetate(Tc O_4^-)by studying its chemical analogue rhenium(Re(VⅡ))to avoid the complication of directly working with radioactive elements.Nanoscale zero-valent iron particles supported on graphene(NZVI/r GOs)from GOs-bound Fe ions were prepared by using a H_2/Ar plasma technique and were applied in the reductive immobilization of perrhenate(Re O_4^-).The experimental results demonstrated that NZVI/r GOs could efficiently remove Re from the aqueous solution,with enhanced reactivity,improved kinetics(50 min to reach equilibrium)and excellent removal capacity(85.77 mg/g).The results of X-ray photoelectron spectroscopy analysis showed that the mechanisms of Re immobilization by NZVI/r GOs included adsorption and reduction,which are significant to the prediction and estimation of the effectiveness of reductive Tc O_4^- by NZVI/r GOs in the natural environment.展开更多
基金supported by the National High Technology Research and Development Program of China (863 Program,2015AA03A401)the National Natural Science Foundation of China (51276039)+1 种基金the Fundamental Research Funds for the Central Universities (020514380020,020514380030)the Postdoctoral Science Foundation of Jiangsu Province,China (1501033A)~~
文摘A series of Fe‐Mn/Al2O3 catalysts were prepared and studied for low temperature selective catalytic reduction （SCR） of NO with NH3 in a fixed‐bed reactor. The effects of Fe and Mn on NO conversion and the deactivation of the catalysts were studied. N2 adsorption‐desorption, X‐ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, H2 temperature‐programmed reduction, NH3 temperature‐programmed desorption, X‐ray photoelectron spectroscopy （XPS）, thermal gravimetric analysis and Fourier transform infrared spectroscopy were used to character‐ize the catalysts. The 8Fe‐8Mn/Al2O3 catalyst gave 99%of NO conversion at 150？？ and more than 92.6%NO conversion was obtained in a wide low temperature range of 90–210？？. XPS analysis demonstrated that the Fe3＋was the main iron valence state on the catalyst surface and the addition of Mn increased the accumulation of Fe on the surface. The higher specific surface area, enhanced dispersion of amorphous Fe and Mn, improved reduction properties and surface acidity, lower binding energy, higher Mn4＋/Mn3＋ratio and more adsorbed oxygen species resulted in higher NO conversion for the 8Fe‐8Mn/Al2O3 catalyst. In addition, the SCR activity of the 8Fe‐8Mn/Al2O3 cata‐lyst was only slightly decreased in the presence of H2O and SO2, which indicated that the catalyst had better tolerance to H2O and SO2. The reaction temperature was crucial for the SO2 resistance of catalyst and the decrease of catalytic activity caused by SO2 was mainly due to the sulfate salts formed on the catalyst.
基金The project supported by the Natural Science Foundation of the Education Committee of Jiangsu Province of China under Grant No.06KJB140009
文摘We have studied the quasiparticle transport in quantum-wire /ferromagnetic-insulator/d wave super- conductor Junction （q/FI/d） in the framework of the Blonder-Tinkham-Klapwijk model. We calculate the tunneling conductance in q/FI/d as a function of the bias voltage at zero temperature and finite temperature based on Bogoliubov- de Gennes equations. Different from the case in normal-metal/insulator/d wave superconductor Junctions, the zero-bias conductance peaks vanish for the single-mode case. The tunneling conductance spectra depend on the magnitude of the exchange interaction at the ferromagnetic-insulator.
基金the support from the National Natural Science Foundation of China(Nos.51904214 and 51804238)the Young Elite Scientists Sponsorship Program by CAST(No.YESS20200276)+3 种基金the Natural Science Foundation of Hubei Province,China(No.ZRMS2021000085)the Fundamental Research Funds for the Central Universities,China(No.2021IVA039)the Open Foundation of State Key Laboratory of Mineral Processing,BGRIMM Technology,China(Nos.BGRIMM-KJSKL-202122 and BGRIMM-KJSKL-2022-02)the Open Project of Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education,China(No.201904)。
文摘A styryl phosphonate ester(SPE) collector was used to improve the flotation performance of ilmenite, and the adsorption mechanism and model were revealed and established, respectively. Microflotation tests showed that SPE exhibited a stronger collecting ability for ilmenite than the traditional collector styrene phosphonic acid(SPA). Zeta potential measurements revealed that both SPE and SPA could negatively shift the zeta potential of ilmenite, while SPE had more effects than SPA, suggesting the stronger adsorption of SPE. The analysis of X-ray photoelectron spectroscopy confirmed the chemisorption of SPA and SPE onto the Fe/Ti sites of ilmenite. According to frontier orbital theory, the chemical activities of SPE are greater than those of SPA. The partial densities of states analysis indicated that the PO—H groups of the collectors could interact with the Ti/Fe atoms of the ilmenite surface to generate a stable four-membered ring. The bonding model of the collector and(104) ilmenite surface showed that the adsorption energy of SPE was higher than that of SPA. Overall, SPE presented a better collecting ability and interaction effect for ilmenite flotation than SPA, and had the potential to replace SPA in the industry.
基金This work was supported by the National Natural Science Foundation of China.
文摘The metastable phase 3c-Fe7S8 with the hexagonal platelet morphology has been prepared by using solvothermal route. The product was characterized by means of X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS). The experiment results show that the as-prepared Fe7S8 is a metastable phase with the hexagonal platelet morphology.
基金supported by the National Natural Science Foundation of China (21620102002, 91422302, 21701198)the Fundamental Research Funds for the Central Universities (17lgjc13, 17lgpy81)
文摘Single-molecule magnets （SMMs） are regarded as promising candidates for ultrahigh-density storage, quantum information processing and molecular spintronics. It is a crucial challenge for chemists to modulate magnetic dynamics of SMMs. Here, we successfully synthesized two 3d-4f polynuclear compounds [Co2Dy（TTTTCl）2（MeOH）]NO3.3MeOH （1） and [Co2Dy（TTTTCl）2 （MeOH）][Co（HTTTTCl）]（NO3）z-2.5MeOH＇2H20 （2）, where H3TTTTCl=2,2＇,2＂-（（（nitrilotris（ethane-2,1-diyl）） tris（azanediyl）） tris（methylene））tris-（4-chlorophenol）. On applying the approach by co-crystallization of bulky diamagnetic moiety, the effective energy barrier enhances from 401 K （1） to 536 K （2）, which are both among the highest d-f heterometallic SMMs.
基金the National Natural Science Foundation of China(21477133,41273134,91326202,21225730)
文摘Technetium-99(~99Tc),largely produced by nuclear fission of ~235U or ~239Pu,is a component of radioactive waste.This study focused on a remediation strategy for the reduction of pertechnetate(Tc O_4^-)by studying its chemical analogue rhenium(Re(VⅡ))to avoid the complication of directly working with radioactive elements.Nanoscale zero-valent iron particles supported on graphene(NZVI/r GOs)from GOs-bound Fe ions were prepared by using a H_2/Ar plasma technique and were applied in the reductive immobilization of perrhenate(Re O_4^-).The experimental results demonstrated that NZVI/r GOs could efficiently remove Re from the aqueous solution,with enhanced reactivity,improved kinetics(50 min to reach equilibrium)and excellent removal capacity(85.77 mg/g).The results of X-ray photoelectron spectroscopy analysis showed that the mechanisms of Re immobilization by NZVI/r GOs included adsorption and reduction,which are significant to the prediction and estimation of the effectiveness of reductive Tc O_4^- by NZVI/r GOs in the natural environment.
