NF3 decomposition in the absence of water over Al2O3, Fe2O3, Co3O4 and NiO, and transition metal oxides （Fe203, CO3O4 and NiO） coated Al2O3 reagents was investigated. The results show that Al2O3 is an active reagent...NF3 decomposition in the absence of water over Al2O3, Fe2O3, Co3O4 and NiO, and transition metal oxides （Fe203, CO3O4 and NiO） coated Al2O3 reagents was investigated. The results show that Al2O3 is an active reagent for NF3 decomposition with 100% conversion lasting for 8.5 h at 400 ℃. Fe203, Co3O4 and NiO coated Al2O3 reagents are superior to bare Al2O3, and 5%Co3O4/Al2O3 has a high reactivity with NF3 full conversion maintaining for 10.5 h. It is suggested that the presence of transition metal oxide is beneficial to the reactivity of Al2O3, and results in a significant enhancement in the fluorination of Al2O3.展开更多
Several Al2O3 samples were prepared by a precipitation method coupled with ultrasonic treatment,and NF3 decomposition without water over Al2O3 reagents is carried out.The effect of preparation parameters of Al2O3 reag...Several Al2O3 samples were prepared by a precipitation method coupled with ultrasonic treatment,and NF3 decomposition without water over Al2O3 reagents is carried out.The effect of preparation parameters of Al2O3 reagents,such as precipitating agents,structure directing agents,and calcining temperatures on their reactivity for NF3 decomposition has been investigated.The results show that NF3 can be decomposed completely at 400-C,and full conversion of NF3 maintains 580 min over the best Al2O3 reagent,calcined at 600-C which was prepared using both PEG-2000 and Tween-60 as structure directing agents,ammonia as a precipitating agent.展开更多
NF3 decomposition over transition metal oxides coated MgO reagents in the absence of water is investigated. The results show that NF3 can be decomposed completely over pure MgO but the time of NF3 steady full conversi...NF3 decomposition over transition metal oxides coated MgO reagents in the absence of water is investigated. The results show that NF3 can be decomposed completely over pure MgO but the time of NF3 steady full conversion kept as short as 80 min, while the reactivities of coated MgO reagents were remarkably enhanced by transition metal oxides, for example the time of NF3 complete conversion over 12%Fe/MgO extended to 380 min. It is suggested that not only an increase in surface area but also a significant enhancement in the fluorination of MgO substrate caused by the surface transition metal oxides result in an improved reactivity of coated MgO reagents for NF3 decomposition.展开更多
The current efficiency for NF3 formation was independent on the current density in the range of 200 to 1,000 mA·cm^2. The average values of NF3 current efficiencies on the BDD （boron-doped diamond） anode with t...The current efficiency for NF3 formation was independent on the current density in the range of 200 to 1,000 mA·cm^2. The average values of NF3 current efficiencies on the BDD （boron-doped diamond） anode with the boron-concentration of 2,500 ppm were 32.3% at 80℃, 63.3% at 100℃ and 59.7% at 120℃. The best current efficiencies for NF3 formation on the BDD anode with boron-concentrations of 2,500, 5,000 and 7,500 ppm were obtained at 100℃ and those were 63.3%, 73.3% and 56.2%, respectively. Although anode effect occurred on the BDD electrodes covered with a part of the surface of the spiculate structure, which had the boron-concentrations higher than 7,500 ppm, it did not take place on the BDD electrodes covered with the surface of diamond structure, even if the BDD electrode had the boron-concentration of 8,000 ppm.展开更多
用密度泛函B3PW91/6-311++G(d,p)方法研究了全氟温室气体NF3与H自由的脱氟反应机理,对反应势能面上各驻点的几何构型进行了全参数优化,并且对所有过渡态进行了确认。为获得更精确的能量,用较高水平QCISD(T)/6-311++G(d,p)//B3PW91/6-311...用密度泛函B3PW91/6-311++G(d,p)方法研究了全氟温室气体NF3与H自由的脱氟反应机理,对反应势能面上各驻点的几何构型进行了全参数优化,并且对所有过渡态进行了确认。为获得更精确的能量,用较高水平QCISD(T)/6-311++G(d,p)//B3PW91/6-311++G(d,p)+ZPE进行了单点能校正。结果表明,NF3可经过两种反应机理脱去一个F原子:即直接抽提机理和加成-消去机理,反应的势垒分别为52.7、70.4和76.5 k J"mol^(-1),直接抽提反应是标题反应的主反应通道。所有反应均为放热反应,裂解产物NF_2+HF相对于反应物的能量为-337.9 k J"mol^(-1)。展开更多
The electronic structure of nitrogen trifluoride was investigated by combining the high-resolution electron momentum spectroscopy with the high-level calculations. The experimental binding energy spectra and the momen...The electronic structure of nitrogen trifluoride was investigated by combining the high-resolution electron momentum spectroscopy with the high-level calculations. The experimental binding energy spectra and the momentum distributions of each orbital were compared with the results of Hartree-Fock, density functional theory （DFT）, and symmetry-adapted- cluster configuration-interaction （SAC-CI） methods. SAC-CI and DFT-B3LYP with the aug-cc-pVTZ basis set can well reproduce the binding energy spectra and the observed momentum distributions of the valence orbitals except 1 a2 and 4e orbitals. It was found that the calculated momentum distributions using DFT-B3LYP are even better than those using the high-level SAC-CI method.展开更多
The temperature dependence of optical and EPR spectra for KZnF3∶Mn2+ crystal is studied by considering the contributions from both the static effect and the vibrational effect.The results are discussed.
基金supported by the National Natural Science Foundation of China (No. 20573089, 20976149)
文摘NF3 decomposition in the absence of water over Al2O3, Fe2O3, Co3O4 and NiO, and transition metal oxides （Fe203, CO3O4 and NiO） coated Al2O3 reagents was investigated. The results show that Al2O3 is an active reagent for NF3 decomposition with 100% conversion lasting for 8.5 h at 400 ℃. Fe203, Co3O4 and NiO coated Al2O3 reagents are superior to bare Al2O3, and 5%Co3O4/Al2O3 has a high reactivity with NF3 full conversion maintaining for 10.5 h. It is suggested that the presence of transition metal oxide is beneficial to the reactivity of Al2O3, and results in a significant enhancement in the fluorination of Al2O3.
基金financially supported by the National Natural Science Foundation of China(No.20976149)
文摘Several Al2O3 samples were prepared by a precipitation method coupled with ultrasonic treatment,and NF3 decomposition without water over Al2O3 reagents is carried out.The effect of preparation parameters of Al2O3 reagents,such as precipitating agents,structure directing agents,and calcining temperatures on their reactivity for NF3 decomposition has been investigated.The results show that NF3 can be decomposed completely at 400-C,and full conversion of NF3 maintains 580 min over the best Al2O3 reagent,calcined at 600-C which was prepared using both PEG-2000 and Tween-60 as structure directing agents,ammonia as a precipitating agent.
基金financially supported by the National Natural Science Foundation of China(No.20976149)
文摘NF3 decomposition over transition metal oxides coated MgO reagents in the absence of water is investigated. The results show that NF3 can be decomposed completely over pure MgO but the time of NF3 steady full conversion kept as short as 80 min, while the reactivities of coated MgO reagents were remarkably enhanced by transition metal oxides, for example the time of NF3 complete conversion over 12%Fe/MgO extended to 380 min. It is suggested that not only an increase in surface area but also a significant enhancement in the fluorination of MgO substrate caused by the surface transition metal oxides result in an improved reactivity of coated MgO reagents for NF3 decomposition.
文摘The current efficiency for NF3 formation was independent on the current density in the range of 200 to 1,000 mA·cm^2. The average values of NF3 current efficiencies on the BDD （boron-doped diamond） anode with the boron-concentration of 2,500 ppm were 32.3% at 80℃, 63.3% at 100℃ and 59.7% at 120℃. The best current efficiencies for NF3 formation on the BDD anode with boron-concentrations of 2,500, 5,000 and 7,500 ppm were obtained at 100℃ and those were 63.3%, 73.3% and 56.2%, respectively. Although anode effect occurred on the BDD electrodes covered with a part of the surface of the spiculate structure, which had the boron-concentrations higher than 7,500 ppm, it did not take place on the BDD electrodes covered with the surface of diamond structure, even if the BDD electrode had the boron-concentration of 8,000 ppm.
文摘用密度泛函B3PW91/6-311++G(d,p)方法研究了全氟温室气体NF3与H自由的脱氟反应机理,对反应势能面上各驻点的几何构型进行了全参数优化,并且对所有过渡态进行了确认。为获得更精确的能量,用较高水平QCISD(T)/6-311++G(d,p)//B3PW91/6-311++G(d,p)+ZPE进行了单点能校正。结果表明,NF3可经过两种反应机理脱去一个F原子:即直接抽提机理和加成-消去机理,反应的势垒分别为52.7、70.4和76.5 k J"mol^(-1),直接抽提反应是标题反应的主反应通道。所有反应均为放热反应,裂解产物NF_2+HF相对于反应物的能量为-337.9 k J"mol^(-1)。
基金supported by the National Natural Science Foundation of China(Grant No.11174175)the Tsinghua University Initiative Scientific Research Program,China
文摘The electronic structure of nitrogen trifluoride was investigated by combining the high-resolution electron momentum spectroscopy with the high-level calculations. The experimental binding energy spectra and the momentum distributions of each orbital were compared with the results of Hartree-Fock, density functional theory （DFT）, and symmetry-adapted- cluster configuration-interaction （SAC-CI） methods. SAC-CI and DFT-B3LYP with the aug-cc-pVTZ basis set can well reproduce the binding energy spectra and the observed momentum distributions of the valence orbitals except 1 a2 and 4e orbitals. It was found that the calculated momentum distributions using DFT-B3LYP are even better than those using the high-level SAC-CI method.
文摘The temperature dependence of optical and EPR spectra for KZnF3∶Mn2+ crystal is studied by considering the contributions from both the static effect and the vibrational effect.The results are discussed.
