氟磷酸钙真空碳热还原反应机理的分子动力学研究

发布时间：2018-05-13 09:10

本文选题：氟磷酸钙 + 真空　；参考：《真空科学与技术学报》2017年01期

【摘要】：由于在高温下缺乏实验检测方法,反应的中间产物寿命短、浓度低,很难通过实验手段获得准确的分析数据,本文采用从头算分子动力学模拟方法对氟磷酸钙真空碳热还原的反应机理进行研究。结果表明:在1723K下,Ca_5(PO_4)_3F与C摩尔比为1∶12时,Ca_5(PO_4)_3F中的P原子态密度(PDOS)比较接近单个P原子态密度,C原子与O原子具有明显的共价键特征,还原效果最好;PDOS结果显示在费米能级附近,Ca原子与P原子、C原子没有形成共价键,故没有出现中间产物Ca_3P_2和CaC_2;由此推测氟磷酸钙碳热还原反应机理,首先C与Ca5(PO4)3F中PO3-4反应,不断脱去PO3-4中的O原子,PO3-4→PO_3~(2-)→PO_2~-→PO→P,然后C与O~(2-)结合生成CO,Ca~(2+)分别与O~(2-)、F~-结合生成CaO、CaF_2。
[Abstract]:Due to the lack of experimental detection method at high temperature, the intermediate product of the reaction has a short life and low concentration, so it is difficult to obtain accurate analytical data by experimental means. The mechanism of vacuum carbothermal reduction of calcium fluorophosphate was studied by ab initio molecular dynamics simulation. The results show that at 1723K, when the molar ratio of C to C is 1:12, the density of states (PDOS) of P atom is closer to that of a single P atom, and the density of states of C atom and O atom has obvious covalent bond characteristics. The results showed that there was no covalent bond between Ca atom and C atom of P atom near Fermi level, so there were no intermediate products Ca_3P_2 and CaC2, so the mechanism of thermal reduction of calcium fluorophosphate was inferred. Firstly, C reacted with PO3-4 in Ca5(PO4)3F. The O atom in PO3-4 is removed from the O atom (PO3-4 / PO3 / T / 2), and then C and O (2) are combined to form COG / CaN 2) and the O ~ (2 / O ~ (2) O ~ (3 +) is combined with O ~ (2 +) to form CaF2 / Caf2, respectively, and then C / O ~ (2) is combined with O ~ (2 +) to form CaF2).
【作者单位】：文山学院化学与工程学院;昆明理工大学云南省有色金属真空冶金重点实验室;云南师范大学化学化工学院;
【分类号】：TQ126.3

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