Role of Dissolved Oxygen in Iron Oxidation in Supercritical Water: Insights from Reactive Dynamics Simulations
Role of Dissolved Oxygen in Iron Oxidation in Supercritical Water: Insights from Reactive Dynamics Simulations
复制标题
溶解氧在超临界水中铁氧化中的作用：来自反应动力学模拟的见解
DOI：
10.1021/acs.jpcc.9b01936
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发表时间：
2019-06-20
影响因子：
3.7
通讯作者：
Chen, Min
中科院分区：
文献类型：
--
作者：
Ai, Liqiang;Zhou, Yusi;Chen, Min
充氧处理被认为是一种有效的化学水处理方法，在超临界电厂中得到了广泛的应用。以往的同位素示踪实验报道了溶解氧和超临界水(SCH(2O)O)同时与金属反应，但其原子机理尚未揭示。我们进行了反应动力学模拟，研究了超临界水中溶解氧在铁氧化中的作用。结构分析表明，O-2，(O-xy)优先反应的O将激活表面的Fe原子与Sch(2)O(O-WA)中的O反应，形成Fe-O-XY-Fe-O-WA-H结构。O-XY除了活化Fe外，还具有吸收Sch(2)O解离后产生的质子的作用。溶解O-2的这两种作用导致了O-2促进的Sch(2)O氧化机制。一系列模拟表明，适当的O-2浓度会加速表面保护性氧化层的形成，而过高的O-2浓度可能会导致Fe的破坏性内氧化。温度升高对表面氧化层的形成影响不大，但会增加O-2的内氧化速率。
Oxygenated treatment is considered to be an effective chemical water treatment method and is widely used in supercritical power plants. Previous isotope tracer experiments reported that dissolved oxygen and supercritical water (scH(2)O) react with metals simultaneously, but the atomistic mechanism remains unrevealed. We performed reactive dynamics simulations to investigate the role of dissolved oxygen in iron oxidation in supercritical water. Structural analysis shows that the prior reacted O from O-2, (O-xy) will activate the surface Fe atom to react with the O in scH(2)O (O-wa), resulting in a Fe-O-xy-Fe-O-wa-H structure. Aside from activating Fe, O-xy has another contribution of absorbing the proton generated after the dissociation of scH(2)O. These two roles of dissolved O-2 result in an O-2-boosted scH(2)O oxidation mechanism. A series of simulations indicate that appropriate O-2 concentration will accelerate the formation of the surface protective oxide layer, whereas excessive O-2 concentration might cause destructive internal oxidation of Fe. The increase of temperature has little influence on the formation of the surface oxide layer but will increase the internal oxidation rate of O-2.