Study on preparation of vanadium trioxide by hydrogen reduction
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摘要: 对氢气还原制备V2O3进行了系统研究，通过V-H-O体系中钒还原氧化热力学分析确定不同条件下钒的稳定存在状态，并分析了反应温度和时间对还原脱氧的影响，获得了氢气还原制备三氧化二钒的最佳工艺参数，在最佳条件下可获得钒含量为67.81%的V2O3产品，同时采用X衍射分析揭示了V2O5还原脱氧过程的物相变化规律：氢气还原V2O5是逐级进行的，还原过程中形成中间产物V3O16和V3O7；随着还原程度的不断增加，聚合物逐渐被解离形成V2O3和VO2，最后VO2被全部还原为单一稳定相V2O3。Abstract: In this paper, the preparation of V2O3 by hydrogen reduction was systematically studied. The stable state of vanadium under different conditions was determined by thermodynamic analysis of vanadium redox reactions in V-H-O system. The influence of reaction temperature and time on deoxidation was analyzed, and the optimum reduction conditions were obtained. Under the optimum conditions, the V2O3 product with a vanadium content of 67.81% can be obtained. At the same time, the phase changes of V2O5 during the reduction process were revealed via X-ray diffraction. It shows a stepwise reduction process of V2O5, with the intermediate products of V3O16 and V3O7 formed during the reduction. As the reduction proceeds, the intermediates can be gradually decomposed into V2O3 and VO2. Finally, VO2 is completely reduced into V2O3.
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图 1 标准状态下钒氧化物氢气还原反应的ΔGθ-T关系
Figure 1. Gibbs free energy change (standard) for hydrogen reduction reactions of vanadium oxides at different temperatures
图 2 标准状态下钒氧化反应的ΔGθ-T关系
Figure 2. Gibbs free energy change (standard) for oxidation reactions of vanadium oxides at different temperatures
图 3 V-H-O体系中p(H2O)和T对钒存在形态的影响
Figure 3. Effects of p(H2O) and T on the occurrences of vanadium in V-H-O system
图 4 V-H-O体系中p(O2)和T对钒存在形态的影响
Figure 4. Effects of p(O2) and T on the occurrences of vanadium in V-H-O system
图 7 不同反应温度条件下还原产物XRD图谱
Figure 7. XRD patterns of the products reduced at different temperatures
表 1 五氧化二钒的主要化学成分
Table 1. The main chemical compositions of V2O5
% TV Fe Si K Na S 55.95 0.017 0.080 0.007 0.016 0.013 
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