熔融盐法制备消除挥发性有机物的氧化铁担载铂纳米催化剂的研究

Based on the following reasons: (i) the significant demand of controlling volatile organic compounds (VOC) emissions, (ii) the urgent need of developing the novel pathways for the efficient use of Saline Lake resources, (iii) rich reserves and low toxicity of iron ore, and (iv) molten salt synthesis with the environmentally friendly characteristic, simple process, and the advantage of easy industrial production, we herein take the inorganic salts of lithium, sodium, potassium and magnesium as reaction medium, and try to fabricate FeOy supported Pt nanoparticles catalysts via the in situ molten salt method. We will investigate the effects of preparation conditions (such as the type and composition of molten salt, precursor, molten salt/precursor weight ratio, calcination temperature and keeping time, etc.) on physicochemical properties (the distribution, size and surface defect of Pt nanoparticles, morphology, crystal plane and phase of FeOy, interface matching and interaction of Pt-FeOy) of the Pt/FeOy nanocatalysts. The catalytic performance of Pt/FeOy will be evaluated for the complete oxidation of typical VOC. Based on the results of various characterization, we will elucidate the “structure-performance” relationship, clarify the involved catalytic mechanisms, and establish the catalytic kinetic models. It is envisioned that the results obtained in the proposed project will provide a useful guidance on molten salt synthesis of highly efficient catalysts for the removal of VOC, and a novel pathway for the efficient use of Saline Lake resources.

基于控制挥发性有机物（VOC）排放的重大需求，开发盐湖资源高效利用新途径的迫切需要，铁矿的丰富储存量和低毒性，以及熔融盐法环境友好、工艺简单和易于实现工业化生产等优点，我们创新性地提出以锂、钠、钾和镁等无机盐为媒介，采用熔融盐法，原位制备FeOy担载Pt纳米颗粒催化剂。系统研究熔融盐种类及组成、前驱体、熔融盐与前驱体的质量比、焙烧温度和保温时间等制备条件对原位担载制得的Pt/FeOy纳米催化剂物化性质（例如Pt纳米颗粒的落位、粒径和表面缺陷，FeOy的形貌、晶面和晶相，特别是Pt和FeOy界面匹配和相互作用力）的影响，评价其对VOC氧化的催化性能，揭示构效关系，探明Pt/FeOy纳米催化剂对VOC氧化的催化作用机制，建立反应动力学模型。研究结果可为发展高效消除VOC催化剂的熔融盐制备技术奠定扎实的实验和理论基础，为盐湖资源高效利用提供新的途径。

基于控制VOC排放的重大需求，开发盐湖资源高效利用新途径的迫切需要，以及熔融盐法环境友好等优点，我们提出以钠、钾等无机盐为媒介，采用熔融盐法，原位制备负载型Pt基催化剂。以Fe(NO3)3和 Pt(NH3)4(NO3)2为金属源，制得0‒0.30 wt% Pt/Fe2O3。0.22 wt% Pt/Fe2O3在空速为40000 mL/(g h)的条件下，对二甲苯氧化具有更好的催化活性，T50%和T90%分别为212和223 oC，这与铂粒子高度分散和低温还原性有关。熔融盐体系和焙烧温度对活性有一定的影响。以Ti(SO4)2和H2PtCl6为金属源，制得0-4.14 wt% Pt/TiO2。Pt的引入促进了TiO2表面晶格氧的还原，使还原峰向低温方向移动。在空速为40000 mL/(g h)的条件下，活性随着Pt负载量的不断增加而提高，丙酮在4.14 wt% Pt/TiO2上的T50%和T90%分别为172和195 oC，在0.05 wt% Pt/TiO2上的T50%和T90%分别为236和274 oC。掺杂Ce、V和W后，0.05 wt% Pt/TiO2催化氧化丙酮的活性得到提高。0.57 wt% CeO2-0.05 wt% Pt/TiO2相比于V-或W-掺杂的催化剂，具有较高的表面吸附氧浓度，其催化活性较好，丙酮的T50%和T90%分别为212和245 oC。此外，其抗水、抗CO2和抗硫性能也得到了改善。当反应气中分别存在20 vol%水蒸气、10 vol% CO2或者100 ppm SO2时，丙酮转化率仍可达85%，70%和60%。抗硫性能的改善归因于Ce、V或W的掺杂增加了表面酸性位的数量，抑制了酸性SO2的吸附；Ce2(SO4)3或VOSO4的形成消耗了部分SO2，抑制了Ti(SO4)2或TiOSO4的生成，而WO3改性的催化剂则抑制了SO2的氧化反应。丙酮在0.57 wt% CeO2-0.05 wt% Pt/TiO2上完全氧化的过程包括：丙酮分子吸附在催化剂的表面，然后部分氧化为甲酸盐物种；随着反应温度的不断升高，甲酸盐物种变为碳酸盐物种，最后被完全氧化为CO2和H2O。上述研究结果可为发展高效消除VOC催化剂的熔融盐制备技术奠定扎实的实验和理论基础，为盐湖资源高效利用提供新的途径。