水热合成一锅法制备FePO4-SBA-15及其水热稳定性能

通过两种水热处理方式，即800 oC水汽条件和100 oC沸水处理，考察了一锅法制备的FePO4–SBA-15(OP)的水热稳定性.水热处理前后样品的结构变化通过小角X射线衍射和N2物理吸附表征.研究发现，经水热条件下原位生成FePO4修饰后的OP样品具有良好的水热稳定性，并且FePO4的担载量(5%和40%)对OP样品的水热稳定性几乎没有影响.这与文献报道的金属担载量会影响介孔材料水热稳定性的结果不同.此外，还对比研究了浸渍法制备的FePO4/SBA-15(IMP)和商品SBA-15的水热稳定性.结果表明，各样品水热稳定性由强到弱的顺序是OP>IMP>>SBA-15. OP和IMP样品水热稳定性优于纯硅分子筛SBA-15的原因可能是FePO4保护层能抑制介孔材料在水热环境下的结构塌陷. OP样品水热稳定性较IMP样品好的原因可能主要是由于OP样品中存在稳定的Si–O–Fe键和较多的微孔.

Highly hydrothermally stable FePO4-SBA-15 synthesized using a novel one-pot hydrothermal method

The hydrothermal stability of FePO4–SBA‐15 synthesized using a novel one‐pot hydrothermal method (OP) was systematically investigated using two methods:treatment with pure steam at 800 °C or with boiling water at 100 °C. The structural changes in the samples were monitored using small angle X‐ray diffraction and N2‐physisorption methods. It was found that the hydrothermal stabilities of OP samples remained high and showed little difference over the FePO4‐doping range 5–40 wt%. These results differ from previous reports that the loading of heterogeneous metal at‐oms significantly influences the hydrothermal stability of the host ordered mesoporous material. For comparison, the hydrothermal stabilities of FePO4–SBA‐15 synthesized using an impregnation method (IMP) and commercially obtained SBA‐15 were also studied. The order of the sample hy‐drothermal stabilities was OP>IMP>>SBA‐15. The formed FePO4 protective layers helped to pre‐vent mesostructure degradation during hydrothermal treatment, therefore modified samples showed superior hydrothermal stabilities compared with pure SBA‐15. The superior performance of OP samples over IMP samples is mainly attributed to the formation of stable Si–O–Fe bonds and more micropores in OP samples.