HPA/Bi_2WO_6光催化剂的制备及其脱氮性能研究

以Na2WO4·2H2O和Bi(NO3)3·5H2O为原料,通过不同表面活性剂为模板剂对所制备催化剂的形貌进行调控,将调控形貌后的催化剂固载不同种类杂多酸(HPA),再进行超临界流体干燥制得HPA/Bi2WO6光催化剂。并采用X射线衍射(XRD)、紫外-可见漫反射(UV-vis)、扫描电镜(SEM)、比表面积测定仪(BET)对所制备的催化剂进行表征,通过含氮模拟油对固载杂多酸后的催化剂的脱氮性能进行评价。结果表明,十二烷基硫酸钠(SDS)能起到更好的模板导向作用,从而获得由二维纳米片组装成的三维中空花状结构。采用超临界流体萃取干燥技术对催化剂进行提纯干燥,可有效地避免孔塌陷、团聚等现象,进一步增大了催化剂的比表面积,其脱氮效果有了进一步的提高。固载磷钨酸能有效地提高催化剂的表面酸性位点,从而显著提高了催化剂的催化活性,磷钨酸固载量为10%、剂油比为1∶100时、氙灯光照3 h脱氮率可达92.08%。

Preparation of HPA/Bi2WO6 and its photocatalytic properties for denitrification

The HPA/Bi₂WO₆ was prepared with Na₂WO₄·2H₂O, Bi(NO₃)₃·5H₂O and different surfactant templates. The prepared sample was dried by the supercritical fluid drying (SCFD) method. It was characterized with XRD, FT-IR and SEM techniques and N₂ sorption experiment. Its photocatalytic properties were evaluated with denitrification of nitrogen-containing simulated oil as model reaction. It was shown that the sodium dodecyl sulfate (SDS) should be chosen as template. With this template, a highly dispersed, crystalline and active photocatalyst was obtained. This catalyst had a larger specific surface area. The SCFD method effectively decreased pore collapse and particles agglomeration degree, consequently increasing the specific surface area and improving the catalytic performance. Immobilization of H₃PW₁₂O₄₀ on Bi₂WO₆ increased the surface acid sites, and hence the photocatalytic activity. When the H₃PW₁₂O₄₀ loading was 10%, about 92.08% of nitrogen in simulated oil were removed by shining for 3 h with a xenon lamp at the m_catalysts/m_simulated oil ratio of 1:100.