Ni-V负载酸改性焙烧高岭土的制备、表征及光催化性能

Preparation and Characterization of Ni-V Supported Calcination Kaolins Modified with H2SO4 and Their Photocatalytic Performance

摘要:

高岭土在773 K焙烧，经H2SO4溶液处理后作为载体，在不同n(Ni2+)):n(V5+)溶液中浸渍制备了Ni-V负载酸改性焙烧高岭土样品，并利用X射线衍射（XRD）、傅立叶变换红外光谱（FTIR）、吡啶吸附FTIR（Py-FTIR）和紫外-可见光漫反射光谱（UV-Vis）技术对样品的性质进行了表征。在高压汞灯下，以甲醇（CH3OH）常压转化制二甲醚（CH3OCH3）为模型反应，评价了Ni-V负载样品的光催化活性。结果表明，所制备的样品对CH3OH的光催化转化有活性。当处理焙烧高岭土的酸溶液中H2SO4质量分数为40%、浸渍液n(Ni2+)):n(V5+)=2:8、样品焙烧温度为773 K时，催化剂样品对CH3OH转化反应活性最高，CH3OH转化率为30.5%，CH3OCH3选择性为76.2%。样品Ni-V的协同作用和表面酸性是促进CH3OH光催化转化制CH3OCH3反应活性的重要因素。

Abstract:

Kaolins were calcined at 773 K and then treated with H2SO4 solution to obtain modified kaolin supports. Ni-V supported modified kaolins were prepared via an impregnating process in different n(Ni2+)):n(V5+) impregnation solution, and the obtained samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), pyridine adsorption in FTIR (Py-FTIR) and ultraviolet-visible spectroscopy (UV-vis) techniques, respectively. Methanol conversion to dimethyl ether was used as a model reaction to evaluate sample activity under high-pressure mercury lamp irradiation. The results showed that the as-obtained samples had photocatalytic activity to methanol conversion. The methanol conversion and dimethyl ether selectivity could be up to 30.5% and 76.2%, respectively, when the Ni-V with n(Ni2+):n(V5+)=2:8 loading calcined kaolin leached with 40% H2SO4 followed by calcination at 773 K was used as catalyst. The synergy of Ni-V elements and the sample acidity played important roles in accelerating the photocatalytic conversion of methanol.