Ce-MCM-41分子筛用于臭氧氧化对氯苯甲酸的活性评价

Synthesis of cerium-doped MCM-41 for ozonation of p-chlorobenzoic acid

通过水热法合成了铈掺杂MCM-41(Ce-MCM-41)介孔分子筛,并将其用于臭氧氧化水中对氯苯甲酸(p-CBA).小角X射线衍射(XRD)、氮气吸附-脱附(BET)、紫外可见漫反射光谱(UV-Vis DRS)、透射电镜(TEM)表征结果表明,铈成功进入MCM-41分子筛骨架,以正四面体形式存在,且Ce-MCM-41保持了纯硅MCM-41有序的介孔结构,具有较高的比表面积;铈的掺杂显著提高MCM-41催化臭氧氧化对氯苯甲酸的活性,反应60 min后,TOC去除率由MCM-41的63%提高到86%(Si/Ce=60),而单独臭氧氧化仅为52%;铈的溶出仅为0.085 mg.L-1,较同样负载量的铈负载Ce/MCM-41的溶出(0.44 mg.L-1)有较大减少.催化剂重复使用3次后仍保持较高的活性,这表明Ce-MCM-41具有较好的活性和稳定性,是一种有前景的臭氧氧化催化剂.

Cerium-doped MCM-41（Ce-MCM-41） was prepared by a hydrothermal method and its catalytic activity for ozonation of p-chlorobenzoic acid（p-CBA） in aqueous solution was studied.Ce-MCM-41 was characterized by low angle X-ray powder diffraction（XRD）,nitrogen adsorption-desorption（BET）,ultraviolet-visible diffuse reflection spectrum（UV-Vis DRS） and transmission electron microscopy（TEM）.The results showed that the material retained a highly ordered mesopore structure of pure silica MCM-41 and had a high surface area.Cerium was incorporated into the framework of MCM-41,locating at tetrahedrally coordinated sites.Ce-MCM-41 significantly improved the effect of ozone oxidation.After 60 min reaction time,TOC removal rate was 63% with MCM-41,86% with Ce-MCM-41（Si/Ce=60）,while only 52% with O3 alone.Besides,Ce-MCM-41 had much less cerium leaching（0.085 mg·L-1） compared with that of Ce/MCM-41（0.44 mg·L-1）.After being used for three times,TOC removal rate decreased only by 5%,while p-CBA removal rate kept nearly constant.Ce-MCM-41 is a promising catalyst for ozonation process.