陈玉柱,李济吾,蔡伟建.铜锰镧铈复合催化剂的制备及其降解对二甲苯的机制[J].环境科学学报,2021,41(8):3089-3099
铜锰镧铈复合催化剂的制备及其降解对二甲苯的机制
- Preparation of copper-manganese-lanthanum-cerium composite catalyst and its degradation mechanism of p-xylene
- 基金项目：浙江省自然科学基金项目（No.LY20E080003）
- 陈玉柱
- 浙江工商大学环境科学与工程学院, 杭州 310018
- 李济吾
- 浙江工商大学环境科学与工程学院, 杭州 310018
- 蔡伟建
- 浙江工商大学食品与生物工程学院, 杭州 310018
- 摘要：采用溶胶凝胶法制备了镧掺杂的铜锰镧铈催化剂，研究了其对对二甲苯的催化性能.通过BET、SEM、H2-TPR、XRD和XPS等对不同元素比例的催化剂进行表征，探讨了催化剂结构和性能的关系；同时，研究了不同影响因素（初始浓度、空速、O2含量和混合物）对其催化氧化性能的影响；最后，利用FT-IR、XRD和 GC-MS对降解产物进行分析，探究了其催化降解对二甲苯的机理.结果表明，La掺杂增加了催化剂的比表面积和孔体积，以及表面氧含量，抑制了晶体形成，增强了催化活性.Cu-Mn-La-Ce（1：2：1：1）催化剂性能最好，在初始浓度为600 mg·m-3，空速为15000 h-1，20% O2的条件下，其T90为230 ℃.对二甲苯的降解率随着初始浓度、空速的增加而降低，随着O2含量的增加而增加.气流中混入苯提高了对二甲苯的降解率.对二甲苯催化反应后催化剂表面的 O—H、C＝O、C—H和金属—氧键都相应减少，降解中间产物主要为对甲基苯甲醛和对甲基苯甲酸.降解反应涉及MVK机理，对二甲苯先氧化成对甲基苯甲醛，再氧化成对甲基苯甲酸，最终生成CO2、H2O.
- Abstract：The lanthanum-doped copper-manganese-lanthanum-cerium catalyst were prepared by the sol-gel method, and the catalytic performance for p-xylene were evaluated. The catalysts with different element molar ratios were characterized by BET, SEM, H2-TPR, XRD and XPS, and the relationship between catalyst structure and the catalytic performance were discussed. The influence factors (initial concentration, space velocity, O2 content and mixtures) on its catalytic oxidation performance were studied. The degradation products were analyzed by FT-IR, XRD and GC-MS, and the mechanism of its catalytic degradation of p-xylene was explored. The results show that La doping increases the specific surface area and pore volume of the catalyst, increases the surface oxygen content, inhibits crystal formation, and enhances the catalytic activity. The Cu-Mn-La-Ce (1：2：1：1) catalyst has the best performance. Under the conditions of an initial concentration of 600 mg·m-3, a space velocity of 15000 h-1, and 20%O2, its T90 is 230 ℃. The degradation rate of p-xylene decreases with the increasing of initial concentration and space velocity, and increases with the increasing of O2 content. The mixing of benzene in the gas stream can increase the degradation rate of p-xylene. After the p-xylene catalyzed reaction, the O—H, C＝O, C—H and metal-oxygen bonds on the catalyst surface are reduced accordingly. The degradation intermediate products are mainly p-tolualdehyde and p-toluic acid. The degradation reaction involves MVK mechanism, the p-xylene is oxidized to p-tolualdehyde, and then oxidized to p-toluic acid to finally generate CO2 and H2O.
