低浓度苯系物在室温下的MnOx/Al2O3催化O3氧化

采用固定床连续流动反应器,研究在室温下MnOx/Al2O3催化剂催化臭氧(O3)氧化.结果表明,在室温下,MnOx/Al2O3催化剂具有良好的催化O3分解和催化臭氧氧化苯系物的性能,Mn的最佳负载量为5%.当入口O3和苯系物浓度分别为70,15 mg/m3时,苯、甲苯、对二甲苯和O3的转化率分别为75%,84%,88%,90%.随着入口O3浓度的升高,苯系物转化率先升高然后基本不变,而O3转化率略有下降;随着入口苯系物浓度的升高,苯系物转化率明显降低,O3转化率略有下降.苯系物及O3转化率皆随催化反应时间的延长而缓慢降低.苯系物催化氧化反应中生成的芳香醛、芳香酸和甲酸等中间产物在催化剂表面的堆积是导致催化剂活性降低的主要原因.

MnOx/Al2O3 catalyzed ozonation for low-concentration BTX removal at room temperature

Catalytic oxidation of low-concentration benzene, toluene and p-xylene (BTX mixture) with ozone over MnOx/Al2O3 catalyst was investigated in a fixed-bed flow reactor at room temperature. MnOx/Al2O3 catalyst significantly promoted decomposition of O3 and ozonation of low-concentration BTX. The optimal Mn loading amount was 5%. With inlet O3 and BTX concentration maintained at 70 and 15 mg/m3, the conversions of benzene, toluene, p-xylene and O3 reached 75%, 84%, 88% and 90%, respectively. The BTX conversion firstly increased and then leveled off with the increase of inlet O3 concentration, while the O3 conversion slightly decreased. The conversions of both BTX and O3 decreased with the increase of inlet BTX concentration. Catalyst deactivation occured as the reaction proceeded, which can be attributed to the buildup of organic intermediates such as aromatic aldehyde, aromatic acid and formic acid over catalyst surface during the catalytic oxidation process.