催化湿式氧化法降解水中的β-萘酚

Degradation of β-Naphthol by Catalytic Wet Air Oxidation

采用催化湿式氧化法降解β-萘酚,制备了一系列MnOx/nano-TiO2催化剂,对其制备条件、反应条件及催化剂的稳定性进行了研究,同时对催化剂进行了X射线衍射(XRD)、X射线光电子能谱(XPS)及程序升温还原(TPR)等表征.结果表明,Mn负载量过高时,高分散的MnO2和Mn2O3聚集形成相应的晶相,导致了β-萘酚COD去除率的降低;焙烧温度过高时,可能是因为形成较多活性较差的Mn2O3,MnO2和Mn2O3之间的电子传递作用被削弱,造成COD去除率的降低;催化剂使用6次后COD去除率略微降低可能是和对应的衍射峰峰强度下降有关.当Mn负载量(质量分数)为4%、焙烧温度为450℃时所制备的MnOx/nano-TiO2催化剂活性较好,其在反应温度为110℃、反应总压力为0.5 MPa的条件下催化β-萘酚降解时COD去除率可达96.4%.该催化剂重复使用6次后β-萘酚COD去除率仍可达92.4%.采用原子吸收光谱(AAS)分别测定50、80、110及150℃时反应后溶液中Mn的溶出量,均低于9.3 mg·L-1,催化剂稳定性较好.根据文献对β-萘酚的降解路径进行了推测.

A series of MnOx/nano-TiO2catalysts were prepared and their application in degradation of β-naphthol by catalytic wet air oxidation（CWAO） was investigated.The catalysts preparation conditions,reaction conditions and its stability were tested.The catalysts had been characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS） and temperature-programmed reduction（TPR） measurements.The results showed that the decrease of the COD removal for the degradation of β-naphthol at high Mn loading was due to the aggregation of the highly dispersed Mn species and the formation of the correlated crystals.The decline of the COD removal at high calcination temperature was probably attributed to the weak electron transfer between Mn2 O3 and MnO2 and the formation of the inactive Mn2 O3.The COD removal had been falling slightly when the catalyst was used 6 times,and this was likely related to the decrease of the diffraction peaks.The catalyst had a high activity when the Mn loading（mass fraction） was 4% and the calcination temperature was 450℃.The COD removal was up to 96.4% at 110℃ and 0.5 MPa with this catalyst.The COD removal of 92.4% could be obtained with the MnOx/nano-TiO2 catalyst was recycled 6 times.The Mn leaching at 50,80,110 and 150℃ were all less than 9.3 mg·L^-1 by means of Atomic Absorption Spectroscopy（AAS）.The probable degradation pathway was proposed according to some publications.