添加金屬助催化劑之擔體氧化鈰觸媒催化含酚廢水濕式氧化反應之研究

Study on Catalytic Wet Air Oxidation of Phenol by Adding Metal Promoter on Supported Ceria Catalyst

本研究使用初濕含浸法（incipient impregnation），合成添加不同助催化劑之CeO2／γ-Al2O3觸媒，並藉由分析酚轉化率與COD去除率，評估不同觸媒對於含酚廢水濕式氧化反應（CWAO）之催化效能，以篩選出最適合添加之助催化劑，同時對於使用過之觸媒做再生方法評估，以製備活性及耐用性更好之觸媒。本研究所添加之助催化劑包括Mn、Mo、Cr、Fe（II），添加量固定為5wt%，Ce含量則為15wt%。研究結果顯示，添加Mn時，對於1000ppm含酚廢水，在220℃、1.5MPa氧氣分壓及3g／l觸媒添加量下，4hr酚轉化率及COD去除率，分別約在95%及80%左右，催化效果已接近未添加助催化劑之CeO2／γ-Al2O3（15wt%或20wt%鈰）觸媒。在180℃，其他反應條件相同之下，對於觸媒再生之測試，吾人發現添加之觸媒中，再生效率以添加Mn者較為理想，再生方法則以鹽酸再生之處理效能較佳，再生後幾乎完全可以達到原來之活性，顯示添加Mn之擔體鈰觸媒耐用性甚佳。

In this study, we prepared promoter-adding supported ceria catalysts to identify a cost-effective alternative to the pure CeO2 catalyst. By using the incipient impregnation method, the CeO2／γ-Al2O3 catalyst with addition of various promoters （Mn, Mo, Cr, and Fe（Ⅱ）） was tested for CWAO of phenol. Via rate of phenol conversion and COD removal, performance of the catalysts was evaluated to screen for the optimal one. Moreover, various regeneration methods were also tested to identify the most efficient one to prepare an active and durable catalyst. With fixed amount of promoter （5wt%） and Ce species （15wt%）, the results showed that MnO2-CeO2／γ-Al2O3 was the most active one. At the condition of 1000 ppm phenol concentration, 220℃, 1.5 MPa of O2 pressure and 3.0 g／l the catalyst loading, the phenol conversion and COD removal after 4 hrs reaction were 95% and 80%, respectively. As for efficiency of regeneration, it was found that regenerated MnO2-CeO2／γ-Al2O3 had higher performance than the other regenerated catalysts tested. Also note that treating the used catalyst with HCl solution could almost completely recover the MnO2-CeO2／γ-Al2O3 activity, the best one among the other regeneration methods.