擔體氧化鈰觸媒催化含酚廢水濕式氧化反應之研究－－反應條件之影響

An Assessment of the Reaction Conditions for the CWAO of Phenolic Wastewater via Supported Ceria Catalyst

本研究利用含浸法合成不同擔體之CeO2擔體觸媒，測試在不同反應條件對於含酚廢水濕式氧化反應之影響，並以此實驗篩選出最佳擔體觸媒與最適操作條件。研究結果顯示，在所測試擔體（γ-Al2O3、SiO2、TiO2、Active carbon）中，以CeO2/g-Al2O3活性最好，Ce含浸量16.7wt.%、反應溫度180℃、酚濃度1000ppm、觸媒添加量3g/L、氧分壓1.5MPa時，反應4小時之酚轉化率將近40%，COD去除率可達30%；而無添加觸媒之WAO反應4小時酚轉化率僅約為6%，COD去除率約2%，證實添加CeO2/γ-Al2O3 觸媒確實有其催化效能。本研究後續實驗利用此觸媒，經過整體反應效能評估最適操作條件為：Ce含浸量15wt.%、反應溫度200℃、酚濃度1000ppm、觸媒添加量1g/L、氧分壓1.5MPa，反應2小時可達酚轉化率95%，COD去除率70%。此外本試驗亦有誘導期之現象產生，由實驗發現反應溫度由180℃提升至200℃可使誘導期由4小時縮減至1小時。

In this study, we prepared several supported ceria catalysts （supporter: γ-Al2O3, SiO2, TiO2 and Active carbon） via impregnation method for the CWAO of phenol to assess performance of supported ceria catalyst. By the rate of phenol conversion and the efficacy of COD removal, CeO2/γ-Al2O3 was found to be the most active catalyst among the four tested. At 180°C, O2 partial pressure of 1.5MPa and 3.0g/L CeO2/γ-Al2O3 （Ce content 16.7wt.%） catalyst loading, with phenol concentration of 1000ppm, could attain about 40% phenol conversion and 30% COD removal, after 4 hrs reaction. Under the same conditions, effectiveness of reaction without catalyst was only about 6% phenol conversion and 2% COD removal, showing that the CeO2/γ-Al2O3 catalyst is a feasible alternative to CeO2 for the CWAO of phenol because it remains an effective catalyst and is cheaper to be prepared. The optimal reaction condition of CWAO of phenolic wastewater using CeO2/γ-Al2O3 catalyst with 15wt.% Ce content is as follows: 200°C, 1.5MPa O2 and 1.0g/L catalyst loading. With the optimal condition, 1000ppm phenolic solution, after 2 hrs reaction, could attain about 95% phenol conversion and 70% COD removal. Moreover, the induction period was found in the reaction, which was 4 hrs at 180°C and 1 hrs at 200°C.