Effect of reaction conditions on the CWAO of phenolic wastewater via supported ceria catalyst

• Main Authors: Chung-ju Lai, 賴重儒
• Other Authors: I-Pin Chen
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/47234771595911820492

碩士 === 嘉南藥理科技大學 === 環境工程與科學系碩士班 === 95 === 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, Ce/γ-Al2O3 was found to be the most active catalyst among the four tested. Using Ce/γ-Al2O3 (Ce content 16.7wt.%) and 180°C, 1.5MPa O2 and 3.0g/L catalyst loading, 1000ppm phenolic solution, 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 Ce/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 Ce/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, various regeneration methods were also tested to identify the most efficient one. The most efficient regeneration method is rinsing the used catalyst with anhydrous alcohol. Under the same condition after 3 hrs, 1000ppm phenolic solution as the optimal one, could attain about 99% phenol conversion and 85% COD removal. This also demonstrates the good durability of the catalyst. Note that the induction period was found in the reaction, which was 4 hrs at 180°C and 1 hrs at 200°C. The effectiveness of various supported ceria catalysts for CWAO of phenol was further demonstrated via BET, XRD, O2-TPD and H2-TPR. XRD analysis reveals that more Ce content corresponds to more CeO2 crystals, but the agglomeration is also higher as to the active sites are reduced. By BET analysis, it was found that the surface area of Ce/γ-Al2O3 has no apparent effect on its catalytic activity. The superior activity of Ce/γ-Al2O3 with 15wt.% Ce content was confirmed by H2-TPR, which showed that 15wt.% Ce/γ-Al2O3 had the highest H2 consumption.