Preparation Of Cu Series Of Catalysts And Degradation Of Organic Pollutant By CWAO Process

Because of the severe operation conditions, wet air oxidation (WAO), a technology for the treatment of hazardous, toxic and high concentrated organic wastewater under the high temperature (125-320℃) and pressure (0.5-20MPa), was not widely used. However, as it could decrease reaction temperature and pressure, shorten reaction time and raise oxidation efficiency, catalytic wet oxidation technique (CWAO) has gained great attention in recent years. In addition, the development of catalysts with high activity and stability has become the hotspot of research and the key point of CWAO application. So, this paper focused on the average mental oxide catalysts in CWAO.Firstly, a series of heterogeneous copper catalysts mounted on aγ-alumina was produced in soakage method, and then it was used in the CWAO process of phenol aqueous solutions to find out the reason of Cu leaching, the results indicated that the key factors of Cu leaching are reaction and low pH value. In order to improve this situation, the Cu-Zn-Al catalysts were produced through the co-sedimentation method. In the experiments, L9(34) orthogonal experiment was designed based on the consideration that the mixture proportion was the main factor, and the optimal proportion of Cu/Zn/A finally obtained was 2:2:3. Under this situation, together with oxygen pressure of 3Mpa at 180°C and 60 min CWAO reaction, the CODCr removal rate reached 97.6% and copper leaching quantum hit 12.5mg/L.After that, the Cu-Zn-Al catalysts were used in the CWAO of H-acid aqueous solution under 3Mpa oxygen pressure at 150°C for 30min. In order to get the optimal condition of the preparation of Cu-Zn-Al catalyst, the L25(56) orthogonal experiments were designed with Cu/Zn/Al mixture proportion, the aging time, the calcining temperature and the calcining time as the main factors, and optimization was also carried out setting COD removal rate and Cu2+ leaching as the standard. What the results indicated was that the optimized scheme of the Cu/Zn/Al mixture proportion, the aging time, the calcining temperature and the calcining time were 4:2:1, 18 hours,700℃and 12 hours respectively followed the standard of COD removal rate; and it was1:5:5, 21 hours,900℃and 8 hours followed the standard of Cu2+ leaching.The preparation of the Cu-Zn catalyst supported on zeolite was also studied in the CWAO of H-acid aqueous solution. The Cu-Zn/ZSM-5 catalysts and Cu-Zn/HY catalysts with different Cu-Zn loading prepared by incipient wetness impregnation, together with the Cu-Zn-Al catalyst prepared by co-precipitation were used in the CWAO process (150℃, 3MPa, 30min, 600r/min) of the H-acid aqueous solution. It showed that compared with Cu-Zn-Al catalyst, the Cu-Zn catalysts supported on zeolite had better activity of COD removal rate of H-acid aqueous solution, the reason of this is that active composites of the Cu-Zn catalyst supported on zeolite were dispersed uniformly better than that of the catalyst prepared by co-precipitation. The optimal concentration of CuO and ZnO supported on the ZSM-5 zeolite were 3.41% and 1.16% respectively; while it was 4.06% and 1.38% on the HY zeolite.The kinetic investigation of the WAO of H-acid aqueous solution was finally studied. The results showed that the two-phase first-order kinetic model could fit both the WAO and CWAO of H-acid well. According to the calculation of the active energies, it found that the main function of the Cu-Zn catalysts supported on zeolite was mainly performed on the first phase of reaction, in which the big molecules were decomposed into smaller ones. Additionally, compared with HY zeolite, the ZSM-5 zeolite was confirmed as the better supporter for the Cu-Zn catalyst in the CWAO of H-acid aqueous solution.