Catalytic wet peroxide oxidation of phenol over Cu/ZSM-5 catalyst
Advancing the chemical engineering fundamentals
Catalysis (T2-13P)
Keywords: Wastewater treatment; Pollutant degradation; CWPO; Catalyst preparation; Cu/ZSM-5; Phenol oxidation; Kinetics; Modeling
Organic compounds, which are extremely toxic and refractory in nature, are common pollutants in many industrial wastewaters. To remove the pollutants there are many remediation technologies, of which only reactive destruction results in the mineralization of the waste. CWAO is an efficient technique to eliminate a variety of organic compounds from wastewater, but the reaction is performed at high operating pressure from 1 to 10 MPa and high temperature from 353 to 473 K, which makes the investment rather costly. But if hydrogen peroxide is used as an oxidant, reaction can be performed under atmospheric pressure and temperature below 323 K on a great number of different catalyst, as example different metals supported on metal oxides, clays, graphite, polymers, and carbon, supported and unsupported metal oxides and so on.
Therefore, in this research heterogeneous CWPO was studied as an organic wastewater treatment technology using phenol as a model compound, because phenol and its derivatives are a common industrial pollutant found in many wastewaters. On of the objectives of this study was to investigate the activity and stability of Cu/ZSM-5 catalyst prepared by direct hydrothermal synthesis.
The kinetic experiments, and activity tests were carried out in stainless steel Parr reactor in batch operation mode at atmospheric pressure and temperature between 50 and 800C. The mass ratio of the active metal component on the zeolite was in the range of 1.62-3.24 wt. %, and the initial concentration of phenol and hydrogen peroxide was 0.01mol dm-3 and 0.1mol dm-3, respectively. A detailed description of the experimental procedure is found elsewhere (Zrnčević and Gomzi, 2005). The catalyst samples (Cu/ZSM-5) were prepared by direct hydrothermal synthesis. Catalyst preparation method was described elsewhere (Maduna Valkaj at al., 2006). Characterization of the catalysts extends to X-ray diffraction (XRD) and scanning electron microscopy (SEM), while the adsorption techniques were used for the measurement of the specific surface area. The stability of the catalyst samples to leaching of the active metal ingredient was verified by atomic absorption of the filtered solution samples.
It was found that the rate of phenol oxidation and hydrogen peroxide decomposition increases with the increase of reaction temperature and concentration of catalytic active material on ZSM-5. The rate of phenol oxidation is almost second order toward the concentration of phenol and first order toward the concentration of H2O2. The rate of H2O2 decomposition is the sum of rates of phenol oxidation and peroxide decomposition.
Reference
Maduna Valkaj, K., Katović, A. and Zrnčević, S. Investigation of the catalytic wet peroxide oxidation of phenol over different types of Cu/ZSM-5 catalyst, J.Hazard.Mat. (in press)
Zrnčević, S. and Gomzi, Z., CWPO: An environmental solution for pollutant removal from wastewater. Ind.Eng.Chem.Res. 44 (2005) 6110-6114.
Presented Wednesday 19, 13:30 to 15:00, in session Catalysis (T2-13P).
