Synthesis of Magnetic Binary Metal Oxide Catalyst and Its Application on Wet Air Oxidation Process for Decomposition of 2,4-Diaminotoluene
Date Issued
2010
Date
2010
Author(s)
Huang, Yu-Wen
Abstract
This study focuses on the synthesis of magnetic binary metal oxide catalyst (Pt/TiO2-ZrO2/SiO2/Fe3O4, Pt/T-ZSM) and the modified of magnetic catalyst (Pt/ZrO2/Fe3O4, Pt/ZM). These magnetic particles are used in the catalytic wet air oxidation process (CWAO) for the decomposition of 2,4-diaminotoluene (TDA). The performances for the treatment of TDA via WAO and CWAO systems are investigated.
The characteristics of Pt/ZM and Pt/T-ZSM prepared in this work are with BET specific surface areas of 86.04 and 111.32 m2 g-1, saturation magnetizations of 13.14 and 6.08 emu g-1 respectively, contents of platinum on the catalyst surface of 2.59 and 1.75 wt.%, diameters of particles are smaller than 100 nm. Further, the superparamagnetic properties of these catalyst are still held after the use in CWAO process.
In WAO system, the dominant operating parameter is temperature (T). The energy supply for the decomposition of contaminants increases with the increasing temperature. To ensure efficient oxidation, of course, the pressure of oxidant (PO2) should be sufficient for the reaction.
After three hours reaction time (t) in WAO, as T = 523 K, PO2 = 1.38 MPa, stirring speed Nr = 500 rpm and initial concentration of TDA (CTDAo) = 500 mg L-1,the decomposition efficiency of TDA (ηTDA) and mineralization efficiency of TOC (ηTOC) are 99 and 75%, respectively. It shows that TDA is nearly decomposed at the condition of high temperature with enough oxidant. For the case with 0.5 g Pt/T-ZSM in CWAO, at the same conditions as above,ηTDA and ηTOC are 99 and 83%, respectively. In the same reaction conditions with 0.5 g Pt/ZM, ηTDA and ηTOC are 99 and 95%, respectively. Thus, as the magnetic catalysts are employed in the WAO system, the CWAO process can lower the activation energy of reaction, promoting the reaction rate and giving a higher ηTOC at the same reaction time. Comparing the performances per mass of Pt for the two catalysts, the ratio of values of ηTOC of Pt/T-ZSM to Pt/ZM is 1.29, indicating the oxidation ability of binary metal oxide catalysts Pt/T-ZSM is better than that of single metal oxide catalyst of Pt/ZM.
Subjects
Binary metal oxide
magnetic catalyst
catalytic wet air oxidation (CWAO)
2,4-Diaminotoluene
superparamagnetic
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