Catalytic Wet Air Decomposition of Dimethyl Phthalate
Date Issued
2008
Date
2008
Author(s)
Chen, Shih-Yun
Abstract
This study investigated the treatment of dimethyl phthalate (DMP) via wet air oxidation (WAO) and catalytic decomposition processes. The Pt/Al2O3 and γ- Al2O3 was used as catalyst to enhance the DMP and total organic compound (TOC) decomposition efficiency (ηDMP and ηTOC).he result shows the ηDMP and ηTOC of WAO process are related to rotating speed (Nr), temperature (T) and pressure (PT). The temperature is the key factor of organic compound oxidation via WAO process. To increasing reaction temperature can promote the DMP decomposition. The DMP decomposition via WAO process can divide into two steps: (1) at the temperature rising stage (298 to 483 K), the DMP was pyrolysis without O2, (2) oxidation at 483 K for 3 h, DMP was decomposition into acid intermediates (such as formic acid), CO2 and H2O. he adding of catalyst makes different pathway for the decomposition of DMP. The working gas plays an important role in wet catalytic decomposition. In aerobic catalytic decomposition (working gas as O2, air and mixing gas), the oxygen molecule adsorb on the active site of the catalyst surface and be excited as O* which is active. The DMP and intermediates reacted with O* and decomposed into CO2 and H2O. With the O2 content working gas, the DMP destroyed totally at 473K and removed 20% of TOC. he mechanism of anaerobic wet catalytic decomposition (working gas as N2) is quite different as aerobic processes. The intermediate of pyrolysis can be absorbed by both Pt/Al2O3 and γ-Al2O3 where the ηTOC are 80 and 20%. It indicated that Pt on the γ-Al2O3 surface not only can absorb the pyrolysis intermediate but also further catalyzed the organic decomposition.
Subjects
catalyst
Pt/Al2O3、γ-Al2O3
wet oxidation (WO)
wet catalytic decomposition
dimethyl phthalate (DMP)
Type
thesis
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