觸媒濕式催化分解DMP之研究

Catalytic Wet Air Decomposition of Dimethyl Phthalate

陳詩韻(Shih-Yun Chen)

指導教授 ： 張慶源

國立臺灣大學/工學院/環境工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.01614

摘要

本研究以濕式氧化法(wet air oxidation, WAO)處理鄰苯二甲酸二甲酯(dimethyl phthalate, DMP)。除研究濕式氧化分解DMP之最適化操作參數外，並添加不同種類之觸媒－Pt/Al2O3及γ-Al2O3以濕式催化分解DMP。
研究結果顯示WAO分解DMP之反應速率效率受到轉速(Nr)、反應溫度(T)、系統壓力(PT)等不同參數影響，其中溫度為主要參數。反應溫度愈高，對DMP降解效果愈明顯。其主要分解程序可分為兩階段式反應: (1)自室溫升溫達反應溫度之期間為DMP之無氧熱解反應，DMP降解為中間產物；(2)氧氣的加入後進行濕式氧化反應，中間產物氧化產生低分子量之羰酸，羰酸再經由氧化分解成CO2及H2O。
添加觸媒進行濕式催化分解反應結果可知，於不同工作氣體環境反應有不同之反應機制，DMP在有氧的環境下(工作氣體為氧、空氣)反應時，觸媒表面活性位置幾乎被O2佔據，此時DMP進行催化濕式氧化分解，升溫至473 K時後其DMP可完全去除，但TOC分解率僅達20%。
若工作氣體僅為N2時，DMP之降解機制主要以無氧裂解及吸附為主。DMP於觸媒催化下無氧裂解形成中間產物吸附於觸媒上之活性位置，並進一步分解。將濕式催化反應後之觸媒進行熱重分析發現，以N2為工作氣體反應後之觸媒之有機物吸附量較以O2為工作氣體多，而γ-Al2O3之吸附量又較Pt/Al2O3為多，Pt/Al2O3能將吸附於觸媒表面之有機物更進一步分解。不論使用何種觸媒皆可有效提升DMP之濕式分解效率。

關鍵字

濕式氧化 ； 濕式催化分解 ； 觸媒 ； 鄰苯二甲酸二甲酯 ； 白金觸媒 ； 氧化鋁

並列摘要

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).
The 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.
The 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.
The 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.

並列關鍵字

catalyst ； Pt/Al2O3、γ-Al2O3 ； wet oxidation (WO) ； wet catalytic decomposition ； dimethyl phthalate (DMP)

參考文獻

57. 盧德笙，「應用磁性吸附劑吸附環境荷爾蒙-以鄰苯二甲酸二甲酯為例」國立台灣大學環境工程學研究所碩士論文，臺北(2006)。

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