| 摘要: | 吸附(濾材)技術已廣泛應用於揮發性有機物(VOCs)之去除，乃一種有
效的控制技術，固定床活性碳回收設備及沸石濃縮轉輪焚化系統技術為業
界經常採用之技術，但實廠上仍面臨一些應用限制。有鑑於此，本研究致
力於改善活性碳及沸石吸附系統之效能，以期提供相關改善建議方法及健
全空氣污染防制技術，為提升空氣品質做出貢獻。於活性碳吸、脫附過程
抑制丁二酮(butanedione, BDO)生成的研究方面，本研究測試5種商用活性
碳、9種改質劑、3種溶劑、多種浸置時間與溫度的處理流程，超過28組以
上的活性碳改質方法。實驗結果顯示使用適當的改質劑、較高的改質劑負
荷、以氮氣作為脫附氣體可有效降低MEK反應生成BDO。證實以改質之活
性碳進行溶劑回收與揮發性有機物控制，初期投資成本雖較高且操作費用
較貴，但可大幅提升系統操作之安全性。此外，在提升沸石濃縮轉輪吸附
大分子均三甲苯性能的研究方面，本研究發現單一種沸石基材吸附劑無法
通用於分子尺寸不同的VOCs，對噴塗製程廢氣的混合性VOCs而言，本研
究整合微孔洞(H-ZSM-5)與中孔洞(MCM-41)兩類沸石串連的工程解決方
案。研究結果指出在含甲苯與均三甲苯兩種VOCs濃度各50 ppm的進流排
氣，單獨使用H-ZSM-5-25沸石的貫穿時間為3.5 min，單獨使用MCM-41-AS
沸石的貫穿時間為6.5 min，串聯兩類型沸石的貫穿時間明顯延長至20.5
min，是單一沸石的3.2倍或5.9倍，實驗結果證實，串聯兩類型沸石組合可
適用於同時含有小分子與大分子的噴塗製程VOCs之有效控制。;Adsorption technologies have been widely used to control the emissions
of volatile organic compounds (VOCs), and it is regarded as an effective way
for VOCs removal. Especially, activated carbon and zeolite are commercially
available for field application. However, they still have some limitations.
Therefore, this study is motivated to improve the performance of adsorption
systems of activated carbon and zeolite. First, methods for inhibiting
butanedione (BDO) formation during activated carbon adsorption-desorption of
methyl ethyl ketone (MEK) were investigated. In total, more than 28 types of
modified activated carbons were extensively examined. The tests included five
types of commercial activated carbons, nine kinds of modifiers, three kinds of
solvents, and a variety of processing time and temperatures. Experimental
results indicated that BDO formation from MEK oxidation could be greatly
inhibited by suitable modifier, high modifier loading, and adopting N2 as
desorption medium. For instance, BDO concentration in the test with raw
activated carbon as adsorbent was 0.123%, and decreased to 0.0115% as
modified activated carbon was applied, indicating that BDO concentration
could be reduced by more than 10 times. Although the capital and running costs
would increase by using modified activated carbon for solvent recovery, the
operational safety can be greatly improved and it is economically feasible. On
the other hand, zeolite adsorption rotor was studied for the enhancement of
mesitylene adsorption. It is found that a rotor with single type of zeolite could
not achieve good removal efficiency due to various VOCs molecular sizes in
the exhausts of spray coating processes. This study hence proposed a possible
engineering solution with the integration of both micropore (H-ZSM-5) and
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mesopore (MCM-41) zeolites. Experimental results indicated that the
breakthrough time with H-ZSM-5-25/MCM-41-AS as adsorbent was greatly
extended to 20.5 min. On the other hand, the breakthrough times were 3.5 and
6.5 min, respectively, when H-ZSM-5 and MCM-41-AS were applied as
adsorbent, respectively, for the gas stream containing 50 ppm toluene and
mesitylene. Obviously, the breakthrough time of the combined zeolite
developed can increase by 3.2 - 5.9 times if compared with individual zeolite. It
is proved that combined H-ZSM-5-25/MCM-41-AS zeolite as adsorbent is
suitable for simultaneous and effective removal of VOCs from spray coating
exhaust. |
