利用沸石及金屬有機架構物觸媒催化及吸附全氟化物之研發

Development for Catalytic Decomposition and Absorption of Perfluorinated Compounds Using Zeolites and MOFs

張敬嚴(Ching-Yen Chang)

指導教授 ： 林錕松

元智大學/工程學院/化學工程與材料科學學系/碩士(2009年)

https://doi.org/10.6838/YZU.2009.00338

摘要

隨著高科技蓬勃發展，應用於高科技產業的高暖化潛勢溫室氣體－全氟化物（PFCs），已引起全球高度關注。台灣半導體業每年使用全氟化物超過300公噸，對於全球暖化與溫室效可能會直接造成影響。半導體業在乾蝕刻及化學氣相層積反應腔清洗製程中須使用全氟化物氣體，而全氟化物對溫室效應的影響遠高過CO2數千倍，對環境與生態造成莫大的衝擊。因此，本研究主要目的是利用高活性/高比表面積之奈米級沸石觸媒、SBA-15觸媒及金屬有機架構物（MOFs）來催化分解及常溫吸附溫室氣體全氟化物（CF4、SF6、NF3、C3F8及C4F8共五種），以取得最佳反應條件及反應機制。另外，亦利用貴重儀器，例如：XRD、FE-SEM、TEM、TGA及FTIR，深入瞭解沸石觸媒、SBA-15觸媒及MOFs觸媒之反應機制，以利提升去除全氟化物效果，以及後續經濟效益評估或基本工程設計之參考。本研究所選定之吸附劑及觸媒分別為Cu-BTC及MIL-53-Al MOFs，自行合成SBA-15觸媒及Y、ZSM-5、Beta沸石觸媒。FE-SEM解析可知Y、ZSM-5及Beta皆為顆粒狀結晶物，大小約在60-100 nm；FTIR之結果顯示MOFs觸媒對CF4有較佳的催化分解能力，但對SF6之催化效果有限；而沸石觸媒中Y、ZSM-5及Beta三種沸石對SF6皆有催化效果，催化分解時產物包括SOF2、SO2F2及SOF4，去除率以ZSM-5沸石最好（100%），其次為Beta沸石（75%）及Y沸石（45%）；在CF4、C3F8及C4F8的催化分解反應中，僅ZSM-5有催化分解效果，其產物為CO2，ZSM-5催化CF4、C3F8及C4F8的反應中，去除效率依序為CF4（80%）＞C3F8（60%）＞C4F8（25%）；但在NF3催化反應中，Y、ZSM-5及Beta三種沸石皆有很強的催化分解能力，去除率皆達100%。因沸石有其獨特的孔道及孔徑大小且有較佳的分子選擇性，利用沸石當吸附劑，在室溫下吸附C3F8及C4F8結果顯示Y、ZSM-5及Beta三種沸石皆可以吸附C3F8及C4F8，吸附能力依序為Beta＞ZSM-5＞Y。
本研究也自行合成SBA-15觸媒催化PFCs，由FE-SEM分析，可以看到SBA-15類似鍊鎖的構造，TEM分析中，可以清楚發現SBA-15特殊的蜂窩狀結構，TGA的分析中，溫度由25℃升溫到1000℃時，重量損失約2%，顯示SBA-15之熱穩定性高。不同酸性濃度合成之SBA-15會產生不同構造，酸性濃度越高，可合成出較完整SBA-15。將SBA-15與全氟化物氣體作催化分解實驗，結果顯示SBA-15只對NF3有催化效果，但去除率僅15％較不理想；為了提升SBA-15對NF3去除率，本研究利用硝酸鎳及硝酸銅以含浸法進行改質，硝酸鎳及硝酸銅濃度為0.10 wt% ~ 0.50 wt%，結果顯示，利用硝酸鎳改質後的SBA-15去除率達65%；而利用硝酸銅改質後的SBA-15去除率達90%。由SBA-15催化分解PFCs之動力學分析中，改質後SBA-15反應速率常數K值較未改質時大，此表示利用硝酸鎳及硝酸銅改質可增加SBA-15之活性。

關鍵字

全氟化物（PFCs）、溫室氣體、沸石、金屬有機架構物（MOFs）、SBA-15、催化分解、吸附。

並列摘要

Recently, severalty of perfluorinated-compounds(PFCs) have been widely used in a variety of industrial, commercial, and consumer applications. Among the different kinds of PFCs are extremely resistant to biological/chemical degradation and exhibit toxicological effects potentially for humans and wide life. In Taiwan, over 300 tons per year (TPY) of PFCs are extensively used for etching silicon wafers or cleaning chambers in chemical vapor deposition processes. These compounds are excellent absorbers of infrared radiation and therefore aggravate global warming. Thus, the main objectives were to understand the catalytical decompose behavior and absorption analysis of PFCs (e.g. CF4, SF6, NF3, C3F8 and C4F8) through the zeolites (Y, ZSM-5 and Beta), SBA-15 and MOFs (Cu-BTC and MIL-53-Al). Structures of zeolites, SBA-15 and MOFs, morphological observations, crystallinity, fine structures has also been conchrded with FE-SEM, XRD, TEM, TGA and FTIR techniques. The optimal operation, conversion, mechanism, basic engineering design, and economic estimation of a lab-scale catalytic performance is already through these above mention experimental techicel data analysis. The FTIR spectra has been analyzed to observe the decompose behavior of PFCs for the zeolites and MOFs. The MOFs has an excellent decomposed behavior for CF4 than SF6 through FTIR. On the other hand, zeolites has performed substantial capabilities for SF6 decomposition to produce SOF2, SO2F2, and SOF4. According to the FE-SEM images the morphologies of the zeolites is consisted as pellet powder with the particle sizes of 60~100 nm. Among the three different types of zeolites, the removed rate of SF6 has been performed excellent through ZSM-5 (100%) than Beta zeolite (75%) and Y zeolite (45%). Moreover, ZSM-5 has only the decomposition capabilities of CF4, C3F8, and C4F8 to produces CO2 with the removal rate of CF4 (80%) > C3F8 (60%) > C4F8 (25%). Similarly, zeolites has stronger decomposition ability to decompose NF3 with the removal rate reach up to 100%. Moreover, zeolites has consisted with absorption C3F8 and C4F8, respectively included the absorptive capacity in an order of Beta>ZSM-5>Y.
This study also synthesized the SBA-15 catalyst to decompose PFCs. The FE-SEM image reveals that SBA-15 material consists of many ropelike domains with an uniform size around 1 μm. TEM images show the hexagonal array of uniform channels with the typical honeycomb appearance of SBA-15 materials. TGA measurements of SBA-15 is indicated that the weight loss about 2% when the temperature from 25℃ until 1000℃. The TGA measurements result has represented the higher thermal stability of SBA-15.There were different structure of SBA-15 that synthesis different acid. The acidic density is higher may synthesize complete SBA-15.The removal rate of 15% is obtained for the decomposition of NF3 through SBA-15. On the other hand, the SBA-15 support material obtains through impregnation method with different aqueous solution of nickel nitrate and nickel cupric at a specific concentration. The aqueous solution of nickel nitrate and nickel cupric was 0.25% and 0.50%. The removal rate was 90% of nickel cupric and 65% of nickel nitrate.

並列關鍵字

Perfluorocompounds(PFCs), Greenhouse gases, Zeolites, MOFs, SBA-15, Decomposition, Absorption.

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