以金屬氧化物吸附劑處理毒性氫化物氣體之研究

Abstract

氫化物氣體為半導體及光電廠廣泛使用之製程氣體，因其具有毒性、自燃性及高度易燃性，故未使用完之殘氣需於製程機台近端予以妥善處理，以免造成危害。乾式化學吸附法為較佳之處理方式，但吸附容量尚待進一步提升，並減少有害固體廢棄物的產生量。本研究以安全性高及具多孔性的γ-Al2O3及中孔矽材為基材，於其上擔載活性金屬氧化物作為吸附劑，並針對具不同結構之氫化物--SiH4與PH3，探討具高吸附量之吸附劑成份組成，並找出影響吸附容量之主要因子。 研究結果發現，對於SiH4氣體，以共沈澱法添加CeO2或ZnO促進劑於CuO-Al2O3中，所合成之吸附劑吸附容量最高，達35.7 mg-SiH4/g-ads，主要原因在於CeO2或 ZnO同時具有結構促進劑及吸附活性等兩項功能，使該吸附劑對SiH4之吸附效果最佳。對於PH3，則以比表面積達680 m2/g之中孔矽材擔載CuO所合成之吸附劑，其吸附效果較佳；其中，以 Cu擔載量為24 wt.%時(命名為Cu-24/ LSBA-15)，可達最高30.8 mg-PH3/g-ads。主要原因在於其擁有高比表面積與與適當孔洞大小，使大量的活性金屬氧化物可以分散良好。 此外，Cu-24/ LSBA-15吸附劑之再生性能優越，對PH3吸附經五次再生使用後，總吸附量達135 mg-PH3/g-ads，為Cu/γ-Al2O3的兩倍，更為文獻中無法再生使用的Cu/zeolite吸附劑之4.5倍；故Cu-24/LSBA-15吸附劑同時擁有高吸附量及較佳再生能力等兩種優異之吸附性能，將能大幅減少吸附劑之使用量，降低有害固體廢棄物固化掩埋之體積。

The hydride gases of phosphine (PH3) and silane (SiH4) are commonly used for semiconductor and optoelectronic industries. They must be immediately abated by the local scrubbers because of their high toxicity. In this study, copper oxide (CuO) loaded on the alumina (Al2O3) and meso-porous silica adsorbents are prepared and tested to investigate the possibility of both hydride gas removal and sorbent regeneration. Test results showed that the mixed oxides (CuO-CeO2/Al2O3, CuO-ZnO/Al2O3) adsorbents prepared by using the co-precipitation method had greater SiH4 adsorption capacities than other adsorbents used in this study. The addition of ZnO or CeO2 in the CuO-Al2O3 system both improved the structure and adsorption activity of adsorbents, which led to a high adsorption capacity. CuO loaded on the meso-porous silica adsorbents had better performance for PH3 removal than other adsorbents. When the Cu loading amount was 24 wt.% ( named Cu-24/LSBA-15), the adsorption capacity of meso-porous silica adsorbent reached the maximum value of 30.8 mg-PH3/g-ads. Cu-24/LSBA-15 was also capable of removing SiH4 effectively and its adsorption capacity was 22.6 mg- SiH4/g-ads. The Cu-24/LSBA-15 had good performance for simultaneous adsorption of PH3 and SiH4. In addition, the cumulative adsorption capacity of Cu-24/LSBA-15 for 5 regeneration cycles was 135 mg-PH3/g-ads, which was about twice of that of the Cu/γ-Al2O3 adsorbent, and 4.5 times of that of the Cu/zeolite adsorbent shown in the literature. The results indicated that the simple preparation method of Cu loaded on meso-porous silica has a high potential for hydride gas removals as well as hazardous waste reduction.