應用在水煤氣轉移反應之銅/氧化鈰觸媒研究

Copper/Ceria Catalysts for Water-Gas Shift Reaction

胡義亭(Yi-tin Hu)

指導教授 ： 陳炎輝

大同大學/工程學院/化學工程學系所/碩士(2004年)

摘要

以甲醇蒸氣重組產生氫氣的反應中，會產生少量的一氧化碳，而水煤氣轉移反應(Water-Gas Shift Reaction)是目前應用在去除反應中大部分一氧化碳(CO)的方法。本研究是在開發在低溫下(200 ℃~280 ℃)具有高效能去除一氧化碳之銅系觸媒。在本研究中，分別運用二氧化矽(SiO2)為載體，以銅跟鈰當作活性金屬，將不同比例的活性金屬含浸在載體上，再經由500 ℃的高溫鍛燒，經過還原過後的觸媒，在對一氧化碳的去除上，能有最佳的效果。
銅系觸媒是以熱重量分析儀(TGA)、程溫還原儀(TPR)、程溫氧化儀(TPO)、X-ray繞射儀(XRD)、感應耦合電漿原子發射光譜儀(ICP)進行觸媒的特性分析。水煤氣反應是在固定床反應器中進行，其在富含氫氣的情形下，以含少量CO來模擬甲醇蒸氣重組反應後的情形，觸媒在進行反應前，先以氫氣還原，另比較氧化態的活性金屬銅跟還原態的活性金屬銅，在對去除CO的效率上有何差別，並尋找最適的觸媒組成比例。
實驗結果顯示，活性金屬鈰添加在Cu/SiO2載體上增進了金屬的分散性，所得活性金屬銅之粒徑較小。而由TPR的還原波峰圖形可以得知，觸媒中活性金屬銅含量越高，易在載體表面形成大顆粒的氧化銅，且還原溫度會較高，表示觸媒在進行WGSR時，活性越差。經由WGSR中，添加鈰的銅系觸媒，其觸媒活性均比沒有添加鈰的銅系觸媒好；利用SiO2為載體的觸媒，Cu含量到達25 wt%時，在250 ℃下去除CO的百分比能達到將近92％；而沒有添加鈰的觸媒，Cu含量到達25 wt%時，在250 ℃下去除CO的百分比僅能達到75％。

關鍵字

銅/氧化鈰觸媒 ； 水煤氣轉移反應

並列摘要

In the methanol steam-reforming reaction, there are small quantities carbon monoxides, and the water-gas shift reaction is the method which is applies recently to converse large amount of carbon monoxide. This research is to develop, Cu-series catalyst with high performance of removing carbon monoxide at low temperature (200 ℃~280 ℃). In this research, silicon dioxide (SiO2) was used as carrier, treats as the active metal by the Cu and Ce, contains the different proportion active metal impregnated on the carrier, then they were calcined at the high temperature of 500 ℃. After being reduced, the catalysts possessed the best efficiency of removing CO.
The characteristic analyses of the Cu-series catalysts were performed by TGA, TPR, TPO, XRD and ICP. The water-gas shift reaction was carried out in the fixed-bed reaction: under the circumstances of the hydrogen-rich atmosphere, a gas containing small quantity of CO for simulating the trailing gas of fuel cell passed through the reactor, and before the reaction took place, the catalysts were reduced with hydrogen; besides, comparisons of the active metals of oxidization state with the active metals of reduction state were made, so as to find out the differences in efficiencies of removing CO and the optimal proportions of catalysts.
The experimental result showed that the active metal Ce increased on the Cu/SiO2 carrier promoted the metal dispersion and particle diameters of active metal copper was smaller. From the reduction peak diagrams of TPR, it could be known that the higher was the active metals content in the catalyst, the easier was on the carrier surface to from large grains of oxidized copper, and the higher was the reduction temperature, showing that when the catalysts carried out WGSR, the activities were poorer. During WGSR, added ceria in Cu-series catalyst, its catalyst activity had not added the ceria in Cu-series catalyst is better than; Using SiO2 was the support, when the Cu content reached to 25 wt%, the CO removing percentage at 250 ℃ could reach 92%; When has not added the ceria the catalyst, the Cu content reached to 25 wt%, the CO removing percentage at 250 ℃ could reach 75%.

並列關鍵字

Copper/Ceria catalyst ； Water-Gas Shift Reaction

參考文獻

1.P. Selvam, Int. J. Hydrogen Energy 17 (1992) 237.

5.Uehara, I., “R and D Program on Hydrogen Energy in Japan”, Tenth Anniversary Conference of Hydrogen Industry Council. 700 (1992) 4.

6.Shokubai Koza, Kodansya, Catalysis Society of Japan (1985) 130.

7.T. Inui, M. Suehiro, Y. Takegami, J. Japan Petro. Inst. 25 (1982) 63.

8.P.G. Patil, J. Power Source 37 (1992) 171.