氧化鋯支撐過渡金屬催化劑對乙醇蒸氣重組與氧化蒸氣重組反應的研究
Abstract
本研究主要是製備Co、Ni、Cu、Ru、Rh、Pd、Ag、Ir、Pd、Au支撐於ZrO2上的催化劑，於乙醇蒸氣重組反應(SR)與氧化乙醇蒸氣重組反應(OSR)時，系統地檢視與比較催化劑的反應趨勢以及機構。
首先，催化劑使用加入PVP(polyvinylpyrrolidone)做為分散劑的含浸法(impregnation)製備，能夠降低催化劑的粒子大小以及增加催化劑的表面積。乙醇重組的實驗包含SR與OSR反應，分別使用四種流量觀測─、N2 78、N2 8、air 100、air 10 sccm。反應溫度於600、550、500、450、400 oC以搭載TCD與FID的氣相層析儀(GC)分別偵測氣態以及液態的產物。對於單一催化劑而言，比較不同反應條件的結果可以發現，溫度越高以及通入越多的O2，能得到更多的H2產率以及乙醇轉換率。在同樣反應條件下比較不同催化劑之間的趨勢，可以發現Rh、Ru、Ir有最好的效能以及最佳的H2產率。這個結果也能與理論計算結論相符，理論計算主要是比較各個催化步驟的能障(barrier)。結果顯示：(1)Ru 、Rh、Ir為脫氫步驟(dehydrogenation)；(2)Co、Ni、Pd、Pt為脫水步驟(dehydration)；(3)Cu、Ag、Au為氧化步驟(oxidation)。對應到產物的趨勢分別為：(1)具有最高的H2產率與C1產物(CO、CO2、CH4)產率、(2)具有最多的C2H4、(3)具有最多的氧化產物(CH3CHO、C2H5COOH)。
The catalysts of Co、Ni、Cu、Ru、Rh、Pd、Ag、Ir、Pd, and Au supported on ZrO2 have been extensively studied for ethanol steam reforming (SR) and oxidative steam reforming (OSR). The experimental observation has also been systematically examined and compared to elucidate the trend of catalysts and reaction mechanism. Initially, these catalysts have been prepared by the impregnation method with PVP (Polyvinylpyrrolidone) dispersant to reduce the particle size and increase the surface area of the catalysts. The reforming experiments, including SR and OSR, are operated in 4 different atmospheres, air 100, air 10, N2 78 and N2 8 sccm, and products are detected at 600, 550, 500, 450 and 400 oC by gas chromatography (GC) with TCD (for gas products) and FID (for liquid products) detectors. Comparing the reforming efficiency in different conditions on a single catalyst, a higher temperature and O2 gas flow results in a better H2 yield and ethanol conversion. Comparing different reformers under identical catalytic condition, the Rh, Ru and Ir show the best performance with the highest H2 yield despite their conversion efficiencies of ethanol are similar to other catalysts. The observation is also compared with previous calculations and we conclude three main reaction routes: dehydrogenation (Ru, Rh and Ir), dehydration (Co, Ni, Pd, Pt) and oxidation (Cu, Ag and Au), which lead to the highest yields of H2 (or C1 products of CO, CO2 and CH4), C2H4 and oxidative products (acetaldehyde and acetic acid), respectively.
The catalysts of Co、Ni、Cu、Ru、Rh、Pd、Ag、Ir、Pd, and Au supported on ZrO2 have been extensively studied for ethanol steam reforming (SR) and oxidative steam reforming (OSR). The experimental observation has also been systematically examined and compared to elucidate the trend of catalysts and reaction mechanism. Initially, these catalysts have been prepared by the impregnation method with PVP (Polyvinylpyrrolidone) dispersant to reduce the particle size and increase the surface area of the catalysts. The reforming experiments, including SR and OSR, are operated in 4 different atmospheres, air 100, air 10, N2 78 and N2 8 sccm, and products are detected at 600, 550, 500, 450 and 400 oC by gas chromatography (GC) with TCD (for gas products) and FID (for liquid products) detectors. Comparing the reforming efficiency in different conditions on a single catalyst, a higher temperature and O2 gas flow results in a better H2 yield and ethanol conversion. Comparing different reformers under identical catalytic condition, the Rh, Ru and Ir show the best performance with the highest H2 yield despite their conversion efficiencies of ethanol are similar to other catalysts. The observation is also compared with previous calculations and we conclude three main reaction routes: dehydrogenation (Ru, Rh and Ir), dehydration (Co, Ni, Pd, Pt) and oxidation (Cu, Ag and Au), which lead to the highest yields of H2 (or C1 products of CO, CO2 and CH4), C2H4 and oxidative products (acetaldehyde and acetic acid), respectively.
Description
Keywords
乙醇重組, 氧化蒸氣重組, 氫能, 蒸氣重組, ethanol reforming, oxidative steam reforming, hydrogen fuel, steam reforming