金屬(Rh, Ni)附載於不同載體(CeO2, BZDy)對乙醇氧化蒸氣重組反應影響
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2016
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本篇論文利用銠(10 wt% Rh)及鎳(30 wt% Ni)金屬分別附載於具有氧空缺之氧化鈰(CeO2)及具有親水性之鋯酸鋇摻雜鏑(Dy-doped BaZrO3, BZDy)，於300℃環境下進行乙醇氧化蒸氣重組反應，探討氧氣量多寡以及乙醇及水比例不同對催化劑之影響。實驗以PVP法及含浸法合成顆粒狀及粉末狀催化劑，進行物化性質鑑定以及催化反應活性。催化劑之晶相以及確認金屬存在、含量鑑定、還原性質、表面物種組成分別利用X光粉末繞射儀(XRD)、能量散射光譜(EDX)、程序升溫還原反應(TPR)、X光光電子能譜儀(XPS)鑑定以及利用原位漫反射紅外線傅立葉轉換光譜(in situ DRIFTS)推測反應路徑及中間產物。在實驗結果中，隨著氧氣量以及乙醇及水比例增加，提升乙醇轉換效率，乙醛選擇率下降並有助於氫氣生成，在過高氧氣條件下促進二氧化碳生成以及氫氣減少形成水。從四個催化劑(Rh,Ni)/(CeO2,BZDy)可以發現，銠及鎳金屬皆具有斷乙醇C-C鍵之特性並生成氫氣、甲烷、一氧化碳、二氧化碳。除此之外，鎳金屬可以斷來自水的OH鍵促使氫氣產率提升，並具有含碳溶解性，因此生成之碳氫產物與氫氣反應生成甲烷，具有較高之甲烷選擇率。以具有親氧性之氧化鈰以及親水性之鋯酸鋇摻雜鏑為載體之催化劑在高氧化境下皆具有高氫氣產率。最後，鎳金屬催化劑在乙醇比水1:7時，C/O ratio為0.8之條件下，有最好的氫氣產率140%。
The present work systematically examined oxidative steam reforming of ethanol (OSRE) on oxygen-active CeO2 and hydrophilic Dy-doped BaZrO3 (BZDy) supported Rh (10%) and Ni (30%) catalysts in various ethanol/oxygen/steam compositions at 300oC to investigate the environmental (oxygen and steam ratios) and catalyst (metal and oxide) effects on OSRE. The catalysts were initially synthesized by PVP and impregnation methods and characterized by powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) for their crystallinity, chemical composition and oxidation states. The catalytic products were analyzed by gas chromagraphy (GC) and the key intermediates were identified by diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). The experimental results with varied oxygen and steam compositions found that increases of oxygen or steam ratios can efficiently enhance the ethanol conversion and block the dehydrogenation pathway to reduce the acetaldehyde selectivity and improve hydrogen yield. The influence of oxygen is more significant than that of steam. Also, higher oxygen and steam ratios will promote full oxidation to raise the CO2 selectivity and diminish hydrogen yield. The experiments on the four catalysts (Rh,Ni)/(CeO2,BZDy) concluded that both Rh and Ni are highly active for C-C bond breaking of ethanol and produce mainly H2, CH4, CO and CO2. Additionally, Ni can better cleavage O-H bond to utilize the hydrogen from water for hydrogen production. Also, Ni can easily dissolve carbon to boost the high CH4 selectivity. The oxygen-active CeO2 and hydrophilic BZDy are highly sensitivity to the oxygen and steam ratios, but the effects from the two oxides are quite similar. Finally, the optimized condition correspond to Ni-based catalysts in ethanol/steam ratio of 1/7 and C/O ratio of 0.8 and give the best hydrogen yield at 140%.
The present work systematically examined oxidative steam reforming of ethanol (OSRE) on oxygen-active CeO2 and hydrophilic Dy-doped BaZrO3 (BZDy) supported Rh (10%) and Ni (30%) catalysts in various ethanol/oxygen/steam compositions at 300oC to investigate the environmental (oxygen and steam ratios) and catalyst (metal and oxide) effects on OSRE. The catalysts were initially synthesized by PVP and impregnation methods and characterized by powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) for their crystallinity, chemical composition and oxidation states. The catalytic products were analyzed by gas chromagraphy (GC) and the key intermediates were identified by diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). The experimental results with varied oxygen and steam compositions found that increases of oxygen or steam ratios can efficiently enhance the ethanol conversion and block the dehydrogenation pathway to reduce the acetaldehyde selectivity and improve hydrogen yield. The influence of oxygen is more significant than that of steam. Also, higher oxygen and steam ratios will promote full oxidation to raise the CO2 selectivity and diminish hydrogen yield. The experiments on the four catalysts (Rh,Ni)/(CeO2,BZDy) concluded that both Rh and Ni are highly active for C-C bond breaking of ethanol and produce mainly H2, CH4, CO and CO2. Additionally, Ni can better cleavage O-H bond to utilize the hydrogen from water for hydrogen production. Also, Ni can easily dissolve carbon to boost the high CH4 selectivity. The oxygen-active CeO2 and hydrophilic BZDy are highly sensitivity to the oxygen and steam ratios, but the effects from the two oxides are quite similar. Finally, the optimized condition correspond to Ni-based catalysts in ethanol/steam ratio of 1/7 and C/O ratio of 0.8 and give the best hydrogen yield at 140%.
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乙醇氧化蒸氣重組反應, 氧化鈰, 鈣鈦礦結構, 銠, 鎳, oxidative steam reforming of ethanol, cerium oxide, perovskite, rhodium, nickle