探討金屬氧化物的支撐物對乙醇蒸氣重組反應的影響

Abstract

本篇論文中，我們將 Rh、Ru兩種金屬分別附著在三種不同金屬氧化支撐上，來進行氧化乙醇蒸氣重組反應，而這三種氧化支撐物分別為，氧化鈰 (CeO2)、參雜了Dy的鈣鈦礦結構(Dy-doped BaZrO3) 和鈣鈦礦結構(BaZrO3)。透過XRD、EDX、TPR探討金屬與金屬氧化物是否符合。在乙醇蒸氣重組實驗中，使用不同氧氣量的條件下乙醇對氧氣比例為2~0.4、不同乙醇與水莫爾比例(1:1、1:3、1:5、1:7、1:10)及不同的溫度(300℃~600℃)來進行實驗。在催化劑中金屬的部分，我們發現Rh、Ru有助於C-C鍵斷裂，產生CO與CO2。在催化劑中支撐物的部分，我們選擇了螢石結構(CeO2)、鈣鈦礦結構(Dy-doped BaZrO3) 和鈣鈦礦結構(BaZrO3)有效的利用環境中氧氣與水，其中氧化鈰對氧具有高活性，在乙醇與莫爾比例為1:3，乙醇對氧氣比例在0.61，氫氣產率為72%，而鈣鈦礦結構(Dy-doped BaZrO3)與鈣鈦礦結構(BaZrO3)可以有效利用水，促使催化劑效能提升及氫氣產率提升，在乙醇與莫爾比例為1:10，乙醇對氧氣比例在0.58，氫氣產率為86%，所以可以看出BZDy及BZO比在氧的氧化鈰下具有更好的在乙醇氧化蒸氣重組反應中具有重要的影響。在乙醇蒸氣反應後，將催化劑進行XRD、EDX、TPO鑑定，在XRD鑑定與反應前並沒有差異，在EDX、TPO發現鈣鈦礦結構(Dy-doped BaZrO3)含碳量大於氧化鈰(CeO2) ，但在長時間反應中卻能維持高乙醇轉換及氫氣產率。

In this present work, we studied oxidative steam reforming of ethanol (OSRE) on the catalysts of Rh and Ru supported on CeO2, Dy-doped BaZrO3 (BZDy) and BaZrO3 (BZO). The samples were initially characterized by XRD,EDX and TPR and followed by the reforming experiments with various C/O Ratio: 2 to 0.4, Ethanol/ H2O molar ratios (1:1,1:3,1:5,1:7,1;10) and temperatures (300℃~600℃) to elucidate the effects from oxygen and steamon OSRE. Both Rh and Ru are well known for their superior capability of C-C bond cleavage and the main products from OSRE are CO and CO2 for all sample. Supports of CeO2, BZDy and BZO, on the other hand, have different specialties for oxygen and steam. CeO2 is highly active for oxygen and further improves OSRE performance at higher oxygen contents. Its best H2 yield 72% in ethanol/H2O=1:3, C/O Ratio: 0.61. BZDy and BZO have excellent activity for steam and enhance the hydrogen production in OSRE at higher steam contents. Its best good H2 yield 86% in ethanol/H2O=1:10, C/O Ratio: 0.58. Additionally, the enhancement from steam in BZDy and BZO-based catalysts are better than that from oxygen in CeO2-related catalysts, indicating that steam plays an more important role to improve OSRE performance. The post-experimental samples were also examined by XRD,EDX and TPO to identify the stability of those samples. The EDX and TPO results found that BZDy and BZO-based materials have more carbon deposition though their long-term stability were as good as CeO2-based catalysts.