摘要 本研究以共沈澱法製備具有不同Mg/Al比例及不同Ni負載量的hydrotalcite先驅物Ni/HT(x)，經高溫煅燒製得觸媒Ni/HTc(x)。利用X光繞射光譜(XRD)、全表面積測定 (BET) 、X-光電子光譜儀 (XPS) 、氫程溫脫附 (H2-TPD) 、氫程溫還原 (H2-TPR) 對觸媒的物理結構及表面性質做鑑定分析。藉由CH4/CO2重組反應測試，探討不同煅燒溫度、還原溫度、Mg/Al比例、Ni負載量及反應溫度之影響，並進行長時間反應穩定性測試，觀察上述之不同變因對觸媒壽命期之影響，並以程溫氫化反應(H2-TPSR)分析觸媒表面積碳，探討觸媒積碳阻抗的能力。 Ni/HTc(x)於800℃煅燒具有高表面積(125 m2/g以上)，原觸媒先驅物Ni/HT(x)的hydrotalcite層狀結構經高溫煅燒瓦解形成Mg-Al-O共氧化物，隨著煅燒溫度上升，NiO與MgO逐漸形成固溶。Ni/HTc(x)觸媒不易還原，所需的還原溫度較傳統觸媒Ni/γ-Al2O3及Ni/SiO2高出釵h，且隨著煅燒溫度和Mg/Al比例的增加而增加，此外XPS表面組成分析發現Ni/(Mg+Al)莫耳比隨著煅燒溫度上升而下降，進一步證實NiO和MgO確實形成固溶，增加NiO-MgO之間的作用力。 CH4/CO2重組反應結果知CO2轉化率皆高於CH4轉化率，且CO/H2比值介於1.0~1.2之間。RWGS反應是主要的副反應，同時亦發生蒸氣重組反應，使CO/H2比值趨近於理論值1。CH4及CO2轉化率隨Ni負載量、還原及反應溫度上升而增加；隨煅燒溫度及Mg/Al比上升而減小。CH4/CO2重組反應結果以800℃煅燒，500℃還原，Mg/Al比3，8%Ni負載量，700℃反應溫度條件下的8%Ni/HTc(3)觸媒有較好的穩定性。8%Ni/HTc(3)與8%Ni/HTc(3)im(含浸法製備)、8%Ni/γ-Al2O3及8%Ni/SiO2觸媒進行CH4/CO2重組反應比較下，8%Ni/HTc(3)觸媒有最佳穩定性，H2-TPD計算得8%Ni/HTc(3)有最佳分散度，H2-TPSR亦發現8%Ni/HTc(3)觸媒有最佳的積碳阻抗。 In this study,we prepared different Mg/Al ratios and Ni loading precursor by coprecipitation method,and then calcined at high temperature to prepare Ni/HTc(x) catalysts. XRD 、BET、XPS、H2-TPR、H2-TPD were used to study the structure and surface properties. The effect of different calcination temperature、reducing temperature、Mg/Al ratios、Ni loading and reaction temperature was studied by CH4/CO2 reforming.H2-TPSR was used to study coking resistance of catalyst. Ni/HT(x) has the same structure with hydrotalcite,after calcined at high temperature,the layer stuucture was collased and became Mg-Al-O mixed-oxides,the surface also increased. As the calcined temperature increased NiO and MgO became solid solution. It is hard to reduce Ni/HTc(x) catalyst,and reducing temperature is higher than Ni/γ-Al2O3 and Ni/SiO2 catalyst. XPS found that Ni/(Mg+Al) ratio reduce as calcination temperature increase,furthre prove NiO and MgO were formed solid solution. In CH4/CO2 reformimg we found that 8%Ni/HTc(3) catalyst ,calcined at 800℃ ,reduced at 500℃ , Mg/Al ratio is 3,and 700℃ reaction temperature had the best stability than 8%Ni/γ-Al2O3,8%Ni/SiO2. H2-TPSR also found that 8%Ni/HTc(3) had best coking resistance.
