摘要
硼烷氨化合物 (NH3BH3, ammonia borane, AB) 為一高含氫化合物，由其化學結構式可知H原子佔整體重量的19.6 wt.%，在常溫常壓下為一安定之白色固體粉末，可藉由 (A) 直接加熱裂解 (>500oC) 或是 (B) 加入觸媒催化再進行熱裂解使其釋氫。在Part-A部分，我們首先合成SBA-15、MCM-41中孔洞材料並進行分析鑑定，接著將AB:中孔洞材料以重量比例1:1進行摻合形成AB/SBA-15、AB/MCM-41複合物，再利用TGA、DSC與ASAP進行進行熱性質分析與鑑定，由實驗結果可知AB與SBA-15、MCM-41摻合後，有較低的釋氫溫度，同時降低borazine和diborane副產物的生成，但提高了NH3的釋出。 在Part-B中，我們合成Fe-Ni等莫耳比 [Fe:Ni = 1:1] 的合金奈米粒子，並以不同重量摻合比例將 Fe-Ni 合金奈米粒子擔載於中孔洞材料SBA-15載體上，形成Fe-Ni/SBAs觸媒。接著我們在常溫常壓下對AB水溶液進行觸媒催化釋氫研究，探討不同重量摻合比例的觸媒和反應溫度 (30、40、50 和 60 oC) 等變因對釋氫反應速率及活化能 (Ea) 的影響。根據實驗結果可知：在30 oC、0.2 wt% AB水溶液下，以不同重量摻合比例的Fe-Ni/SBAs觸媒催化釋氫，其釋氫反應速率呈現先升後降的趨勢，其中以Fe-Ni-5/SBA觸媒之釋氫速率最大，根據 Arrhenius equation 計算後，可知其Ea約為75 kJ mol-1，優於其他不同重量摻合比例的Fe-Ni/SBAs觸媒。
並列摘要
In this study, part A, we report the thermal decomposition behavior of neat ammonia borane (AB) and AB embedded in SBA-15 and MCM-41 silica scaffolds. We show that embedding AB in SBA-15 and MCM-41 results in a lower hydrogen release temperature, decreases in the borazine and diborane release quantities, and an increase in the ammonia release quantity while the compounds are heated from room temperature to 250oC. These phenomena are attributed to the followings: (1) the Lewis base property of the “–O－” groups of the silica scaffolds, leading to the formation of silica-O﹕→ BH3–NH3 coordination bonding and the loosening of the H3B←:NH3 coordination bonding; and (2) the reduction of AB intermolecular hydrogen bonding when AB molecules are confined and form small nanoparticles in the mesoporous of the scaffolds, which have lower AB intermolecular interactions than in the large neat AB particles. We also prepared an unsupported iron-nickel (Fe-Ni) alloy and several Fe-Ni alloy deposited on SBA-15 (Santa Barbara Amorphous-15) supports (Fe-Ni/SBA) with various Fe-Ni contents for the catalysis of the AB hydrolysis for hydrogen generation. By maintaining a constant concentration of Fe-Ni in the AB aqueous solutions, we investigate the influence of the SBA-15 support on the Fe-Ni catalytic activity in the AB hydrolysis reaction. The SBA-15 support helps disperse the Fe-Ni alloy particles on its surface, which consequently improves the catalytic activity of the Fe-Ni. However, the presence of SBA-15 particles in the aqueous solution also retards the migration of the AB molecules in solution toward the Fe-Ni catalysts, increasing the induction time of the AB hydrolysis reaction. Therefore, there is an optimal Fe-Ni content in Fe-Ni/SBA for the catalysis of the AB hydrolysis reaction.