质子响应型铱配合物催化氨硼烷水解放氢研究

发布时间：2018-06-03 21:50

  本文选题：氨硼烷 + 质子响应型配合物　； 参考：《大连理工大学》2015年硕士论文

【摘要】：随着当前化石燃料的急剧消耗及能源需求的日益增加,探寻新的替代能源迫在眉睫。氢能作为高效清洁的绿色新能源备受关注,而安全高效的储运氢气又是推广氢能应用、发展氢经济的关键。氨硼烷具有超高的含氢密度(19.6 wt%),成为目前热门研究的储氢材料。在其多种放氢方式中,催化氨硼烷水解制氢具有放氢速率快,放氢量大,反应温度低且反应不产生有毒副产物等优势。多相催化氨硼烷水解制氢已有相当程度的研究,然而放氢速率距实际应用仍有差距；且催化剂用量大、回收困难,失去多相催化的优势。与多相催化相比,均相催化的反应活性中心分散均匀,催化效率及选择性高。但是均相催化的氨硼烷水解制氢却鲜有报道,其中的一个重要原因是缺少易溶于水的稳定的催化剂。本文针对目前存在的问题,合成了一系列的水溶性配合物,并用于均相催化氨硼烷水解制氢反应。对配合物的催化活性及催化反应机理进行了探索性研究。1)合成了一系列含羟基的联吡啶、联嘧啶双齿配体,并与[Cp*Ir(OH2)3]SO4或[Cp*IrCl2]2反应合成了相应的四种质子响应型铱配合物。由于羟基官能团的存在,该类配合物展示出良好的水溶性和稳定性。2)将该系列质子响应型配合物应用于均相催化氨硼烷水解制氢的反应中,并考察了温度、催化剂量、pH值以及氨硼烷浓度对催化反应的影响。综合比较,最终确定的最优反应条件为：反应温度65℃,催化剂用量1 μmol,溶液pH为9,氨硼烷浓度为0.1 mol/L。3)本文还研究了压力因素对反应的影响。使催化水解放氢反应在密闭的反应釜中进行。最终发现即使在压力条件下,该类催化剂仍能催化氨硼烷水解,并完全释放3当量的氢气。3小时内所有氨硼烷底物(3.6 mmol)都完全转化,TON值达到3600。4)在最优反应条件下,筛选出催化效果最好的催化剂为[Cp*Ir(6,6'-(OH)2-bpy)-(OH2)]S04。该催化剂于最优反应条件下,可在0.7 h内完全释放3当量的氢气,初始转化频率(TOF值)达5496 h-1(最初5 min)。根据实验结果及前人的研究,我们提出了设想的氨硼烷水解制氢的催化机理。在水分子参与下,质子响应型配合物上的羟基官能团与金属中心协调作用催化氨硼烷脱氢。
[Abstract]:With the rapid consumption of fossil fuels and the increasing demand for energy, it is urgent to explore new alternative energy sources. Hydrogen energy, as a new green energy source with high efficiency and cleanliness, has attracted much attention, and safe and efficient storage and transportation of hydrogen is the key to promote the application of hydrogen energy and develop hydrogen economy. Aminoborane, with a high hydrogen density of 19.6 wtcm, has become a hot research material for hydrogen storage. The catalytic hydrolysis of ammonioborane to produce hydrogen has the advantages of fast hydrogen release rate, large amount of hydrogen release, low reaction temperature and no toxic by-products. Heterogeneous catalytic hydrolysis of ammonium-borane to produce hydrogen has been studied to a considerable extent, but the rate of hydrogen release is still far from the practical application, and the amount of catalyst is large, the recovery is difficult, and the advantage of heterogeneous catalysis is lost. Compared with heterogeneous catalysis, the active centers of homogeneous catalytic reaction are uniform, and the catalytic efficiency and selectivity are higher. However, homogeneous catalytic hydrolysis of aminoborane to produce hydrogen is rarely reported, and one of the important reasons is the lack of stable catalyst which is easily soluble in water. In this paper, a series of water-soluble complexes were synthesized in allusion to the existing problems, and were used for homogeneous catalytic hydrolysis of aminoborane to produce hydrogen. A series of hydroxy bipyridine and bipyrimidine didentate ligands were synthesized and reacted with [Cp*Ir(OH2)3] SO4 or [Cp*IrCl2] 2 to synthesize four proton responsive iridium complexes. Due to the existence of hydroxyl functional groups, the complexes exhibit good water solubility and stability. 2) the series of proton responsive complexes were used in homogeneous catalytic hydrolysis of aminoborane to produce hydrogen, and the temperature was investigated. The effect of the amount of catalyst pH and the concentration of ammonia borane on the catalytic reaction. The optimum reaction conditions were as follows: reaction temperature 65 鈩，

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