摘要
氢能作为一种清洁高效的能源载体，可有效解决化石燃料带来的环境污染问题。甲酸（HCOOH，FA）是一种无毒的液态化学储氢材料，具有安全稳定、合成简单且含氢量高（4.4 wt%）等优点。在催化剂作用下，FA可以选择性发生快速脱氢反应，且脱氢后可用二氧化碳加氢反应进行再生。因此，开发低成本、高性能的催化剂是FA商业化应用的前提。
本文在文献调研的基础上，设计研制了3-氨丙基三乙氧基硅烷（C9H23NO3Si，APTS）改性的不同载体负载PdCoNi基催化剂，详细研究它们在甲酸钠（HCOONa，SF）/ FA体系中催化FA脱氢的性能与机理。
首先，本文制备了APTS改性的三维片层状TiO2(B)作为催化剂载体，并负载上PdCoNi金属纳米颗粒（NPs），以增强活性组分PdCoNi NPs的催化活性。研究结果表明，APTS的添加能在TiO2表面上修饰氨基（-NH2），合适的APTS 与TiO2配比能得到性能更为优异的催化剂Pd0.6Co0.2Ni0.2/NH2-Si-TiO2。该催化剂在室温下的初始转换频率TOF inital为397 mol H2∙mol metal-1∙h-1（此后简写h-1），表观活化能Eα为49.92 kJ∙mol-1。分析表明，TiO2(B)载体经APTS修饰后，能抑制PdCoNi NPs的团聚，减小NPs尺寸，且不会影响Co、Ni对Pd的电子转移，同时-NH2增加了催化剂与HCOO−接触的机会，从而大幅提升催化活性。
其次，本文将APTS改性的含氮空心碳球（C Ball）用作FA脱氢催化剂的载体，成功制备了PdCoNi/N-Si-C Ball催化剂。对比研究表明，在无载体的情况下，APTS的添加就能显著增强PdCoNi NPs的催化活性，而APTS改性载体后负载PdCoNi NPs，其催化活性可获得进一步的提升。通过优化APTS添加量和金属配比，所研制的Pd0.8Co0.1Ni0.1/N-Si-C Ball具有100 %氢气选择性和良好的循环稳定性，在室温下的TOF inital达到了745 h-1，Eα为39.50 kJ∙mol-1。研究表明，APTS 在C Ball上掺杂了吡咯N，既不影响载体结构又能避免生成极端大颗粒，且当Pd 含量为80 at%时催化剂性能最佳，并能有效保护部分Co、Ni不受腐蚀，从而提升催化剂稳定性。
最后，本文制备了APTS改性含氮纳米片（CN）负载的PdCoNi催化剂。分析表明，APTS与CN结合只形成吡咯N的掺杂（N-CN），并不会影响CN中原有的吡啶N和石墨N比例。N-CN作为载体组分负载NPs，能诱导形成超细、单分散、类二维的PdCoNi NPs，有效增加了催化活性位点和反应活性组分占比。与CN相比，N-CN具备了一定程度的疏水性，且不会影响Pd、Co、Ni相互之间的电子转移。优化配比制备的Pd0.6Co0.2Ni0.2/N-CN具有高度的催化脱氢选择
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性，在室温下的TOF initial达到了1249.0 h-1，是无APTS改性的Pd0.6Co0.2Ni0.2/CN 催化剂的6倍以上，Eα为20.04 kJ mol-1，且在4次循环后没有明显衰退，且仍保持着94 %的转化率。分析表明，N-CN在循环过程中能有效保护部分Co、Ni 不受腐蚀，从而使得催化剂的循环稳定性上升。
关键词：甲酸，脱氢，非均相催化剂，PdCoNi，APTS改性载体
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Abstract
Hydrogen, as a clean and efficient energy source, can effectively solve the pollution trouble of fossil fuel. Formic acid (HCOOH, FA) is a liquid chemical hydrogen storage material. It is safe, stable, non-toxic, simple to synthesize, with a high gravimetric hydrogen capacity (4.4 wt%). With the help of catalysts, FA is able to dehydrogenate lectively into CO2and H2. More importantly, FA can be regenerated after dehydrogenation by carbon dioxide hydrogenation reaction. Therefore, finding cost-effective catalysts is an esntial issue for the commercial application of FA.
Bad on literature rearch, this paper designed and prepared 3-aminopropyltriethoxysilane (C9H23NO3Si, APTS) modified PdCoNi catalyst nanoparticles supported by different substrates, and studied their catalystic performance and mechanism for dehydrogenation of FA in sodium formate (HCOONa, SF)/FA system.
First, an APTS modified three-dimensional lamella TiO2 (B) is prepared as a substrate to support Pd
豆芽的做法
CoNi nanoparticles (NPs), which is further ud to enhance the catalytic activity of the active component PdCoNi NPs effectively. The results indicate that the addition of APTS can modify the amino group (-NH2) on the surface of TiO2, and Pd0.6Co0.2Ni0.2/NH2-Si-TiO2 is prepared by changing the ratio of APTS and TiO2, which demonstrates excellent catalytic performance. The initial conversion frequency TOF inital of the catalyst is 397 mol H2∙mol metal-1∙h-1 (h-1) at room temperature, and the apparent activation energy Eα is 49.92 kJ∙mol-1. The analysis shows that TiO2 (B) modified by APTS can inhibit the agglomeration of PdCoNi NPs, reduce the size of NPs, without affecting the electron transfer of Co and Ni to Pd. Furthermore, -NH2 increas the opportunity of sufficient contact for the HCOO− with catalysts, which also greatly improves the catalytic activity.
Subquently, APTS-modified nitrogen-containing hollow carbon spheres (C Ball) is also ud as substrate for FA dehydrogenation catalysts, and the catalyst PdCoNi/N-Si-C Ball is successfully prepared. Control experiments prove that without C Ball, APTS can still significantly enhance the catalytic activity of PdCoNi NPs, and the catalytic activity of PdCoNi NPs loaded on C Ball modified by APTS can be further improved. By optimizing the amount of APTS and the ratio among metals,
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Pd0.8Co0.1Ni0.1/N-Si-C Ball is prepared with 100% hydrogen lectivity and good cycle performance, the value of TOF inital can reach 745 h-1 at room temperature, Eα is 39.50 kJ∙mol-1. It is found that APTS is doped with pyrrole N on C Ball without affecting carrier structure, which could avoid the formation of extremely large particles. When the content of Pd comes to 80 at%, the catalyst shows the best performance, and Pd can effectively protect part of Co and Ni from corrosion which improves the stability of the catalyst.
Finally, APTS-modified nitrogen-containing nanosheets (CN) is prepared and ud to support PdCoNi NPs. The combination of APTS and CN only forms the doping of pyrrole N (N-CN) without change the original ratio of pyridine N and graphite N in CN. N-CN as a substrate can induce the formation of ultrafine, monodisper, two-dimensional PdCoNi NPs, increasing the proportion of catalytically active sites and effective active components. Compared with CN, N-CN has a certain degree of hydrophobic performance and does not affect the electron transfer between Pd, Co and Ni. Pd0.6Co0.2Ni0.2/N-CN with optimal ratio exhibits high catalytic activity with a TOF initial of 1249.0 h-1at room temperature, which is more than 6 times that of Pd0.6Co0.2Ni0.2/CN. And Eαis determined to be 20.04 kJ∙mol-1. The reusable catalyst still can relea 232 mL ofgas in 10 rnin and achieves 94% conversion in the 4th catalytic reu. The analysis shows that N-CN can effectively pr
otect part of Co and Ni from corrosion during the cycle, which enhance the cycle stability of Pd0.6Co0.2Ni0.2/N-CN.
Keywords:formic acid, dehydrogenation, heterogeneous catalyst, PdCoNi, APTS modified substrate日期函数
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目录
丈母娘过生日摘要............................................................................................................................................. III 目录........................................................................................................................................... V 第一章绪论 (1)
扶老1.1 氢能概述 (1)
1.2 氢的制备 (1)
1.3 氢的存储 (2)
1.3.1 物理储氢 (2)
1.3.2 化学可逆储氢 (3)
1.3.3 化学不可逆储氢（化学制氢） (5)
1.4 甲酸概述 (6)
1.4.1 均相催化剂 (7)
1.4.2 非均相催化剂 (9)
1.4.3 添加剂 (14)
如何正确使用手机1.5 本文的意义和研究思路 (14)
第二章实验方法 (17)
2.1 材料制备方法 (17)
表示安静的词语
2.1.1 水（溶剂）热法 (17)
2.1.2 热分解法 (17)
2.1.3 液相还原法 (17)
2.2 实验试剂和仪器 (18)钱令希
2.2.1 实验试剂 (18)
2.2.2 实验仪器 (19)
2.3 材料的性能表征 (19)
2.3.1 材料的催化性能测试 (19)
2.3.2 TOF inital值的计算 (20)
2.3.3 活化能的计算 (20)
2.4 材料的结构表征 (20)
2.4.1 X射线衍射仪（XRD） (20)元宵佳节
V
