Ni-Fe合金催化剂催化木质素解聚

发布时间：2018-07-09 23:37

本文选题：生物质 + 木质素　；参考：《中国科学技术大学》2017年硕士论文

【摘要】：木质素是来源于木质纤维素的一种重要的可再生生物质资源,可用于制备化学品和燃料。由于木质素本身结构的复杂性和稳定使其难以有效利用。目前大量的制浆和造纸工业的木质素没有得到有效利用,仅有部分用于燃烧供能,造成了一定程度的环境污染。为了保护环境、实现可持续发展,催化转化木质素制备高附加值化学品成为了研究的热点。木质素转化的研究众多,但是进展依然相对缓慢。目前主要的转化方法包括碱催化解聚、酸催化解聚、热化学转化、加氢处理解聚,氧化解聚等。由于加氢处理解聚木质素可以获得低聚木质素、酚类等有价值的化学品和制备烃类燃料,是目前研究的热点和最有效的方法之一。但是,催化剂失活和解聚产物产率不高等依然是需要进一步解决的问题。木质素主要由甲氧基苯丙醇单元组成,可以用于制备芳香化合物。因此,为了有效的解聚木质素并保留芳香结构,我们制备了一系列的Ni-Fe/AC催化剂用于解聚木质素。当使用有机溶剂桦木木质素被用于解聚时,我们发现Ni1-Fe1/AC(Ni和Fe的比例为1:1)催化剂表现出了最好的催化效果。在225℃、2 MPa氢气、6 h的反应条件下,最高的单体产率可以达到23.2 wt%。GPC分析的结果也充分的证明了木质素已经获得了有效的解聚。通过一系列的分析(XRD、HRTEM、H2-TPR和XPS表征),证明催化剂中存在镍铁和金的结构。基于模型物的研究,Ni1-Fe1/AC催化剂在醚键的氢解反应中表现出了很高的反应活性,并且能够保留芳香环不被过度加氢,保留产物的芳向性。催化剂表现出的优异的反应活性可能要归因于镍铁合金结构在催化过程中的协同效应。将催化剂应用于真实生物质体系——桦木木屑的解聚反应时也表现出了良好的反应活性。总的单体产率可以达到39.5 wt%,并且PG和PS两种产物的选择性可以达到88%。
[Abstract]:Lignin is an important renewable biomass resource derived from lignocellulose, which can be used in the preparation of chemicals and fuels. Due to the complexity and stability of the lignin itself, the lignin is difficult to be used effectively. A certain degree of environmental pollution. In order to protect the environment and achieve sustainable development, catalytic conversion of lignin to the preparation of high value-added chemicals has become a hot spot. There are many studies on lignin conversion, but the progress is still relatively slow. The main methods of conversion include alkali catalytic depolymerization, acid catalytic depolymerization, thermochemical conversion, and hydrogenation treatment. Depolymerization, oxidative depolymerization, and so on. Due to the hydrogenation of depolymerization lignin to obtain oligomeric lignin, phenol and other valuable chemicals and the preparation of hydrocarbon fuels, it is one of the hotspots and most effective methods for the study. However, the problem that the deactivation of the catalyst and the yield of the depolymerization products are not high still need to be solved. The methoxy phenylpropanol unit can be used to prepare aromatic compounds. Therefore, in order to effectively depolymerization lignin and retain the aromatic structure, we have prepared a series of Ni-Fe/AC catalysts for depolymerization of lignin. When the use of organic solvents Betula lignin is used for depolymerization, we found that Ni1-Fe1/AC (the proportion of Ni and Fe is 1:1) catalysis. The best catalytic effect was shown. At 225 C, 2 MPa hydrogen and 6 h, the highest monomer yield could reach 23.2 wt%.GPC analysis. The results also proved that the lignin has been effectively depolymerization. A series of analysis (XRD, HRTEM, H2-TPR and XPS characterization) showed the presence of nickel iron and gold in the catalyst. Based on the study of the model, the Ni1-Fe1/AC catalyst shows a high reaction activity in the hydrosolution reaction of the ether bond, and can retain the aromatic ring not overhydrogenation and retain the aromatics of the product. The excellent activity of the catalyst may be attributed to the synergistic effect of the nickel iron alloy gold structure in the catalytic process. The chemical agent was also used in the depolymerization reaction of the real biomass system - birch wood chips. The total monomer yield can reach 39.5 wt%, and the selectivity of two products of PG and PS can reach 88%.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;O636.2

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