钴基催化剂催化木质素酚类加氢脱氧

发布时间：2018-03-26 04:56

  本文选题：生物质　切入点：加氢脱氧　出处：《中国科学技术大学》2017年硕士论文

【摘要】：随着人类社会的快速发展,化石资源的日益枯竭以及温室效应的不断恶化,发展可再生资源来部分替代传统化石资源迫在眉睫。通过绿色植物光合作用产生的生物质资源,是唯一一种可再生的有机碳资源。生物质资源含量丰富,开发和研究生物质转化对代替传统化石资源具有非常重大的意义。木质素作为木质纤维素的重要组成部分,用于制备可再生的生物燃料和化学品具有很大的潜力。然而,木质素解聚后获得的产物主要为甲氧基取代的酚类化合物,这种化合物含有甲氧基官能团并且含氧量较高,很难被直接应用。因此,加氢脱氧过程被用于转化木质素酚类化合物制备生物燃料和化学品。目前用于催化木质素酚类的催化剂主要集中于贵金属催化剂,如Pd,Ru,Pt等。这些催化剂虽然催化效果较好但催化剂成本较高,不利于工业中大规模的应用。非贵金属Ni也被用于加氢脱氧的研究,但反应条件较为苛刻。针对以上问题,我们研究并发展了非贵金属钴基催化剂用于催化木质素酚类化合物加氢脱氧。在我们第一个工作中,我们使用纤维素为碳源,硝酸钴为钴源,氨气为氮源一步热解制备CoNx@NC催化剂。以丁香酚为模型物,发现在650℃下制备的催化剂(CoNx@NC-650)具有最佳的丁香酚加氢脱氧效果。在200℃,2MPaH2条件下反应2h,丙基环己醇收率99.9%。此外,在外加固体酸HZSM-5条件下,丙基环己烷收率达到99.1%。我们对催化剂进行表征发现,在氨气氛围下形成的钴氮化物(CoNx)在催化加氢脱氧过程中起到了重要作用。通过反应动力学研究表明,该催化剂能在较温和条件下对Caryl-OR键具有很高的断键活性。基于第一个工作,我们发展了一系列负载型钻基催化剂,研究了不同氧化物载体对钴金属催化活性的影响。Co/TiO2催化剂在一系列钻基催化剂中表现出了最佳的催化活性,在200℃,1 MPa H2下反应2 h,丁香酚可以完全转化为丙基环己醇(99.9%)。通过催化剂的表征结果,金属与载体间的不同的相互作用是导致催化活性差异的主要原因。在180℃,0.4MPa反应8h的条件下,丙基环己醇的收率达99%。这是目前报道的使用非贵金属催化丁香酚加氢脱氧的最低条件。通过机理研究和底物拓展,发现当甲氧基出现在邻位时Co/Ti02能在对苯环加氢之前高效地对邻位的Cary1-OR键进行断裂。
[Abstract]:With the rapid development of human society, the depletion of fossil resources and the deterioration of Greenhouse Effect, it is urgent to develop renewable resources to partly replace the traditional fossil resources. Is the only renewable organic carbon resource. Biomass resources are rich, the development and graduate material conversion is of great significance to replace the traditional fossil resources. Lignin as an important component of lignocellulose, There is great potential for the preparation of renewable biofuels and chemicals. However, the main product of lignin depolymerization is methoxy substituted phenolic compounds, which contain methoxyl functional groups and have high oxygen content. Therefore, the hydrodeoxidation process is used to convert lignin phenolic compounds to biofuel and chemicals. At present, the catalysts used to catalyze lignin phenols are mainly concentrated on precious metal catalysts. For example, PdN Ru-Pt and so on. Although these catalysts have better catalytic effect, their cost is higher, which is not conducive to large-scale application in industry. Non-noble metal Ni is also used in hydrodeoxidization research, but the reaction conditions are relatively harsh. We have studied and developed non-noble metal cobalt based catalysts for the hydrogenation of lignin phenolic compounds. In our first work, we used cellulose as a carbon source and cobalt nitrate as a cobalt source. CoNx@NC catalyst was prepared by one step pyrolysis of ammonia as nitrogen source. Using eugenol as model material, it was found that the catalyst prepared at 650 鈩，

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