基于氢转移反应的木质素催化降解

发布时间：2018-04-12 19:27

  本文选题：木质素 + 氢转移反应　； 参考：《中国科学技术大学》2017年硕士论文

【摘要】：在最近的一个世纪,由于钢铁,汽车等行业的飞速发展,随着化石能源的不断消耗,一些尖锐的问题已经渐渐的成为了全世界所关注的焦点。其中包括由于化石能源的不可再生导致的能源问题,以及由于大量废气排放而导致的大气污染问题以及温室效应。为了解决这些问题,生物质能源逐渐成为了人们所关注的焦点。世界各国解决能源危机的一个重要途径就是利用生物质能源来制造人们所需要的燃烧或高附加值化学品。而在生物质资源当中,最受人们所关注的就是木质纤维素了。由于木质纤维素产量巨大而利用率较低,导致每年都有大量的木质纤维素无法得到有效利用,被白白的燃烧而浪费,造成了巨大的损失。因此,如何有效地催化降解木质素得到可以利用的产物是一个十分重要的课题。而在催化降解木质素的过程中,使用氢转移反应来进行降解由于其条件温和、绿色、清洁、环境友好等特点已经越来越受到人们的关注。基于以上背景,本论文主要分为以下几个方面:第一章,详细介绍了各类木质素的结构以及性质,氢转移反应的背景以及研究进展。以及氢转移反应催化剂以及氢供体的种类及其作用,包括贵金属催化剂以及金属负载型催化剂。第二章,介绍了一种基于氢转移反应使用两步法将木质素转化为有价值的低分子量化合物。在这部分实验中,首先对于两种不同类型的木质素进行分析,然后对不同的氢转移反应催化剂对木质素的催化效果进行分析。最终得出最优反应条件:首先使用Raney Ni催化剂在氢转移反应下对木质素进行催化,最优反应条件为在180℃下反应18h,将木质素液化为分子量较大的初级产物,转化率达到90%以上。然后使用钯碳催化剂在氢转移反应下对木质素的液化产物进行降解。最优反应条件为80℃下反应12h,最终得到高转化率高选择性的产物。各产物通过气相色谱-质谱联用法进行标定,主要产物收率总计达到30%以上。第三章,介绍了一种金属负载于石墨烯的氢转移反应催化剂对木质素及其模型化合物进行催化的方法。通过使用这种催化剂对木质素模型化合物进行催化降解,发现其可以很好的使木质素中的β-O-4键断裂。将这种氢转移反应催化剂应用于木质素的催化,可以检测出两种单体形成,并对这两种单体的产率以及反应的转化率进行分析。
[Abstract]:In the last century, due to the rapid development of steel, automobile and other industries, with the constant consumption of fossil energy, some sharp problems have gradually become the focus of attention all over the world.These include energy problems caused by non-renewable fossil fuels, air pollution caused by massive emissions and Greenhouse Effect.In order to solve these problems, biomass energy has gradually become the focus of attention.One of the most important ways to solve the energy crisis in the world is to use biomass energy to produce the burning or high added value chemicals that people need.Among biomass resources, lignocellulosic is the most concerned by people.Because of the huge yield and low utilization rate of lignocellulose, a large number of lignocellulose can not be used effectively every year, which is wasted by burning and causing huge losses.Therefore, how to effectively catalyze the degradation of lignin to obtain the available products is a very important issue.In the process of catalytic degradation of lignin, hydrogen transfer reaction has attracted more and more attention because of its mild conditions, green, clean and environmentally friendly.Based on the above background, this paper is divided into the following aspects: chapter 1, the structure and properties of lignin, the background of hydrogen transfer reaction and the research progress are introduced in detail.And the types and functions of hydrogen transfer reaction catalysts and hydrogen donors, including noble metal catalysts and metal supported catalysts.In chapter 2, a two-step method for converting lignin into valuable low molecular weight compounds based on hydrogen transfer reaction is introduced.In this part of the experiment, two different types of lignin were analyzed firstly, and then the catalytic effect of different hydrogen transfer reaction catalysts on lignin was analyzed.Finally, the optimal reaction conditions were obtained: firstly, Raney Ni catalyst was used to catalyze lignin under hydrogen transfer reaction. The optimum reaction conditions were as follows: the lignin was liquefied into the primary product with high molecular weight at 180 鈩，

本文编号：1741099