【作者】 郭仕鹏；

【导师】 杨正宇；

【作者基本信息】 中国科学院研究生院（理化技术研究所） ， 物理化学， 2009， 博士

【摘要】 随着能源需求的不断增加和温室效应的日益加剧,人们越来越渴望找到一种新的可再生能源来改变现在的能源结构,促进能源的可持续发展。在过去的20年里,生物质作为一种清洁的可再生资源越来越受到世界工业的关注。据统计,生物质每年提供的能量占到世界总能源的10-14%。除此以外,生物质具有CO2净排放为零,低的硫、氮含量的特点,使生物质燃烧利用排放的SO2、NOx比传统化石燃油低得多。因此,生物质能的广泛开发利用将可能缓解日益严重温室效应和能源短缺等能源问题。本论文从脱氧的角度考虑,提出了一种不同于快速热解和高压液化的新的反应方法即“直接脱氧液化法”。实验在密闭的环境中进行,不需要加氢气和其它载气。生物质中大量的氧以CO和CO2的形式脱除,所以得到的液体燃油具有较高热值、低含氧量、高H/C比;初步筛选了可选控的催化重组催化剂,以控制产物中的芳香化合物和直链烷烃的分布。本论文着重研究了果壳类生物质中的纤维素、半纤维素、木质素三种主要组份在直接脱氧液化中的反应机理,并确定:纤维素脱氧液化的主要产物是苯酚类衍生物、苯类衍生物、呋喃衍生物和环戊酮类物质;木质素液化的主要产物是苯酚衍生物,其中最为典型的例子就是核桃壳(苯酚衍生物含量为75.88%);对比可提取物和烷烃的含量关系论证了可提取物可能是烷烃的主要来源。另外,由于在生物质中纤维素、半纤维素和木质素交错混生在一起,所以纤维素、半纤维素在生物质脱氧液化过程会受到各组份相互间立体位阻的影响,阻碍呋喃衍生物的生成。同时,也对其它组份液化产生影响。本论文对四种常见生物质:大豆秧、核桃壳、葵花籽壳、花生壳进行脱氧液化实验,采用GC-MS、FTIR和元素分析等多种方法定性、定量分析了液化产物组成并进行了质量衡算。研究发现葵花籽壳(其中葵花籽含量低于5wt%)可以通过脱氧液化的方式得到高质量的液体燃油,其主要成分为C7-C19的直链烷烃、苯的衍生物。其最高产率为19.2%、最高热值的液体燃油在450℃反应温度下得到;其物理特性及热值(46.9MJ/kg),都表明这是一种更有可能作为汽柴油的替代品的高品位植物基合成油。高木质素含量生物质脱氧液化更容易生成固体焦炭物质,其油相产物中主要是苯酚衍生物,典型的生物质为核桃壳(苯酚衍生物含量最高可达到75.88%),所以高木质素含量生物质可以作为提供苯酚衍生物中间体及化工品的一种来源。脱氧液化过程所产生的气体主要成份是H2、CO、CH4和CO2,其中CO2的含量在75-90%,充分说明了反应过程中脱除了大量的氧原子。总之,生物质经过直接脱氧液化,产物中氧含量明显降低,热值明显提高,为生物质更为有效的利用开辟了新的途径。更多还原

【Abstract】 With the increasing demand for energy and the rising atmospheric greenhouse gas levels, renewable energy should be widely explored to renovate the energy source structure and keep sustainable development safe. Biomass as a clean and renewable energy resource has become more and more attractive to industry in the past 20 years. It is estimated to contribute 10-14% of the total energy supply in the world. In addition, biomass has zero net emission of CO2 and has very low contents of sulfur and nitrogen, which gives lower emissions of SO2, NOx than conventional fossil fuels. Therefore, the widely exploration of biomass has great potential for alleviating energy problems, such as the greenhouse effect and the depletion of fossil energy sources.A new methord“Direct deoxy-liquefaction”was introduced in this paper, which was different from fast pyrolysis and high pressure liquefaction. Experiments were conducted in an airtight reactor without adding H2, and other carrier gas. In this liquefaction process,the most oxygen in biomass was released in the forms of CO and CO2,thus, high heating value oil can obtained with a low oxygen content and high H/C ratio. Several catalysts were selected and prepared to control the distribution of the aromatic compounds and long-chain alkanes in the liquid oil.In this paper, the deoxy-liquefaction mechanics of cellulose, hemicellulose and lignin were studied. The liquid oil obtained from cellulose was mainly composed of phenols, benzenes, furans and cyclopentanones. Abundant phenol derivatives were obtained from high lignin content biomass, for example walnut shell (75.88%). Furthermore, long chain alkanes may come from the extractive part of biomass was confirmed due to the analysis of extractive content and the yield of alkanes. In addition, cellulose, hemicelluloses and lignin mixed with staggered in biomass, they affect each other in deoxy-liuqefaction processes for steric hindrance.Four usual biomasses: soybean stalk, walnut shell, sunflower shell, peanut shell was chosen for preparing liquid oil in this paper. Gas chromatography-mass spectrometry (GC-MS) with the National Institute of Standards and Technology (NIST) 98 MS library was used to analyse the composition of liquid oil, while the functional groups analysis was carried out by Fourier transform infrared spectroscopy (FTIR). The element contents of biomass and liquid oil was analyzed by elemental analysis. So the liquid oil components can be analysed qualitatively and quantitatively and the mass distribution of products was done. The liquid oil with a maximum yield 19.2%wt and H/C molar ratio of 1.99 and higher heating value (HHV) of 46.9 MJ/kg was obtained at 450℃from sunflower shell samples via deoxy-liquefaction. Furthermore, the oil analyzed by GC-MS was mainly composed of benzene derivatives, phenolic derivatives, and alkanes (C7-C19). It has more potential to be a substitute for petroleum fuels than the oil that consisted mainlyof aldehydes, ketones, esters, and ethers. On the other hand, the productions of high lignin content biomass are mainly char, and the liquid oil is manily composed of phenolic derivatives. So, high lignin content biomass can be used to prepare phenolic derrivetives and other chemicals. The gaseous products were H2、CO、CH4 and CO2. The major gas product was carbon dioxide (75-90%) for all samples, suggesting that great amount of oxygen atoms have been removed during the process. In conclusion, direct deoxy-liquefaction can limited the oxygen content in the liquid oil and increased the high heating value significantly. It would provide a new prospect for the utilization of biomass.更多还原