【作者】 姜嵩；

【导师】 陈纪忠；

【作者基本信息】 浙江大学 ， 化学工程， 2012， 博士

【摘要】 随着化石燃料的枯竭和全球环境的严重恶化,开发可再生的清洁能源迫在眉睫。生物质能作为一种清洁能源,更是一种可再生能源,越来越受到关注。竹材,重要的森林资源之一,在我国,分布广,资源蕴藏量大,是一种理想的可再生生物质资源。同时,近年来,以甲醇为反应介质的超临界流体液化技术得到了广泛研究。本文在综述了大量参考文献的基础上,制定了一套竹材在亚、超临界甲醇中醇解的实验方案,并引入了K2CO3和MCM-41两种催化剂,进行了一系列比较实验研究,针对竹材在不同情况下的醇解行为进行了深入和全面的分析。实验结果对深入认识竹材醇解规律、设计及优化竹材醇解加工工艺、开发高附加值的醇解产品具有重要的指导意义。首先,本文采用甲醇作为反应介质与浙江毛竹粉末在不锈钢高压反应釜内进行亚、超临界醇解反应,用气相色谱-质谱联用仪(GC-MS)和气相色谱(GC)分别分析了醇解液体产物的成分组成和部分产物的产率。考察了反应温度、反应时间和竹材粉末与甲醇的固液比对竹材亚、超临界产率的影响。实验结果表明,反应温度和压力达到甲醇的超临界条件时,竹材粉末的醇解较亚超临界时更为彻底,且转化率与时间成正比。根据GC-MS分析,亚、超临界醇解产物的组成很复杂,可检测出数十种化合物,主要是糠醛(纤维素和半纤维素的主要醇解产物)、含氧有机物、含苯环化合物和杂环化合物。其中,糠醛的含量最高。研究表明,采用超临界醇解技术,在相对温和的条件下(低于300℃)可使竹材中有极大分子选择性的降解,尤其是竹材中纤维素和半纤维素的降解,达到了降解废弃竹材的目的。为详细了解竹材的结构信息和亚、超临界醇解反应的机理奠定了基础,也为开发废弃竹材的高效利用的新工艺提供了理论依据。同时采用模式函数法对等温动力学过程进行拟合,通过对动力学结果进行比较和分析,结合可能的醇解机理,对毛竹的亚、超临界醇解行为进行了讨论。结果表明,超临界状态下,醇解反应的活化能降低,反应更容易进行,反应受温度的影响变小；亚临界状态下反应可简单模拟为一级反应,而超临界状态下,反应为二级反应,反应更为复杂,有更多的成分参与反应。其次,本文以正硅酸乙酯(TEOS)、十六烷基三甲基溴化铵(CTAB)、氢氧化钠(NaOH)为原料,采用水热法合成了介孔分子筛MCM-41催化剂,并用五水硝酸锆(Zr(NO3)4·5H2O)为Zr源,水为溶剂,采用浸渍法制备了负载型Zr-MCM-41介孔分子筛催化剂。同时对MCM-41和Zr-MCM-41进行了XRD、IR、N2吸附、TG等表征分析。最后,本文将自行合成的MCM-41分子筛和K2CO3催化剂加入到竹材的亚、超临界醇解体系中,考察了反应温度、反应时间、竹材粉末与甲醇的固液比和催化剂用量对竹材亚、超临界催化醇解产率的影响。实验结果表明,两种催化剂均能不同程度的提高反应速率,K2CO3的催化效果更好,反应进行更加彻底,但MCM-41可循环利用,是一种理想的适合于创造环境友好工艺的催化剂；两种催化剂对竹材的催化机理不同,MCM-41分子筛孔道大小均匀、六方有序排列,具有高比表面积和大吸附容量,有利于有机分子的快速扩散,这使得它能为大分子进行择型反应提供有利空间和有效酸性活性中心,液体产物中C10以下的醇、醚、酯类等有机小分子的含量明显增多,尤其是乙酸甲酯的含量,但它对木素的降解并无太大贡献;K2CO3催化剂则更多的起到溶解木素的作用,减少氧杂环的生成。采用模式函数法对催化醇解的等温动力学过程进行拟合,发现有K2CO3催化时,更多的木素开始降解,醇解机理更为复杂,不能用简单的一步反应来描述；使用MCM-41分子筛催化时,在亚、超临界状态下,反应活化能都有不同程度降低,反应受温度影响更小,达到反应平衡的时间更短。更多还原

【Abstract】 Along with the fossil fuel being used up and the global environment being destroyed badly, it is extremely urgent to develop a clean and renewable energy. If biomass is utilized reasonably, it is not only a renewable energy, but also a clean energy. In recent years, the liquefaction technology of supereritical fluid taking methanol as the solvent and reaction medium has got extensive research. Bamboo is an ideal renewable resource as one of the most important forest resources in China with wide distribution and large amount. Based on summarizing of many literatures, an experimental scheme that bamboo was liquefied in subcritical and supercritical methanol with or without K2CO3and MCM-41has been worked out, and then, a series ofexperimental researches have been carried out. Results here will contribute to the understanding the disciplines of alcoholysis, also provide guide for product processing design and high value-added product development.Firstly, Bamboo powder (BP) collected from Shengzhou, Zhejiang. were deploymerized with supercritical methanol in a stainless-steel magnetically stirred autoclave. The alcoholysis products were analyzed with GC-MS system. The effect of reaction temperature, reaction time, and on the yields of the alcoholysis products was examined. The experiment results show that BP were more deeply deploymerized by methanol under supercritical condition than under subcritical condition and the yields of the alcoholysis products are proportional to reaction time. Dozens of organic compounds were detected by GC-MS analysis from supercritical alcoholysis products, and most of the species detected are furfural which is the main product of the cellulose and the hemicellulose and oxygen-containing organic chemicals, especially the methoxy compounds. A large number of phenol derivatives which can be used as high-value-added chemicals and farty acid esters which can be used to produce high class lubricating oils and bio-oil with high quality were detected from supercritical alcoholysis products. Moreover, the results show that the big molecule of BP, especially the cellulose and the hemicellulose, can be deploymerized under relatively gentl℃e condition(<300癈)by using supercritical alcoholysis, which will offer an important means to understanding the molecule structure of the bamboo. Simultaneity, it will provide theoretical basis of exploiting new technology for the effective utilization of bamboo.Secondly, in this paper, mesoporous molecular sieve MCM-41was perpared hydrothermally with TEOS, CTBA, NaOH as source materials and then used as supports for mesoporous molecular sieve Zr-MCM-41with Zr(NO3)4·5H2O as Zr source and H2O as solvent via impregnation method.Finally, in this paper, as catalyst. MCM-41and K2CO3were added into the subcritical and supercritical alcoholysis system of bamboo, the effects of reaction temperature, reaction time, bamboo powder and solid-liquid ratio of methanol and catalyst content were examined. The results show that the reaction rate with this two catalysts can be improved to varying degrees, of which the catalytic effect of K2CO3is better, and MCM-41can be recycled, which is an ideal catalyst to create an environment friendly; the catalytic mechanism of this two catalysts is different, such as MCM-41zeolite whose pore size is uniform, ordered the six-party, with the rapid proliferation of high specific surface area and adsorption capacity, can make it optional type for the macromolecular favorable space and effective acid active centers of reaction, and make the C10alcohols, ethers, esters liquid product increased significantly, especially the methyl acetate content, but it has little contribution to the degradation of lignin; K2CO3serves to dissolve the lignin, and reduce the generation of oxygen heterocycles. By using the model function to fit the isothermal kinetics of catalytic alcoholysis process, it is found that with K2CO3, more lignin begin to degrade, and alcoholysis mechanism is more complex, which can not be described with a simple step reaction; with MCM-41, no matter in the subcritical or supercritical process, the activation energy has reduced to varying degrees, the reaction is affected by temperature less, and the reaction reaches the equilibrium quickly.更多还原