【作者】 王君；

【导师】 张明旭； 陈明强；

【作者基本信息】 安徽理工大学 ， 环境工程， 2007， 博士

【摘要】 生物质是一种重要的可再生资源，基于裂解技术将生物质转化为优质液体燃料对于缓解我国能源紧张、减轻环境污染和实现国民经济可持续发展具有重要意义。利用热分析仪考察了若干种生物质的裂解特性。研究表明，三种陆地生物质（松木、棉秆、杉木）的裂解温度与其灰分产率呈反变关系。六种无机化合物（NaOH、Na₂CO₃、Na₂SiO₃、NaCl、TiO₂、HZSM-5）对三种陆地生物质的催化裂解行为随无机添加剂的酸碱性变化呈现一定规律性的变化。六种海藻的热稳定性远低于三种陆地高等植物的热稳定性。建立了描述不同类型生物质裂解的一步反应模型，同时建立了描述木质纤维素类生物质裂解的三组分平行独立反应模型。建立了一套小型生物质微波裂解装置，微波频率2450MHz，微波功率在0-4kW范围内线性可调，串联三级冰浴U形管冷却可凝组分，使用锯末作裂解原料时，采用碳化硅作微波吸收剂，木块微波裂解无需外加微波吸收剂。利用该装置进行了三种陆地生物质锯末的微波裂解实验，裂解温度控制在470℃左右，着重考察了八种无机添加剂对三种陆地植物在微波场中裂解的催化效应。三种陆地生物质锯末微波裂解液体产率在10-30％之间，液体产物中水分含量30％左右。八种无机添加剂显著增加固体产物产率，减少气体产物产率，而对液体产率的影响不是很显著。其中NaCl、H₃PO₄和Fe₂（SO₄）₃使液体产率有较显著提高。裂解气体主要是H₂、CH₄、CO和CO₂。八种添加物均使四种气体的析出时间提前，其中NaOH、Na₂CO₃、Na₂SiO₃、NaCl作用效果最明显，它们可使气体析出时间提早4-6min。八种添加剂中多数使H₂、CH₄和CO的摩尔分数增加，CO₂的摩尔分数下降。与Py-GC-MS分析及喷动流化床裂解液体产物相比，微波裂解产物中轻组分含量较大，其中羟基丙酮为绝对优势组分，NaOH、Na₂CO₃等碱性催化剂能进一步促进羟基丙酮的生成，其相对浓度可达50％左右；而H₃PO₄、Fe₂（SO₄）₃可以大大提高糠醛和4-甲基愈创木酚或（z）-2-丁烯-1,4-二醇的生成选择性，二者总相对浓度可达80％。同时，研究表明，松木微波裂解半焦具有很好的气化反应性。最后，结合传统的煤炭间接液化技术路线及最新的生物质基原料合成液体烷烃的研究思路，提出了充分利用微波裂解得到的具有独特组成与分布的液体产物、富氢气体及活性半焦制备优质液体燃料的综合技术路线。更多还原

【Abstract】 Biomass is an important renewable resources and its conversion to high qulity liquid fuels based on pyrolysis technology is of great significance to relax energy tension and environmental pollution of our country and to realize sustainable development of national economy.The thermal characteristics of several types of biomass were investigated by utilizing thermal analyzer.The study indicates that the pyrolysis temperature for the three land biomass species（pine wood,cotton stalk and fir wood） changes inversely with the yield of the ash from the biomass.The catalytic effects of the six inorganic compounds（NaOH,Na₂CO₃,Na₂SiO₃,NaCl,TiO₂ and HZSM-5） on pyrolysis of the three land biomass species vary regularly to some extent with the acidity or basicity of these compounds.The thermal stability of the six seaweeds are much lower than that of the three land plants. The one-step reaction models for pyrolysis of all the studied biomass species have been established and a three compoment-parallel-independent reaction model for pyrolysis of lignocellulusic biomass has also been proposed.A bench scale microwave pyrolysis installation has been set up, the frequency employed is 2450MHz and the power capacity can be adjusted from zero to 4kW proportionally. A serial three phase U-shaped tube train immersed in the ice-water mixture bath is used for cooling and collecting the condensable components. SiC is used as microwave absorber when the sawdust is to be pyrolyzed and it is not used when the wood blocks are the feedstock. This installation is used for pyrolysis of the sawdust of the three land plants at ca. 470℃and the emphasis is put on the catalytic effects of the eight inorganic additives on the microwave pyrolysis.The oil yield is between 10-30% and ca. 30% water exists in the liquid products. All of the eight additives have increased yields of solid products greatly and decreased yields of gaseous products more or less. Yields of liquid products are subjected to no dramatic change except NaCl, H₃PO₄ and Fe₂（SO₄）₃ have increased the liquid yields moderately.The gases produced from pyrolysis consist mainly of H₂, CH₄, CO and CO₂. All of the eight additives have made these gases evolve earlier, among which the four sodium additives have the most marked effect, which can make the gases evolve 4-6min earlier. Most additives have made the molar fraction of H₂, CH₄ and CO increase and those of CO₂ decrease.More light components, among which acetol takes priority, appear in the liquid products from microwave pyrolysis compared with Py-GC-MS analysis and fast pyrolysis in the conduit-spouting fluidized reactor. The acetol formation can be further enhanced up to a relative concentration of 50% by alkaline catalysts NaOH, Na₂O₃ etc, whereas furfural and 4-methyl guaiacol or （z）-2-butene-1,4-diol can be selectively formed with a total relative concentration of the two components up to 80% when H₃PO₄ or Fe₂（SO₄）₃ is used as the catalyst. Meanwhile, the study indicates that the semicoke from microwave pyrolsysis has good gasification reactivity.The reactivity and gasification kinetics of the semicoke from pine wood by microwave pyrolysis have been investigated by utilizing thermal analyzer. The results show that strong bases NaOH and Na₂CO₃ have greatly increased the reactivity of the semicoke and complete gasification time is very short. Neutral salts NaCl and Fe₂（SO₄）₃ have also increased the reactivity of the semicoke considerably. The reactivity of the semicoke in the low conversion range mainly depends on the microstructure of itself, whereas that rising quickly in the high conversion range can be ascribed to the prompt concentration rise of the minerals. The reactivity of the semicoke from microwave pyrolysis is higher than that from conventional pyrolysis and this can be due to the more open hole and higher specific surface area of the former formed by devolatilization from inner part to external part. It is found that the gasification process is controlled by external diffusion through applying non-reacted shrinkage reaction core model.Finally, an integrated technology route for preparing high quality liquid fuel has been proposed through fully utilizing the liquid products with unique composition and distribution, hydrogen rich gases and active semicoke obtained by microwave pyrolysis, combining the traditional technological route for indirect liquefaction of coal and the latest thoughtway for synthesis of liquid alkanes from biomass-derived feedstock. Figure [74] table [26] reference [126]更多还原