【作者】 刘军利；

【导师】 蒋剑春；

【作者基本信息】 中国林业科学研究院 ， 林产化学加工工程， 2011， 博士

【摘要】 生物质资源是唯一可再生的碳资源,通过热化学、生物等方法可转化成常规的液态和气态燃料以及其它化工原料或者产品。作为唯一能够直接转化为液体燃料的可再生能源,生物质以其产量巨大、可储存和碳循环等优点已引起全球的广泛关注。快速热解技术是以制备液体产品为目的一种新型生物质热化学转化技术。困扰基于生物质热解技术生产化学品工业腾飞发展的主要问题是热解产物极其复杂和产物的不稳定性。论文总体思路是采用居热解-气质联用技术,创新研究生物质定向热解行为,揭示纤维素类生物质热解产物的定向调控机理;通过热重与傅立叶红外联用技术（TG-FTIR）,研究生物质热解动力学,并建立热解反应动力学模型;通过高温介质热解技术,开发新型热解产物高热值气体、高品质液体油以及高性能碳材料综合利用技术,为生物质高值化综合利用提供理论依据。论文的主要研究内容和结果如下:1.生物质基本组分居热解行为研究纤维类生物质资源主要由纤维素、半纤维素、木质素组成,其热解行为可以归结为三种主要组分的热解。论文以微晶纤维素、木聚糖和碱木素作为生物质基本组分的模型化合物,采用居热解-气质联用技术（CP-GC-MS）,研究了生物质三大基本组分以及纤维素热解中间体左旋葡聚糖的居热解行为,剖析了生物质基本组分热解行为的差异性和主要热解产物组成,研究结果表明:生物质基本组分居热解行为具有明显的差异性。左旋葡聚糖始终是纤维素热解的主体产物,纤维素热解生成糠醛、左旋葡烯酮、吡喃型葡萄糖苷、5-羟甲基-糠醛和呋喃半乳糖酐等化合物,经过了左旋葡聚糖中间体步骤;木聚糖的居热解区域以300℃为分界线,小于300℃,仅生成以糠醛和糖类单体为主的化合物,有利于定向热解;大于300℃时,木聚糖热解极其活跃,小分子的醛酮类物质开始生成,糖类和糠醛等化合物含量降低,不利于定向热解反应;木质素居热解产物中,主要生成了以二氧化碳和愈创木酚类化合物为主体的化合物。酚羟基和甲氧基的电子效应,使与愈创木基相连的键更容易断裂,愈创木酚在居热解过程中始终是热解的主体产物,同时,木质素单体间基本连接键形中C-O-C和C-C相比较更容易断裂生成二氧化碳。2.纤维素定向催化居热解行为研究催化热解技术是以获取高值化产品和目标产品高得率为目的的定向调控技术。论文利用CP-GC-MS联用技术研究了纤维素在Fe₂（SO₄）₃,CuSO₄,ZnCl₂,H₃PO₄等催化剂作用下的定向居热解行为,重点考察了糠醛、左旋葡聚糖和左旋葡烯酮等热解产物的变化,提出了左旋葡烯酮与左旋葡聚糖之间的定向调控途径与机制,结果表明:Fe₂（SO₄）₃,CuSO₄,ZnCl₂,H₃PO₄等催化剂具有选择性调控糠醛、左旋葡聚糖和左旋葡烯酮等纤维素热解产物形成途径的作用,催化剂主要是增强了纤维素脱水和脱CO基作用,但由于脱除水和CO2的能力不同,导致最终热解产物中三种主体产物左旋葡聚糖、左旋葡烯酮、糠醛的相对含量不同。左旋葡烯酮主要通过左旋葡聚糖脱除两分子水生成,左旋葡烯酮通过进一步脱CO基生成糠醛。H₃PO₄、CuSO₄催化热解可以作为定向调控降低左旋葡聚糖、提高左旋葡烯酮以及糠醛含量的有效手段;ZnCl₂催化热解可以作为定向调控制备糠醛化学品的有效手段;Fe₂（SO₄）₃吸附法预处理样品可以作为定向调控降低左旋葡聚糖、提高左旋葡烯酮以及糠醛含量的有效手段,离子络合法预处理样品可以作为定向调控获得高的左旋葡聚糖、低的左旋葡烯酮的方法。四种催化剂中,H₃PO₄定向调控制备左旋葡烯酮效果最好;ZnCl₂定向调控制备糠醛能力最好;Fe₂（SO₄）₃离子络合法预处理样品可使糖类主体产物停留在左旋葡聚糖上。3.木质纤维类生物质定向催化热解行为研究木质纤维类资源是由具有复杂空间结构的高分子化合物纤维素、半纤维素和木质素相互结合而形成的超分子复合物。论文以廉价的H₃PO₄和ZnCl₂作为催化剂,以具有代表性的竹子、沙柳和柠条三种木质纤维类生物质为原料,利用CP-GC-MS联用技术研究了木质纤维类生物质定向催化热解行为,重点分析了糠醛、左旋葡聚糖、左旋葡烯酮、酚类化合物等热解产物的调控机制,结果表明:ZnCl₂和H₃PO₄催化剂能选择性调控木质纤维类生物质热解产物的种类和含量,是定向调控降低酚类化合物含量、乙酸含量,提高糖类化合物、呋喃类化合物的有效手段。H₃PO₄和ZnCl₂预处理生物质均增强了左旋葡聚糖中间体脱水和脱CO基作用而生成了较多的糠醛和左旋葡烯酮,促进了木质素形成碳,而非酚类化合物,同时抑制乙酸化合物的生成;H₃PO₄催化剂有助于选择性催化生成左旋葡烯酮;ZnCl₂催化剂有助于选择性催化生成左旋葡聚糖和糠醛;对于酚类和乙酸两种化合物的抑制能力ZnCl₂>H₃PO₄。4.木质纤维类生物质高温介质热解行为研究高温介质热解是一种新型热解技术,该技术的瓶颈是如何廉价地获取高温介质。本论文采用蜂窝陶瓷热交换技术廉价地获得高温介质,在固定床热解反应器中研究了高温介质（蒸汽、氮气）热解行为及其对热解产物的影响,结果表明:高温蒸汽热解技术有助于制备出高性能固体炭产品、高热值气体以及高品质生物油产品。随着热解介质温度的提高,生物质热失重速率提高,热解时间明显缩短。在相同的热解温度下,蒸汽介质中生物质热失重率大于氮气介质。高温蒸汽热解可以获得挥发份低、比表面积大的固体炭产品。高温蒸汽热解对热解气体H₂、CO、CH₄、CO₂和C₂Hy等影响显著,各种气体组分含量均明显高于氮气热解。随着热解温度的提高,高温蒸汽热解过程中主要气体组分含量均有所提高,且随着温度的升高,各组分出现的时间前移,尤其是H₂、CH₄和C₂Hy等高热值气体组分含量大幅度提高;同时由于蒸汽热解过程中没有大量氮气稀释现象的存在,且在热解气体冷凝后,蒸汽析出,有助于制备高热值气体。高温蒸汽热解制备的生物油具有H/C高、O/C低的特点,经验计算的生物油热值高达33.54MJ/kg,具有进一步开发作为燃料油和化学品利用的前景。5.基于TG-FTIR的生物质热解机理研究生物质热解机理研究包括热解产物生成途径以及热解动力学两个方面。论文采用TG-FTIR联用技术,研究了生物质热解特性参数、动力学参数、反应途径、热解产物红外特征官能团析出过程,并对生物质热解反应动力学进行了数学模拟。结果表明,催化剂有效改变了生物质热解特性参数、动力学参数、反应途径、热解产物的析出转化过程。纤维素、木聚糖和木质素三种基本组分的动力学分析表明纤维素和木聚糖属于平行竞争反应途径,木质素属于先形成中间体随后发生竞争反应模型;木质素在热解过程中出现了比较明显的CH₄吸收峰（3016cm-1）。在H₃PO₄和ZnCl₂两种催化剂作用下,纤维素热失重区间整体向低温区移动,有效降低了纤维素的热解活化能,CO的特征吸收峰变宽,并出现二次吸收峰。磷酸催化剂促使纤维素热解倾向于形成中间体的竞争反应途径。H₃PO₄、ZnCl₂催化剂使竹材、沙柳和柠条热解失重温区向低温区迁移,动力学分析表明,催化剂使用降低了竹材热解反应活化能,提高了柠条和沙柳热解反应活化能。竹材热解经历一步反应途径,磷酸催化剂未改变反应途径,氯化锌催化剂使竹材热解倾向于平行连串反应模型;沙柳热解经历一步反应途径,磷酸处理未改变反应途径,氯化锌处理沙柳热解倾向于平行竞争反应模型;柠条热解属于竞争反应模型,磷酸处理后的柠条呈现出一步反应途径,氯化锌处理柠条仍然倾向于平行竞争反应模型。催化剂处理木质纤维类生物质后,热解产物中CO、CH₄的红外吸收峰出现明显拖后现象,主要是由富氧官能团的碳表面二次热解,以及苯环支链高温热解形成。氯化锌催化剂更加有助于抑制气相产物的生成。更多还原

【Abstract】 Biomass resources, the only renewable carbon resources, can be turned into conventional liquid, gaseous fuels and other chemical raw material or product by thermo-chemical, biological and other methods. As the only renewable energy directly translated into liquid fuels, biomass with the advantages of huge output, storage and the carbon cycle has attracted widespread interests all over the world. Fast pyrolysis technology is a new type of technologies of biomass thermochemical conversion for the purpose of. preparing the liquid products. The main problems of impeding the development of preparing chemicals from biomass are the pyrolytic products extremely complex and unstable. The general idea of this paper is to investigate the behavior of directed pryolysis from biomass by Curie-point Pyrolysis -gas chromatography-mass spectroscopy（CP-GC-MS）,reveal the mechanism of directionally controlling the products pyrolyzed from lignocellulose biomass,study the dynamics of biomass pyrolysis by TG-FTIR and establish the kinetics models of biomass pyrolysis, exploit the technology of comprehensive utilization of pyrolytic products including high heating value gas, high quality liquid oil and high performance carbon material by the method of the super-high temperature medium pyrolysis in order to provide the theoretical basis of high value, comprehensive utilization of biomass. The main research content and results of the paper were as follows:1. The curie-point pyrolysis behavior of biomass major componentsThe lignocellulose biomass resources are the greatest amount of biomass resources on the earth, mainly composed of cellulose, hemicellulose, lignin. And its pyrolysis behavior can be attributed to the summation of its major components pyrolysis. In this paper, the curie-pyrolysis behaviors of the three main components of biomass and the levoglucosan as the intermediate products pyrolyzed from cellulose were investigated by the apparatus of CP-GC-MS from the microcrystalline cellulose,xylan and Alkali-lignin,which were considered as the model compounds of cellulose, hemicellulose and lignin. The differences of the pyrolysis behavoir of biomass basic components and the composition of major pyrolysis products were analyzed. The research results indicated that the curie-point pyrolysis behavior of biomass major components has obvious differences. The levoglucosan is the main component of pyrolysis products from cellulose all the time. The intermediate step of levoglucosan was experienced in the process of preparing the furfural, levoglucosenone and HMF from cellulose pyrolysis. The process of xylan curie-point pyrolysis could be broke into two region: At the area of less than 300℃, xylan by random glycosidic cleavage was pyrolyzed into furan derivatives and saccharidic compounds,furfural content reaches to 54.38 % in the pyrolysate. At the area of more than 300℃, the kind and content of chemicals of small molecular aldehyde,ketone were improved greatly with the enhancement of pyrolysis temperature. The carbon dioxide and guaiacol unit compounds were produced from the lignin pyrolysis. The cause of that guaiacol always was the main products in the process of lignin curie-point pyrolysis was more easy rupture of the bond between guaiacol and methoxy resulted from the electronic effect of methoxy and phenolic hydroxyl group. The carbon dioxide was prepared from the rupture of C-O-C.2. The directionally catalytic curie-point pyrolysis behavior of celluloseThe technology of catalytic pyrolysis is a directionally controlling techniques in order to get high value products and the high yield of the target product. In this paper, the directed pryolysis behaviors of cellulose catalyzed by Fe₂（SO₄）₃,CuSO₄,ZnCl₂,H₃PO₄ were investigated by the apparatus of CP-GC-MS. The variation of pyrolysate such as furfural, levoglucosenone and levoglucosan was reviewed. the pathway and mechanism of selectively controlling levoglucosenone and levoglucosan were brought forward. The research results indicated that the catalysts of Fe₂（SO₄）₃,CuSO₄,ZnCl₂,H₃PO₄ can play the role of selectively controlling the forming pathway of cellulose pyrolysate such as furfural, levoglucosenone and levoglucosan. The catalysts can enhance the dehydration and decarbonylation of cellulose. The distinctness of the dehydration and decarbonylation between four catalysts resulted in the dissimilarity of furfural, levoglucosenone and levoglucosan contents. The levoglucosenone was made from the levoglucosan by dehydrating two molecules H₂O. And the furfural was prepared from the levoglucosenone by decaronylation. It is a very effective method of selective pyrolysis cellulose catalyzed by H₃PO₄ and CuSO₄ to reduce the content of the levoglucosan and enhance the content of levoglucosenone and furfural. The directed pyrolysis of cellulose catalyzed by ZnCl₂ is a very good way to selectively prepare the furfural.They were very good means of selectively reducing the content of levoglucosan and enhancing the content of levoglucosenone and furfural by treating the cellulose by the adsorption of the Fe₂（SO₄）₃ solution,directionally preparing high levoglucosan and low levoglucosenone by treating the cellulose by the complexation of the Fe₂（SO₄）₃ solution3. The directed pyrolysis behavior of lignocellulose biomassThe lignocellulosic biomass composed of three major components of lignin, cellulose and hemicelluloses is supramolecular polymer with complex spatial structure. In this paper, the directed pryolysis behaviors of lignocellulose biomass including bamboo,willow and caragana catalyzed by ZnCl₂,H₃PO₄ with low cost were investigated by the apparatus of CP-GC-MS. The regulation mechanism of biomass pyrolysis products such as furfural, levoglucosenone,levoglucosan and phenolic compounds was ananlyzed. The research results indicated that the species and content of lignocellulose biomass pyrolysate could be regulated by the catalysts of ZnCl₂ and H₃PO₄ selectively, which was the effective method of reducing the content of acetic acid and phenolic compounds and enhancing the content of the sugar compounds and furan compounds directionally. The enhancement of the dehydration and decarbonylation of the levoglucosan intermediate by treating the lignocellulose biomass with ZnCl₂ and H₃PO₄ resulted in preparing more furfural and levoglucosenone, promoting the lignin to form carbon rather than phenolic compounds. and restraining the production of acetic acid. The catalyst of H₃PO₄ made for the selectively forming of levoglucosenone. The catalyst of ZnCl₂ helped to selectively prepare the levoglucosan and furfural. The ability for the inhibition of the acetic acid and phenolic compounds was ZnCl₂>H₃PO₄.4. The pyrolyis behavior of lignocellulose biomass via the super-high temperature mediumThe super-high temperature medium pyrolysis was a new type technology of pyrolysis,existed the bottle-neck of obtaining the super-high temperature medium with low cost. In this paper, the super-high temperature medium with low cost was obtained by the technology of the honeycomb ceramic heat exchanger. The pyrolysis behavior of super-high temperature medium（steam and nitrogen） and the influence of it on the pyrolysis products were investigated in the fixed bed pyrolysis reactor. The research results showed that the technology of super-high temperature steam pyrolysis helped to prepare high value solid carbon materials,high heating value gas and high quality bio-oil. The solid carbon product with low volatile content and big specific surface area can be got by high-temperature steam pyrolysis. The influence of high temperature steam pyrolysis on pyrolytic gas such as H₂, CO, CH₄, CO2 and C2Hy was remarkable. The contents of various gas components by high temperature steam pyrolysis are significantly higher than nitrogen. With the improvement of pyrolysis temp. the contents of the major gases in the process of high temp. steam pyrolysis were increased and the times of various gas components appear were moved up. Specially, the contents of high heating value gas such as H₂、CH₄ and C2Hy were improved significantly. As the same time, it was in favor of preparing high heating value gas because of not existing the diluted phenomena of a great deal of nitrogen during the steam pyrolysis and condensing steam after cooling the pyrolytic gas.The characterization depending on the analysis of the bio oil obtained from high temperature steam pyrolysis has shown that a low O/C and high H/C ratio product can be obtained. Heating value of the liquid fraction based on GC-MS data was calculated and found equal to 33.54 MJ kg-1. These facts imply that this product can be used as a potential source of renewable fuel and chemical feedstock.5. The pyrolysis mechanism of biomass by TG-FTIRThe study of the biomass pyrolysis mechanism includes two aspects of the forming pathway of pyrolytic products and pyrolysis kinetics. In this paper, the pyrolysis characteristic parameters, kinetics parameters, reaction pathway and the evolutions of pyrolytic products were investigated by TG-FTIR and the kinetics model of biomass pyrolysis reaction was simulated. The research results showed that the pyrolysis characteristic parameters, kinetics parameters, reaction pathway and the evolutions of pyrolytic products could be varied effectively by catalysts.The kinetics analysis of three major components such as cellulose,xylan and lignin showed that the reaction pathways of cellulose and xylan pyrolysis are attribute to the parallel and competitive reaction, and that of lignin is attribute to first forming medium and occuring the competitive reaction subsequently. The FTIR peak（3016cm-1） of CH₄ appeared in the process of lignin pyrolysis. The mass loss scope of cellulose pyrolysis under H₃PO₄ and ZnCl₂ catalysts moved to low temperature region, the activation energy of cellulose was reduced in effect. The characteristic absorbance peak of CO was broadened and the second absorbance peak of CO appeared. The catalyst of H₃PO₄ made the cellulose pyrolysis for the competitive reaction pathway of forming medium.The mass loss scopes of bamboo,willow and caragana pyrolyzed under H₃PO₄ and ZnCl₂ catalysts moved to low temp. region. The kinetics analysis showed the activation energy of bamboo pyrolysis reaction was reduced,but that of willow and caragana pyrolyisis reaction were enhanced under the catalysts. The pyrolysis of bamboo experienced one step pathway.The reaction pathway of bamboo pyrolysis under H₃PO₄ was not changed. The catalyst of ZnCl₂ made the bamboo pyrolysis for the competitive reaction pathway of three steps.The pyrolysis of willow experienced one step pathway too.The reaction pathway of willow pyrolysis under H₃PO₄ was not changed. The catalyst of ZnCl₂ made the willow pyrolysis for the competitive reaction pathway of two steps.The pyrolysis of caragana experienced the competitive reaction pathway of two steps. The catalyst of H₃PO₄ made the caragana pyrolysis for the one step reaction pathway. The reaction pathway of caragana pyrolysis under ZnCl₂ was not changed. The FTIR absorbance peak of CO、CH₄ in the pryolysate from the lignocellulose biomass pyrolyzed by catalysts showed a significant drag. It was resulted from the secondary cracking of rich oxygen functional groups in carbon surface and the branched ring cracking of benzene at the high temperature. The catalyst of ZnCl₂ helped to restrain the forming of gaseous products.更多还原