【作者】 王刚；

【导师】 李爱民；

【作者基本信息】 大连理工大学 ， 能源与环境工程， 2009， 博士

【摘要】 随着化石能源的日益枯竭和环境污染的日益严重,生物质能作为一种低硫、低氮以及二氧化碳“零排放”的清洁和可再生能源,逐渐受到了研究者的重视。生物质热化学转化技术是生物质能源利用研究的一个重点,其中生物质热解是一种转化生物质到热解油、固体炭和可燃气的高效转化技术。热解油具有能量密度高、存储和运输与燃料油相似等特点,并可以精制成燃料油或者化学产品;固体炭可以制取活性炭用于吸附分离过程;而具有中低热值热量的可燃气可以用来补充热解反应所需要的部分热量。生物质热解所得热解油常常含有较高的水分含量,这是热解油的主要缺点之一。提高生物油的适用性以及竞争力,减少生物油的水分含量和氧含量,提高热值是生物油主要精制目的;通过共热解技术可以部分实现此目的。生物质与石油基塑料共热解已经被广泛研究,而可生物降解聚乳酸塑料作为特殊的塑料品种,应用前景广泛。即使此类塑料具有可降解性,但是绝大多数此类塑料废弃之后仍被认为是一种固体废弃物。通过生物质与聚乳酸塑料共热解可以提高生物质热解油产率,降低含水率和提高热值。该技术可作为废弃聚乳酸塑料处理的替代方法或作为生物质热解处理的升级处理技术。本论文研究将着眼于探索生物质与聚乳酸塑料的共热解研究,具体研究内容与结果如下:（1）利用热重分析,研究了三种木质纤维素类生物质玉米芯（CC）、核桃壳（WS）、白松（PS）与聚乳酸塑料共热解特性。研究发现,生物质样品主要降解温度区间在220～400℃,而聚乳酸塑料（PLA）和生物质具有明显不同的热解特性,主要在300～372℃范围内发生剧烈热解,相比生物质热解温度范围较窄。在300～400℃温度区域内,三种生物质样品与聚乳酸塑料的混合物,在热解过程产生了不同程度的耦合作用。其中WS/PLA、CC/PLA较PS/PLA的耦合作用更为明显。另外,对共热解进行了动力学分析表明:采用一级动力学反应模型结合Arrhenius定律能很好地拟合生物质样品和聚乳酸塑料热解实验数据;而生物质/聚乳酸塑料混合热解则应采用1至2个连续一级反应模型来描述。（2）采用TGA/FTIR、Py-GC/MS联用技术研究了玉米芯的气体释放过程及其热解产物分布。研究表明,玉米芯在220～400℃区间发生剧烈热解反应,DTG曲线在339℃时出现最大值。热解气体的逸出情况由FTIR进行实时检测,并且定性分析了CH₄,CO₂,CO和有机物的析出情况。Py-GC/MS联用技术用来分析玉米芯热解产物分布,结果表明酚、呋喃、酮及其衍生物是主要降解产物。（3）采用TGA/FTIR、Py-GC/MS联用技术研究了聚乳酸塑料的气体释放过程及其热解产物分布。研究表明,聚乳酸塑料在300～372℃区间发生剧烈热解反应,DTG曲线在359℃时出现最大值。热解气体的逸出情况由FTIR进行实时检测,并且定性分析了CH₄,CO₂,CO和有机物等产物的析出情况。Py-GC/MS联用技术用来分析聚乳酸塑料热解产物分布,分析表明醛、酮、酯及低聚物是主要降解产物。（4）通过TGA/FTIR联用实时考察了玉米芯,聚乳酸塑料及其二者混合条件下的热解气体析出特性,FTIR分析发现玉米芯与聚乳酸塑料在共热解条件下存在明显的耦合作用。通过自制快速固定床热解反应器研究了玉米芯与聚乳酸塑料的共热解。结果表明,玉米芯与聚乳酸塑料的共热解使热解油产率和热值增加,而水分含量在降低。并且对共热解生物油进行了FTIR,¹H NMR,GC分析与表征。（5）热解生物质后的固体残渣活化实验以及吸附实验表明,以水蒸气为活化剂,可以制得吸附重金属效果良好的吸附剂。系统研究了吸附接触时间、溶液初始浓度、溶液pH值、吸附剂质量以及温度对Ni²⁺吸附性能。试验表明,吸附剂最大吸附量为15.33mg/g;Ni²⁺吸附速率服从Langmuir吸附等温式;吸附动力学符合准二级吸附速率方程。更多还原

【Abstract】 Great consumption of fossil fuels and increasing concern over the environmental pollution have been promoting an urgent search for new and cleaner energy.Biomass has received much attention in recent years,due to the lower contents of sulfur and nitrogen in the biomass.Thermochemical processes are thought to have great promise as a means for convening biomass into higher value fuels.Pyrolysis lies at the heart of all the themochemical fuel conversion processes and is assumed to become a thermocbemical conversion technology for the production of chars,liquids or gases.Pyrolytic oil has strategic value because,as a liquid with high calorific value,its handling,storage,transportation,and utilization are similar to that of oil.It can be upgraded to obtain light hydrocarbons for transport fuel.Bio-oil can be used in fuel applications or upgraded to refined fuels and chemical products.The solid char can be used as a fuel or it can be upgraded to activated carbon and used in purification processes.The gases generated have a low to medium heating value,but may contain sufficient energy to supply the energy requirements of a pyrolysis plant.The fast pyrolysis of biomass inherently results in the production of pyrolyic water, which is one of the major drawbacks of the hie-oil produced.The reduction of the water content and the augment of the heating value are essential upgrading steps in order to increase the applicability of bio-oil and to make the production of bio-oil competitive.The use of copyrolytic techniques on biomass/plastic ratios has already been investigated on based-petroleum plastics.Biopolymers（such as PLA）,which are a special kind of platic,will be widely applied in the future.Despite their biodegradability,however,most biopolymers still have to be considered as waste,since it would be ecologically unacceptable to dispose of them in the environment.The copyrolysis and polylatic acid plastic is aimed to increase the production of bio-oil,reduce the content of pyrolytic water and increase the heating value of bio-oil.The technique offers an alternative waste treatment option and may act as an upgrading step during the pyrolysis of biomass.The following works are carried main experimental results and conclusions are as follows in this dissertation:（1） Thermal decomposition of polylactic acid（PLA） was studied in the presence of pine wood sawdust（PS）,walnut shell（WS）,corncob（CC） in order to understand the pyrolytic behavior of these components occurring in waste.A thermogravimetric analyzer（TGA） was applied for monitoring the weight loss profiles under heating rate of 10℃/min.Results obtained from this comprehensive investigation indicated that PLA was decomposed in the temperature range 300～372℃,whereas the thermal degradation temperature of hiomass was 220～400℃.The difference of weight loss（ΔW） between experimental and theoretical ones, calculated as algebraic sums of those from each separated component,was about 17～46%at 300～400℃.These experimental results indicated a significant synergistic effect during PLA and biomass copyrolysis.Moreover,a kinetic analysis was performed to fit thermogravimetric data,the global processes being considered as one to two consecutive reactions.A reasonable fit to the experimental data was obtained for all materials and their blends.（2） Gas release and products distribution in corncob pyrolysis was investigated by simultaneous TGA/FTIR（Thermogravimetry-Fourier Transform Infrared） and Py-GC/MS （Pyrolysis-Gas chromatography/Mass spectrometry） techniques.The results showed that the mainly prolytic reaction occurs in the range of 220～400℃,and DTG（Differential Thermogravimetry） curves reached the maximum at 339℃.The real-time gas evolution was detected by FTIR and the evolutions of CH₄,CO₂,CO and organics were qualitatively analyzed.FTIR data was compared with TGA/DTG curves and an agreement between DTG and FTIR results was observed.Py-GC/MS was used for studying products distribution of corncob pyrolysis.Results indicated that the oxygenated organic compounds such as phenol, furan,ketone etc.were the main components.（3） Gas release and products distribution in PLA pyrolysis was investigated by simultaneous TGA/FTIR and Py-GC/MS techniques.The results showed that the mainly prolytic reaction occurs in the range of 320～372℃,and DTG curves reached the maximum at 359℃.The real-time gas evolution was detected by FTIR and the evolutions of CH₄,CO₂, CO and organics were qualitatively analyzed.FTIR data was compared with TGA/DTG curves and an agreement between DTG and FTIR results was observed.Py-GC/MS was used for studying products distribution of PLA pyrolysis.Results indicated the organic compounds such as acetaldehyde,ketone,esters,oligomers etc.were the main components.（4） Pyrolytic process has a promising potential for the environmentally friendly upgrading of biomass and other materials such as plastic,coal.The thermal degradation of corncob,PLA and their blends under nitrogen were studied using TGA/FTIA as a function of temperature.The gases evolved during degradation were inspected by in situ FTIR.The results showed that obvious synergies between corncob/PLA during copyrolysis were observed.Furthermore,the influence of a polylactic acid（PLA） plastic on the pyrolysis of corncob was investigated using a fast pyrolysis fixed-bed reactor.The results indicated that the coprocessing of PLA with corncob increased liquefaction yields and a lower water content as a function of the corncob/PLA ratios were obtained.（5） Studies on a batch sorption process using activated carbon derived from biomass were investigated to remove Ni²⁺ ions from aqueous solutions.The influence of operational conditions such as contact time,solution initial pH,Ni²⁺ initial concentration,sorbent mass and temperature on the sorption were studied.The kinetic data was fitted to pseudo-first order model and pseudo-second order model for different initial concentration to evaluate the model parameters.Pseudo-second order model was better to represent the adsorption process.更多还原