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类型 基础研究 预答辩日期 2018-01-31
开始(开题)日期 2016-01-22 论文结束日期 2017-10-11
地点 动力楼422 论文选题来源 973、863项目     论文字数 9.1 (万字)
题目 稻壳热解多联产及其产物改性应用的基础研究
主题词 稻壳,热解多联产,生物油提质,稻壳焦活化,多孔碳材料
摘要 稻壳是水稻加工的副产物,是一种重要的农林生物质资源,因此在我国大力发展稻壳生物质资源化利用技术,对有效保障能源供给安全、改善环境污染和减少碳排放具有重要的意义。生物质热解多联产技术由于其在工艺和经济性方面的优势,现阶段较符合我国生物质能源的发展需求。但是,由于热解所得热解气、生物油和生物焦产物品质较低,直接利用困难,限制了生物质热解多联产技术的进一步发展。基于此,本文从稻壳热解多联产及其产物改性利用方面,开展了相应的基础和应用研究。 (1)采用联合酸洗-烘焙预处理从源头上调控生物质原料的品质,并揭示预处理过程对稻壳样品理化特性的影响机制。对预处理前后稻壳样品的燃料特性、表面官能团、晶体结构、微观形貌、可磨性和疏水性等物理化学特性进行分析,结果发现联合预处理脱除了稻壳样品中大量的无机矿物元素,尤其是碱金属和碱土金属(AAEMs),同时也提高了稻壳样品的燃料特性,改善了样品的可磨性和疏水性。通过对比未酸洗和酸洗后稻壳样品烘焙过程的固、液、气三相产物收益率和烘焙液与气体产物的品质,发现酸洗预处理过程对随后烘焙过程具有显著的影响,酸洗后稻壳烘焙过程的固体收益率提高,烘焙液中乙酸含量降低,糖类含量提高。 (2)通过热重分析仪和固定床热解实验台,研究了联合酸洗-烘焙预处理对热解动力学及热解多联产气、液、固三相产物特性的影响机制。热解动力学分析结果发现,对于所有稻壳样品活化能E总体上都是随着转化率α的增加而逐步增加的,酸洗预处理对稻壳样品热解平均活化能有些许提高,且随着烘焙温度的升高,平均活化能值逐渐增大。采用等转化率法和模型拟合方法求解热解反应机理的模型函数,发现在主要热解反应区间内,反应级数模型函数占主导作用。基于固定床热解反应器,研究分析了预处理对稻壳样品热解多联产三相产物的影响。结果发现酸洗过程增加了生物油的收益率,降低了生物焦和不可凝气产物的收益率,而随后的烘焙过程则降低了生物油的收益率,增加了生物焦的收益率。进一步研究发现,联合酸洗-烘焙预处理提高了生物油的热值和pH值,降低了生物油的含水率,预处理对生物油的化学组分影响较大,预处理后热解生物油中酚类和糖类的含量增大,而酸类、酮类、醛类和呋喃类等小分子组分的含量降低;热解不可凝气体产物中CO、CH4和H2等可燃组分的体积浓度均有所提高,气体产物的热值提高;所有热解稻壳焦的比表面积在215.8~300.9 m2/g范围内,且预处理后稻壳焦灰分中SiO2相对含量增加到97.76%~97.98%。 (3)采用两段式热解-催化固定床实验系统探究了联合酸洗-烘焙预处理与热解气在线催化耦合对生物油品质改性的影响机理。研究发现,随着Fe负载量的增加,提质后生物油的收益率逐渐下降,但生物油中芳香烃的相对含量逐渐增加,芳香烃中苯、萘和萘的衍生物的选择性提高,而二甲苯、乙苯和三甲苯的选择性相对降低。综合比较不同的Fe负载量的ZSM-5分子筛催化剂,发现过高的负载量影响生物油收益率,而4Fe/ZSM-5分子筛催化剂被认为是最优的催化剂。联合酸洗-烘焙预处理与热解气在线催化耦合可提高生物油中芳香烃类组分的含量,并进一步提高了芳香烃类组分中苯、甲苯和二甲苯的选择性。综合考虑收益率和芳香烃选择性等方面的因素,认为中度的烘焙条件即240 ℃的烘焙温度是比较适合的。 (4)以热解稻壳焦为原料,采用NaOH-KOH混合碱直接活化改性制备出高性能的多孔碳材料,其物理化学性能和电容特性分析表明,NaOH-KOH混合碱活化综合了NaOH和KOH活化各自的特点,所得的多孔碳材料不仅具有较大的比表面积(3046.06 m2/g)和总孔容(1.69807 cm3/g),同时还具有微孔/介孔的发达孔隙结构,介孔率达到46.74%,平均孔径为2.22986 nm。电化学测试结果表明,NaOH-KOH混合碱活化后的多孔碳材料具有良好的倍率特性、充放电可逆性和循环稳定性。在0.2 A/g电流密度下,此多孔碳材料的比电容达到312 F/g,其对应的双电层超级电容器能量密度达到10.8 Wh/kg。 (5)提出了一种稻壳焦脱硅-活化两步法同时制备白炭黑与多孔碳材料的工艺路线,并研究稻壳焦中SiO2对随后混合碱活化过程孔隙结构形成的影响。通过优化白炭黑的制备条件所得白炭黑产品超过沉淀水合二氧化硅的国标性能参数。相比于原稻壳焦直接活化,脱硅后稻壳焦活化制备的多孔碳材料具有更大的比表面积(3255.83 m2/g)和总孔容(1.75426 cm3/g),同时具有更深的石墨化程度。电化学测试结果表明,脱硅后稻壳焦活化所得多孔碳材料呈现出优异的电化学性能,在0.2 A/g电流密度下,此多孔碳材料的比电容达到345.6 F/g,其对应的双电层超级电容器能量密度达到12.0 Wh/kg。综合各因素,发现相比于稻壳焦直接活化制备多孔碳材料,稻壳焦脱硅-活化两步法同时制备白炭黑与多孔碳材料是一种更为理想的稻壳焦改性提质方法。
英文题目 Fundamental study on rice husk pyrolysis polygeneration and modification for application of pyrolysis products
英文主题词 Rice husk, Pyrolysis polygeneration, Bio-oil upgrading, Rice husk char activation, Porous carbon material
英文摘要 Rice husk, the by-product of rice processing factory, is an important agriculture and forestry biomass resource. Therefore, it is necessary to develop rice hull biomass utilization technology in our country, which has important significance to effectively guarantee the safety of energy supply, improve environmental pollution and reduce carbon emissions. Because of its advantages in the process and economy, biomass pyrolysis polygeneration technology is in line with China’s biomass energy development needs at this stage. However, due to the low quality of pyrolysis products (non-condensable gases, bio-oil and char), direct use of these products is difficult which can limit the further development of biomass pyrolysis polygeneration technology. Based on this, this thesis carried out the basic and applied research on rice husk pyrolysis polygeneration and its pyrolysis product modification for utilization. (1) The quality of biomass raw materials was regulated by combined acid washing and torrefaction pretreatment, and the mechanism of pretreatment process on the physical and chemical properties of rice husk samples was revealed. The fuel characteristics, surface functional groups, crystal structure, microstructure, grindability and hydrophobicity of rice husk samples before and after pretreatment were analyzed. The results indicated that combined pretreatment not only removed a large amount of inorganic mineral elements from rice husk samples, especially alkali and alkaline earth metals (AAEMs), but also improve the fuel characteristics of rice husk samples. The grindability and hydrophobicity of rice husk samples were also improved by combined acid washing and torrefaction pretreatment. By comparing the yields of solid, liquid and gas products and the quality of torrefaction liquid and gas products during the torrefaction process of rice husk samples, it was found that the acid washing pretreatment process had a significant effect on the subsequent torrefaction pretreatment process. The solid yield of torrefaction process after acid washing was improved, meanwhile, the relative content of acetic acid in torrefaction liquid was reduced and the relative content of sugars was increased. (2) The influence mechanism of combined acid washing and torrefaction pretreatment on pyrolysis kinetics and gas, liquid and solid three-phase pyrolysis products was revealed by thermogravimetric analysis and fixed-bed pyrolysis reactor. The pyrolysis kinetics analysis showed that activation energy E of all rice husk samples increased with the increase of conversion rate α. The torrefaction process slightly increased the value of average activation energy. With the increasing of torrefaction temperature, the value of average activation energy was gradually increased. Model-fitting method and isoconversional method were used to obtain the reaction model function. It was found that the main pyrolysis process could be described by reaction-order model function. The effect of combined pretreatment on three-phase pyrolysis products of rice husk samples was analyzed using a fixed-bed pyrolysis reactor. The results showed that acid washing process increased the yield of bio-oil, but reduced the yields of char and non-condensable gases products. However, the subsequent torrefaction process reduced the yield of bio-oil and increased the yield of char. Combined pretreatment resulted in a significant increase of pH and calorific values along with a reduction of the water content of bio-oil. It also has an important effect on the chemical composition of bio-oil, which resulted in a significant increase in the relative content of phenols and sugars in bio-oil along with a reduction of acids, ketones, aldehydes and furans. After combined pretreatment, the volume fraction of CO, CH4 and H2 in non-condensable gases was increased, resulting in the high calorific values of gas product. The specific surface areas of rice husk char from all the rice husk samples were in the range of 215.8~300.9 m2/g, and the relative content of SiO2 in the ash of rice husk char was increased to 97.76%~ 97.98% after pretreatment. (3) The influence mechanism of combined acid washing and torrefaction pretreatment and on-line catalytic cracking of pyroysis volatiles on the upgrading of bio-oil were studied using two-stage catalytic pyrolysis system. It was found that the yield of bio-oil decreased gradually with the increase of Fe loading, but the content of aromatic hydrocarbons in bio-oil gradually increased. With the increase of Fe loading, the selectivity of benzene, naphthalene and naphthalene derivatives was enhanced, but the selectivity of xylene, ethylbenzene and trimethylbenzene was reduced. Comparing the results of different Fe loading in ZSM-5 zeolite catalyst, it was found that the high loading reduced the bio-oil yield. Therefore, 4Fe/ZSM-5 zeolite catalyst was considered as the best catalyst. Coupling pyrolysis volatiles on-line catalytic cracking with combined acid washing and torrefaction pretreatment improved the relative content of aromatic hydrocarbons in bio-oil and further enhanced the selectivity of benzene, toluene and xylene. Considering the factors such as the yield and selectivity of aromatic hydrocarbons, it is considered that the torrefaction condition, i.e., the torrefaction temperature of 240 ℃, was more suitable. (4) Pyrolysis rice husk char was used as raw material, high performance porous carbon materials were prepared by NaOH-KOH mixed alkali activation modification. The physical and chemical properties and capacitance characteristics of obtained porous carbon materials indicated that NaOH-KOH mixed alkali activation combined with the characteristics of NaOH and KOH activation. The obtained porous carbon material not only exhibited a specific surface area as high as 3046.06 m2/g with total pore volume of 1.69807 cm3/g, but also had the microporous/mesoporous developed pore structure with the mesopore percentage of 46.74%, meanwhile the pore size of this porous carbon material was 2.22986 nm. Electrochemical test results showed that the porous carbon material prepared by NaOH-KOH mixed alkali activation has an excellent rate capability, charge and discharge reversibility and cycle stability. At the current density of 0.2 A/g, the specific capacitance of obtained porous carbon material reached 312 F/g, and the electric double layer supercapacitor fabricated with this porous carbon material delivered a high energy density of 10.8 Wh/kg. (5) A process route for simultaneous preparation of silica and porous carbon material by two-stage desiliconization and activation of rice husk char was proposed. Furthermore, the effect of SiO2 in rice husk char on the formation of pore structure during the process of mixed alkali activation was studied. By optimizing the preparation conditions of silica, the features of the silica prepared were superior to that of precipitated hydrated silica according to national standard. Compared with direct activation of rice husk char, the porous carbon material prepared by activation of rice husk char after desiliconization has a larger surface area (3255.83 m2/g) and total pore volume (1.75426 cm3/g). Furthermore, it has a higher a high degree of graphitization. Electrochemical test results showed that the porous carbon material obtained by activation of rice husk char after desiliconization exhibited excellent capacitance performance. The specific capacitance of this porous carbon material reached 345.6 F/g at the current density of 0.2 A/g, and the energy density of corresponding electric double layer supercapacitor was 12.0 Wh/kg. In general, it was found that simultaneous preparation of silica and porous carbron material by two-stage desiliconization and activation of rice husk char was an ideal upgrading method of rice husk char.
学术讨论
主办单位时间地点报告人报告主题
东南大学 2015.06.25 动力楼429 Yong-Chil Se 燃煤烟气脱汞技术研究进展
东南大学 2015.06.28 吴健雄纪念馆报告厅 白俊文 第九届中国制冷竞赛技术交流
东南大学 2015.12.28 东南院102 宋启磊 Functional Nanomaterials for Energy and Sustainability
南京理工大学 2014.12.11 能源与动力学院807教研室会议室 张书平 基于预处理调制的生物质热解多联产及其生物焦改性应用的基础研究
东南大学 2015.04.12 礼西308 张书平 微波辐照活性炭同时脱硫脱硝技术研究
东南大学 2016.03.18 礼西308 张书平 褐煤桨叶干燥过程研究
东南大学 2016.09.07 礼西308 张书平 微波技术处理固体废弃物
东南大学 2014.11.08 动力楼429 John Edward Anthony Gasification Technology-Developments
     
学术会议
会议名称时间地点本人报告本人报告题目
2016 3rd Int. Conf. on Power and Energy Systems Energineering 2016.09.08-12 Kitakyushu, Japan Effect of washing with aqueous fraction of bio-oil on pyrolysis behavior of rice husk and preparation of amorphous silica from combustion of pyrolysis char
江苏省颗粒学会(江苏省颗粒学会青年科技(能源环境)论坛) 2015.11.08 南京市浦口高新开发区丽景路1号莱福城A区苏台合宴1楼百灵厅 High quality syngas production from microwave pyrolysis of rice husk with char-supported metallic catalysts
     
代表作
论文名称
Effects of water washing and torrefaction pretreatments on rice husk pyrolysis by microwave heating
High quality syngas production from microwave pyrolysis of rice husk with char-supported metallic ca
Effects of water washing and torrefaction on the pyrolysis behavior and kinetics of rice husk throug
Combination of Light Bio-oil Washing and Torrefaction Pretreatment of Rice Husk:
Effects of torrefaction on yield and quality of pyrolysis char and its application on preparation of
Effects of wet torrefaction on the physicochemical properties and pyrolysis product properties of ri
Influence of coupling demineralization with torrefaction pretreatment process on pyrolysis character
Physicochemical Properties and Combustion Behavior of Duckweed during Wet Torrefaction
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
沈来宏 正高 教授 博导 东南大学
卢平 正高 教授 硕导 南京师范大学
沈德魁 正高 教授 博导 东南大学
章名耀 正高 教授 博导 东南大学
朴桂林 正高 教授 硕导 南京师范大学
      
答辩秘书信息
姓名职称工作单位备注
王沛 其他 工程师 东南大学