【作者】 宋成芳；

【导师】 计建炳； 艾宁；

【作者基本信息】 浙江工业大学 ， 化学工程， 2013， 博士

【摘要】 随着生物质固体废弃物量的增多,土壤污染和退化问题的日益严峻,合理开发和利用生物质资源,研发新型有效的土壤修复剂已成为当前紧迫的研究课题。生物质炭对增加土壤碳库贮量、提高土壤肥力以及维持土壤生态系统平衡意义重大,日益受到全世界的关注。热转化技术是实现生物质利用的最有效途径,催化热解被认为是改变生物质热解条件和热解产物分布与性质的最有效方法。本文对生物质(水稻秸秆和竹废料)的催化热解炭化试验和机理展开了系统的研究,主要研究内容及成果如下：1、对生物质原料的理化性质进行了分析,结果显示：竹废料有相对较高的纤维素和木质素含量,水稻秸秆则含有更多的半纤维素；工业分析显示竹废料的挥发份含量约为86%,水稻秸秆的灰分含量较大为15%；两种原料中的N、S的含量均是微量的。2、以生物质三种组分为原料进行热重试验,考察了七种添加剂(KOH、TiO2、 CuCl、CaCl2、FeCl2、KCl和NaCl)和升温速率对热解特性的影响,并求取了热解动力学参数。结果显示：半纤维素的热解起始温度最低,纤维素的最大热解速率最高：KOH可显著增大纤维素和木质素热解固体产物的得率；CuCl主要是可降低木聚糖热解温度,增大木聚糖热解速率；CaCl2可降低木聚糖和木质素热解温度,而FeC12可降低聚糖热解温度。随热解升温速率的增大,热解曲线逐渐向高温区移动,失重速率增大。3、以水稻秸秆和竹废料为原料进行热重试验,考察了KOH、TiO2和加热速率的影响,并求取了热解动力学参数,同时采用TG-FTIR分析了两种原料热解过程中挥发性产物的析出特性。结果显示：竹废料热解的起始温度较低,热解速率较快；水稻秸秆热解的固体得率大,而竹废料热解的气液得率高。竹废料热解反应的表观活化能在172.04-233.48KJ/mol之间,水稻秸秆热解反应的表观活化能在152.05-233.46KJ/mol之间。KOH可改变生物质热重曲线,TiO2对失重曲线的影响不明显；两种生物质热解的挥发性产物主要为CO2、H2O、CO、CH4、烷烃和脂类、C-O-C化合物和醛以及有机酸,竹废料的挥发性产物量较大。4、以水稻秸秆和竹废料为原料,在自制的热解反应器上进行热解炭化试验,结果显示：竹生物质炭的得率在28-35%之间,水稻秸秆炭的得率在41-52%之间,常规热解法较适宜于生物质热解制炭；随着热解温度的升高,炭得率逐渐减小；添加Ti02可略增大生物质炭的得率；而KOH的添加量较低时,可促进炭的得率,当添加剂的量大于30%的生物质量后,生物质炭得率反而下降,低温热解添加剂对炭的得率影响较大；两种添加剂均抑制液态产物的生成,但KOH能提高竹废料热解气的得率。5、采用仪器或化学的方法,分析了生物质炭的理化性质,得到如下结论：随着热解温度的升高,生物质炭中碳元素含量增大,而氢和氧元素含量降低,而且竹生物质炭的碳元素含量远远高于水稻秸秆炭的；生物质炭均含有多种矿物质元素,水稻秸秆炭中矿物质元素含量均较高；两种生物质炭均显示出碱性,随热解温度的升高,碱性增强,Ti02可降低生物质炭的pH值,而KOH则相反；生物质炭表面含有多种官能团,包括O-H、C-O、芳香环的C=C等,随热解温度升高炭中的脂肪族官能团消失,而芳香族官能团增大,当添加KOH后炭中出现了无机的碳酸根官能团；水稻秸秆炭的表面疏松多孔,温度越高,生物质炭的表面越疏松,孔也越明显,Ti02可促进炭表面的裂解程度；Ti02在生物质热解前后晶型不变,而添加KOH的生物质炭中含有无机和有机钾盐,因此KOH与生物质热解产物发生了化学反应,同时K具有催化作用。可见KOH催化生物质热解可得到一种富钾生物质炭土壤修复剂材料,而Ti02与生物质热解可得到一种含光催化剂的生物质炭基环保材料。6、生物质热解气中有4种主要成分,H2、CO、CH4和C02,在低温热解时CO2的含量最高；热解温度升高,CH4的含量明显增大,可燃性气体含量增大；添加KOH可显著提高H2的得率,可进一步处理获得H2,因此热解气的品质得到了提高。7、水稻秸秆生物油的化学组成主要由酮类、酚类和烷烃类、糠醛、糠醇和脂构成；竹生物油的主要组成是酚类化合物,还有酮类和烷类化合物,以及少量的醇、酸和脂类物质。两种添加剂都提高了生物油中酚类物质的相对含量。利用本文提出的思路,即选择合适的添加剂及添加量和生物质原来共热解可以获得不同类型的生物质炭复合材料,同时热解条件和副产物的成分也可以得到显著改善。更多还原

【Abstract】 As the increasing in quantity of solid biomass waste, soil pollution and degradation problems increasingly serious, reasonable development and utilization of biomass resources, research and development of new effective soil restoration agent have become the current urgent research subject. Biochar to increase soil carbon library, improve soil fertility and maintain soil ecosystem balance is of great significance, therefore is becoming more and more attention all over the world. Thermal conversion technology is the most effective way to realize the biomass utilization,and catalytic pyrolysis is regarded as the most effective method of change of biomass pyrolysis conditions and pyrolysis product distribution and properties, the mechanism of catalytic pyrolysis and carbonized technology of biomass (rice straw and bamboo waste) were systematically researched in this paper, the main research contents and results were as:1.The physical and chemical properties of biomass materials were analyzed, the results showed that bamboo waste have relatively high content of cellulose and lignin, and more hemicellulose in the rice straw. The industrial analysis showed that volatile content of bamboo waste is about86%, and ash content of rice straw is15%. Two kinds of raw materials in the content of N, S are trace.2. Three components of biomass as raw material to carry out thermogravimetric experiment, and the effects of seven additives (KOH, TiO2, CuCl, CaCl2, FeCl2, KCl and NaCl) and heating rate were investigated, and calculated the pyrolysis kinetics parameters. Results show that the pyrolysis rate of cellulose is highest, and lignin pyrolysis is relatively slow. The initial pyrolysis temperature of hemicellulose is lowest. KOH can significantly increase the yield of solid products of cellulose and lignin pyrolysis, CuCl mainly can reduce xylan pyrolysis temperature and increase xylan pyrolysis rate, CaCl2can reduce xylan and lignin pyrolysis temperature, and FeCl2can decrease the glycan pyrolysis temperature. With the increase of heating rate, the pyrolysis curve moves to the high temperature and weight loss rate increased.3. The rice straw and bamboo waste as raw material, the effects of KOH, TiO2, and heating rate have investigated by thermogravimetric experiment, and calculated the pyrolysis kinetic parameters, at using TG-FTIR to analyse the characteristics of volatile products of pyrolysis separation of the two kinds of raw materials. Results show that: the initiation temperature of bamboo waste pyrolysis is lower and pyrolysis rate is faster. The yield of solid production of rice straw pyrolysis is high, and the yield of gas and liquid of bamboo waste pyrolysis is high. The apparent activation energy of pyrolysis reaction of bamboo waste is between172-233KJ/mol, and rice straw is between152-233KJ/mol. KOH can change thermogravimetric curve of biomass. The volatility of pyrolysis products of two kinds of biomass are mainly for CO, CO2, H2O, CH4, alkanes and lipid, C-O-C compounds and aldehydes and organic acids, volatile products of bamboo waste is high.4. The rice straw and bamboo waste as raw materials, pyrolysis carbonization experiment was carried out on self-made pyrolysis reactor. The results showed that the yield of bamboo biochar is between28-35%, and the yield of rice straw charcoal is between41-52%, conventional pyrolysis way more suitable for biomass carbonization. With the increase of pyrolysis temperature, carbon yield decreases. Adding TiO2can slightly increase the yield of biochar, and a small amount of KOH can promote the yield of biochar, the yield of biochar decline when the content KOH is higher than30%. Pyrolysis temperature is lower, the greater the influence of additives on the yield of biochar. Two kinds of additives are inhibiting the production of liquid products, but KOH can improve the yield of gas of bamboo waste pyrolysis.5. The following conclusion is obtained by analyzing the physical and chemical properties of biochar:with the increase of pyrolysis temperature, the carbon content of biochar increases, and the content hydrogen and oxygen is reduced, and carbon content of bamboo biochar is much higher than rice straw charcoal. Biocharl contain a variety of minerals, the content of mineral elements in rice straw charcoal were higher than in bamboo charcoal; Both kinds of biomass carbon shows alkaline, TiO2can reduce biomass charcoal pH, and KOH is opposite. Biochar contain a variety of surface functional groups, including O-H, C-O, aromatic ring of C=C, etc., the aliphatic functional groups is lost gradually and aromatic functional groups is increasesed as the temperature rise of carbonization,. There were inorganic carbonate roots in biochar when adding KOH, Rice straw charcoal surface is porous, and the surface of the biochar is loose with the higher the temperature, the holes are more apparent, TiC^can promote the degree of cracking on the surface of the biochar. Pyrolysis process did not affect TiO2crystal structure, biochar contain inorganic and organic sylvite by adding KOH. That KOH catalytic biomass pyrolysis can get a rich potassium of biochar soil restoration agent, TiO2catalytic biomass pyrolysis can get a kind of biochar environmental protection material containing photocatalyst.6. There are four major constituents of biomass pyrolysis gas H2, CO, CH4and CO2, the highest content of CO2with low pyrolysis temperature. With pyrolysis temperature increasing, the content of CH4and combustible gas increased obviously. Adding the KOH can significantly increase the yield of H2, so the quality of the pyrolysis gas get improved.7. Chemical composition of rice straw bio-oil is mainly composed of ketones, phenols and alkane, furfural, furfural alcohol and fat. Bamboo bio-oil is the main composition of phenolic compounds, and ketones, alkanes compounds, and a small amount of alcohol, acid and lipid. Both additive improves the bio-oil phenolics relative content.Using the proposed ideas, namely, choosing the appropriate quantity additives and biomass pyrolysis can obtain different types of biochar composite products, at the same time, the conditions of pyrolysis and quality of by-products can be improved significantly.更多还原