【作者】 高桂梅；

【导师】 甘树才；

【作者基本信息】 吉林大学 ， 应用化学， 2010， 博士

【摘要】 本文以吉林省桦甸油页岩灰渣为原料,研究了水玻璃的提取工艺技术,进而以水玻璃为原料,成功地制备出性能优良的白炭黑、纳米Si02和疏水Si02气凝胶,为油页岩灰渣的综合利用提供了新的途径,具有重要的理论意义和潜在的经济效益。实验采用Box-Behnken实验设计对SiO2的提取过程中的物化条件进行优化,并确定了最佳的SiO2提取条件。实验结果表明,SiO2的提取率随着反应时间、反应温度和氢氧化钠浓度的增加而增加,当反应时间为5h、反应温度100℃、氢氧化钠的浓度为40wt.%时,SiO2的提取率达到最大73±0.50%。采用传统沉淀法并结合热风干燥(模拟流化床干燥技术)制备了技术指标符合国家标准的白炭黑。探究了反应条件对白炭黑比表面积和DBP吸油值的影响,确定了制备白炭黑的最佳工艺。本文首次联用了表面活性剂、超声振荡和共沸蒸馏相结合的纳米粉体分散技术,有效地控制了纳米粒子的团聚,制备出粒径小而均一的纳米SiO2粒子。实验发现聚乙二醇的加入能够有效的降低纳米SiO2粒子的表面能,减少粒子的团聚；超声波空化作用释放出的巨大冲击波和微射流,能够有效的击散纳米SiO2团聚体,获得粒径小、分散性好的纳米SiO2；共沸蒸馏技术能够地脱出颗粒之间的水分子和自由非桥接羟基,从而有效的控制SiO2粒子团聚。采用改进的溶剂交换-表面改性工艺,在常压下制备了多孔疏水SiO2气凝胶,探索了硅烷偶联剂的种类、水玻璃中SiO2含量、溶胶pH值和热处理温度对气凝胶性质的影响,确定了气凝胶的最佳制备工艺。实验首次采用微波干燥制备了SiO2气凝胶。采用微波干燥制备气凝胶,弥补了传统的烘箱干燥使凝胶受热不均而产生温度梯度的缺点,缩短了干燥时间,减少了粉体团聚,使气凝胶尽可能的保持原有的孔结构。综上所述,论文首次以油页岩灰渣为原料成功的制备了性能较好的白炭黑、纳米SiO2和气凝胶等硅系列化工产品,为油页岩灰渣的利用提供了一条新的途径,具有重要的社会意义和经济意义。更多还原

【Abstract】 With the increasing demand on the energy all over the world, the development of the global economy has been constrained by the shortage of oil resources. Oil shale is an important supplementary energy resource for oil and gas. At present, one of the main technologies available for utilizing oil shale resources is retorting oil shale to produce shale oil and gas, and the other is burning oil shale to generate electricity. Both of them produce a huge amount of residue. It can not only cause serious environmental pollution, but also lead to enormous waste of the other available elements. These problems limit the development of oil shale industry. So, to effectively utilize oil shale ash (OSA) becomes an important issue. In this paper, the sodium silicate solution was produced using Huadian OSA as silica source, and then the silica white, spherical silica nanoparticles and hydrophobic aerogels using the prepared sodium silicate solution. This method developed a new way for the comprehensive utilization of OSA. The samples were characterized by SEM、TEM、BET、FT-IR、XRD和TG-DTA. At present, there is little available information about silica series chemical products such as silica white, silica nanoparticles and aerogels from OSA.The water glass was produced through alkali extraction with OSA calcined and leached by acid. Box-Behnken statistical design was firstly used to optimize the factors affecting the extraction efficiency of the silica such as the sodium hydroxide concentration, the reaction time and the reaction temperature, to explore the interaction of the factors and to determine the optimum conditions for the extraction process. Multiple regression analyses showed that the extraction efficiency was in an agreement with the generated model and the experimental results. It was observed that the extraction efficiency of silica was increased by increasing the concentration of sodium hydroxide, the reaction time and the reaction temperature. At the optimum condition of reaction time 5 h, reaction temperature 100℃, and the concentration of sodium hydroxide 40 wt.%, the extraction efficiency reached 73±0.50%.The silica white was successfully synthesized using water glass prepared, and hot air drying simulating fluidized bed drying was employed for drying precipitation at an ambient pressure. The effects of the silica concentration, sulfuric acid concentration, temperature, pH value and aging time on the value of DBP adsorption and the BET specific surface of silica had been investigated. The optimum conditions were determined, such as the silica concentration 8.0 wt.%, sulfuric acid concentration 1.5mol/L, temperature 70-80℃, pH value 8 and aging time 8h. The microstructure analysis showed that the shape of silica white is sphere with an average size of about 50nm.The spherical silica nanoparticles were firstly synthesized using water glass as silica source and polyethylene glycol (PEG) as the surfactant via ultrasonic technique followed by azeotropic distillation. The results showed that the addition of PEG could effectively prevent the aggregation of silica nanoparticles and change the particle size, and the particle size and distribution depend on the PEG concentration. When the PEG concentration and molecular weight was 3wt.% and 10000, respectively, the silica particles with average diameter of 10 nm were uniformly distributed. The results indicated that ultrasonic is a key factor to the formation of small, uniform nanoparticles and an optimum hydrolysis-condensation period and powder of the ultrasonic cavitation is 0.5 h and is 70 W, respectively. The azeotropic distillation evidently restrains agglomerating. Possible mechanism of azeotropic distillation can be explained by the following facts. Firstly, the excess n-butanol molecules can not draw particles together through the formation of hydrogen bonds. Secondly, during the following solvent removal process, no hydrogen bond can be formed among neighboring particles because the hydroxyl groups on the particle surface are replaced by butoxy ones. Thirdly, the butoxy group has steric hindrance that can prevent the approach of particles. As a result, the azeotropic distillation dramatically reduces the possibility of the formation of chemical bonds and prevents the formation of hard agglomerates. The FT-IR spectra showed C-H peaks 3132 and 1402 cm-1, clearly indicating the organic modification of the nanoparticles surface. The hydrophobic silica aerogels were prepared using sodium silicate solution based on OSA via ambient pressure drying by improved method of solvent exchange-surface modification for the hydrogel. The influences of the kind of surface modification agents, SiO2 concentration, the pH value of sol and heat-treated temperature on properties of the aerogel were investigated. The results indicated that all the silica aerogels prepared under different conditions were nanoporous material with the meshwork structure, the BET surface area of 800-980 cm2/g, tapping density of 0.084-0.11 g/cm3, pore diameter of 9.38-10.10 nm. In the process of heat-treatment between 180 and 300℃, it was very hard for the gas to escape because of the heat expansion and low-permeability of the gas inside the aerogel. The gas compressed the framework of aerogel so as to enlarge the surface aera and pore size of silica aerogel. With the increasing of the temperature,-CH3 which was on the surface of the silica aerogel burned to decompose and became hydrophilic gradually.The aerogel with large specific surface area of 1360 cm2/g and big pore diameter of 12.4 nm was firstly synthesized by microwave heating technique. This method compensated for the shortcomings of oven drying of the temperature gradient, shortened drying time and reduced the agglomeration of the powders, so the aerogels maintained the original pore structure as much as possible.In summary, the silica series chemical products such as silica white, nanoparticles and aerogels, had been firstly synthesized using OSA as a new silica source. This method developed a new way for the comprehensive utilization of OSA and had important social and economic significance.更多还原