【作者】 张兵兵；

【导师】 苏海全；

【作者基本信息】 内蒙古大学 ， 生态学， 2013， 博士

【摘要】 本论文针对目前膨润土资源开发利用存在的技术落后、资源利用率低、环境污染严重、产业链短、产品性能落后、工艺能耗高等问题,以生态设计思想为指导,按照不同的膨润土原矿特点,研究开发资源利用率高、能源消耗少、对环境友好、产品性能优良的膨润土深加工清洁生产工艺。通过上述工艺得到使用性能优良、环境协调性好、附加值高的新型蒙脱土生态环境材料,并评价所制得的材料性能以及其在费托合成催化过程的应用。本文的研究内容主要包括三部分：(1)不含方英石膨润土深加工工艺研究；(2)富含方英石膨润土深加工工艺研究；(3)有机蒙脱土在费托合成中的应用研究。主要工作如下：(1)针对于不含方英石的膨润土综合利用难题,采用提纯和改型同步进行的湿法钠化工艺制备高纯蒙脱土,通过对湿法改型工艺中的反应条件对产品质量的影响以及它们之间的关系的研究,确定出最佳的单元操作条件,最终得到蒙脱石含量高达95.6%的高纯钠基蒙脱土。进而,针对其湿法提纯工艺中“脱水难”的问题,在考虑膨润土的物理化学性质的基础上,依据结构以及性质的不同,选择了五种天然有机高分子絮凝剂羧甲基淀粉钠、羧化壳聚糖、瓜尔胶、羟丙基瓜尔胶、阳离子瓜尔胶,利用分光光度法考察了不同絮凝剂对高纯钠基膨润土矿浆的絮凝性质,并依据其絮凝性质的差别探讨了五种絮凝剂絮凝膨润土的絮凝机理。以膨润土湿法提纯后得到的钠基膨润土浆液为原料,以氧化钙和氯化钙为胶化剂制备了钠基膨润土无机凝胶。比较了胶化剂类型、用量、时间、转速等条件对凝胶性能的影响,并依据其凝胶性能的差别探讨了钠基膨润土无机凝胶的胶化机理。以钙基膨润土原矿为起点,制备出吸水快、吸水量大、白度高、强度高的膨润土猫砂。(2)针对富含方英石膨润土的提纯难题,研究使用碱法提纯方案有效地实现了富含方英石膨润土矿产资源的经济、高效、可持续利用。所制备的高纯蒙脱土其蒙脱石含量高达97%。为了尽可能提高资源的利用率及实现废弃物的资源化利用,研究以上述富含方英石膨润土碱法提取液为原料使用沉淀法制备白炭黑及纳米二氧化硅。考察不同沉淀剂的沉淀效果,研究反应温度、pH值、浓度、反应时间对白炭黑产品性能及产率的影响。研究不同表面活性剂对所得纳米二氧化硅的粒径的影响,确定了富含方英石膨润土碱法提取液的最佳沉淀方法及条件。该工艺不仅实现了富含方英石膨润土碱法提取废液的回收利用,而且实现了资源循环利用,提高了生产效益,又没有对环境造成污染,体现了绿色工艺的思想。(3)使用有机修饰剂改性后的蒙脱土作为新型载体用于费托合成研究,得益于优良的热稳定性、独特的气体阻隔性和温度开关的性质。有机修饰剂作为催化剂活性组分的有机保护层可以简单有效地实现催化剂反应状态的原位隔离和保护,从而被成功应用于对钴基费托合成反应过程的详细研究。就像将古代生物原始状态保存完好的的琥珀一样,聚合物链在原位固化隔离和保护了实际催化剂的结构,以确保离位分析的催化剂状态充分代表了真实催化剂的工作状态。使得费托合成研究中仍然存在争议的一些关键问题得以解决,如还原过程中的钴纳米粒子的相变和团聚、费托反应中活性相态的变化、费托催化剂结构与性能的关系等得以阐明。通过设计不同的有机改性剂,我们可以通过传统的离位表征技术表征各种催化反应的催化剂在真实反应条件下的纳米结构,为将来其它催化体系的研究开辟了一条新途径。更多还原

【Abstract】 Focusing on the present problems that exist in bentonite resource development and utilization such as low-level technology, low resource utilization ratio, serious environmental pollution, short industry chain, poor product performance and high energy consumption; guided by the concept of ecological design, on the basis of the different characteristics of bentonite raw mineral; this thesis develop clean technology of bentonite deep processing with the advantages features including high utilization ratio of resources, less energy-consuming, environmental friendliness and excellent product property. The new montmorillonite ecomaterials obtained through the above technique were featured by excellent property, well environmental benignity and high additional value. Furthermore, the applications of ecomaterials performances in Fischer-Tropsch synthesis process were evaluated as well. This thesis mainly includes three parts:(1) deep processing technology of christobalite-free bentonite;(2) deep processing technology of cristobalite-rich bentonite;(3) application of orgnic modified montmorillonite in Fischer-Tropsch synthesis.The main work is as follow.(1) For christobalite-free bentonite, high purity montmorillonite was prepared by wet sodium modification process, which the purification and modification were carried out simultaneously. The optimal unit operation conditions were determined by researching the influence of wet modification process conditions on product quality and the relationship between them. Consequently, the final montmorillonite content of the resulting high purity sodium bentonite is as high as95.6%. Furthermore, the efficient dewatering of colloidal stable bentonite suspensions presents an intractable challenge for the wet purification process. On the basis of the consideration of the bentonite physical and chemical properties, five natural polymer flocculants, inchuding carboxymethylstach sodium, carboxyl chitosan, guar gum, hydroxypropyl guar gum and cationic hydroxypropyl guar gum, were choosed depending on the structure and property difference. The sodium bentonite slurry flocculation conditions of the five flocculants were studied by spectrophotometry. The bentonite flocculation mechanism of the five flocculants was explored based on their different flocculation properties. The sodium bentonite inorganic gel was prepared by bentonite wet purification slurry as raw material, and calcium oxide or calcium chloride as gel agent. The influences of gel agent type, gel agent dosage, dispersion time, dispersion speed and other reaction conditions on gel performance were compared. The mechanism of sodium bentonite inorganic gel was explored based on the difference gel performance. Finally, the bentonite Litter with advantages features including fast water uptake, more water uptake volume, high whiteness and high strength was prepared by the calcium bentonite..(2) For cristobalite-rich bentonite mineral resources, alkaline purification scheme was utilized economicly, efficiently and sustainably. Consequently, the montmorillonite content of the resulting high purity sodium bentonite through the alkaline purification process is as high as97%. In order to improve the utilization ratio of resources as far as possible and realize the recycl usage of the wastes, silica and nano SiO2were prepared by precipitated the extract wastes of cristobalite-rich bentonite alkaline purification. The effects of different precipitating agents were investigated. The influence of reaction temperature, pH, concentration and reaction time on the properties and yield of silica were compared. The effects of different surfactant on the resulting nano SiO2particle size were investigated as well. Then the optimal precipitation method and condition were determined. The alkaline purification process is not only to achieve the cristobalite-rich bentonite alkaline extraction liquid wastes recycl usage, but also to improve production efficiency, and do not pollute the environment. It reflects the thought of green technology.(3) Organic modified montmorillonite was used as a new carrier for Fischer-Tropsch synthesis. Due to the excellent thermal stability, special gas barrier and temperature switch behavior, the organic modifier as the protective coating of catalyst active components were used to in-situ isolate and protect the actual catalyst structure, consequently, to study the reaction involved in the cobalt-based Fischer-Tropsch synthesis in detail. Just like the original state of ancient organisms preserved well by amber, the polymer chains were in situ solidified to isolate and protect the actual catalyst structure, which ensured the ex situ analyzed catalyst state to fully represent the working state of the catalysts. Accordingly, some critical important issues which could not be studied clearly in past days, such as the phase transformation and sintering agglomeration of cobalt nanoparticles in reduction procedure, the identification and phase transformation of the active species during reaction, and the structure-property relationship of catalysts for the FTS, have been thoroughly revealed. By designing different organic modifiers, we can characterize nanostructure evolution of catalysts of various catalytic reactions under operation reaction conditions via ex situ characterization techniques. Therefore, a new way was opened for the future research of other catalytic systems.更多还原