生物质热解制备双金属催化剂及煤热解中硫的转化机制研究

发布时间：2018-01-12 14:16

本文关键词：生物质热解制备双金属催化剂及煤热解中硫的转化机制研究　出处：《中国科学技术大学》2017年硕士论文　论文类型：学位论文

【摘要】：生物质是一种丰富的可再生资源,热解是生物质的一种利用手段。通过热解生物质制备功能化材料是处置废弃生物质回收资源的有效手段,引起了学术界较大的关注。此外,热解还是一种洁净的煤利用方法,也是煤各种利用途径中的一个关键中间过程。煤热解过程中污染物的转化关系到热解的实际应用。因此,在本文中,我们通过生物质热解合成了一种双金属催化剂,并研究了其环境应用;利用TG-FTIR-MS在线分析手段研究了煤热解过程中硫的迁移和转化。本文的主要内容和结论如下:1.生物质热解制备生物炭基功能材料是一种双赢策略,既可以以环境友好的方式实现生物质的充分利用,又可以实现功能材料的简易合成。我们通过一种绿色简单的方法,即生物质热解和置换反应,制备了一种碳负载的铜钌双金属材料(Ru-Cu/C)。负载痕量Ru的Ru-Cu/C对催化水合肼还原六价铬有良好的催化活性,远优于单金属催化剂Cu/C和Ru/C。Ru-Cu/C在3分钟内可实现六价铬的完全还原,且在不需额外沉淀过程的情况下总铬去除率达到94%。我们对材料进行了多种表征,结果显示了双金属催化剂的协同效应与其物理化学结构之间的关系,如XPS结果显示Ru-Cu/C中的Cu和Ru之间存在强烈的相互作用。我们探索了该催化过程的可能机制,发现六价铬还原起主要作用的是Ru-Cu/C催化水合肼分解产生的活性氢。2.煤热解是煤各种利用过程的中间阶段,如气化,燃烧,液化,同时煤热解也是一个有效的脱硫方法。由于煤中硫种类和煤热解过程的复杂性,煤热解过程中硫的演化行为尚不清楚。为了开发和评价脱硫方法,认识和理解煤热解过程中硫的转化极为重要。我们利用在线的热重-红外-质谱联用技术(TG-FTIR-MS)研究了添加CaO和不添加CaO的煤热解过程中硫的转化行为。我们检测到了 10种含硫物质,包括H2S、SO2、S03、硫醇类和噻吩类化合物。结合TG-FTIR-MS提供的气相产物结果和XRD和XPS给出的固相中硫的信息,我们解释了煤热解中可能的硫转化机制。
[Abstract]:Biomass is a rich renewable resource, pyrolysis is a means of utilization of biomass, the preparation of functional materials through pyrolysis of biomass is an effective means to dispose of waste biomass recovery resources. In addition, pyrolysis is a clean coal utilization method. It is also a key intermediate process in various ways of coal utilization. The transformation of pollutants in coal pyrolysis is related to the practical application of pyrolysis. Therefore, in this paper. A bimetallic catalyst was synthesized by pyrolysis of biomass and its environmental application was studied. The transport and transformation of sulfur in coal pyrolysis were studied by means of TG-FTIR-MS on-line analysis. The main contents and conclusions of this paper are as follows:. 1. It is a win-win strategy to prepare bio-carbon-based functional materials by biomass pyrolysis. We can realize the full utilization of biomass and the simple synthesis of functional materials in an environmentally friendly way. We use a simple green method, that is, biomass pyrolysis and displacement reaction. A carbon-supported copper-ruthenium bimetallic material, Ru-Cu / C, was prepared. The Ru-Cu/C supported on trace Ru has good catalytic activity for the reduction of hexavalent chromium with hydrazine hydrate. Compared with Cu/C and Ru/C.Ru-Cu/C, hexavalent chromium can be completely reduced in 3 minutes. The removal rate of total chromium reached 94% without additional precipitation process. The results show the relationship between the synergistic effect of bimetallic catalyst and its physical and chemical structure. For example, XPS results show that there is a strong interaction between Cu and Ru in Ru-Cu/C. We have explored the possible mechanism of the catalytic process. It is found that the main role of hexavalent chromium reduction is the catalytic decomposition of hydrazine hydrate catalyzed by Ru-Cu/C. 2. Coal pyrolysis is the intermediate stage of coal utilization process, such as gasification, combustion and liquefaction. At the same time, coal pyrolysis is also an effective desulfurization method. Because of the complexity of sulfur species in coal and coal pyrolysis process, the evolution behavior of sulfur in coal pyrolysis process is not clear. In order to develop and evaluate the desulfurization method. It is very important to know and understand the conversion of sulfur in coal pyrolysis. We use the on-line thermogravimetric infrared mass spectrometry (TG-FTIR-MS). The conversion behavior of sulfur in the pyrolysis of coal with or without CaO was studied. Ten sulfur compounds were detected. It includes H _ 2S _ 2SO _ 2H _ 2O _ 3, mercaptan and thiophene compounds, combined with the gas product results provided by TG-FTIR-MS and the information of sulfur in solid phase given by XRD and XPS. We explain the possible sulfur conversion mechanism in coal pyrolysis.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ530.2;X70

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