论文中文题名: | 超细煤粉体的光催化氧化反应性及动力学研究 |
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学号: | B2002006 |
保密级别: | 公开 |
学科代码: | 081902 |
学科名称: | 矿物加工工程 |
学生类型: | 博士 |
学位年度: | 2006 |
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论文外文题名: | Reactivity and Kinetics of Ultra-fine Coal Powder in Photo-catalytic Oxidation |
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论文中文摘要: |
在西部大开发中,如何对煤炭资源进行高效、洁净、高附加值转化利用,是目前迫切需要解决的战略问题。随着人类对环境的日益重视和“白色污染”的加剧,可降解材料的研究开发已成为世界瞩目的热点问题之一。煤基可降解材料的生产是实现煤炭非燃料高附加值利用和解决“白色污染”的有效途径,该材料降解周期精确控制的技术关键是阐明煤的光催化氧化降解反应性及动力学。 本文引入分形维数定量表征了煤超细粉体颗粒分布均匀程度和颗粒表面的光滑程度。超细煤粉体的FTIR图谱研究表明:随煤变质程度的提高,煤中含氧官能团减少,缩合程度增大,脂肪氢(Al-CH)含量下降和芳香氢(Ar-CH)的含量上升;羟基-羟基氢键、环羟基氢键呈减少趋势,而羟基-醚氢键呈增加趋势。 将煤结构与光化学理论相结合,采用分形分析及现代测试方法,在自行设计的紫外光光催化氧化反应装置上,首次系统研究了煤低温光催化氧化反应性及影响因素。研究发现:反应温度、氧气流量、光强度及煤粉粒度是影响煤光催化氧化反应性的重要外部因素;煤的光催化氧化反应分为三个阶段;低变质程度煤具有较高的光催化氧化反应活性;煤低温光催化氧化的气体产物组成为CO2、CO、CH4和C2H4等,进而揭示出在光催化氧化反应中存在煤大分子烷基侧链的NorrishⅡ型光分解反应。 通过超细粉碎-浮沉试验联合方法分离获得了煤的不同密度级组分,发现神府长焰煤的密度级组分主要富集在1.350-1.375g/cm3(D2),1.375-1.400g/cm3(D3)及>1.400g/cm3(D4)三个密度级别中。首次通过不同密度级煤组分的结构和光催化氧化特性研究,揭示了煤的结构和光催化氧化反应性的关系。不同密度级煤组分的光催化氧化反应活性顺序为:D2>D3>D4。腐植酸产率随着光催化氧化时间的增加而增大,各密度级煤组分光催化氧化产物的腐植酸产率大小为:D2>D3>D4。在煤光催化氧化过程,存在煤大分子分解与交联两类竞争反应。煤光催化氧化后,煤不同密度组分的表面官能团结构的变化规律不同。 对比研究了原煤及其不同密度级组分的光催化氧化反应性与热氧化性的差异,结果表明:煤光催化氧化的反应活性高于其热氧化的反应活性。光氧化煤的腐植酸产率远高于热氧化煤。 不同过渡金属离子、纳米二氧化钛(nano-TiO2)及其稀土金属盐复合催化剂与煤大分子之间存在光催化氧化协同作用。发现通过外加金属离子、nano-TiO2和稀土金属盐/nano-TiO2复合催化剂,可以控制煤光催化氧化产物的组成。探讨了煤的结构参数与煤光催化氧化反应性的关系,发现煤的光催化氧化反应性可以用其结构参数的线性方程表示。首次提出了煤自光敏化光催化氧化降解机理,建立了煤光催化氧化的表观动力学模型,发现负载过渡金属离子能明显降低煤发生光催化氧化反应所需的活化能。 深入研究煤光敏化光降解薄膜的降解特性及控制因素发现:煤粉在聚合物中的光敏作用与煤质和煤粉添加量有关,煤粉与铁盐对聚合物降解有协同光敏化作用,通过控制煤/铁盐复合光敏剂的种类和添加量可控制煤光敏化光降解膜的降解周期。 本文的研究结果不仅对煤光敏化光降解薄膜的开发和应用具有一定的理论指导意义,同时也为用光催化氧化方法进行煤的定向转化开拓了新途径。
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论文外文摘要: |
How to utilize coal resource with high efficiency,cleanliness and high-attached value is a
strategic problem in grand development of West China.Due to“white pollution’’becoming
more and more serious and human focusing more and more on environment protection,the R
&D of degradable materials are becoming a hotspot.The preparation of coal-based
degradable materials is one effective way of coal in non-—fuel utilization and high·-attached
value processing transformation.The technique key problem of accurate control in the
degraded periods of the coal—based degradable materials is to clarify the reactivity and
kinetics in coal photo—catalytic oxidation.
In this paper,the grades of ultra—fine coal powder’s uniformity and coal granular surface
morphology were characterized by the fractal dimensions.The functional groups of ultra—fine
coal powder were studied by Fourier Transform Infrared spectroscopy(FTIR)and
curve—fitting analysis.The results showed that oxygen—containing functional groups and
content of aliphatic hydrogen(A1一CH)decreased,whereas the degree of ring condensation
and content of aromatic hydrogen(Ar—CH)increased with increasing coal rank.Meanwhile,
main hydrogen bonds in coal structure were OH—OH,cyclic OH tetramers and OH—ether O.
With increasing coal rank,OH-OH and cyclic OH tetramers reduce,but OH—ether increases.
The reactivity and their affecting factors of different rank coals in photo—catalytic
oxidation were firstly systemically studied in a self-made photo-catalytic oxidation reactor on
the basis of the combination of coal structure and photochemistry in theory,fractal analysis
and modem characteristic methods.The experimental results indicated that the temperature,
rate of oxygen flow,ultraviolet radiation intensity and coal particle’s size were important
exterior factors in coal photo—catalytic oxidation,the reaction procedure of coal
photo—catalytic oxidation could be divided into three periods.Low—rank coal has higher
activity than high·rank coal in photo-catalytic oxidation.It can be deduced that there is the
photolysis reaction of Norrish 11 of coal macromolecule in photo—catalytic oxidation because
the gases released in the reaction are C02,CO,CH4 and C2l-h,etc.
The different density grade components of coal were selected by the method combining
the coal ultra—fine pulverization and the float—sinking experiment.It showed that the density
grade components of Shenfu coal were three main density groups of D2(1-350-1.375 g/cm3),
D3(1.375—1.400 eCcm3)and D4(>1.400 g/cm。).It’S firstly discovered the relationships
between coal’S struCture and its activity in photo—catalytic oxidation by studying the structure
of coal different density grade components.The order of coal components’activity in
photo.catalytic oxidation iS D2>D3>D4.The humic yield ratio of coal different component
increases with increasing the time of photo-catalytic oxidation.The order of humic yield ratio
also is D2>D3>D4.There are two kinds of competing reaction,decomposed and cross—liked
reaction, and the surface functional groups of coal components change in the coal
photo—catalytic oxidation.The activity of coal in photo—catalytic oxidation is higher than in
thermal oxidation.The humic yield ratio of photo—oxidized coal is also hi【gher than
thermal.oxidized coal.
The synergic photo—catalytic effect between transition metal ions,nano—Tit2,rare metal
ions compound catalysts and coal macromolecules were discovered.It’S also found that the
products of coal photo—catalytic oxidation Can be controlled by addition of metal
ions/nano—Ti02.The relationships between reactivity of coal in photo—catalytic oxidation and
its structural parameters were discussed and the linear formula wasproposed.The mechanism
of self-photosensitized photo-catalytic oxidation degradation of coal was firstly proposed and
the dynamics model of photo-catalytic oxidation of coal was presented.The active energy of
coal loading metal ions in photo-catalytic oxidation decreases.
The degraded properties and degradation control theory of coal photosensitive
degradable films were illustrated.It’S discovered the photosensitive activity of coal powder
for polymers is correlated to the coal quality and its adding amount,the synergic
photosensitivity between coal powder and ferric stearic acid for polymers degradation is
existed,the degraded periods of the coal photosensitive degradable films can be holed by
adjusting the species and amount of coal/ferric compound photosensitizeL
The research is not only directive significance in theory for the development and
application of coal photosensitized degradable films,but also exploits a new route for coal
orient transformation by photo·catalytic oxidation.
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中图分类号: | TQ530.2 O643.32 |
开放日期: | 2011-09-12 |