【作者】 李疆；

【导师】 单永奎；

【作者基本信息】 华东师范大学 ， 物理化学， 2010， 博士

【摘要】 近年来原油供应的持续短缺,供需矛盾日益尖锐,石油资源日趋枯竭已成为小争的事实。据有关报道,世界上的石油储量可供人类使用30-40年。而我国是贫油国家,情况尤为突出,可供使用的石油储量会更少,能源和原料供应面临严峻的挑战。从资源方面考虑,普遍地认为我们的基本国情是富煤,缺油,少气。但如果从可有效利用成分的角度来看,事实并非如此。与天然气具有类似组成的,性质相似或相同,以甲烷为主要成分的碳资源（包括天然气,煤层气,天然气（甲烷）水合物和沼气）是储量极其丰富的资源,其中天然气资源比石油资源丰富,据预测可满足世界需求120年以上;煤层气主要成分与常规天然气相似,全球埋深浅于2000米的煤层气资源约为240万亿立方米,是常规天然气探明储量的两倍多。我国煤层气资源丰富,居世界第三；目前,国际间公认全球的天然气水合物总储量是地球上所有煤、石油和天然气总和的2倍至3倍,可供人类使用1000年以上（当然其开采技术尚不成熟）；沼气（主要成分甲烷）来源于生物质,属于可再生资源。此外,与石油和煤相比,它们还有清洁和热值高的优点。因而这类资源备受世人关注与重视,大力开发和利用这种资源几乎已经成为世界各国改善环境和维持可持续发展的最佳选择。然而甲烷在热力学上的稳定性成为其广泛应用的最大障碍。本博士论文的工作就是采用光化学卤化甲烷的方法,在甲烷气中添加低碳烷烃的方法以及采用原位涂层法合成了系列负载有磷酸铁的介孔催化材料作催化剂等方法来实现甲烷的低温高选择性的可控转化,以求实现低温常压条件下的高选择性的活化甲烷。主要工作有:1.甲烷的光化学碘化反应的研究本部分我们首先设计制作了适合气体光化学反应的反应器。并对甲烷与碘的光化学反应进行了研究。研究结果表明:甲烷与碘的光化学反应,只有紫外光部分起作用。可见光部分对光反应无效果。紫外光作用下的甲烷碘化反应,碘甲烷的产率较低。2.甲烷的光化学溴化反应的研究本部分的研究表明:甲烷与液溴的光化学反应的有效光的波长范围在可见光区。在没有加入任何催化剂的条件下,通过甲烷与溴的光反应,高选择性的活化甲烷生成一溴甲烷和二溴甲烷。经过对光源的选择,设计和改进光反应器,控制温度等方法实现了低温常压条件下的高选择性制备二溴甲烷。以溴来计算转化率可达98%。低溴甲烷（即一溴甲烷和二溴甲烷之和）的选择性之和可达93%。反应温度在16～140℃之间。这一结果远远高于国际上文献报道的结果。3.本章主要是采用添加低碳烃的方法考察了对甲烷的活化的影响。得到的主要结论有:①在一定的实验条件下,添加乙烯对甲烷的活化最为有利。在Ga、稀土金属-Zn、Ce-Mo和Cr-Mo等负载的HZSM-5催化剂上,原料气中添加乙烯后甲烷在较低温度（450℃-520℃）下可实现活化。甲烷的转化率超过35.0%；而在相同的实验条件下,没有添加其它气体时,催化剂对甲烷活化作用就不明显。因此原料中添加第二组分对于甲烷活化具有十分重要的意义。②以乙烯为第二组份气时,稀土金属氧化物的添加能够增加催化剂的活性,一定程度延长催化剂的寿命。③添加丙烷在我们初步研究中对甲烷的活化影响有限。在研究丙烷的添加对甲烷芳构化的影响时,在1%Cu-1.35%Zn/HZSM-5、0.1%Gd-1.35%Zn/HZSM-5催化剂上,当CH₄/C₃H₈=0,1.17,2.25三种摩尔比条件下,实验中没有发现丙烷对甲烷的活化有明显作用,甲烷的转化率均为负值。反而是甲烷的添加似乎对丙烷的转化有抑制作用使其转化率下降。④在研究丁烷的添加对甲烷芳构化的影响时,在450℃时,0.1%Gd-1.35%Zn-/HZSM-5上,CH₄/C₄H₁₀=0.00,0.45,1.01,1.50和3.12摩尔比条件下的实验结果表明:甲烷的转化率从摩尔比为0.45的负值-9.8%,增加到摩尔比为3.125时的6.9%。说明一定条件下,增加甲烷气体的量有利于其被丁烷活化;在较低的温度下有利于实现甲烷的活化,但从芳烃的收率和选择性随摩尔比增加而降低的趋势来看,说明被活化的甲烷可能主要是参与到生成低碳烃等产物中。4.原位涂层法合成FePO₄/SBA-15材料及其表征成功地（直接）合成了FePO₄修饰的SBA-15介孔硅材料,在这种一步合成方法中,硝酸铁不仅作为磷酸铁的铁源,而且有助于形成有序的介孔结构。此外,由于与传统的浸渍法相比,这种方法也许提供了一种新的修饰介孔材料的方法,可以应用在许多功能化材料的合成过程中。另外,用原位涂层法合成出的FePO₄-SBA-15介孔硅材料作为甲烷部分氧化制甲醛的催化剂经过实验考察发现:比硅基材料上负载有磷酸铁（5wt%）的催化剂和用浸渍法合成出的FePO₄/SBA-15催化剂催化活性要强10～100倍。更多还原

【Abstract】 In recent years, the continuing shortage of crude oil supply, an increasingly acute contradiction between the supply and demand, the increasing depletion of oil resources have already been an indisputable fact. According to some reports, the world’s oil reserves available for human use would last about 30-40 years. As our country is short of oil, the situation of the oil supply is particularly prominent. The available oil reserves are keeping dwindling and we are facing severe challenges in energy and raw material supply. In terms of feedstock resources, it is generally believed that the basic national situation is aboundant in coal, shortage of oil and lack of gas in China.However, from the point of effective use of components, this is not the case. Being similar or same with natural gas in composition, properties, the carbon resources （including natural gas, coal-bed methane, natural gas and methane hydrate）, which all have methane as the main component, are extremely rich among all natural resources. Natural gas resources are richer than the oil, which has been estimated to meet the needs of the world for more than 120 years. The main components of coal-bed methane which are similar to nature gas are methane. It is proven that the coal-bed gas buried in the depth of 2000 meters underground are about 240 trillion cubic meters reserve, which is more than twice as much as nature gas. China’s coal-bed methane resources are very aboundant, ranking the third in the world; At present, it is internationally recognized that the world’s total reserves of gas hydrates on earth are as much 2 to 3 times as the grand sum of all coal, oil and natural gas, which would last more than 1000 years for human use （but it is so pity that the technology has not been put into practice in mining）. Marsh gas（being methane as the main component） from biomass are reproducible resources. In addition, compared with oil and coal, they have the advantages of cleanness and high calorific value as an energy. Therefore, such resources are so important that they attract worldwide attention and make nearly all countries in the world to make effort to develop and utilize such resources, which is the best choice in improving the environment and maintaining sustainable developement.However, the biggest obstacle widely to use methane is its thermodynamic stability. The work of the doctoral thesis is aimed at realization of methane conversion through halogenation of methane with higher selectivity around normal pressure at lower temperature by photochemistry; or through thermal reaction of methane by some metals or rare metals promoted HZSM-5 zeolite as catalysts in mixture of methane and ethylene or some low alkanes; by synthesis of a series of iron phosphate supported mesoporous materials as catalysts by a simple one-step synthetic method.The thesis has four parts as follows:Part I Methane Iodination By PhotochemistryIn this part, the methane reactor for the photochemical gas reaction of methane with iodine was designed at first, and iodination reaction of methane by light have been studied. Some results are showed that the available light wavelength must be ultraviolet and the yield of methyl iodide is very low, which makes the process unpractical.Part IIMethane Bromination By PhotochemistryWithout addition of any catalyst, our research in this part focus on high activation of methane with higher selectivity via bromination reaction by photochemical method, since the products （bromomethane and dibromomethane） can be easily converted into methanol and formaldehyde. Through our effort on the choice of light sources, design and manufacture of special reactor, controlling reaction temperature and changing some other factors, an outstanding results is obtained. The products（ bromomethane and dibromomethane） are synthesized with high selectivety （8.0% and 85% respectively） and 98% conversion based on bromine at the temperature of 16～140℃around atmosphere pressure. The available light wavelength for methane bromination is visable. The results are better than any other reported in the world.Part IIILow-Temperature Activation of Methane over some metals or rare metalspromoted HZSM-5 zeoliteIn this part, methane conversion in the presence of ethylene has been investigated. It shows that methane can well be activated in the presence of ethylene over rare earth metal or Ce-Mo, or Cr-Mo promoted Zn/HZSM-5 at lower temperature （450℃-520℃） . Especially, methane can be converted to higher hydrocarbons, including aromatic compounds at much lower temperature （723K） over Gd promoted Zn/HZSM-5, and at the same time methane conversion is relatively high （about 37%）. In addition, the catalyst （Gd promoted Zn/HZSM-5） has longer life-time than Ga/HZSM-5 does.Part IVDirect Synthesis and Characterization of Mesoporous SBA-15 Loaded FePO₄MaterialsMesoporous SBA-15-loaded FePO₄ materials （FePO₄/SBA-15） have been directly obtained by a simple one-step synthetic method. The investigation results from the X-ray diffraction, transmission electron microscopy, electron spin resonance, ³¹P solid-state MAS-NMR, and N₂ adsorption-desorption analysis indicate that Fe and P are successfully loaded on the mesoporous SBA-15 in the form of FePO₄. From the characterization, the direct synthesized mesoporous FePO₄/SBA-15 materials are revealed the well textural properties and the ordered mesostructures. FePO₄ supported on mesoporous SBA-15 has the uniform dispersion state, even at 70wt% high loading amount. From our experiments, some conclusions are obtained that the catalysis of the direct synthesized mesoporous FePO₄/SBA-15 materials in partial oxidation of methane to formaldehyde is as much 100 times as that of indirect synthesized FePO₄/SB A-15. The catalysis of direct synthesized mesoporous FePO₄/SBA-15 is also better than that of the silica-supported FePO₄.更多还原