【作者】 刘蕾；

【导师】 袁忠勇；

【作者基本信息】 南开大学 ， 物理化学， 2012， 博士

【摘要】 多孔碳材料由于其特有的组成与结构、高的比表面积、有序的孔径分布及其高的热力学稳定和化学惰性，在催化、吸附分离、能量储存等领域具有很重要的应用前景。这也使得多孔碳材料的合成、表面修饰、功能化及应用成为了新的研究热点。本论文合成出一系列有序介孔碳材料、微孔碳材料以及碳基复合材料，并对其进行表面改性修饰，应用于丙烷脱氢、二氧化碳捕获以及染料脱色等领域。主要包括以下几个方面：1.以柠檬酸为一种环境友好的催化剂，在低温水热的条件下催化间苯二酚和甲醛的聚合得到了有序的介孔碳材料。所合成的碳材料具有较高的热稳定性，二维六方的孔道结构，孔径约为5.1nm，同时材料的比表面积可高达612–851m²g^-1。本制备方法合成有序介孔碳材料可以在较宽的合成条件下得到，其中反应温度为50–80oC，甲醛和柠檬酸的比例≥3。在合成体系中引入柠檬酸，一方面它可以作为催化剂催化间苯二酚的聚合，另一方面，它还可以增强碳前躯体和表面活性剂之间的相互作用，从而进一步在产物中引入更多的微孔，从而利于CO₂的吸附。高温条件下（650–1000oC），在氨气流中对有序介孔碳材料进行氮化可以有效的引入碱性的含氮官能团，从而增强吸附剂和CO₂之间的相互作用，提高吸附量。氮掺杂的有序介孔碳材料表现出优异的CO₂吸附性能，1000oC氮化后的样品其吸附量在298K时可以达到3.46mmol/g。材料的结构特性和表面化学性质对其CO₂捕获性能起着非常重要的作用。2.以无金属负载的介孔碳材料为催化剂，考察了其丙烷脱氢制丙烯的催化性能。通过对几种不同结构的碳材料进行对比考察研究了碳材料本身的特性对丙烷直接脱氢制丙烯催化性能的影响。结果显示，不负载任何金属成分，有序介孔碳材料可以有效的催化丙烷直接脱氢，有传统的金属基催化剂相比，表现出很好的催化活性和反应稳定性。反应50h后，丙烷的转化率仍可达到12.1%，丙烯的选择性保持在95.1%。而纳米结构的碳纳米管和石墨碳材料的催化活性很差。介孔碳材料在丙烷氧化脱氢制丙烯的过程中也表现出很好的催化活性，反应50h后，丙烷的转化率仍有20.1%，但丙烯的选择性较低（25%），可能是由于在氧气存在的氛围下，产物丙烯的在大比表面积催化剂上的再吸附使其发生了进一步的裂解。将介孔碳材料用硝酸进行活化处理，可以明显的提高催化剂的丙烷直接脱氢制丙烯的催化性能。反应50h后，丙烷转化率和丙烯选择性分别为22.4%和86.6%。硝酸活化明显提高催化活性归因于在活化处理的过程中可以引入更多的作为活性中心的酮基/醌基官能团。3.采用六次甲基四胺为碳源和氮源通过一种简单的一步水热方法合成出含氮的聚合物和微孔碳材料。合成过程中不添加任何表面活性剂，合成方法具有很高的经济效益，而且可以很容易的进行工业化生产。所合成的碳材料为微孔材料，具有球形的形貌，比表面积可高达568936m²g^-1。所合成的微孔碳材料具有较强的CO₂捕获能力，主要是由于材料中存在很多的含氮官能团和大量的微孔（<10）。在常压条件下，0oC时CO₂的吸附能力可达3.95.6mmol g^-1，25oC时CO₂的捕获量为2.74.0mmol g^-1。另外，将高含氮量的密胺树脂引入到上述酚醛树脂的体系中，结合两种材料的优点，得到具有核壳结构的富氮微孔碳材料。700oC碳化后的样品的氮含量可高达7.92wt%，远高于不含密胺树脂的碳材料的氮含量（2.29wt%）。较多的碱性含氮官能团可以引入更多的化学吸附，提高材料的CO₂吸附性能。蜜胺树脂的引入可以将700oC碳化后的样品的CO₂吸附量由3.4mmol g^-1（25oC）提高到4.3mmol g^-1（25oC）。4.将天然凹凸棒土在不同浓度的盐酸溶液中或者在不同的温度焙烧进行活化处理。以活化前后的凹凸棒土为硬模板，结合有机-有机自组装的软模板方法，合成出具有多级孔结构的纤维状碳材料，并对盐酸处理的浓度和活化处理温度对最终碳材料的结构的影响进行了考察。所合成的碳材料具有较大的比表面积(310892m²g^-1)和较大的孔容(0.441.32cm3g^-1)。考虑到所合成的碳材料具有多级的孔结构和较大的孔径尺寸，对其进行了溶菌酶吸附性能考察，结果显示，所得到的多级结构碳材料对溶菌酶的吸附量可达13.433.1μmol g^-1。另外，所合成的多级结构的碳材料在CO₂捕获中也表现出良好的性能，吸附量可达1.102.78mmol g^-1。5.将共吸附剂引入到二氧化钛的体系中，可以提高其脱色活性。以四氯化钛为无机源，间苯二酚甲醛树脂为碳前躯体，F127为表面活性剂通过无机-有机-有机三元自组装的方法合成出具有多级孔结构的碳-二氧化钛复合材料。其中碳的引入可以抑制二氧化钛晶粒的长大。碳的引入能够增大材料的比表面积，复合材料的比表面积可达156530m²g^-1，进而增强二氧化钛的吸附性能，复合材料对染料废水表现出很好的脱色性能。研究发现，复合材料对染料的脱色符合Langmuir吸附等温方程。在较低的染料浓度下，脱色过程符合一级反应动力学方程；较高的染料浓度时，脱色过程更接近准二级反应动力学方程。更多还原

【Abstract】 Porous carbon materials are now attracting great research interests due to their high thermalstability, extremely large surface area large and chemical inertness. And has been widely used inareas of catalysis, adsorption, hydrogen storage and electrochemistry etc. In this thesis, a seriesof porous carbons and carbon-based nanocomposites with ordered mesoporous structure ormicroporous strucuture were fabricated. These carbons were also functonalized and applied ascatalysts for propane dehydrogenation, adsorbents for CO₂capture and dye decorlorizaiton.1. Supermalecular aggregate and assembly is an effective method for synthesis of mesoporouscarbon materials. Ordered mesoporous carbon materials （OMCs） were synthesized with the useof citric acid as an environmentally friendly catalyst to catalyze the polymerization ofresorcinol/formaldehyde resin. The obtained carbon materials with high thermal stability have a2-D hexagonal mesopore system with uniform pore size of⁵.2nm and a high surface area of612⁸51m²/g, which were available under a wide composition range of reaction system, withreaction temperature of50–80oC and the molar ratio of formaldehyde to citric acid≥3. Thepresence of citric acid in the synthesis system can enhance the hydrogen bonding betweentriblock copolymer and resol and further introduce more micropores to the final carbon material,which is favorable for CO₂adsorption. The nitridation of the OMCs in ammonia flow at thetemperature of650^-1000oC is demonstrated to be effective in introducing basic functionalitiesthat enhances the specific interaction of CO₂and adsorbent. The N-doped OMCs exhibitenhanced CO₂uptake with CO₂capture capacity of3.46mmol/g for1000oC-nitrided sample.Both textual and surface chemistry influenced the CO₂capture performance of the resultantmesoporous carbon adsorbents.2. Monolithic carbons with ordered mesopores were used as catalyst for dehydrogenation ofpropane to propylene, exhibiting high catalytic activity and stability. After50hours in steam, thepropane conversion of12.1%was observed with propylene selectivity of95.1%in the directdehydrogenation process, while the propane conversion of20.1%with propylene selectivity of25.8%in oxidative dehydrogenation process. It has been found that the surface basic groups controlthe catalytic turnover. Activated with HNO3could dramatically improve the catalytic activity of themesoporous carbon, exhibiting high selectivity and stability. The final propane conversion is22.4%with stable propylene selectivity of86.6%after50hours. HNO3activation introduces more basicoxygen groups than the pristine carbon, which is believed to be active site in the dehydrogenationprocess. 3. Spherical nitrogen-containing polymer and microporous carbon materials have beensynthesized by using hexamethylenetetramine as nitrogen source and one of the carbonprecursors under solvothermal conditions, without using any surfactant and toxic reagent suchas formaldehyde. The synthesis strategy is cost-effective and can be easily scaled up forproduction. The microporous carbon spheres exhibit high surface areas of528936m²g^-1withmicropore size of0.61.3nm. The synthesized microporous carbons show a good capacity tostore CO₂, which is mainly due to the presence of nitrogen-containing groups and a largeamount of narrow micropores （<1.0nm）. At1atm, the equilibrium CO₂capture capacities ofobtained microporous carbons are in the range of3.95.6mmol g^-1at0oC and2.74.0mmolg^-1at25oC. Core-shell structured nitrogen-rich microporous carbon materials were alsoprepared by introducing the melamine-formaldehyde （MF） resin as co-carbon precursor. Thistype of carbon material contains a large amount of nitrogen-containing groups with the700oC-carbonized sample as high as7.92wt%and consequently basic sites, resulting in a fasteradsorption rate and a higher adsorption capacity (4.3mmol g^-1) for CO₂than pure carbonmaterials (3.4mmol g^-1) under the same conditions. The potential for large scale productionand facile regeneration makes this material useful for industrial applications.4. Mesoporous carbons with specific surface areas in the range of310–892m²g^-1, mesoporevolumes in the range of0.40–1.22cm3g^-1are prepared by using crude attapulgite, calcinedattapulgite and HCl-treated attapulgite as inorganic templates and resorcinol-formaldehyde resin asthe carbon source through impregnation method. The influences of the calcination temperature andHCl concentration on the pore structure of the resultant carbons are investigated. The results indicatethat the the calcination temperature and the HCl concentration are600oC and4M, respectively, andthe corresponding carbons have the maximum surface areas and mesopore volumes. Adsorption oflosyzyme on the mesoporous carbons in aqueous solution reveals that the equilibrium adsorptioncapacities （qe） are in the range of13.4–33.1μmolg^-1. It was also found that the monolayeradsorption capacity increased with increasing the accessible specific surface area and the porevolume. The large mesopores and their hierarchical porous structure could facilitate the easydiffusion of protein molecules, and also be responsible for the excellent adsorption capability forproteins. Moreover, the obtained carbons exhibit high CO₂capture capacity of1.102.78mmol g^-1.5. Hierarchical mesoporous carbon-titania nanocomposites with nanocrystal-glass frameworkshave been synthesized via the organic-inorganic-amphiphilic coassembly by using resol polymer as acarbon precursor prehydrolyzed TiCl4as an inorganic precursor, and triblock copolymer F127as atemplate. The carbon-titania nanocomposites with controllable texture properties and compositioncan be obtained in a wide range from0to85wt%TiO₂by adjusting the initial mass ratios. TheC-TiO₂nanocomposites exhibit high thermal stability up to700°C, high surface area of200–355 m²g^-1and hierarchical pore size （5.2nm,6–18nm）. Additionally, the nanocomposites show goodperformance in decolorizaiton of Rhodamine B due to the photocatalytic activity of the titaniananocrystals and the strong adsorptive capacity of the porous carbon.更多还原