【作者】 罗永明；

【导师】 郑小明； 侯昭胤；

【作者基本信息】 浙江大学 ， 物理化学， 2006， 博士

【摘要】 介孔分子筛具有高的比表面、规则排列且可调控的孔道（直径2-50nm）。这些特性使得其在化工、光学、电磁学、生物医学、工业催化、环境保护和制备新型纳米材料等领域展现了非常诱人的应用前景,因此引起人们的普遍关注。众所周知,水热法是合成介孔分子筛最普遍和行之有效的方法。与碱性条件下合成分子筛相比较,酸性条件下合成分子筛具孔壁厚、水热稳定性好、表面活性剂便宜且容易回收等优点。然而用传统水热法制备具有特定结构的微孔和介孔材料,其最致命的缺陷是使用大量液体酸和需要过长的晶化时间。 通过在低浓度液体酸合成介质中添加少量杂多酸或其相应含氧阴离子等促进剂,成功地在低浓度液体酸介质中合成了稳定的有序介孔分子筛,所需晶化时间也大大缩短。与传统合成方法相比较,该合成方法具有如下特点:（a）反应产物具有高的水热稳定性,在100℃的水中处理72小时后仍然保持高度有序的介孔结构;（b）可大幅度降低腐蚀性液体酸的使用,其用量约为传统方法的3.8%;（c）能显著地缩短分子筛形成的晶化时间,合成与传统方法相同物化特性的介孔分子筛所需晶化时间为传统方法的四分之一。（d）该合成方法容易实现杂多酸的回收与利用,是一种成本低且环境友好的绿色合成工艺。 利用N₂吸脱附、XRD和TEM等手段对不同P/Mo摩尔比、不同PO₄^3-添加量以及添加Mo和W含氧阴离子的合成介质所得产物进行表征可知对有序介孔分子筛形成起促进作用不是杂多酸阴离子而是与模板剂P123相结合而被稳定的八面体Mo₈O₂₄^4-物种。 利用杂多酸完全替代液体酸,成功地合成了系列不同结构的介孔分子筛。其中,以非离子三嵌段高聚物P123为模板,首次通过添加NaCl、NaBr和KI等无氟无机盐,在pH大于2.0的介质中快速合成了高度有序的介孔分子筛:通过添加NH₄HF₂,在pH大于4.0的介质中所合成介孔分子筛的比表面、孔体积、BJH孔径和晶胞参数分别为605m²/g、1.56cm³/g、118.3（?）和162.8（?）,这是目前世界上以单一模板剂所合成晶胞参数、孔体积和孔径最大的六方相结构介孔分子筛;通过在合成介质中添加KF·2H₂O（pH大于6.0）,首次以单一模板剂合成了MCF型介孔分子。更多还原

【Abstract】 Mesoporous molecular sieves have attracted considerable attention in the region of chemical engineering, optics, electromagnetics, biomedicine, industrial catalysis, environmental protection, and fabrication of novel nano-object materials due to high surface area, well-defined and adjustable pore diameter of 2-50 nm.It is well known that the hydrothermal method is the most prevailing and effective route for synthesis of mesoporous sieves. Mesoporous molecular sieves synthesized under acid media have many advantages over those prepared in alkaline media such as thicker pore wall, higher hydrothermal stability, using inexpensive template and easy reutilization. However, there are two obvious drawbacks for synthesis of ordered mesoporous molecular sieves with conventional in acid condition. On the one hand, a large amount of liquid was required to synthesize ordered mesostructure. On the other hand, most ordered mesoporous prepared with hydrothermal methods was generally suffered from long crystallization time.With addition small amounts of heteropoly acids or corresponding oxoanions in low concentration liquid acid media, hexagonal ordered mesoporous molecular sieves with highly hydrothermal stability have been rapidly synthesized. Compared with conventional method, the features of our synthesis route are as follows:The reaction products prepared with our synthesis route exhibit highly hydrothermal stability. For instance, the highly hexagonal ordered mesostructure of the molecular sieve was perfectly maintained after treated in 100℃ water over 72 h.The liquid acid utilization has been saliently reduced, and the concentration of HC1 in synthesis media is 3.8 percent less than that of the conventional method.The crystallization time for synthesis of ordered mesoporous molecular was shortened to great extent. To obtain the same physicochemical properties of ordered mesoporous molecular sieve prepared with conventional method, the corresponding crystallization time could be reduced to 6 hours, which is about one-fourth that of conventional synthesis process.In addition, the heteropoly acid can be easily recycled and reused to synthesize SBA-15 via a series of appropriate intermediate disposal process, which indicates that the synthesis route is inexpensive and environmentally benign green method.The reaction products prepared with different P / Mo molar ratio, various PO43", Mo and W oxoanions have been characterized by N2 adsorption-desorption, XRD and TEM. It has been confirmed that the promotable structure for synthesis of ordered mesoporous is MogC^/’octahedra species stabilized by PI23 template other than heteropoly anions.A series of mesoporous molecular sieves with different structure have been synthesized by use of nonionic triblock copolymer PI 23 as template under heteropoly acids media. With addition small amounts of non-fluorids inorganic salts such as NaCl, NaBr and KI, highly hexagonal ordered mesoporous silica moleculare sieves have been rapidly synthesized under pH above 2.0 media. The ordered mesoporous sieve with unusual large pore volume, BJH pore size, and unit cell dimension has been synthesized with addition of NH4HF2 under pH above 4.0 media. The BET surface area, pore volume, BJH pore size and cell of the molecular sieve are 605m2/g, 1.56cm3/g.. 118.3 A and 162.8 A respectively. According to the previous reports, the molecular sieve is the largest hexagonal mesoporous silica structure prepared with a single template up to date. Under pH value above 6.0, MCF-type sieve has been successfully synthesized by use of a single template and addition of KF?2H2O for the first time.UV-Vis and Raman results demonstrate that the hydrophilic moieties of PI23 can interact with HPMo to produce the organic-inorganic hybrid structure REOm[HxMo8O264T"4, which play a key role in synthesis of ordered mesoporous sieves. It has been proved that the protonated degree of [H^MosC^4"]*"4 increases with the pH value decreasing. On the basis of these results, the concept of organic-inorganic hybrid template has been putted forward to synthesize ordered mesoporous silica molecular for the first time. With the aid of heteropoly acids, ordered mesoporous sieves could be synthesized by using nonionic triblock copolymers as a template through the following three routs, if the counterions in the synthesis media are sufficient. When pH value is higher than 2.0, ordered mesoporous sieves have been synthesized by use of (S°Mo")(M+T) synthesis route. At pH value from 1.0 to 2.0, ordered mesoporous sieves have been synthesized with (S°MoT) synthesis route. When pH value is lower than 0.3, ordered mesoporous sieves have been synthesized via (S°Mo")(M+F) synthesis route. To best of our knowledge, it is the first time to report that the ordered mesoporous sieves can be synthesized with nonionic triblockcopolymers such as PI23 as a structure-directing agent via the former two routes.By utilizing mesoporous SBA-15 as a hard "template", two kinds of highly ordered mesoporous aluminosilicates molecular sieves with ultrastable hydrothermal stability have been successfully synthesized via twice recrystallization both in zeolite precursor diluted solution and glycerol media in turn. Herein, ZSM-5 and Beta precursor diluted solution was used to prepare MSAMS-2 and MSAMS-4 respectively. The hexagonal ordered mesoporous structure of MSAMS-2 and MSAMS-4 was maintained perfectly both after steaming at 800 °C for 6 h and treating at 100°C water for 120 h. XRD and N2 adsorption-desorption results demonstrate that the MSAMS-2 can retain it’s hexagonal ordered mesostructure after treating in 100°C water over 434 h. According to the previous document reports, MSAMS-2 and MSAMS-4 are the mesoporous molecular sivers with the most hydrothermal-stability up to date. The ultrastable hydrothermal-stability of MSAMS-2 and MSAMS-4 might be ascribed to the synergistic effect of the thicker wall, the high condensation of surface silanol groups, and formation of zeolite five-ring subunits in the mesostructure framework wall and original complementary pores of SBA-15.Ga2O3-Al2O3 prepared with sol-gel method has attracted much attention because the catalysts showed relatively high activity and tolerance toward SO2 for selective catalytic reduction of NOX in presence of oxygen. However, the relatively small surface (BET surface area below 200m2/g) and non-uniform pore size of the Ga2O3-Al2O3 prepared with sol-gel method might limit further improving the activity and tolerance toward SO2 for the reaction. In this paper, Ga2O3 - AI2O3 nanorods with mesoporous structure, high BET surface area (253m2/g) and narrower pore size distribution has been successfully synthesized for the first time by using PI23 as a structure-directing agent. No diffraction peak ascribed to any kinds of Ga2C>3 crystalline form was detected in the XRD patterns of as-syntheiszed and calcined Ga2O3- AI2O3 nanorods because the [(GaTAli.^)OOH] was formed, which originated from interaction between hydrolysis product of gallium nitrate and aluminum tri-isopropoxide with the aid of PI23. After calcined at 600°C, the material was converted into GaA103 or [GaxA\].x)]2Oi (x<l) solid solution.Beta gallium oxide is an important wide band gap (Eg = 4.9 eV at 300 K) material. The conduction, luminescence, good chemical and thermal stability of(3-Ga2O3 make it a candidate for gas sensing, catalytic, and optoelectronic device applications. Compared with 13 - G&2O3 powder, /3 - Ga2C>3 with ID nanostructure reveals more intensive blue emission. In the dissertation, GaaOj rod with regular has been synthesized by using PI23 and CTAB as template, respectively. The diameter of Ga^Cb rod decreases with the template concentration increasing, whereas the Ga^C^ rod would be transformed into cuboid structure if the template concentration in synthesis media is too high. After 900°C calcination, high purity monoclinic /S -Ga2O3 phase (a = 12.22 A, b = 3.04 A, c = 5.81 A, 0 = 103.8°, C2 / m) rod was formed. The PL spectrum of & - Ga2C>3 rod exhibits that the blue emission is very strong, which is comparable with that of (3 - Ga2C>3 nanostructure prepared with other high temperature method.更多还原