【作者】 李莎；

【导师】 范杰； 肖丽萍；

【作者基本信息】 浙江大学 ， 化学， 2014， 博士

【摘要】 石油炼制过程涉及烯烃水合和聚合、芳烃烷基化、烃类裂解、重整、异构化等酸催化反应过程,可以说酸催化剂是工业的重要基础。自20世纪40年代以来,人们就在不断地寻找强酸性、低成本和环境友好的固体酸催化剂。工业上常用的固体酸催化剂是强酸性的HZSM-5分子筛、beta分子筛及Y型分子筛,但是小的孔径限制了他们在大分子催化反应中的应用。介孔材料的问世为大分子催化反应开辟了新的领域。介孔两相复合金属氧化物材料大量应用于酸催化领域。在本论文中主要介绍硅铝、钛硅、锆钨等复合金属氧化物材料的合成、酸性调节及其在傅克烷基化反应中的应用。第三章中,我们使用溶胶-凝胶法在非离子表面活性剂为结构导向剂的条件下合成了高度有序二维六方结构的介孔硅铝酸盐材料,提高材料在大分子催化反应中的酸催化活性。合成过程中,表面活性剂的用量、硅铝比会影响材料结构的有序性,而醋酸用量对材料结构有序性影响很小。硅铝比会影响材料在苯甲醇和苯甲醚烷基化反应的酸催化活性,当Si/Al=10时材料的酸催化活性最高,而同样条件下,HZSM-5分子筛则不具备催化活性。介孔硅铝材料的热稳定性、耐酸碱性较差。第四章中,我们合成了具有中强Bronsted酸位点的有序氧化钛-氧化硅复合金属氧化物。钛硅摩尔比对材料的酸性影响很大,只有当存在六配位钛原子时,材料才具有酸催化活性。在此基础上,我们首次通过高温加氢反应将材料中的Ti4+还原为Ti3+,增加材料的Bronsted酸含量,提高了其酸催化活性。此外,我们使用有机硅烷——苯基三甲氧基硅烷(PTMS)为硅前驱体,对氧化钛-氧化硅材料进行改性,改性后的材料酸催化活性得到一定提高。第五章中,我们使用溶胶-凝胶法合成了一系列强酸性介孔氧化锆-氧化钨酸性材料。亚纳米WOx团簇具有很强的B酸酸性,是烷基化反应的活性位点。可以通过调节W的含量、焙烧温度来调控WOx团簇的形成,对于形成WOx团簇而言,存在一个最低的W浓度和焙烧温度。更重要的是,这种亚纳米WOx团簇活性位点,可以在800℃温度下保持稳定。第六章中,我们在低温焙烧条件下合成了强酸性氧化锆-氧化钨材料,强酸位点可以通过改变表面活性剂的种类和浓度来调节,WOx团簇在表面活性剂的作用下可以在远低于常用焙烧温度下形成。第七章中,我们研究了NH3处理对材料结构和酸性的影响。材料经过NH3焙烧后催化活性下降,但是将N-H3焙烧后的材料再在空气中焙烧后材料的催化活性提高很大,材料酸性的提高可能来源于N原子掺杂形成的W-N-O键。更多还原

【Abstract】 Acid catalysts play a vital role in the economic development of the chemical industry. Many organic reactions, for example, alkylation, unsaturated hydrocarbon isomerization, esterification, cracking, condensation and so on are accomplished by acid catalysts. Since1940s, solid acids have been widely investigated to reduce the impact on the environment and to decrease costs.Among all kinds of heterogeneous acid catalysts, zeolite such as HZSM-5, beta zeolite and zeolite Y which have strong acidity and large amount of active sites have been extensively applied in industrial acid catalysis since the last century. However, their microporous structure has restricted their applications in large molecule acid reaction. In the early1990s, the meso-structured silicates firstly reported opens the new application field for the heterogeneous acid catalytic system for large molecular substrates. Binary mixtures of metallic oxides were applied in acid catalysis.In this dissertation, we synthesized a series of mixed metal oxides, adjusted the acidity of these catalysts and applied them into Friedel-Crafts (F-C) reaction.In chapter3, ordered mesoporous aluminum silicates with strong acid sites were synthesized by sol-gel method. The amount of surfactant and the Si/Al mole ratio would both affect the materials’meso-structure; while, the amount of HAc has little effect on the structure. The Si/Al mole ratio played an important role in catalytic activity and the aluminum silicates with Si/Al=10showed the best acid catalytic activity. NH3-TPD and Py-FT-IR suggested that the aluminum silicates with Si/Al=10had much more Bronsted acidic sites than that of other Si/Al ratios.In chapter4, we have successfully synthesized mesoporous titania-silica materials with moderate strong Bronsted acid sites via a sol-gel with nonionic surfactants precursors. The Ti/Si mole ratio plays a very important role in determining the acidic property of materials, only six-coordinated Ti species can generate Bronsted acid sites. The number of the Bronsted acidic sites can be increased via a high-temperature hydrogenation process, which subsequently improves their catalytic performance in the F-C reaction of anisole and benzyl alcohol. Furthermore, TEOS partly submitted by PTMS as the silica precursor can increase the activity of materials.In chapter5, we synthesized mesoporous zirconia-tungsten oxide via a sol-gel process with nonionic surfactants precursors. We identified that the subnanometer WOx clusters act as the most active sites for the F-C reaction. Most importantly, we show that the formation of these subnanometer WOx clusters can be rationally controlled by adjusting W concentration and calcination temperatures, which is of great importance in the design of solid acid catalyst. It is shown that a minimum W concentration (0.07at the calcination temperature of800℃) and a minimum calcination temperature (650℃at a given W concentration of0.1) are required during the preparation of these acid catalysts for the development of highly active subnano WOx clusters.In chapter6, mesoporous ZrO2-WO3materials with strong acid sites were successfully synthesized by low temperature calcination that is far below the threshold temperature to develop strong acidity. The formation of these strong acid sites can be well controlled by varying the type and concentration of the added surfactants, which is of great importance for the design of the solid acids with strong acid sites.In chapter7, The number of the Bronsted acidic sites of mesoporous ZrO2-WO3materials can be increased via calcined in Air after NH3calcination, which subsequently improves their catalytic performance in F-C reaction of anisole and benzyl alcohol. More important, the way to increase the acid sites via air calcinations after calcined in NH3provides a rational process to regulate their acid property and corresponding catalytic performance.更多还原