【作者】 周旭平；

【导师】 姜廷顺；

【作者基本信息】 江苏大学 ， 应用化学， 2010， 硕士

【摘要】 自从1992年Mobil公司首次合成M41S系列介孔分子筛以来,引起了研究者的广泛关注。由于纯硅M41S的离子交换能力小、酸含量低及强度低、水热稳定性差及催化活性低,限制了它们在催化领域的应用,因此合成高质量、高稳定、强酸性的M41S系列介孔分子筛,对介孔分子筛在催化领域的应用,具有重要的理论和现实意义。本文采用微波法和水热法合成出了不同Si/Zr摩尔比的Zr-MCM-41介孔分子筛,并详细考察了两种方法所合成样品的热稳定性和水热稳定性。结果表明,两种方法所合成的样品结构性能相似,相比于水热法,微波法合成大大缩短了其晶化时间；两种方法所合成样品都具有很高的稳定性,样品经100℃水热处理6d或750℃焙烧4h后,仍然具有有序的介孔结构。通过直接将氟化钠加入起始凝胶内,水热法合成出含Zr-MCM-48介孔分子筛。并考察了加入不同F-的量,不同温度,不同时间,不同Si/Zr摩尔比对合成样品结构性能的影响。热和水热稳定性表明所合成的Zr-MCM-48介孔分子筛经800℃焙烧4h或100℃水热处理24h后,立方介孔结构仍被保持。F-的加入有效缩短了其晶化时间并增强了其水热稳定性。采用合成含Zr-MCM-48的方法,合成出了不同Si/Co和Si/Al摩尔比的Co-MCM-48和Al-MCM-48介孔分子筛,并研究了Co-MCM-48的热稳定和水热稳定性。所合成的样品具有MCM-48典型的三维立方结构。在经过800℃焙烧4h或100℃水热处理12h后,样品介孔有序性变差,但仍然保持MCM-48的立方介孔结构。通过NH4NO3和H2SO4溶液修饰M-MCM-48(M=Zr, Al)后得到H-M-MCM-48和SO42-/M-MCM-48强酸性介孔分子筛。实验结果表明,经过NH4NO3和H2SO4溶液修饰,并未使样品的结构造成完全破坏；修饰后的样品仍具有MCM-48的三维立方结构；修饰后的样品比未经修饰的样品具有更多强酸中心。以H-M-MCM-48和SO42-/M-MCM-48强酸性介孔分子筛做催化剂对苯酚与叔丁醇烷基化反应催化性能进行了研究,考察了催化剂的种类,反应温度,反应时间对反应结果的影响。实验结果表明,H-Al-MCM-48的催化活性要高于其它催化剂；H-Al-MCM-48和SO42-/Zr-MCM-48在反应8h后,仍然保持着较高的催化活性,体现了较高的稳定性；在相同反应条件下,H-Al-MCM-48和SO42+/Zr-MCM-48展示了较H-Zr-MCM-48和SO/42-/Al-MCM-48更高的苯酚转化率和2,4-二叔丁基苯酚选择性。更多还原

【Abstract】 A series of M41S mesoporous molecular sievs were firstly discovered by Mobil in 1992.However, pure silica M41S possesses some disadvantages such as small ion-exchange capacity, low catalytic activity, weak surface acidity and poor hydrothermal stability, which limited their application in catalytic reactions. Enhancing its practicability and improving its hydrothermal stability and catalytic activity seemed to be a more interesting task.Zr-MCM-41 mesoporous molecular sieves with different Si/Zr ratios were successfully synthesized by microwave irradiation method and hydrothermal method. The thermal and hydrothermal stabilities of the as synthesized samples were investigated.The results show that the textural properties of the samples syntheszed via novel microvave method are similar to that of the samples by traditional hydrothermal method.By comparing with hydrothermal method, the microwave irradiation method needs short crystallization time.The thermal and hydrothermal stability experimental results show that the samples obtained by two different methods have highly thermal and hydrothermal stabilities, the mesoporous framework still retain even after of the two Zr-MCM-41 mesoporous molecular sieves were calcined at 750℃for 4h or hydrothermal treated at 100℃for 6d.Zr-MCM-48 mesoporous molecular sieves were synthesized hydrothermal by directly adding fluoride ions to the initial gel.The influences of various factors, such as the amount of NaF addition, the Si/Zr molar ratios,crystallization temperature and crystallization time, on the crystalline structure and textural property of Zr-MCM-48 were investigated in detail.The thermal and hydrothermal stabilities results show that Zr-MCM-48 still maintains the Ia3d mesoporous structure after calcination at 800℃for 4h or hydrothermal treatment at 100℃for 24h.The addition of fluoride ions results in short crystallization time and highly hydrothermal stability.Co-MCM-48 and Al-MCM-48 mesoporus molecular sieves were prepared by the above method.The experimental results show that the as synthesized samples possess typical Ia3d cubic mesoporous structure of MCM-48.The thermal and hydrothermal stabilities of Co-MCM-48 mesoporous molecular sieves were also investigated.The results show that the Co-MCM-48 sample still maintains the Ia3d cubic mesoporous framework even after calcination at 800℃for 4h or hydrothermal treatment at 100℃for 12h.The mesoporous structure has completely collapsed after Co-MCM-48 was hydrothermal treated at 100℃for 24h, and the mesoporous ordering becomes poor.SO42-/M-MCM-48 and H-M-MCM-48 (M=Zr, Al) molecular sieve catalyst were prepared by the wet impregnation method with H2SO4 and NH4NO3 solution. Compared with M-MCM-48, the mesoporous ordering of SO42-/M-MCM-48 and H-M-MCM-48 becomes poor, but the cubic structure of MCM-48 still retains.The NH3-TPD profiles suggest the amount of the strong acid and weak acid for SO42-/M-MCM-48 and H-M-MCM-48 are obviously more than these for M-MCM-48.In the alkylation reaction of phenol with tert-butanol, the effects of the different catalysts, reaction temperature and reaction time on the reaction results were examined.The experimental results show that the phenol conversion is higher for the H-Al-MCM-48 than the other catalysts. In addition, the H-Al-MCM-48 and SO42-/Zr-MCM-48 catalyst still maintain higher catalytic activity and hydrothermal stability after alkylation reaction of phenol with tert-butanol for 8h. Compared with H-Zr-MCM-48 and SO42-/Al-MCM-48, we found that the catalytic activities of H-Al-MCM-48 and SO42-/Zr-MCM-48 were enhanced and exhibit higher catalytic activity in the phenol alkylation with tert-butanol under the same conditions.更多还原