无溶剂法合成特殊形貌ZSM-5分子筛及其晶化机理研究
发布时间：2018-07-16 14:45
【摘要】：乙烯和丙烯等低碳烯烃一直是有机化工和石油化工的重要原料,关乎着国计民生。传统的烯烃的制备都是通过的石油原料的催化裂解,由于近些年资源的消耗,石油的价格也是逐年上涨,我国是属于少油多煤多气的资源格局,因此也制约着烯烃产业的发展。近些年甲醇制低碳烯烃(MTO)技术和甲醇制丙烯(MTP)技术不断地发展与成熟,已经进行大规模工业生产,由于甲醇的合成简单廉价(以煤炭或天然气作为原料),因此此方法成本远低于传统工艺。ZSM-5是当前科研人员发现的对甲醇转化制丙烯反应中丙烯选择性最高的催化剂。沸石的催化性能与其结构密切相关,因此可以采用不同的合成和改性方法来控制分子筛,制备出具有良好MTO/MTP催化性能的催化剂。在日常科学研究以及工业成产,水热合成是最主要的合成分子筛的手段。但是其也有不足之处,一方面在水热合成的过程需要添加大量的溶剂,并且在随后的样品处理过程中也需要大量的水溶剂,因此很容易造成环境污染。另一方面合成的过程中需要昂贵的模板剂,提高了反应成本。因此寻找一种合适的分子筛合成方法至关重要。为了克服上述缺陷,近期一种新型的制备分子筛的方法被提出来-固相合成法。固相合成法是浙江大学肖丰收教授首次提出来的,是一种通过固相研磨合成分子筛的方法,反应的过程不需要添加溶剂,因此减少对环境的污染。此合成结晶时间短(24h),固体原料进行物理研磨并在180℃进行反应。此合成路线的关键因素在于选取NH4HF2,此原料在高温下可以分解成HF和NH3,其中NH3可以和水反应生成OH-化物,沸石合成中的矿化组分OH-和F-将反应物转化为具有活性和反应性的硅酸盐物质,并且有利于原材料从完全无定形物质转化为有序沸石结晶的转化过程促进反应的进行。在整个高温加热期,固体原料并未熔化,并且较短的合成时间和固态样品可以进行原位固相NMR研究。在沸石合成凝胶中,有机和无机组分之间的相互作用不清楚,其结晶过程中的关键步骤难以鉴定。因此,沸石的结晶机理难以理解,没有一个通用的晶化机理去描述分子筛的晶化过程。作为最具商业价值的沸石之一,ZSM-5(MFI拓扑)晶化过程的研究显得格外重要。在纯二氧化硅ZSM-5(Si-ZSM-5)的结构中,平行的线性通道与正弦通道相交,并且TPA分子位于孔道的交叉点,延伸的丙基位于线性通道和正弦通道中。通过一系列先进技术,尤其是通过核磁共振(NMR)技术分析ZSM-5的结晶机理,并提出了分子筛的晶化过程主要是正电荷与负电荷之间的库仑相互作用,也就是阳离子TPA与孔道骨架中的F阴离子和Si-O...OSi氢键相互作用。二维1H DQ-SQ MAS NMR方法是一个强大的工具来探测核质子-质子空间邻近性。该技术利用同核偶极-偶极耦合相互作用来关联多自旋偶极耦合网络,两个自旋关联占主导地位。ZSM-5的1HDQ-S MASNMR核磁共振光谱提供了丰富的关于在ZSM-5中的质子邻近性信息。其中TPA的甲基组和硅酸盐骨架之间的相互作用已明确展现在1HDQ-SQ MAS核磁共振光谱上。我们的合成方法更取决于氟在沸石骨架中的位置,一系列固体核磁共振谱的获得有助于我们更全面地了解氟离子的作用。通过19F MAS和19F-29Si CP/MAS NMR发现氟离子直接键合到硅氧四元环其中的一个硅原子上,形成五配位的硅SiO4/2F-。我们通过应用SSNMR技术,确认了模板剂TPA的情与骨架上的负电中心在距离上的相关信息,进而确定了模板剂TPA是通过Columbic相互作用来导向合成具有特别孔道的分子筛ZSM-5。
[Abstract]:Low carbon olefin, such as ethylene and propylene, has always been an important raw material in organic chemical industry and petrochemical industry. The preparation of traditional olefin is the catalytic cracking of petroleum raw materials. Because of the consumption of resources in recent years, the price of petroleum is rising year by year. China is a resource pattern of less oil and multi gas, so it is also made. In recent years, the development and development of the olefin industry. The technology of methanol low carbon olefin (MTO) and methanol propylene (MTP) have been developed and mature in recent years, and large-scale industrial production has been carried out. Because the synthesis of methanol is simple and cheap (with coal or natural gas as raw material), the cost of this method is far lower than that of the traditional technology.ZSM-5. The catalyst of the highest selectivity of propylene in the reaction of methanol conversion to propylene. The catalytic performance of zeolite is closely related to its structure. Therefore, different methods of synthesis and modification can be used to control the molecular sieve to prepare the catalyst with good MTO/MTP catalytic performance. In the daily study and industrial production, the hydrothermal synthesis is the most important. The main means of synthesis of molecular sieves. But there are also shortcomings. On the one hand, a large amount of solvent is needed in the process of hydrothermal synthesis, and a large amount of water solvent is needed in the process of subsequent sample treatment. Therefore, it is easy to cause environmental pollution. On the other hand, an expensive template is needed in the process of synthesis, and the reaction is improved. Therefore, to find a suitable method of molecular sieves synthesis is very important. In order to overcome the above defects, a new method of preparing molecular sieves has been proposed in the near future - solid phase synthesis. Solid phase synthesis is first proposed by Professor Xiao Fengshou of Zhejiang University. It is a method of synthesizing molecular sieves by solid phase grinding. The process of reaction is not It is necessary to add a solvent to reduce the pollution of the environment. This synthetic crystallization time is short (24h). The solid material is physically lapping and reacting at 180 C. The key factor for this synthetic route is the selection of NH4HF2, which can be decomposed into HF and NH3 at high temperature, in which NH3 can react with water to produce OH- chemicals, and the mineralized group in zeolite synthesis OH- and F- convert the reactant into active and reactive silicate, and help the raw materials to convert from completely amorphous to ordered zeolite crystallization to promote the reaction. In the whole high temperature heating period, the solid material is not melted, and the shorter synthesis time and solid sample can be in situ. Solid phase NMR studies. In zeolite synthetic gels, the interaction between organic and inorganic components is not clear, and the key steps in the crystallization process are difficult to identify. Therefore, the crystallization mechanism of the zeolite is difficult to understand. There is no general crystallization mechanism to describe the crystallization process of molecular sieves. As one of the most commercially valuable zeolites, ZSM-5 (MFI extension) The study of the crystallizing process is particularly important. In the structure of pure silica ZSM-5 (Si-ZSM-5), the parallel linear channel intersects with the sinusoidal channel, and the TPA molecules are located at the intersection point of the channel, and the extended propyl is located in the linear channel and the sinusoidal channel. A series of advance techniques, especially the NMR technology, are used to analyze the ZS. The crystallization mechanism of M-5 and the crystallization process of the molecular sieves are mainly the Coulomb interaction between the positive charge and the negative charge, that is, the interaction between the cationic TPA and the F anion and the Si-O... OSi hydrogen bond in the pore framework. The two-dimensional 1H DQ-SQ MAS NMR method is a powerful tool to detect the nuclear proton proton space proximity. Using the same nuclear dipole coupling interaction to relate the multi spin dipole coupling network, the two spin correlation 1HDQ-S MASNMR NMR spectra provide rich information about the proton proximity in ZSM-5, in which the interaction between the TPA group and the silicate skeleton has been clearly displayed in the 1HDQ-SQ MAS nuclear magnetic resonance spectra. Our synthesis method depends more on the position of fluorine in the zeolite framework. A series of solid nuclear magnetic resonance spectra help us to understand the effect of fluorine ion more comprehensively. Through the discovery of 19F MAS and 19F-29Si CP/MAS NMR, fluorine ions are directly bonded to a silicon atom in the four element ring of silicon oxygen, forming five By using SSNMR technology, we confirm the information about the distance between the template agent TPA and the negative electric center on the skeleton, and then determine that the template agent TPA is guided by the Columbic interaction to guide the synthesis of the molecular sieve ZSM-5. with special pass.
【学位授予单位】：安徽大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ424.25
[Abstract]:Low carbon olefin, such as ethylene and propylene, has always been an important raw material in organic chemical industry and petrochemical industry. The preparation of traditional olefin is the catalytic cracking of petroleum raw materials. Because of the consumption of resources in recent years, the price of petroleum is rising year by year. China is a resource pattern of less oil and multi gas, so it is also made. In recent years, the development and development of the olefin industry. The technology of methanol low carbon olefin (MTO) and methanol propylene (MTP) have been developed and mature in recent years, and large-scale industrial production has been carried out. Because the synthesis of methanol is simple and cheap (with coal or natural gas as raw material), the cost of this method is far lower than that of the traditional technology.ZSM-5. The catalyst of the highest selectivity of propylene in the reaction of methanol conversion to propylene. The catalytic performance of zeolite is closely related to its structure. Therefore, different methods of synthesis and modification can be used to control the molecular sieve to prepare the catalyst with good MTO/MTP catalytic performance. In the daily study and industrial production, the hydrothermal synthesis is the most important. The main means of synthesis of molecular sieves. But there are also shortcomings. On the one hand, a large amount of solvent is needed in the process of hydrothermal synthesis, and a large amount of water solvent is needed in the process of subsequent sample treatment. Therefore, it is easy to cause environmental pollution. On the other hand, an expensive template is needed in the process of synthesis, and the reaction is improved. Therefore, to find a suitable method of molecular sieves synthesis is very important. In order to overcome the above defects, a new method of preparing molecular sieves has been proposed in the near future - solid phase synthesis. Solid phase synthesis is first proposed by Professor Xiao Fengshou of Zhejiang University. It is a method of synthesizing molecular sieves by solid phase grinding. The process of reaction is not It is necessary to add a solvent to reduce the pollution of the environment. This synthetic crystallization time is short (24h). The solid material is physically lapping and reacting at 180 C. The key factor for this synthetic route is the selection of NH4HF2, which can be decomposed into HF and NH3 at high temperature, in which NH3 can react with water to produce OH- chemicals, and the mineralized group in zeolite synthesis OH- and F- convert the reactant into active and reactive silicate, and help the raw materials to convert from completely amorphous to ordered zeolite crystallization to promote the reaction. In the whole high temperature heating period, the solid material is not melted, and the shorter synthesis time and solid sample can be in situ. Solid phase NMR studies. In zeolite synthetic gels, the interaction between organic and inorganic components is not clear, and the key steps in the crystallization process are difficult to identify. Therefore, the crystallization mechanism of the zeolite is difficult to understand. There is no general crystallization mechanism to describe the crystallization process of molecular sieves. As one of the most commercially valuable zeolites, ZSM-5 (MFI extension) The study of the crystallizing process is particularly important. In the structure of pure silica ZSM-5 (Si-ZSM-5), the parallel linear channel intersects with the sinusoidal channel, and the TPA molecules are located at the intersection point of the channel, and the extended propyl is located in the linear channel and the sinusoidal channel. A series of advance techniques, especially the NMR technology, are used to analyze the ZS. The crystallization mechanism of M-5 and the crystallization process of the molecular sieves are mainly the Coulomb interaction between the positive charge and the negative charge, that is, the interaction between the cationic TPA and the F anion and the Si-O... OSi hydrogen bond in the pore framework. The two-dimensional 1H DQ-SQ MAS NMR method is a powerful tool to detect the nuclear proton proton space proximity. Using the same nuclear dipole coupling interaction to relate the multi spin dipole coupling network, the two spin correlation 1HDQ-S MASNMR NMR spectra provide rich information about the proton proximity in ZSM-5, in which the interaction between the TPA group and the silicate skeleton has been clearly displayed in the 1HDQ-SQ MAS nuclear magnetic resonance spectra. Our synthesis method depends more on the position of fluorine in the zeolite framework. A series of solid nuclear magnetic resonance spectra help us to understand the effect of fluorine ion more comprehensively. Through the discovery of 19F MAS and 19F-29Si CP/MAS NMR, fluorine ions are directly bonded to a silicon atom in the four element ring of silicon oxygen, forming five By using SSNMR technology, we confirm the information about the distance between the template agent TPA and the negative electric center on the skeleton, and then determine that the template agent TPA is guided by the Columbic interaction to guide the synthesis of the molecular sieve ZSM-5. with special pass.
【学位授予单位】：安徽大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ424.25
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