無溶劑法合成特殊形貌ZSM-5分子篩及其晶化機理研究
發(fā)布時間：2018-07-16 14:45
【摘要】：乙烯和丙烯等低碳烯烴一直是有機化工和石油化工的重要原料,關乎著國計民生。傳統(tǒng)的烯烴的制備都是通過的石油原料的催化裂解,由于近些年資源的消耗,石油的價格也是逐年上漲,我國是屬于少油多煤多氣的資源格局,因此也制約著烯烴產(chǎn)業(yè)的發(fā)展。近些年甲醇制低碳烯烴(MTO)技術和甲醇制丙烯(MTP)技術不斷地發(fā)展與成熟,已經(jīng)進行大規(guī)模工業(yè)生產(chǎn),由于甲醇的合成簡單廉價(以煤炭或天然氣作為原料),因此此方法成本遠低于傳統(tǒng)工藝。ZSM-5是當前科研人員發(fā)現(xiàn)的對甲醇轉(zhuǎn)化制丙烯反應中丙烯選擇性最高的催化劑。沸石的催化性能與其結構密切相關,因此可以采用不同的合成和改性方法來控制分子篩,制備出具有良好MTO/MTP催化性能的催化劑。在日�？茖W研究以及工業(yè)成產(chǎn),水熱合成是最主要的合成分子篩的手段。但是其也有不足之處,一方面在水熱合成的過程需要添加大量的溶劑,并且在隨后的樣品處理過程中也需要大量的水溶劑,因此很容易造成環(huán)境污染。另一方面合成的過程中需要昂貴的模板劑,提高了反應成本。因此尋找一種合適的分子篩合成方法至關重要。為了克服上述缺陷,近期一種新型的制備分子篩的方法被提出來-固相合成法。固相合成法是浙江大學肖豐收教授首次提出來的,是一種通過固相研磨合成分子篩的方法,反應的過程不需要添加溶劑,因此減少對環(huán)境的污染。此合成結晶時間短(24h),固體原料進行物理研磨并在180℃進行反應。此合成路線的關鍵因素在于選取NH4HF2,此原料在高溫下可以分解成HF和NH3,其中NH3可以和水反應生成OH-化物,沸石合成中的礦化組分OH-和F-將反應物轉(zhuǎn)化為具有活性和反應性的硅酸鹽物質(zhì),并且有利于原材料從完全無定形物質(zhì)轉(zhuǎn)化為有序沸石結晶的轉(zhuǎn)化過程促進反應的進行。在整個高溫加熱期,固體原料并未熔化,并且較短的合成時間和固態(tài)樣品可以進行原位固相NMR研究。在沸石合成凝膠中,有機和無機組分之間的相互作用不清楚,其結晶過程中的關鍵步驟難以鑒定。因此,沸石的結晶機理難以理解,沒有一個通用的晶化機理去描述分子篩的晶化過程。作為最具商業(yè)價值的沸石之一,ZSM-5(MFI拓撲)晶化過程的研究顯得格外重要。在純二氧化硅ZSM-5(Si-ZSM-5)的結構中,平行的線性通道與正弦通道相交,并且TPA分子位于孔道的交叉點,延伸的丙基位于線性通道和正弦通道中。通過一系列先進技術,尤其是通過核磁共振(NMR)技術分析ZSM-5的結晶機理,并提出了分子篩的晶化過程主要是正電荷與負電荷之間的庫侖相互作用,也就是陽離子TPA與孔道骨架中的F陰離子和Si-O...OSi氫鍵相互作用。二維1H DQ-SQ MAS NMR方法是一個強大的工具來探測核質(zhì)子-質(zhì)子空間鄰近性。該技術利用同核偶極-偶極耦合相互作用來關聯(lián)多自旋偶極耦合網(wǎng)絡,兩個自旋關聯(lián)占主導地位。ZSM-5的1HDQ-S MASNMR核磁共振光譜提供了豐富的關于在ZSM-5中的質(zhì)子鄰近性信息。其中TPA的甲基組和硅酸鹽骨架之間的相互作用已明確展現(xiàn)在1HDQ-SQ MAS核磁共振光譜上。我們的合成方法更取決于氟在沸石骨架中的位置,一系列固體核磁共振譜的獲得有助于我們更全面地了解氟離子的作用。通過19F MAS和19F-29Si CP/MAS NMR發(fā)現(xiàn)氟離子直接鍵合到硅氧四元環(huán)其中的一個硅原子上,形成五配位的硅SiO4/2F-。我們通過應用SSNMR技術,確認了模板劑TPA的情與骨架上的負電中心在距離上的相關信息,進而確定了模板劑TPA是通過Columbic相互作用來導向合成具有特別孔道的分子篩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.
【學位授予單位】：安徽大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：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.
【學位授予單位】：安徽大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TQ424.25
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