一維孔結(jié)構(gòu)沸石的傳質(zhì)特性研究
發(fā)布時間：2018-07-28 16:07
【摘要】：近年來,絲光沸石和EU-1沸石因其獨特的結(jié)構(gòu)優(yōu)勢和優(yōu)良的水熱穩(wěn)定性而在催化領(lǐng)域中應(yīng)用廣泛,如將絲光沸石應(yīng)用于烷烴與芳烴異構(gòu)化領(lǐng)域,將EU-1沸石用作二甲苯異構(gòu)化反應(yīng)催化劑等。這兩種沸石分子篩在精細化工、石油化工等領(lǐng)域均具有潛在的巨大的應(yīng)用價值。并且絲光沸石及EU-1沸石均為一維孔道結(jié)構(gòu)的沸石,這種結(jié)構(gòu)特色即使其具有一定的擇形選擇功能,又會衍生傳質(zhì)問題而限制它們的進一步應(yīng)用。因此,多級孔絲光及EU-1沸石也相繼被開發(fā)出來。對于一個催化反應(yīng),反應(yīng)物以及產(chǎn)物分子的吸附與擴散在其中扮演著十分重要的角色。因此,對吸附質(zhì)分子在沸石孔道內(nèi)吸附與擴散性能的研究將有助于優(yōu)化催化反應(yīng)過程。一些熱力學(xué)和動力學(xué)數(shù)據(jù)的計算和分析對于沸石分子篩催化劑的設(shè)計、制備以及更好的應(yīng)用具有一定的指導(dǎo)意義。目前集中在絲光及EU-1沸石上的研究主要還是在制備及催化方面,對這種結(jié)構(gòu)如此有特色的沸石,其吸附和擴散性能卻幾乎沒有相關(guān)報道。為了探究這類具有一維孔道結(jié)構(gòu)的沸石,其吸附與擴散機制的獨特性,以及中孔的引入對這類沸石吸附與擴散性能的影響,本文選取了甲苯及均三甲苯為探針分子,探究了多級孔絲光及EU-1沸石上的吸附與擴散性能,以期能夠為多級孔絲光及EU-1沸石的評價、應(yīng)用以及制備奠定理論基礎(chǔ)。本論文的研究內(nèi)容及主要結(jié)論如下:1.甲苯及均三甲苯在多級孔絲光沸石中的吸附與擴散甲苯可以吸附進入絲光沸石的微孔孔道,但是脫附異常困難,需高溫方可脫附出來。均三甲苯不能進入絲光沸石的微孔孔道,但可在多級孔絲光樣品中進行吸附,說明中孔的引入有利于提高大分子的可接近性。甲苯與均三甲苯在微孔絲光沸石中的吸附主要表現(xiàn)為化學(xué)吸附的特征,而在多級孔絲光沸石中,為物理吸附。甲苯在絲光樣品中的TPD實驗證明了,絲光沸石中確實存在著作用力不同的兩種吸附中心,一種吸附作用力相對較弱,另一種則作用力較強。雙位Toth模型可以很好地描述甲苯在多級孔絲光沸石中的吸附行為,擬合參數(shù)表明中孔有利于促進吸附,且減弱了甲苯分子與吸附劑間相互作用力。吸附動力學(xué)實驗結(jié)果說明中孔的存在為吸附質(zhì)分子縮短了擴散路徑,提高了分子的傳質(zhì)速率。2.甲苯及均三甲苯在多級孔EU-1沸石中的吸附與擴散甲苯在微孔EU-1沸石中的吸附等溫線為I型等溫線,而在對應(yīng)多級孔EU-1沸石中為I型和IV型復(fù)合等溫線。均三甲苯不能進入EU-1沸石的微孔孔道,但可以進入多級孔EU-1的中孔,說明中孔的引入有利于提高大分子的可接近性。當(dāng)吸附質(zhì)分子僅吸附在EU-1沸石表面時,為物理吸附,而進入沸石的微孔孔道中后,由于分子受到強烈的擴散限制,則會表現(xiàn)為化學(xué)吸附的特征。采用雙位Toth模型對甲苯在多級孔EU-1沸石中的吸附等溫線進行擬合,擬合效果較好。相關(guān)參數(shù)分析表明,中孔引入有利于提高吸附量,且對于EU-1-3樣品,中孔的引入打開了側(cè)袋結(jié)構(gòu),使甲苯在微孔區(qū)和中孔區(qū)的吸附量均顯著增加。吸附動力學(xué)研究表明中孔的存在有利于提高分子在EU-1沸石中的傳質(zhì)過程。
[Abstract]:In recent years, mordenite and EU-1 zeolite have been widely used in the field of catalysis because of their unique structural advantages and excellent hydrothermal stability. For example, mordenite is used in the field of alkanes and aromatics isomerization, and EU-1 zeolite is used as a catalyst for the isomerization of xylene. These two kinds of boiling stone molecular sieves are in the fields of fine chemical, petrochemical and other fields. Both mercerite and EU-1 zeolite are one of the one-dimensional pore structure zeolite. This structure characteristic, even if it has a certain shape selection function, will also limit the further application of mass transfer. Therefore, multistage mercerized and EU-1 zeolite have been developed successively. The adsorption and diffusion of chemical reactions, reactant and product molecules play a very important role. Therefore, the study of adsorption and diffusion properties of adsorbate molecules in the pore of zeolite will help to optimize the catalytic reaction process. Some thermodynamic and kinetic data calculation and analysis are designed for zeolite catalysts. Preparation and better application have certain guiding significance. The research focused on mercerized and EU-1 zeolite is mainly in preparation and catalysis. The adsorption and diffusion properties of this kind of zeolite with such a characteristic structure are hardly reported. In order to explore the adsorption and diffusion of zeolite with one-dimensional pore structure, the adsorption and diffusion of zeolite have been investigated. The uniqueness of the mechanism and the influence of the introduction of mesopore on the adsorption and diffusion properties of this type of zeolite. In this paper, toluene and three toluene are selected as probe molecules to explore the adsorption and diffusion properties of multistage orifice mercerizing and EU-1 zeolite, in order to lay a theoretical foundation for the evaluation, application and preparation of multilevel oropes and EU-1 zeolites. The contents and main conclusions are as follows: 1. the adsorption and diffusion of toluene and three toluene in the multistage mordenite can be adsorbed into the micropore of mordenite, but the desorption is difficult and the high temperature can be removed. All three toluene can not enter the micropore of mordenite, but it can be used in the multistage pore mercerizing sample. The introduction of the mesopore is helpful to improve the accessibility of the macromolecules. The adsorption of toluene and three toluene in the microporous mordenite is mainly characterized by chemical adsorption, while in the multistage mordenite, it is a physical adsorption. The TPD experiment in the mercerized sample of toluene has proved that there is a real force in mordenite. Two different adsorption centers, one kind of adsorption force is relatively weak, the other is stronger. The two bit Toth model can well describe the adsorption behavior of toluene in multistage mordenite. The fitting parameters show that the pore is beneficial to promote adsorption and weaken the interaction force between toluene molecules and adsorbents. Adsorption kinetics experiment. The results show that the existence of mesopore shortens the diffusion path for adsorbate molecules, improves the mass transfer rate of.2. and three toluene in multistage pore EU-1 zeolite, and the adsorption isotherm of toluene in microporous EU-1 zeolite is I isotherm, while I and IV type compound isotherms in the corresponding multistage EU-1 zeolite are both three. Toluene can not enter the micropore of the EU-1 zeolite, but it can enter the mesopore of the multistage hole EU-1, indicating that the introduction of the mesopore is beneficial to the improvement of the accessibility of the macromolecules. When the adsorbate molecules adsorb only on the surface of the EU-1 zeolite, they are physically adsorbed and enter the pore channels of the zeolite. For the characteristics of chemical adsorption, the adsorption isotherm of toluene in the multilevel pore EU-1 zeolite was fitted by two bit Toth model. The fitting effect was good. The analysis of related parameters showed that the introduction of mesopore was beneficial to the increase of adsorption capacity, and the side bag structure was opened for the introduction of EU-1-3 samples and the mesopore was introduced, and the adsorption amount of toluene in the microporous and mesoporous areas was made. The adsorption kinetics showed that the existence of mesopores improved the mass transfer process of EU-1 in zeolites.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ424.25
本文編號：2150833
[Abstract]:In recent years, mordenite and EU-1 zeolite have been widely used in the field of catalysis because of their unique structural advantages and excellent hydrothermal stability. For example, mordenite is used in the field of alkanes and aromatics isomerization, and EU-1 zeolite is used as a catalyst for the isomerization of xylene. These two kinds of boiling stone molecular sieves are in the fields of fine chemical, petrochemical and other fields. Both mercerite and EU-1 zeolite are one of the one-dimensional pore structure zeolite. This structure characteristic, even if it has a certain shape selection function, will also limit the further application of mass transfer. Therefore, multistage mercerized and EU-1 zeolite have been developed successively. The adsorption and diffusion of chemical reactions, reactant and product molecules play a very important role. Therefore, the study of adsorption and diffusion properties of adsorbate molecules in the pore of zeolite will help to optimize the catalytic reaction process. Some thermodynamic and kinetic data calculation and analysis are designed for zeolite catalysts. Preparation and better application have certain guiding significance. The research focused on mercerized and EU-1 zeolite is mainly in preparation and catalysis. The adsorption and diffusion properties of this kind of zeolite with such a characteristic structure are hardly reported. In order to explore the adsorption and diffusion of zeolite with one-dimensional pore structure, the adsorption and diffusion of zeolite have been investigated. The uniqueness of the mechanism and the influence of the introduction of mesopore on the adsorption and diffusion properties of this type of zeolite. In this paper, toluene and three toluene are selected as probe molecules to explore the adsorption and diffusion properties of multistage orifice mercerizing and EU-1 zeolite, in order to lay a theoretical foundation for the evaluation, application and preparation of multilevel oropes and EU-1 zeolites. The contents and main conclusions are as follows: 1. the adsorption and diffusion of toluene and three toluene in the multistage mordenite can be adsorbed into the micropore of mordenite, but the desorption is difficult and the high temperature can be removed. All three toluene can not enter the micropore of mordenite, but it can be used in the multistage pore mercerizing sample. The introduction of the mesopore is helpful to improve the accessibility of the macromolecules. The adsorption of toluene and three toluene in the microporous mordenite is mainly characterized by chemical adsorption, while in the multistage mordenite, it is a physical adsorption. The TPD experiment in the mercerized sample of toluene has proved that there is a real force in mordenite. Two different adsorption centers, one kind of adsorption force is relatively weak, the other is stronger. The two bit Toth model can well describe the adsorption behavior of toluene in multistage mordenite. The fitting parameters show that the pore is beneficial to promote adsorption and weaken the interaction force between toluene molecules and adsorbents. Adsorption kinetics experiment. The results show that the existence of mesopore shortens the diffusion path for adsorbate molecules, improves the mass transfer rate of.2. and three toluene in multistage pore EU-1 zeolite, and the adsorption isotherm of toluene in microporous EU-1 zeolite is I isotherm, while I and IV type compound isotherms in the corresponding multistage EU-1 zeolite are both three. Toluene can not enter the micropore of the EU-1 zeolite, but it can enter the mesopore of the multistage hole EU-1, indicating that the introduction of the mesopore is beneficial to the improvement of the accessibility of the macromolecules. When the adsorbate molecules adsorb only on the surface of the EU-1 zeolite, they are physically adsorbed and enter the pore channels of the zeolite. For the characteristics of chemical adsorption, the adsorption isotherm of toluene in the multilevel pore EU-1 zeolite was fitted by two bit Toth model. The fitting effect was good. The analysis of related parameters showed that the introduction of mesopore was beneficial to the increase of adsorption capacity, and the side bag structure was opened for the introduction of EU-1-3 samples and the mesopore was introduced, and the adsorption amount of toluene in the microporous and mesoporous areas was made. The adsorption kinetics showed that the existence of mesopores improved the mass transfer process of EU-1 in zeolites.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ424.25
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