納米沸石及其在有機(jī)微球模板上的組裝制備大孔沸石
發(fā)布時(shí)間：2018-08-24 13:52
【摘要】：在可預(yù)見的未來,化石能源將仍然是人類能源供應(yīng)的主要組成部分,伴隨著目前原油的過度開采和使用,未來原油供應(yīng)中,原油重質(zhì)化和劣質(zhì)化的趨勢不可避免,因此,優(yōu)化目前的石油煉化工藝成為目前亟待解決的技術(shù)問題。沸石類催化劑以其高的比表面積、均勻的微孔結(jié)構(gòu)、可調(diào)控的酸性能以及良好的穩(wěn)定性成為石油化工領(lǐng)域中最重要的催化材料,被廣泛的應(yīng)用于催化裂化、烷基化和異構(gòu)化。然而,其狹窄的微孔孔道導(dǎo)致了物質(zhì)在孔道內(nèi)的擴(kuò)散限制,因此,縮短微孔內(nèi)的擴(kuò)散路徑和增大沸石催化材料的外表面積成為目前沸石材料的主要研究方向。解決上述沸石材料所存在的缺陷主要有兩種方法:一種是通過減小沸石晶粒的尺寸,制備具有納米尺寸的沸石分子篩,得到高的外比表面積和短的微孔長度；另一種是通過在沸石結(jié)構(gòu)中引入多級(jí)孔結(jié)構(gòu),即在微孔沸石的基礎(chǔ)上引入介孔或大孔,增加活性位的可接近性。這兩種解決方法同樣存在一定的局限性:納米沸石顆粒過小回收困難,而多級(jí)孔沸石則大多受制于其高昂的制備成本。本論文致力于以廉價(jià)的有機(jī)微球?yàn)槟０?通過納米自主裝的方法,將納米沸石組裝于有機(jī)模板之上,得到納米堆積的大孔沸石。該方法結(jié)合了納米沸石和多級(jí)孔沸石的優(yōu)點(diǎn),具有高的外壁表面和短的擴(kuò)散路徑,同時(shí)避免了納米沸石分離困難以及介孔沸石制備成本高昂的缺點(diǎn),均勻的大孔對(duì)原油具有選擇性的分離作用,在重油的催化裂化中存在極大的應(yīng)用潛力。論文具體的研究內(nèi)容分為:納米沸石的制備、有機(jī)微球模板的制備及在大孔材料中的應(yīng)用、納米沸石在有機(jī)微球模板上的組裝三個(gè)部分。在納米沸石的制備的章節(jié)中,通過不同方法分別制備出納米Y和方鈉石,詳細(xì)探討了水相中納米Y沸石的制備和干凝膠法Y沸石的制備。首先納米Y沸石的制備是在水熱合成體系中采用無模板法進(jìn)行制備,文中詳細(xì)考察了堿度、陽離子濃度和凝膠硅鋁比等因素對(duì)納米Y沸石的形成、形貌及骨架硅鋁比的影響。利用XRD、SEM、TEM、NH_3-TPD、FT-IR、氮吸附-脫附、NMR等表征手段對(duì)納米Y沸石的結(jié)構(gòu)及形貌進(jìn)行了詳細(xì)的表征,結(jié)果表明:這種制備納米沸石的方法具有很寬的相區(qū)間,凝膠配比經(jīng)大幅度的調(diào)節(jié)后仍能得到具有高的外比表面積的納米Y沸石；從納米Y沸石的形貌上看,根據(jù)凝膠中各物質(zhì)比例的不同,納米沸石具有小晶粒、片狀、緊密團(tuán)聚的球狀、疏松堆積的不規(guī)則塊狀等多種形貌,其大小和團(tuán)聚狀態(tài)均可根據(jù)變量進(jìn)行調(diào)節(jié)；從孔結(jié)構(gòu)看,所有的樣品均保持了良好的微孔結(jié)構(gòu)且外表面都得到了很大的提升,外表面積最高達(dá)到186m~2/g,總孔容達(dá)到0.81cm~3/g；而從納米Y沸石結(jié)構(gòu)的骨架硅鋁比來看,根據(jù)堿度和凝膠硅鋁比的改變,沸石骨架的硅鋁比、酸性能和結(jié)構(gòu)的穩(wěn)定性可在一定的范圍內(nèi)進(jìn)行改變。本論文中首次采用干凝膠法在低于100℃的溫度下制備出Y沸石,采用骨架紅外、熱重、固體核磁等手段對(duì)干凝膠和晶化后的樣品進(jìn)行分析,結(jié)果表明:干凝膠中已經(jīng)具備Y沸石的部分初級(jí)結(jié)構(gòu)單元,而這些初級(jí)結(jié)構(gòu)單元中的硅鋁比明顯低于晶化后樣品的骨架硅鋁比,證明富鋁的體系有利于Y沸石的晶核的形成,而晶化過程中則使得較多的硅進(jìn)入到骨架中。在干凝膠法制備方鈉石的過程中首次將干凝膠法制備沸石的溫度降低至70℃。在有機(jī)微球的模板的制備中,分別采用乳液聚合法和無皂乳液聚合法制備出聚苯乙烯(PS)和聚甲基丙烯酸甲酯(PMMA)微球,通過改變引發(fā)劑用量、單體用量、乳化劑用量等反應(yīng)條件對(duì)模板的粒徑在200~430nm內(nèi)進(jìn)行連續(xù)調(diào)節(jié)。為制得小于200nm的模板,分別采用稀乳液體系、阻斷聚合反應(yīng)和更換乳化劑等方法使模板在30~200nm內(nèi)連續(xù)可調(diào)。以有機(jī)微球?yàn)榇罂啄０?成功制備出三維有序大孔氧化硅、Al_2O_3/γ-Al_2O_3以及空性球材料,以有機(jī)微球?yàn)槟０逯频玫牟煌拇罂撞牧暇３至艘?guī)則的球狀大孔結(jié)構(gòu)和良好的熱穩(wěn)定性。以納米沸石和大孔模板為基礎(chǔ)制備大孔沸石,對(duì)PS模板的表面性質(zhì)及改性進(jìn)行了探索,詳細(xì)討論了模板與沸石結(jié)合的可行性方案,并以實(shí)驗(yàn)進(jìn)行驗(yàn)證,結(jié)果表明:通過對(duì)凝膠進(jìn)行改性處理,首次證明晶化后有機(jī)微球模板可以進(jìn)入到沸石的晶體內(nèi)部,而離心處理可以進(jìn)一步增大模板的空間限制作用有利于制備大孔沸石。分別將本文中納米沸石的制備方法應(yīng)用于大孔沸石的制備,結(jié)果表明:(1)沸石合成中由于凝膠的溶解與再生長的過程以及有機(jī)相與無機(jī)相的不兼容性是阻礙模板進(jìn)入沸石結(jié)構(gòu)的主要影響因素；(2)疏松的堆積狀及規(guī)則的晶體形貌使得大孔結(jié)構(gòu)很難呈現(xiàn)規(guī)則的球狀；(3)通過干凝膠法和適當(dāng)?shù)母男詶l件及離心處理,可以制得具有均一孔徑大孔(~300nm)的沸石結(jié)構(gòu)。
[Abstract]:In the foreseeable future, fossil energy will still be the main part of human energy supply. With the over-exploitation and use of crude oil, the trend of heavy and inferior crude oil will be inevitable in future crude oil supply. Therefore, optimizing the current petroleum refining process has become an urgent technical problem. Because of its high specific surface area, uniform microporous structure, controllable acidity and good stability, the catalyst has become the most important catalytic material in the petrochemical field. It is widely used in catalytic cracking, alkylation and isomerization. However, its narrow micropore leads to the diffusion restriction in the pore, so the micropore is shortened. Nowadays, the main research directions of zeolite materials are the diffusion path and the increase of the external surface area of zeolite catalytic materials. There are two main methods to solve the defects of zeolite materials: one is to prepare nano-sized zeolite molecular sieves by reducing the size of zeolite grains, and obtain high external specific surface area and short micropore length. The other is to increase the accessibility of active sites by introducing mesoporous or macroporous zeolites into the zeolite structure, which has some limitations: it is difficult to recover nano-zeolite particles when they are too small, while the cost of preparation is limited. In this paper, we focus on the preparation of macroporous nano-zeolites by self-assembly of nano-zeolites onto organic templates using cheap organic microspheres as templates. Difficulty and high cost of preparation of mesoporous zeolite, homogeneous macropore has selective separation of crude oil, and has great potential for application in heavy oil catalytic cracking. In the chapter of preparation of nano-zeolite, nano-Y and sodalite were prepared by different methods. The preparation of nano-Y zeolite in aqueous phase and the preparation of Y zeolite by dry gel method were discussed in detail. The effects of alkalinity, cationic concentration and silica-alumina ratio on the formation, morphology and framework of nano-Y zeolite were investigated in detail. The structure and morphology of nano-Y zeolite were characterized by XRD, SEM, TEM, NH_3-TPD, FT-IR, nitrogen adsorption-desorption and NMR. Nano-Y zeolite with high specific surface area can be obtained by adjusting the proportion of gel in a wide range of phases. According to the morphology of nano-Y zeolite, nano-Y zeolite has many morphologies, such as small grains, flakes, compact agglomeration spheres, loose accumulation of irregular blocks and so on. Size and agglomeration state can be adjusted according to the variables; from the pore structure, all samples have maintained good microporous structure and the external surface has been greatly improved, the maximum external surface area reached 186 m~2/g, the total pore volume reached 0.81 cm~3/g; from the framework of nano-Y zeolite structure, according to the basicity and the ratio of silica to aluminium gel. In this paper, Y zeolite was prepared by dry gel method at temperatures below 100 C for the first time. The samples were analyzed by skeleton infrared spectroscopy, thermogravimetry, solid state nuclear magnetic resonance and so on. The results showed that: dry gel. Some primary structural units of zeolite Y have been found, and the Si/Al ratios in these primary structural units are obviously lower than those of the crystallized samples, which proves that the Al-rich system is beneficial to the nucleation of zeolite Y, while the crystallization process makes more silicon into the framework. The temperature of zeolite prepared by dry gel method was reduced to 70 degrees. The polystyrene (PS) and polymethyl methacrylate (PMMA) microspheres were prepared by emulsion polymerization and soap free emulsion polymerization in the preparation of organic microspheres. The particle size of polystyrene (PS) and polymethyl methacrylate (PMMA) microspheres were changed by changing the amount of initiator, the amount of monomer and the amount of emulsifier. Continuous adjustment was carried out in 200~430nm. In order to make the template smaller than 200nm, dilute emulsion system, blocking polymerization and replacing emulsifier were used to make the template continuously tunable in 30~200nm. With organic microsphere as macroporous template, three dimensional ordered macroporous silicon oxide, Al_2O_3/ -Al_2O_3 -Al_2O_3 and hollow sphere material were successfully prepared, and organic microspheres were prepared. Macroporous zeolites were prepared on the basis of nano-zeolite and macroporous templates. The surface properties and modification of PS templates were explored. The feasibility of combining template with zeolite was discussed in detail. The results were verified by experiments. The results show that the template of the crystallized organic microspheres can enter the crystal of zeolite for the first time by modifying the gel, and the centrifugal treatment can further increase the spatial restriction of the template, which is beneficial to the preparation of macroporous zeolite. The dissolution and regeneration of gel and the incompatibility of organic and inorganic phases are the main factors that hinder the template from entering the zeolite structure in the synthesis of zeolite; (2) the loose accumulation and regular crystal morphology make it difficult for the macroporous structure to appear regular spherical; (3) through the dry gel method and appropriate modification conditions and The zeolite structure with uniform pore size (~300nm) can be prepared by centrifugation.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ426
本文編號(hào)：2201021
[Abstract]:In the foreseeable future, fossil energy will still be the main part of human energy supply. With the over-exploitation and use of crude oil, the trend of heavy and inferior crude oil will be inevitable in future crude oil supply. Therefore, optimizing the current petroleum refining process has become an urgent technical problem. Because of its high specific surface area, uniform microporous structure, controllable acidity and good stability, the catalyst has become the most important catalytic material in the petrochemical field. It is widely used in catalytic cracking, alkylation and isomerization. However, its narrow micropore leads to the diffusion restriction in the pore, so the micropore is shortened. Nowadays, the main research directions of zeolite materials are the diffusion path and the increase of the external surface area of zeolite catalytic materials. There are two main methods to solve the defects of zeolite materials: one is to prepare nano-sized zeolite molecular sieves by reducing the size of zeolite grains, and obtain high external specific surface area and short micropore length. The other is to increase the accessibility of active sites by introducing mesoporous or macroporous zeolites into the zeolite structure, which has some limitations: it is difficult to recover nano-zeolite particles when they are too small, while the cost of preparation is limited. In this paper, we focus on the preparation of macroporous nano-zeolites by self-assembly of nano-zeolites onto organic templates using cheap organic microspheres as templates. Difficulty and high cost of preparation of mesoporous zeolite, homogeneous macropore has selective separation of crude oil, and has great potential for application in heavy oil catalytic cracking. In the chapter of preparation of nano-zeolite, nano-Y and sodalite were prepared by different methods. The preparation of nano-Y zeolite in aqueous phase and the preparation of Y zeolite by dry gel method were discussed in detail. The effects of alkalinity, cationic concentration and silica-alumina ratio on the formation, morphology and framework of nano-Y zeolite were investigated in detail. The structure and morphology of nano-Y zeolite were characterized by XRD, SEM, TEM, NH_3-TPD, FT-IR, nitrogen adsorption-desorption and NMR. Nano-Y zeolite with high specific surface area can be obtained by adjusting the proportion of gel in a wide range of phases. According to the morphology of nano-Y zeolite, nano-Y zeolite has many morphologies, such as small grains, flakes, compact agglomeration spheres, loose accumulation of irregular blocks and so on. Size and agglomeration state can be adjusted according to the variables; from the pore structure, all samples have maintained good microporous structure and the external surface has been greatly improved, the maximum external surface area reached 186 m~2/g, the total pore volume reached 0.81 cm~3/g; from the framework of nano-Y zeolite structure, according to the basicity and the ratio of silica to aluminium gel. In this paper, Y zeolite was prepared by dry gel method at temperatures below 100 C for the first time. The samples were analyzed by skeleton infrared spectroscopy, thermogravimetry, solid state nuclear magnetic resonance and so on. The results showed that: dry gel. Some primary structural units of zeolite Y have been found, and the Si/Al ratios in these primary structural units are obviously lower than those of the crystallized samples, which proves that the Al-rich system is beneficial to the nucleation of zeolite Y, while the crystallization process makes more silicon into the framework. The temperature of zeolite prepared by dry gel method was reduced to 70 degrees. The polystyrene (PS) and polymethyl methacrylate (PMMA) microspheres were prepared by emulsion polymerization and soap free emulsion polymerization in the preparation of organic microspheres. The particle size of polystyrene (PS) and polymethyl methacrylate (PMMA) microspheres were changed by changing the amount of initiator, the amount of monomer and the amount of emulsifier. Continuous adjustment was carried out in 200~430nm. In order to make the template smaller than 200nm, dilute emulsion system, blocking polymerization and replacing emulsifier were used to make the template continuously tunable in 30~200nm. With organic microsphere as macroporous template, three dimensional ordered macroporous silicon oxide, Al_2O_3/ -Al_2O_3 -Al_2O_3 and hollow sphere material were successfully prepared, and organic microspheres were prepared. Macroporous zeolites were prepared on the basis of nano-zeolite and macroporous templates. The surface properties and modification of PS templates were explored. The feasibility of combining template with zeolite was discussed in detail. The results were verified by experiments. The results show that the template of the crystallized organic microspheres can enter the crystal of zeolite for the first time by modifying the gel, and the centrifugal treatment can further increase the spatial restriction of the template, which is beneficial to the preparation of macroporous zeolite. The dissolution and regeneration of gel and the incompatibility of organic and inorganic phases are the main factors that hinder the template from entering the zeolite structure in the synthesis of zeolite; (2) the loose accumulation and regular crystal morphology make it difficult for the macroporous structure to appear regular spherical; (3) through the dry gel method and appropriate modification conditions and The zeolite structure with uniform pore size (~300nm) can be prepared by centrifugation.
【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TQ426
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