層狀分子篩的層間修飾與結(jié)構(gòu)解析
發(fā)布時(shí)間：2018-07-17 07:39
【摘要】：本論文以改善分子篩對(duì)大分子反應(yīng)物與大分子產(chǎn)物的擴(kuò)散限制,提高催化活性中心的可接近性,合成新型分子篩材料為目的,先后開(kāi)展分子篩層狀前驅(qū)體的層間擴(kuò)孔、硅鍺分子篩后處理與直接合成分子篩納米片等研究工作。第一部分采用有機(jī)硅烷Me2Si(OEt)2 (DEDMS)對(duì)分子篩層狀前驅(qū)體Nu-6(1)插硅,獲得結(jié)構(gòu)新穎的IEZ-Nu-6(1)分子篩。通過(guò)考察合成條件,首次發(fā)現(xiàn)在乙醇溶液中可以獲得有序的晶體材料,而在水溶液中有序程度要差。因Nu-6(1)的層間模板劑在水中易從層間擴(kuò)散至溶液中,此時(shí)有機(jī)硅烷沒(méi)有插入層間,導(dǎo)致擴(kuò)孔失敗,而在乙醇中模板劑擴(kuò)散速度較慢,模板劑脫除過(guò)程與插硅過(guò)程速度平衡,擴(kuò)孔易成功。對(duì)IEZ-Nu-6(1)進(jìn)行結(jié)構(gòu)優(yōu)化與精修,表明IEZ-Nu-6(1)具有兩套孔徑大小不同的十元環(huán)孔道。將Nu-6(2)、IEZ-Nu-6(2)用于催化乙醇與乙酸的酯化反應(yīng),后者具有更高的轉(zhuǎn)化率,因其具有更大的孔徑和親水性。第二部分利用分子篩層狀前驅(qū)體的結(jié)構(gòu)特點(diǎn),合成超大孔分子篩。目前為止,采用層間插硅合成的分子篩,其孔道均不超過(guò)十二元環(huán)。本文采用分子篩層狀前驅(qū)體PREFER,以及有機(jī)硅烷1,3,5,7-四甲基環(huán)四硅烷(D4h),在硝酸溶液中層間插硅擴(kuò)孔,獲得含有十四元環(huán)的晶體材料IEZ-FER(D4h)。采用DFT對(duì)結(jié)構(gòu)進(jìn)行優(yōu)化與精修,結(jié)果表明IEZ-FER(D4h)具有一套十四元環(huán)和一套十二元環(huán)孔道。通過(guò)XRD、 UV-Ramaru NMR、IR、N2吸附等手段表征IEZ-FER(D4h)物理化學(xué)性能,并采用蒸汽吸附表征材料的孔道大小、親疏水性與水熱穩(wěn)定性。第三部分采用1-丁基-3-甲基咪唑鹽為模板劑,合成了2個(gè)晶胞厚度的硅鍺分子篩納米片ECNU-9,不僅具有很高的比表面積,而且含有多級(jí)孔道。分子篩納米片ECNU-9具有規(guī)則的形狀,而且分散性好。ECNU-9沿著c軸方向具有一套十元環(huán)和一套十二元環(huán)。在ECNU-9的晶化研究基礎(chǔ)上,首次提出在球狀膠束作用下,彎曲限制晶化的機(jī)理。加入有水合作用的無(wú)機(jī)鹽后,導(dǎo)致離子液體團(tuán)聚形成表面帶正電荷的膠束,而SiO44-與GeO44-帶負(fù)電荷,由于電荷平衡作用,SiO44-與GeO444-被吸引到膠束表面,沿膠束表面原位晶化,當(dāng)彎曲的晶體厚度達(dá)到一定值時(shí),外表面受到的張力限制晶體的進(jìn)一步生長(zhǎng)。第四部分考察了IM-20分子篩在不同酸性條件下后處理的結(jié)構(gòu)變化。硅鍺分子篩IM-20的拓?fù)浣Y(jié)構(gòu)為UWY,其骨架含有兩類雙四元環(huán),本文利用ADoR機(jī)理,首次選擇性脫除雙四元環(huán)。在室溫、強(qiáng)酸性水溶液下,對(duì)IM-20酸洗,可以獲得兩類雙四元環(huán)均脫除的結(jié)構(gòu),記作ECNU-12.而在333 K、強(qiáng)酸性乙醇溶液下,可以獲得只有一類雙四元環(huán)脫除的結(jié)構(gòu),記作ECNU-13.采用DFT優(yōu)化兩種結(jié)構(gòu),并用優(yōu)化的結(jié)構(gòu)得到了與實(shí)驗(yàn)值接近的XRD譜圖。
[Abstract]:In order to improve the diffusion limitation of molecular sieve to macromolecular reactants and macromolecular products, to improve the accessibility of catalytic active centers and to synthesize new molecular sieve materials, the interlaminar pore reaming of molecular sieve layered precursors was carried out successively. Study on the post-treatment and direct synthesis of silica-germanium molecular sieve nanoparticles. In the first part, organosilane Me2Si (OET) 2 (DEDMS) was used to intercalate the molecular sieve layered precursor Nu-6 (1) to obtain the novel structure of IEZ-Nu-6 (1) molecular sieve. By investigating the synthesis conditions, it was found for the first time that the ordered crystal material could be obtained in the ethanol solution, but the order degree was poor in the aqueous solution. Because Nu-6 (1) interlaminar template diffuses easily from interlayer to solution in water, the organic silane does not insert into the interlayer at this time, which leads to the failure of pore reaming, while in ethanol, the diffusion rate of template agent is slow, and the removal process of template agent is balanced with that of silicon intercalation process. Reaming is easy to succeed. The structure optimization and refinement of IEZ-Nu-6 (1) show that IEZ-Nu-6 (1) has two sets of 10-element annular channels with different pore sizes. Nu-6 (2) IEZ-Nu-6 (2) was used to catalyze the esterification of ethanol with acetic acid. The latter has higher conversion due to its larger pore size and hydrophilicity. In the second part, super porous molecular sieves were synthesized by using the structure of layered precursors. Up to now, molecular sieves synthesized by interlayer intercalation silicon have no more than 12 rings. In this paper, molecular sieve layered precursor PREFER and organosilane 1 / 3 / 5 / 7- tetramethylcyclotetrasilane (D 4 h) were used to fabricate the crystal material IEZ-FER (D 4 h) with tetrad ring in the middle of nitric acid solution. The structure was optimized and refined by DFT. The results show that IEZ-FER (D4h) has a set of 14-member rings and a set of 12-member ring channels. The physical and chemical properties of IEZ-FER (D4h) were characterized by means of XRD, UV-Ramaru NMR-IRN _ 2 adsorption, and the pore size, hydrophobicity and hydrothermal stability of the materials were characterized by steam adsorption. In the third part, using 1 Ding Ji-3-methyl imidazole salt as template, two silicon-germanium molecular sieve nanocrystals ECNU-9 with cell thickness were synthesized, which not only have high specific surface area, but also contain multilevel pore channels. The molecular sieve nanochip ECNU-9 has regular shape and good dispersibility. ECNU-9 has a set of 10-member ring and a set of 12-member ring along the c-axis direction. On the basis of the crystallization of ECNU-9, the mechanism of bending limiting crystallization under the action of spherical micelles is proposed for the first time. The addition of inorganic salts with water cooperation results in the aggregation of ionic liquids to form positively charged micelles on the surface, while SiO44- and GeO44- are negatively charged. Due to charge balance, SiO44- and GeO444- are attracted to the micelle surface and crystallized in situ along the micellar surface. When the thickness of the curved crystal reaches a certain value, the tension on the outer surface limits the further growth of the crystal. In the fourth part, the structure changes of IM-20 molecular sieve after treatment under different acidic conditions were investigated. The structure of SiGe molecular sieve IM-20 is UWY, and its skeleton contains two kinds of double quaternary rings. In this paper, the first selective removal of double quaternary rings is made by using the ADoR mechanism. At room temperature and in strong acidic aqueous solution, two kinds of double quaternary ring structures can be obtained for IM-20 acid pickling, which can be described as ECNU-12. However, at 333K, strong acid ethanol solution, only a class of double quaternary ring destructions can be obtained, which can be described as ECNU-13. The two structures were optimized by DFT, and the XRD spectra close to the experimental values were obtained by using the optimized structure.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.1
本文編號(hào)：2129631
[Abstract]:In order to improve the diffusion limitation of molecular sieve to macromolecular reactants and macromolecular products, to improve the accessibility of catalytic active centers and to synthesize new molecular sieve materials, the interlaminar pore reaming of molecular sieve layered precursors was carried out successively. Study on the post-treatment and direct synthesis of silica-germanium molecular sieve nanoparticles. In the first part, organosilane Me2Si (OET) 2 (DEDMS) was used to intercalate the molecular sieve layered precursor Nu-6 (1) to obtain the novel structure of IEZ-Nu-6 (1) molecular sieve. By investigating the synthesis conditions, it was found for the first time that the ordered crystal material could be obtained in the ethanol solution, but the order degree was poor in the aqueous solution. Because Nu-6 (1) interlaminar template diffuses easily from interlayer to solution in water, the organic silane does not insert into the interlayer at this time, which leads to the failure of pore reaming, while in ethanol, the diffusion rate of template agent is slow, and the removal process of template agent is balanced with that of silicon intercalation process. Reaming is easy to succeed. The structure optimization and refinement of IEZ-Nu-6 (1) show that IEZ-Nu-6 (1) has two sets of 10-element annular channels with different pore sizes. Nu-6 (2) IEZ-Nu-6 (2) was used to catalyze the esterification of ethanol with acetic acid. The latter has higher conversion due to its larger pore size and hydrophilicity. In the second part, super porous molecular sieves were synthesized by using the structure of layered precursors. Up to now, molecular sieves synthesized by interlayer intercalation silicon have no more than 12 rings. In this paper, molecular sieve layered precursor PREFER and organosilane 1 / 3 / 5 / 7- tetramethylcyclotetrasilane (D 4 h) were used to fabricate the crystal material IEZ-FER (D 4 h) with tetrad ring in the middle of nitric acid solution. The structure was optimized and refined by DFT. The results show that IEZ-FER (D4h) has a set of 14-member rings and a set of 12-member ring channels. The physical and chemical properties of IEZ-FER (D4h) were characterized by means of XRD, UV-Ramaru NMR-IRN _ 2 adsorption, and the pore size, hydrophobicity and hydrothermal stability of the materials were characterized by steam adsorption. In the third part, using 1 Ding Ji-3-methyl imidazole salt as template, two silicon-germanium molecular sieve nanocrystals ECNU-9 with cell thickness were synthesized, which not only have high specific surface area, but also contain multilevel pore channels. The molecular sieve nanochip ECNU-9 has regular shape and good dispersibility. ECNU-9 has a set of 10-member ring and a set of 12-member ring along the c-axis direction. On the basis of the crystallization of ECNU-9, the mechanism of bending limiting crystallization under the action of spherical micelles is proposed for the first time. The addition of inorganic salts with water cooperation results in the aggregation of ionic liquids to form positively charged micelles on the surface, while SiO44- and GeO44- are negatively charged. Due to charge balance, SiO44- and GeO444- are attracted to the micelle surface and crystallized in situ along the micellar surface. When the thickness of the curved crystal reaches a certain value, the tension on the outer surface limits the further growth of the crystal. In the fourth part, the structure changes of IM-20 molecular sieve after treatment under different acidic conditions were investigated. The structure of SiGe molecular sieve IM-20 is UWY, and its skeleton contains two kinds of double quaternary rings. In this paper, the first selective removal of double quaternary rings is made by using the ADoR mechanism. At room temperature and in strong acidic aqueous solution, two kinds of double quaternary ring structures can be obtained for IM-20 acid pickling, which can be described as ECNU-12. However, at 333K, strong acid ethanol solution, only a class of double quaternary ring destructions can be obtained, which can be described as ECNU-13. The two structures were optimized by DFT, and the XRD spectra close to the experimental values were obtained by using the optimized structure.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB383.1
【參考文獻(xiàn)】
相關(guān)期刊論文 前1條
1 王一川;常見(jiàn)的分子篩──沸石的妙用[J];化學(xué)世界;1995年05期
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