具有Pm3n對稱結(jié)構(gòu)的超微孔氧化硅和硅鋁材料的合成及其催化性能研究
發(fā)布時間：2018-09-14 17:55
【摘要】：超微孔材料(孔徑大小為1-2 nnm)有望同時解決沸石分子篩孔道內(nèi)擴(kuò)散受限和引入介孔后擇形性消失或減弱的問題�，F(xiàn)有報道的超微孔材料絕大多數(shù)具有p6mm或者無序的結(jié)構(gòu),但三維結(jié)構(gòu)(如Pm3n結(jié)構(gòu))的孔道內(nèi)的擴(kuò)散限制更小。Pm3n結(jié)構(gòu)的孔道由籠狀孔和連接“窗口”構(gòu)成,這種特殊的結(jié)構(gòu)有利于擇形催化的發(fā)生。傳統(tǒng)合成Pm3n結(jié)構(gòu)氧化硅使用不可從市售獲取的十六烷基三乙基溴化銨模板劑在強(qiáng)酸性條件下進(jìn)行。本論文中使用短鏈模板劑合成Pm3n結(jié)構(gòu)的氧化硅和硅鋁材料,目的在于：1)得到孔徑更小的(超微孔)材料；2)逐步解決模板劑不可從市售獲取的問題；3)避免使用強(qiáng)酸,合成條件更綠色、環(huán)保,原料中鋁源的利用率更高,主要包括以下結(jié)果：1、使用十二烷基三乙基溴化銨(DTEAB)模板劑合成得到了Pm3n結(jié)構(gòu)的超微孔氧化硅和硅鋁材料。當(dāng)合成在弱堿性進(jìn)行時,SO42-的Hofmeister salting-out陰離子效應(yīng)有助于減小表面活性劑的堆積參數(shù)(g)；當(dāng)合成在弱酸性條件下進(jìn)行時,有機(jī)固體羧酸的親疏水性決定了氧化硅的對稱結(jié)構(gòu),其中丙二酸、丁二酸親水性較好,可以有效降低表面活性劑的堆積參數(shù),因而容易得到Pm3n結(jié)構(gòu)氧化硅。超微孔硅鋁材料在環(huán)己酮與季戊四醇的縮酮反應(yīng)中表現(xiàn)出了高于分子篩催化劑的催化活性和較好的穩(wěn)定性。2、使用市售的十二烷基三甲基溴化銨(C12TMAB)模板劑合成得到了Pm3n結(jié)構(gòu)的超微孔氧化硅和硅鋁材料。合成中使用了氨水為堿源(弱堿性合成條件),但需要少量H2SO4水解TEOS,并且利用SO42-的Hofineister salting-out陰離子效應(yīng)使表面活性劑g參數(shù)減小以得到Pm3n結(jié)構(gòu)的氧化硅。超微孔硅鋁材料在環(huán)己酮與季戊四醇的縮酮反應(yīng)中表現(xiàn)出了高活性和很好的穩(wěn)定性；在鄰苯二酚與叔丁醇的氣相烷基化反應(yīng)中具有最高的催化活性和目標(biāo)產(chǎn)物4-叔丁基鄰苯二酚(4-TBC)產(chǎn)率。3、為了進(jìn)一步縮小材料的孔徑,使用碳鏈更短的癸基三甲基溴化銨(C10TMAB)模板劑合成得到了Pm3n結(jié)構(gòu)的超微孔氧化硅和硅鋁材料。合成中使用了氨水為堿源(弱堿性合成條件),表面活性劑本身堆積參數(shù)較小,SO42-和NH4+的Hofmeister salting-out離子效應(yīng)也促進(jìn)了Pm3n結(jié)構(gòu)的生成。在甲縮醛和三聚甲醛縮合制聚甲醛二甲醚(PODEW)的反應(yīng)中,Pm3n結(jié)構(gòu)的超微孔硅鋁材料表現(xiàn)出了高催化活性和最高的目標(biāo)產(chǎn)物PODE3-8的選擇性,體現(xiàn)出了超微孔材料孔道內(nèi)獨(dú)特的擇形催化。4、除了控制氧化硅的孔徑之外,在合成體系中加入羧甲基纖維素鈉(CMC)作分散劑還可以控制氧化硅的形貌、顆粒尺寸和粒徑分布。在優(yōu)化的條件下,可以合成得到Pm3n結(jié)構(gòu)的單分散氧化硅納米顆粒,氧化硅的初級孔尺寸在超微孔價孔的邊界上,納米顆粒尺寸小于100 nm,氧化硅的總孔容在1cm3·g-1以上。
[Abstract]:Ultrafine porous materials (pore size is 1-2 nnm) are expected to solve the problem of confined diffusion in zeolite channels and the disappearance or weakening of shape selectivity after introducing mesoporous materials. The traditional synthesis of Pm3n-structured silica is carried out using cetyltriethylammonium bromide templates which are not available for commercial use under strong acidic conditions. In this paper, short-chain templates were used to synthesize Pm3n-structured silica and silica-aluminium materials. The purpose is: 1) to obtain smaller pore size (ultra-micro porous) materials; 2) to gradually solve the template can not be obtained from the market; 3) to avoid the use of strong acid, synthesis conditions are greener, environmental protection, the utilization of aluminum sources in raw materials is higher, mainly including the following results: 1, the use of dodecyl triethyl ammonium bromide (DTEAB) template synthesis of Pm3n The anionic effect of SO42-Homeister salting-out helps to reduce the stacking parameters (g) of surfactants when synthesis proceeds in weak alkalinity; the hydrophobicity of organic solid carboxylic acids determines the symmetrical structure of silicon oxide, in which malonic acid, succinic acid Pm3n-structured silica is easily obtained because of its good hydrophilicity and can effectively reduce the stacking parameters of surfactants. Ultrafine porous silica-aluminium materials exhibit higher catalytic activity and better stability than zeolite catalysts in the ketal reaction of cyclohexanone with pentaerythritol. 2. The commercially available dodecyl trimethyl ammonium bromide (C12TMA) is used. Ultrafine porous silica and silica-aluminium materials with Pm_3n structure were synthesized by template synthesis. Ammonia water was used as alkaline source (weak alkaline synthesis condition), but a small amount of H2SO4 was needed to hydrolyze TEOS. The surfactant g parameters were reduced by using the anionic effect of SO42-Hoofineister salting-out to obtain Pm_3n-structured silica. The material exhibited high activity and good stability in the ketal reaction of cyclohexanone with pentaerythritol, and had the highest catalytic activity and yield of 4-tert-butyl catechol (4-TBC) in the vapor phase alkylation of catechol with tert-butanol. Ultrafine porous silica and silica-aluminium materials with Pm3n structure were synthesized by using C10TMAB as template. Ammonia water was used as alkaline source (weak alkaline synthesis condition). The surfactant accumulation parameters were small. The ionic effect of SO42 - and NH4 + on the formation of Pm3n structure was also promoted. The formation of Pm3n structure was also promoted by the ionic effect of Homeister salting-out. In the reaction of aldehyde condensation to polyoxymethylene ether (PODEW), Pm3n-structured ultra-micro-porous silica-aluminium materials exhibit high catalytic activity and the highest selectivity of the target product PODE3-8, reflecting the unique shape-selective catalysis in the pores of the ultra-micro-porous materials. 4. Besides controlling the pore size of silica, sodium carboxymethylcellulose (C-MC) was added into the synthesis system. MC) can also be used as dispersant to control the morphology, particle size and particle size distribution of silica. Under the optimized conditions, monodisperse silica nanoparticles with Pm3n structure can be synthesized. The primary pore size of silica is less than 100 nm at the boundary of the valence pore of the ultramicro-pore, and the total pore volume of silica is more than 1 cm 3.g-1.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：O643.36;TB383.4
本文編號：2243444
[Abstract]:Ultrafine porous materials (pore size is 1-2 nnm) are expected to solve the problem of confined diffusion in zeolite channels and the disappearance or weakening of shape selectivity after introducing mesoporous materials. The traditional synthesis of Pm3n-structured silica is carried out using cetyltriethylammonium bromide templates which are not available for commercial use under strong acidic conditions. In this paper, short-chain templates were used to synthesize Pm3n-structured silica and silica-aluminium materials. The purpose is: 1) to obtain smaller pore size (ultra-micro porous) materials; 2) to gradually solve the template can not be obtained from the market; 3) to avoid the use of strong acid, synthesis conditions are greener, environmental protection, the utilization of aluminum sources in raw materials is higher, mainly including the following results: 1, the use of dodecyl triethyl ammonium bromide (DTEAB) template synthesis of Pm3n The anionic effect of SO42-Homeister salting-out helps to reduce the stacking parameters (g) of surfactants when synthesis proceeds in weak alkalinity; the hydrophobicity of organic solid carboxylic acids determines the symmetrical structure of silicon oxide, in which malonic acid, succinic acid Pm3n-structured silica is easily obtained because of its good hydrophilicity and can effectively reduce the stacking parameters of surfactants. Ultrafine porous silica-aluminium materials exhibit higher catalytic activity and better stability than zeolite catalysts in the ketal reaction of cyclohexanone with pentaerythritol. 2. The commercially available dodecyl trimethyl ammonium bromide (C12TMA) is used. Ultrafine porous silica and silica-aluminium materials with Pm_3n structure were synthesized by template synthesis. Ammonia water was used as alkaline source (weak alkaline synthesis condition), but a small amount of H2SO4 was needed to hydrolyze TEOS. The surfactant g parameters were reduced by using the anionic effect of SO42-Hoofineister salting-out to obtain Pm_3n-structured silica. The material exhibited high activity and good stability in the ketal reaction of cyclohexanone with pentaerythritol, and had the highest catalytic activity and yield of 4-tert-butyl catechol (4-TBC) in the vapor phase alkylation of catechol with tert-butanol. Ultrafine porous silica and silica-aluminium materials with Pm3n structure were synthesized by using C10TMAB as template. Ammonia water was used as alkaline source (weak alkaline synthesis condition). The surfactant accumulation parameters were small. The ionic effect of SO42 - and NH4 + on the formation of Pm3n structure was also promoted. The formation of Pm3n structure was also promoted by the ionic effect of Homeister salting-out. In the reaction of aldehyde condensation to polyoxymethylene ether (PODEW), Pm3n-structured ultra-micro-porous silica-aluminium materials exhibit high catalytic activity and the highest selectivity of the target product PODE3-8, reflecting the unique shape-selective catalysis in the pores of the ultra-micro-porous materials. 4. Besides controlling the pore size of silica, sodium carboxymethylcellulose (C-MC) was added into the synthesis system. MC) can also be used as dispersant to control the morphology, particle size and particle size distribution of silica. Under the optimized conditions, monodisperse silica nanoparticles with Pm3n structure can be synthesized. The primary pore size of silica is less than 100 nm at the boundary of the valence pore of the ultramicro-pore, and the total pore volume of silica is more than 1 cm 3.g-1.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：O643.36;TB383.4
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