基于离子液体微介孔材料的制备及其性能研究

发布时间：2018-09-01 12:06

【摘要】：介孔材料是孔径大小在2～50 nm范围内的孔道结构材料,具有规则的介孔孔道、高的比表面积,大的孔容及可调变的组成等特点,能为较大分子的烷基化、异构化等催化反应提供较理想的反应场所。但是,材料中的介孔孔道由无定型孔壁构筑而成,存在着水热稳定性较低及不活泼等弱点,极大影响了其在催化领域的应用。微孔材料的水热稳定性虽然较高,但其较小的孔径,限制了大分子的反应进入材料内部,降低了催化反应活性。相比较而言,微介孔材料具有微孔和介孔双模型的孔分布,并兼有介孔材料大孔径、高比表面积以及微孔材料的酸性位和高稳定性等优点。因此在吸附分离和催化领域有着广阔的应用前景。同时,纯硅的微介孔材料由于缺少相应的杂原子活性组分,不利于后续催化反应的进行。锆的掺杂,不仅可以在硅材料表面或结构内部嵌入杂原子,并且可进一步调控材料的酸性及孔道结构,有助于增强催化反应的活性与稳定性。二芳基乙烷(PXE)是压敏复写纸显色剂的优良溶剂,主要通过邻二甲苯和苯乙烯的烷基化反应获得。本论文以离子液体和表面活性剂为双模板,以正硅酸四乙烷(TEOS)为硅源、五水硝酸锆为锆源,一步水热法制备了微介孔硅锆材料,将所制备的硅锆材料酸化制备酸性催化剂,并以邻二甲苯和苯乙烯合成PXE的烷基化反应为探针反应来考察催化剂的催化活性。以离子液体醋酸三正丁胺(CH3CH2CH2CH2)3NH+Ac-为微孔模板剂引入微孔结构,聚环氧乙烷-聚环氧丙烷-聚环氧乙烷三嵌段共聚物(P123)为介孔模板剂引入介孔结构,以TEOS为硅源、Zr(N03)4·5H20为锆源,水热法制备了具有微介孔结构的硅锆材料NTA-X-Y,考察了离子液体占混合模板剂质量的百分比(X)、pH(Y)对NTA-X-Y结构的影响。研究表明:NTA-X-Y具有微孔和介孔双重孔道结构,其孔径分别为4.0 nm和7.3 nm,并且这两种孔道分别是由离子液体胶束和P123胶束做模板形成的。当离子液体加入量较低时,微介孔材料结构的有序性提高;随着离子液体加入量的增加,其有序结构遭到破坏。在烷基化反应中,将所制备的材料酸化后得到的催化剂NTA-30-2-SO42-的催化性能较好,PXE产率大于80%,这可能与NTA-30-2的微孔结构有关。以质子型离子液体醋酸三正丁胺(CH3CH2CH2CH2)3NH+Ac-为微孔模板剂、P123为介孔模板剂的双模板体系,TEOS为硅源、Zr(NO3)4·5H20为锆源,—步水热法制备了微介孔硅锆材料,考察了 Si/Zr和焙烧温度对所制备的材料结构的影响。研究表明:当Si/Zr为10时,所制备的微介孔材料SZ-10不仅能够保持有序的孔道结构,而且具有较大的比表面积,其比表面积为613 cm2·1g-1。将所制备的微介孔材料SZ-10经过700℃高温焙烧,所得的材料仍具有规则的孔道结构并且酸性增强,在烷基化反应中,表现出较高的催化活性,PXE的产率可达87.8%,这可能是因为所制备材料独特的微介孔结构。以表面活性剂CTAB和质子型离子液体做混合模板剂,TEOS为硅源,一步法水热制备了放射状多孔硅材料。考察了质子型离子液体与CTAB质量比对放射状硅材料结构、形貌及其他性能的影响。研究表明:当质子型离子液体加入量较少时,随着离子液体加入量的增加,其孔道变小并且有序性下降。在烷基化反应中,以放射状硅材料PIL-X为载体负载HPW制备的催化剂HPW/PIL-X与SBA-15为载体负载HPW得到的催化剂HPW/SBA-15相比,HPW/PIL-X的催化性能较好。综上所述,以质子型离子液体和表面活性剂为双模板制备的微介孔硅锆材料具有较高的比表面积、较大的孔体积、和独特的孔道结构,这些优点使得微介孔硅材料能够作为催化剂载体应用到烷基化反应中。
[Abstract]:Mesoporous materials are porous materials with pore sizes ranging from 2 nm to 50 nm. They have regular mesoporous channels, high specific surface area, large pore volume and adjustable composition. They can provide ideal reaction sites for catalytic reactions such as alkylation and isomerization of larger molecules. However, mesoporous channels in materials are composed of amorphous pore walls. The hydrothermal stability of microporous materials is high, but their small pore size limits the reaction of macromolecule into the material and reduces the catalytic activity. Comparatively speaking, microporous materials have microporous and mesoporous double. The pore distribution of the model has the advantages of large pore size, high specific surface area, acidic sites and high stability of mesoporous materials, so it has a broad application prospect in the field of adsorption separation and catalysis. PXE is an excellent solvent for pressure sensitive carbon paper developer, which is mainly obtained by alkylation of o-xylene and styrene. In this paper, mesoporous silica-zirconium materials were prepared by one-step hydrothermal method using ionic liquids and surfactants as double templates, tetraethyl orthosilicate (TEOS) as silicon source and zirconium nitrate pentahydrate as zirconium source. The acidic catalysts were prepared by acidizing the prepared silica-zirconium materials, and the alkylation reaction of o-xylene and styrene to synthesize PXE was investigated as probe reaction. Catalytic activity of the catalyst. The mesoporous structure was prepared by hydrothermal method using ionic liquid tri-n-butylamine acetate (CH_3CH_2CH_2CH_2) _3NH + Ac - as microporous template, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) as mesoporous template, TEOS as silicon source, Zr (N03) 4.5H20 as zirconium source. The effects of ionic liquids (X) and pH (Y) on the structure of NTA-X-Y were investigated. The results show that NTA-X-Y has a dual pore structure of micropore and mesoporous, and the pore sizes are 4.0 nm and 7.3 nm, respectively. The two pore sizes are formed by ionic liquid micelles and P23 micelles. In alkylation reaction, the catalyst NTA-30-2-SO42-obtained by acidifying the prepared materials has better catalytic performance, and the yield of PXE is more than 80%, which may be related to the microporous structure of NTA-30-2. Microporous silicon-zirconium materials were prepared by one-step hydrothermal method using proton-type ionic liquid tri-n-butylamine acetate (CH_3CH_2CH_2) _3NH+Ac-as microporous template, P123 as mesoporous template, TEOS as silicon source, Zr (NO_3) _4.5H20 as zirconium source. The effects of Si/Zr and calcination temperature on the structure of the materials were investigated. When the ratio of SZ-10 to Zr is 10, the prepared microporous material SZ-10 can not only keep the ordered pore structure, but also have a large specific surface area. The specific surface area of SZ-10 is 613 cm 2.1 g-1. The prepared microporous material SZ-10 still has regular pore structure and enhanced acidity after calcination at 700 C. With high catalytic activity, the yield of PXE can reach 87.8%. This may be due to the unique micro-mesoporous structure of the materials. Radial porous silicon materials were prepared by one-step hydrothermal method using CTAB and proton ionic liquids as mixed templates and TEOS as silicon source. The results show that the pore size decreases and the ordering decreases with the increase of the amount of proton ionic liquids. In the alkylation reaction, the HPW / PIL-X and SBA-15 supported catalysts prepared by HPW supported on the radioactive silicon PIL-X were prepared. In summary, the mesoporous silica-zirconium materials prepared by proton ionic liquids and surfactants as double templates have higher specific surface area, larger pore volume and unique pore structure. These advantages make the mesoporous silica materials can be used as catalyst support. It is used in alkylation reaction.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.4;O643.36

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