介孔磷酸铝分子筛的研究进展

从合成方法、特性和应用三个方面综述了介孔磷酸铝分子筛(AlPO4)的国内外研究进展,分析了水热或溶剂热在合成介孔AlPO4分子筛工艺上的特点,介绍了介孔AlPO4分子筛的结构组成和在化工领域中的一些应用。     

磷酸铝介孔分子筛的合成

选用了不同类型的表面活性剂作为模板剂合成磷酸铝介孔分子筛,实验结果表明,脂肪胺模板剂的浓度不会影响分子筛介孔相构型,介孔分子筛的孔径随烷基胺的链长增加而增大,其比表面积均达到了200 m2/g以上.类型相同的表面活性剂作模板剂时,分子筛的孔径和比表面积并不随其浓度增加而增加.所合成的磷酸铝分子筛TG和DTA曲线表明,磷酸铝分子筛在850 ℃以前具有一定的热稳定性.     

合成条件对SBA-15介孔分子筛晶体结构及水热稳定性影响

以X射线衍射(XRD)为表征手段,研究了SBA-15介孔分子筛合成过程中酸类型、加料顺序和搅拌时间对介孔分子筛晶体结构的影响,结果表明:不同酸合成的SBA-15介孔分子筛的结晶度顺序为高氯酸盐酸硫酸氢氟酸。同时研究了焙烧法和溶剂萃取法去除模板剂对SBA-15介孔分子筛水热稳定性的影响,结果表明:焙烧法去除模板剂后得到的分子筛的水热稳定性更高。     

模板剂对原位水热合成等级孔ZSM-5分子筛的影响

以正丁胺为模板剂制备硅铝摩尔比为40的ZSM-5分子筛,分别使用不同的介孔模板剂合成了等级孔ZSM-5分子筛,并采用XRD、NH_3-TPD、BET等对合成的分子筛进行表征。结果表明,采用不同介孔模板剂均可合成等级孔ZSM-5分子筛,其中以CTAB及P123为介孔模板剂合成的等级孔分子筛,介孔结构明显且保留了完整的微孔结构,微孔比表面在200 m²/g以上,介孔比表面均达到了100 m2/g以上,介孔比表面均达到了100 m²/g,且孔径分布较广。为等级孔分子筛的进一步研究提供了基础数据支持。     

AlPO_4-5负载溴化铝催化酮的Baeyer-Villiger氧化反应

以异丙醇铝为铝源,正磷酸为磷源,三乙胺作模板剂,采用水热反应合成了AlPO4-5分子筛。应用不同浓度氢溴酸对AlPO4-5分子筛进行化学剪裁,制备AlPO4-5-AlBr3催化剂。FESEM、XRD、N2吸附-脱附等表征结果表明,合成的AlPO4-5是规整的微孔六方棱柱,化学剪裁制备的担载型催化剂AlPO4-5-AlBr3依然保持规整的六方棱柱。催化氧化实验表明,质量分数30%双氧水作为氧化剂,在乙酸乙酯溶剂中,催化剂AlPO4-5-AlBr3对部分环酮具有较好的催化活性。     

新型多级孔ZSM-5沸石分子筛制备与研究

本研究通过在传统ZSM-5沸石分子筛的基础上引入有机硅烷季铵盐作为介孔导向模板剂制备了四种新型多级孔ZSM-5沸石分子筛。利用XRD、N2吸附脱附、SEM、TEM进行结构表征,结果表明以十四烷基双氨基甲酸酯基有机硅烷季铵盐作为介孔模板剂,所制得的ZSM-5-L2新型多孔级分子筛表面结晶度较好,SEM图为椭圆形颗粒,晶体表面密集粗糙,具有有序的介孔孔道,介孔孔道占总孔容的比例相对于其他样品更大,且介孔孔道约为4.0 nm左右,满足企业对材料改性及提升性能的需求。     

介孔分子筛合成中模板剂的研究与应用

对介孔分子筛催化剂中的模板剂的研究进展进行了综述,重点介绍了模板剂的发展过程、分类以及模板剂在介孔分子筛合成中的机理。     

原位合成W-MSU-2介孔分子筛

以壬基酚聚氧乙烯醚作为模板剂,在中性条件下原位合成了W-MSU-2介孔分子筛.采用X射线衍射、原位红外光谱、低温N2吸附对样品进行了表征.结果表明,W原子较好地分散于分子筛表面,W-MSU-2介孔分子筛的孔径为3.7 nm,加入W后仍保持介孔结构.     

以聚乙二醇/十六烷基三甲基溴化铵为模板剂制备MCM-41分子筛

通过将聚乙二醇(PEG)直接引入MCM-41分子筛合成模板剂十六烷基三甲基溴化铵溶液中,经脱洗和焙烧处理得到厚孔壁有序介孔材料.选用X射线衍射(xRD)、透射电子显微镜(TEM)和等温吸附(BET)对样品进行了表征,结果显示,添加PEG的合成产物孔壁厚度增加,孔壁厚度可达1.45 nm,孔径尺寸和比表面积减小,有序性降低,低相对分子质量PEG的添加有助于厚孔壁产物生成.     

晶化过程中无机盐及pH值调节对介孔分子筛水热稳定性的影响

以十六烷基三甲基溴化铵为模板剂,正硅酸乙酯为硅源,在碱性条件下合成了介孔分子筛MCM-41.借助XRD,SEM等检测手段考察了晶化过程中加入无机盐对介孔材料稳定性的影响.实验结果表明:加入NaF的样品其XRD衍射峰较强,表现出较好的结构有序性;在最初凝胶晶化24h后引入(NH4)2SO4,同样可获得有序的介孔结构;晶化过程中降低体系pH值能使硅酸盐的聚合度增大,孔壁厚度增加.由于所得产物具有完整的介孔结构,很好的结晶度及较大的孔壁厚度,因而在一定程度上提高了介孔分子筛的水热稳定性.     

Hydrophilic microporous PES membranes prepared by PES/PEG/DMAc casting solutions

Microporous poly(ether sulfones) (PES) membranes were prepared via phase inversion using poly (ethylene glycol) (PEG) as additive and N,N‐dimethylacetamide (DMAc) as solvent. Thermodynamic of the casting solutions was studied by coagulation value while precipitation rate was observed by light transmittance measurement. It was found that casting solution with PEG200 as additive was thermodynamically less stable than those with PEG400 and PEG600 as additive and easier to cause phase separation in exposure time. With the increase of PEG200 concentration, the casting solution became thermodynamically less stable and easier to cause phase separation in exposure time, but precipitation rate during immersion precipitation decreased because of the increased viscosities. ATR‐FTIR spectra and TGA curves showed that the membranes prepared using PEG200 as additive had less PEG residual than those of PEG400 and PEG600, but it showed better permeation performance than that prepared using PEG400 and PEG600 as additive. With the increase of PEG200 concentration from 30 to 70 wt %, the cross section structure changed from macrovoid to sponge‐like, micropores with a mean pore size around 0.1 μm began to form on the top surface. When the PEG200 concentration is 60 wt %, the pure water flux was 1845 L m^?2 h^?1 bar^?1, which is the highest value. As the PEG200 concentration increased from 30 to 60 wt %, the contact angles decreased from 82.1° to 58.2°. As the addition amount of PEG200 increased, the residual PEG made the prepared membranes more hydrophilic. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Characterization of cellulose triacetate membranes, produced from sugarcane bagasse, using PEG 600 as additive

Cellulose Acetate (CA) produced from sugarcane bagasse cellulose was used to produce membranes, using poly(ethylene glycol) (PEG 600) as additive. Results showed that PEG 600 was washed out the membranes during the preparation step. Thermal Analysis showed that the temperature of degradation of the membranes increased in 10 °C when PEG 600 was added to the composition, but did not change as more PEG 600 was added in the composition. On the other hand, the crystalline content (%C) of the membranes increased as PEG 600 was added. The addition of PEG 600 also increased the resistance of the membranes to pressure and the pure water flux rate, but membranes produced with PEG 600 content lower than 5% did not present water flux. PEG 600 also increased the coefficient of ion diffusion of the membranes.     

添加剂聚乙二醇对堇青石蜂窝陶瓷载体γ-Al_2O_3涂层性能的影响

以拟薄水铝石为原料,硝酸为胶溶剂,添加聚乙二醇(PEG)制备铝溶胶,并对堇青石蜂窝陶瓷载体进行γ-Al2O3涂层。考察了不同分子量(400,6000和20000)聚乙二醇的添加对溶胶黏度,粒径分布以及涂覆涂层负载量和重现性的影响;利用BET法测定了溶胶中添加不同分子量的聚乙二醇后,涂层比表面积的变化;超声波振荡检测了堇青石蜂窝陶瓷载体涂层的结合牢固性;由SEM照片观察涂层的表面形貌。结果表明,聚乙二醇的添加,增大了溶胶的黏度,提高了载体涂层的负载量、比表面积和结合牢固度。添加剂聚乙二醇分子量的不同对溶胶和载体涂层性能的影响也不同,聚乙二醇20000的添加使溶胶黏度和涂层负载量的增加程度更明显,而添加聚乙二醇400制备溶胶的粒径小,分布范围窄,涂覆涂层均匀、牢固且比表面积大。     

Effect of polyethylene glycol on phase and morphology of calcium carbonate

Calcium carbonate (CaCO₃) with different phases and morphologies were prepared and characterized by scanning electron microscopy (SEM), powder X‐ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. The effect of polyethylene glycol (PEG) with different molecular weight and concentrations on the phase and morphology of CaCO₃ was studied. The results showed that aragonite was the only phase in the solution without PEG, while calcite phase could be obtained by the use of PEG as the additive. The possible crystallization mechanism for the formation of CaCO₃ polymorphs in the presence of different PEG was also discussed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and properties of soluble polypyrrole doped with dodecylbenzenesulfonate and combined with polymeric additive poly(ethylene glycol)

Soluble polypyrrole (PPy) samples advanced in electrical conductivity σ were chemically synthesized with dodecylbenzenesulfonate (DBS) sodium salt as a dopant, with poly(ethylene glycol) (PEG) as an additive, and with ammonium persulfate as an oxidant. The PPy–DBS–PEG samples were soluble in organic solvents (N‐methylpyrrolinone and m‐cresol). The greater the molar percentage ratio was of DBS, the greater the solubility was of synthesized PPy composites (PPy–DBS–PEG). The maximum electrical conductivity at room temperature for PPy–DBS–PEG was 1.02 S/cm, which was in fact the true conductivity of 100/10 (mol %) PPy/DBS. The chemical composition and doping level of PPy–DBS–PEG were determined by elemental analysis. The results of Fourier transform infrared spectroscopy were used for the structural characterization of PPy–DBS–PEG. The scanning electron microscopy results showed that the electrical conductivity was related to the morphology of PPy–DBS–PEG. According to thermogravimetric analysis, PPy–DBS–PEG was more thermostable than PPy–DBS. Electron spin resonance measurements showed that the polaron and bipolaron acted as charge carriers of PPy–DBS–PEG. According to the temperature dependence of the electrical conductivity, PPy–DBS–PEG was a semiconductor and followed the three‐dimensional variable‐range hopping model. The improved electrical conductivity apparently resulted from the reduction of the crosslinking and structural defects of the PPy chains. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1170–1175, 2005     

表面活性剂对铝酸钠溶液中一水软铝石晶种分解的影响

研究了非离子及阴离子型表面活性剂(聚乙二醇、聚氧乙烯月桂醚和十二烷基苯磺酸钠)对铝酸钠溶液晶种分解制备一水软铝石的影响. 结果表明,十二烷基苯磺酸钠抑制溶液分解及晶体附聚,导致产物粒度细化;聚乙二醇可强化溶液分解,并促进晶体附聚;PEG1000添加量为1 g/L时获得最高分解率(32.39%),较空白提高8.37%;PEG1000添加量为5 g/L时附聚效果最好,产物的中位粒径为23.86 mm,较空白提高4.5%. XRD和热重分析结果表明,添加剂未改变产物晶型,产物均为一水软铝石和三水铝石.     

Effect of surfactant on structure and performance of catalysts for DME synthesis in slurry bed

The Cu-Zn-Al slurry catalysts prepared via modified sol-emulsion-gel method by adding different water-soluble surfactants were studied for CO hydrogenation to produce dimethyl ether (DME) in slurry bed reactor. The results indicated that the catalyst adding Tween80 or PEG600 had higher activity than the catalyst with the PVP additive. All the catalysts had good stability. X-ray diffraction (XRD) results showed that Cu and Cu₂O existed in the pre-reduced Cu-Zn-Al catalysts, while ZnO did not appear. Nitrogen adsorption studies showed that the catalyst prepared with the additives of PEG600 or Tween80 was mesoporous structure with higher specific surface area compared with the one prepared with the additive of PVP. X-ray photoelectron spectroscopy (XPS) results indicated that the Cu/Zn ratio on the surface of all catalysts increased after subject to reduction and reaction. The morphology and size of the catalyst particles could be adjusted by adding water-soluble surfactants.     

Effect of PEG additives on properties and morphologies of membranes prepared from poly(2,6‐dimethyl‐1,4‐phenylene oxide) by benzyl bromination and in situ amination

This study investigated the effect of PEG additive on the structure formation and permeation properties of membranes. The membranes were prepared from a bromomethylated poly(2,6‐dimethyl‐1,4‐phenylene oxide)/chlorobenzene/ethanol system using the phase inversion method with PEG as an additive. As expected, PEG with a fixed molecular weight (e.g., PEG 600) acted as a pore‐forming agent, and membrane porosity increased as the PEG content of the casting solution increased. However, when the PEG content was fixed, the effect of PEG on the membrane properties and morphology was largely dependent on its molecular weight. It was found that when the molecular weight of PEG was less than 800, it acted as a pore former, but when the molecular weight of PEG was more than 1000, the pore size and porosity of the resulting membrane decreased. These results can be explained by the membrane‐forming system's thermodynamic and kinetic properties, which can be assessed by coagulation value and viscosity. Furthermore, the membranes were characterized for pure water flux and rejection of solute and by SEM observation. The filtration results agreed well with the SEM observations. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2414–2421, 2005     

杂原子磷铝分子筛BSiAPO-5的合成结构及催化性能的研究

用水热合成法合成了一种硼-硅磷铝分子筛,通过化学分析、测定晶胞参数及用XRD,MAS—NMR方法进行表征,证实了硼、硅原子进入了分子筛骨架,并且具有和AIPO4-5相似的结构;用IR,NH3-TPD表征方法测出了它的酸性,测定结果表明,它具有L酸和B酸中心,以中等强度酸为主。在苯与烯烃烷基化反应中表现出良好的催化活性和长寿命,并且对2-LAB和3-LAB具有高选择性,有可能替代HF成为一种环境友好的新型催化剂。