N,N-二甲基甲酰胺对介孔二氧化硅空心球结构参数和形貌的影响

采用聚酚醛树脂球(RF)为硬模板,十六烷基三甲基溴化铵(CTAB)作为软模板,考察不同N,N-二甲基甲酰胺(DMF)含量以及晶化温度对介孔二氧化硅空心球(H-BMMs)合成的影响。采用XRD、TEM、低温N2吸附-脱附和FTIR分析产物的结构、形貌、孔道织构参数和骨架结构,并采用高效液相色谱(HPLC)法考察了H-BMMs装载布洛芬(IBU)的性能。研究表明,制备的H-BMMs具有较高的比面积(1 100 m2/g),并且壁上有孔径大小均匀的蠕虫状短孔道(2.3 nm)。随着DMF含量的增加,H-BMMs的介孔孔道逐渐减小,并且过高的晶化温度会破坏HBMMs的介孔结构。载药动力学研究发现,H-BMMs有较高的载药率(32%)。     

HCl用量对介孔二氧化硅形貌的影响

以十六烷基三甲基溴化铵为模板剂、甲酰胺为共溶剂、正硅酸乙酯为硅源,室温下在HCl介质中合成了纤维状、圆盘状和花卉状等多种混合形貌的介孔二氧化硅.采用XRD、SEM、TEM等方法对样品进行表征,探讨了HCl用量对产物形貌的影响.结果表明,增加HCl用量会导致孔间距减小,但有助于提高介孔结构有序性和纤维状形貌的产率;过低的HCl用量条件下介孔二氧化硅不能形成规则外形.     

N,N-二甲基甲酰胺的气相色谱分析

采用气相色谱法测定N,N-二甲基甲酰胺的含量.以无水乙醇为溶剂,以联苯为内标物,使用QF-1固定液涂渍在GAS CHRAME Q担体为填充物的玻璃柱和氢焰离子化检测器,对试样中的N,N-二甲基甲酰胺进行气相色谱分离和测定.结果表明,方法的标准偏差为0.35%,变异系数为0.41%,平均回收率为100.24%,线性相关系数为0.9996.     

含N,N-二甲基甲酰胺废水的处理方法研究

N,N-二甲基甲酰胺(DMF)作为一种性能优良的有机溶剂被广泛运用于农药医药等行业作为中间体及气体吸收剂,化工废水中含有大量DMF,具有毒性高、稳定性强、难生物降解等特点。近年来废水中的DMF问题已成为国内外研究的重点和难点,本文针对含DMF的化工废水处理方法进行了综述,主要从物理法、化学法以及生物法等工艺的研究概括及原理介绍,指出了含DMF废水的主要问题并提出了未来的发展方向。     

N,N-二甲基甲酰胺的合成方法

N,N-二甲基甲酰胺（DMF）作为一种重要的化工原料及溶剂,被人们广泛用于染料、医药、农药、电子等行业。本文综述了DMF的合成方法,特别是2000年后合成DMF的新技术、新方法,并对各种合成DMF的催化剂以及合成路线的优缺点进行了讨论。为以后进一步研究DMF合成的方法及催化剂的选择提供理论依据。     

N,N-二甲基甲酰胺的生产技术与市场分析

介绍了国内外N ,N -二甲基甲酰胺 (DMF)的生产技术及生产能力 ,对国内外DMF的供需情况进行了详尽分析     

低浓度N,N-二甲基甲酰胺废水的活性炭吸附及再生研究

采用椰壳活性炭对低浓度的N,N-二甲基甲酰胺(DMF)废水进行吸附处理,研究了活性炭吸附等温线及活性炭动态吸附对DMF废水的处理效果,并采用热空气对吸附饱和的活性炭进行再生。实验结果表明,0.850~0.425mm的椰壳活性炭对低浓度DMF废水有很好的吸附性能,在动态吸附中,0.850~0.425mm活性炭对DMF的饱和吸附容量为45mg/L。经动态吸附后,废水中的DMF基本得到去除,达到国家一级排放标准。热空气对吸附饱和的活性炭有较好的再生效能,再生率达到90%以上。     

以N,N-二甲基甲酰胺为溶剂萃取精馏制备高纯度甲缩醛

通过溶剂选择原理粗选出萃取精馏制备甲缩醛产品的溶剂,既而通过Chemcad软件模拟和汽液平衡实验确定合适的溶剂及溶剂比。结果表明,N,N-二甲基甲酰胺(DMF)能够消除甲缩醛-甲醇共沸物系的共沸点;采用UNIQUAC模型对常压下甲缩醛-甲醇物系和加入溶剂N,N-二甲基甲酰胺的汽液平衡进行模拟,模拟结果和实验数据吻合较好...     

不同形貌介孔二氧化硅的可控制备与表征

介孔材料由于具有比表面积和孔体积较大、孔径均一、纳米尺寸可调、二氧化硅无生理毒性、热稳定性较好等一系列特点而引起了人们广泛的兴趣和关注．控制介孔二氧化硅的形貌和尺寸可以拓展介孔二氧化硅的应用，尤其是开发介孔二氧化硅在生物医学、     

晶化温度对介孔材料SBA-15结构与形貌的影响

以P123嵌段共聚物表面活性剂为模板剂,在不同晶化温度下合成了不同孔径和比表面积的六方相介孔氧化硅SBA-15,通过XRD, SEM, N2吸附-脱附及TEM等手段系统考察了不同晶化温度对SBA-15晶胞参数、比表面积、孔径及形貌的影响,得到反应最佳晶化温度为120℃. 随着晶化温度的升高,SBA-15的孔径增大,比表面积下降,团聚体颗粒打开形成散落短棒状. 同时还对温度影响SBA-15结构和形貌的机理进行了探讨.     

A cationic surfactant assisted selective etching strategy to hollow mesoporous silica spheres

Hollow mesoporous silica spheres have recently attracted increasing attention. However, effective synthesis of uniform hollow mesoporous spheres with controllable well-defined pore structures for fundamental research and practical applications has remained a significant challenge. In this work, a straightforward and effective "cationic surfactant assisted selective etching" synthetic strategy was developed for the preparation of high-quality hollow mesoporous silica spheres with either wormhole-like or oriented mesoporous shell. The as-prepared hollow mesoporous silica spheres have large surface area, high pore volume, and controllable structure parameters. Our experiments demonstrated that cationic surfactant plays critical roles in forming the hollow mesoporous structure. A formation mechanism involving the etching of solid SiO(2) accelerated by cationic surfactant followed by the redeposition of dissolved silica species directed by cationic surfactant is proposed. Furthermore, the strategy can be extended as a general strategy to transform silica-coated composite materials into yolk-shell structures with either wormhole-like or oriented mesoporous shell.     

手性钨酸离子液体空心介孔硅球用于苯乙烯双羟化反应

以1,12-二溴十二烷、S-烟碱和钨酸钠为原料制备手性钨酸离子液体，硅酸钠为硅源，经一步水热法制得功能化的空心介孔硅球。用SEM、TEM、FTIR、UV-Vis、N2吸附-脱附、XPS、ICP-OES、水接触角和圆二色谱(ECD)等对其结构进行表征，并考察其对于苯乙烯双羟化反应的催化性能。结果表明，空心介孔硅球的直径约为100 nm，比表面积为20 ~ 53 m2/g，平均孔径为7.7 ~ 16 nm；手性钨酸离子液体成功嵌入到介孔空心硅球，固体具有圆二色性，可用于苯乙烯双羟化反应，使n(W)∶n(Si)=0.25∶0.75时制得的催化剂催化性能最好、(R)-苯基乙二醇产率达89.6%，循环使用5次后产率仍可达87%；比较未含钨酸离子液体的样品为无定形纳米颗粒，因此推测钨酸基手性离子液体对介孔空心硅球形成具有导向作用。     

Silica foams with ultra-large specific surface area structured by hollow mesoporous silica spheres

Ceramic foams with multi-scale pores and large specific surface area have received extensive attention due to their unique structure and superior properties. Considering that there are still challenges to synthesize porous ceramics with large specific surface area, a novel ceramic foam material with ultra-large specific surface area has been prepared using hollow silica mesoporous spheres (HMSSs) as building block in this work. These building blocks were made weakly hydrophobic in order to produce HMSS particle stabilized foams. The foams exhibit a uniform primary macropore structure, which is composed of a three dimensional HMSS-assembled network, via HMSS-stabilized foams. The influence of sintering temperature on the microstructure and properties of HMSS foams is investigated. The HMSS foams exhibit highest specific surface area of 1733 m²/g, attributed to the radial mesopores in HMSS shell, when sintered at between 500°C and 800°C. This specific surface area is much higher than that of existing ceramic materials. The uniform pore structure and ultra-large specific surface area make it a promising lightweight material in potential application fields, including catalyst, adsorption, fire-resistant thermal insulation, and load and control release system.     

二氧化硅空心球的制备及研究

在乙醇/水的混合溶液中,采用聚乙烯吡咯烷酮（PVP）为分散剂,偶氮二异丁腈（AIBN）为引发剂,通过分散聚合法制备出聚苯乙烯（PS）微球。然后以微球为模板,PS粒子作为核,SiO_2作为壳,在600℃时经过热分解得到SiO_2空心球。通过热分析仪、扫描电子显微镜对制得的空心球进行了表征和分析,并讨论其影响因素。     

介孔中空二氧化硅及硅基微球制备研究进展

介孔中空材料有特定孔道结构,具有中空、密度小、比表面积大的特点,因而具有较好的渗透性、吸附性、筛分分子能力和光学性能,成为具有广泛应用前景的热点研究材料。详细地介绍了国内外新型功能材料介孔中空二氧化硅及硅基微球主要制备方法,包括表面沉积法、层层组装法、原子转移自由基聚合法、喷雾法、微乳液法。同时介绍了合成的介孔、中空二氧化硅和硅基微球的形貌特点及应用。指出不同方法、不同制备条件对材料的形貌、孔径大小、孔形状及材料晶形有很大影响,条件温和、步骤简单、环境友好的制备方法是发展趋势。     

The porosity and morphology of mesoporous silica agglomerates

The synthesis of mesoporous MCM-41 silica materials was investigated at various conditions. A series of ordered mesopores MCM-41 silica materials was synthesized in concentrated reaction mixtures. The influence of water concentration at the constant ratio of the remaining reagents on the morphology and structural parameters of MCM-41 was studied. Hexadecyltrimethylammonium bromide CTAB was used as a structure-directing agent. The pore size, the wall thickness and cylindrical pores array were characterized by powder X-ray diffraction and nitrogen adsorption. The presented results show that in concentrated reaction mixtures, the pore size and the thickness of the pore walls remain practically constant. However, the dimensions of silica particles depend strongly on the water concentration. A high regularity of pore structure for large MCM-41 particles synthesized in concentrated solution was supported by independent AFM technique.     

Synthesis of porous hollow silica spheres using functionalized polystyrene latex spheres as templates

Uniform sized and integrated hollow silica spheres with porous shells were prepared by using sulfuric and carboxylic acid-functionalized polystyrene latex spheres as templates, sodium silicate as a precursor, and cetyltrimethylammonium bromide as a shell structure-directing agent. When polystyrene-methyl acrylic acid latex spheres were used as the templates, the pores in the shells of the resultant hollow silica spheres were composed of both micropores and mesopores. The pores in the shells of the hollow silica spheres were mainly composed of mesopores when sulfonated polystyrene-methyl acrylic acid latex spheres were used as the templates. The shell thickness and the specific surface area of the hollow silica spheres increased with the increase in the surface acidity of the latex spheres.     

Synthesis of monodispersed mesoporous spheres of submicron size amorphous silica

A technique has been developed for synthesis of submicron monodispersed mesoporous spheres of amorphous silica from an alcohol-water-ammonia mixture by means of tetraethoxysilane hydrolysis in the presence of hexadecyltrimethylammonium bromide. The mechanism of sphere formation from aggregates of close-packed surfactant cylindrical micelles coated by silica has been proposed. The specific surface area in the synthesized spheres is higher than 800 m²/g, whereas the pore volume and average diameter are equal to 0.63 cm³/g and 3 nm, respectively. The average size of particles is shown to decrease twice after the temperature of the synthesis is increased twice. According to the data of atomic force spectroscopy and dynamic light scattering, the average diameter of mesoporous spheres can be controllably varied in the range 300–1500 nm with a root-mean-square deviation of no more than 6%.     

Synthesis and catalytic properties of sulfonic acid-functionalized monodispersed mesoporous silica spheres

A new type of sulfonic acid-functionalized monodispersed mesoporous silica spheres (MMSS) were synthesized directly by co-condensation and subsequent oxidation. By changing the methanol ratio, sulfonic acid-functionalized MMSS with different particle diameters (390–830 nm) and the same mesopore sizes were successfully synthesized. TEM observations revealed that the mesopores were aligned radially from the center towards the outside of the spheres, even in the sulfonic acid-functionalized MMSS. The catalytic activities of the sulfonic acid-functionalized MMSS were studied in condensation reactions between 2-methylfuran and acetone, and it was found that their catalytic activities are highly dependent on the particle diameters. In addition, the catalytic activity of MMSS was much higher than that of other forms of mesoporous silica due to its radially-aligned mesopores.