TiO2介孔分子筛的光催化制氢活性Ⅱ:热稳定性的影响

以三乙醇胺为模板剂,合成了具有蚯蚓状孔道结构的高比表面积二氧化钛介孔分子筛.通过用XRD,BET法等手段对其进行表征,考察了用萃取法脱除模板剂后二氧化钛介孔分子筛的热稳定性,并发现其与光催化制氢反应相关联,同时探讨了催化剂比表面积、晶型对其催化活性的影响.     

介孔二氧化钛的合成及其对甲基橙降解的光催化活性

以十六烷基三甲基溴化铵为模板剂,通过水解钛酸正丁酯合成了介孔二氧化钛分子筛,探讨了合成条件的影响。采用X射线粉末衍射(XRD)、红外光谱(FT-IR)、透射电子显微镜(TEM)和N2吸附-脱附等技术对介孔二氧化钛的晶相、结构、形貌、比表面积和孔径分布进行了表征。实验结果表明:得到的介孔二氧化钛分子筛的孔径为4-4.3nm,用抽提的方法去除模板剂得到的介孔二氧化钛的比表面积比焙烧的要高。以甲基橙为模型污染物,检验了所合成介孔二氧化钛的光催化性质。     

模板剂对全硅MCM-41介孔分子筛结构的影响

分别采用十六烷基三甲基溴化铵和十六烷基三乙基溴化铵作为模板剂,硅溶胶为硅源,用水热晶化法在碱性（NaOH）介质中合成了MCM-41介孔分子筛样品.通过XRD、N2吸附-脱附、TG-DTA、IR等测试手段对这两种样品进行了对比表征分析.考察了两种不同模板剂对其晶体结构、比表面及孔径大小的影响.实验结果表明,相对于十六烷基三甲基溴化铵做模板剂,采用大头基的十六烷基三乙基溴化铵可以合成较大孔径和孔容（分别为4.72 nm和1.14 cm3•g-1）的MCM-41介孔分子筛,而且具有较窄的孔径分布,因此对于合成大孔径的介孔分子筛MCM-41,十六烷基三乙基溴化铵是一种很好的模板剂.     

二氧化钛介孔分子筛的合成和表征

以高嵌段共聚物为模板剂在中性条件下制备二氧化钛介孔分子筛,并以TG-DTA,XRD,TEM和N~2吸附方法对脱除模板剂后的样品进行了表征。实验结果表明,该介孔分子筛具有较高的比表面,以及六方堆积的均匀孔道,焙烧过程中孔壁可部分晶化成锐钛矿型TiO~2的小晶粒。在分子筛孔壁中引入稀土元素可提高介孔结构稳定性。     

TiO2介孔分子筛的光催化制氢活性Ⅰ:脱出模板法的影响

采用模板剂导向自组装法以三乙醇胺为模板剂合成具有蚯蚓状孔道结构的二氧化钛介孔分子筛.通过研究不同脱除模板剂的方法,造成催化剂的织构特性发生改变,同时用XRD和BET比表面测定,高分辨透射电镜(TEM),紫外漫反射吸收光谱(UV-DRS)等手段对催化剂进行了表征,并以草酸为牺牲剂的光催化制氢反应为模型,探讨了其晶相改变对催化剂活性的影响.     

以伯胺为模板剂合成含铁介孔分子筛FeHMS

以非离子型表面活性剂伯胺为模板剂合成了含铁介孔分子筛FeHMS,并对其结构和形态进行了表征。发现FeHMS的颗粒比SiHMS小,粒子表面更为光滑。除了2.5nm的介孔外,FeHMS还原10nm左右的孔。FeHMS介孔分子筛在脱除模板剂之前,铁主要处于四面体配位状态的骨架位,经焙烧脱除模板剂之后,部分铁由骨架位迁移到孔壁表面。用酸化的乙醇溶液抽提脱除模板剂,能更有效地让铁保留在四面体配位状态的骨架位上。高温脱除模板剂后,孔壁表面的铁物种处于一种高分散的状态。此外还研究了HMS类介孔分子筛材料的水热稳定性,发现铁的引入可改善介孔分子筛材料的水热稳定性。     

以伯胺为模板剂合成含铁介孔分子筛FeHMS

以非离子型表面活性剂伯胺为模板剂合成了含铁介孔分子筛FeHMS,并对其结构和形态进行了表征。发现FeHMS的颗粒比SiHMS小,粒子表面更为光滑。除了2.5nm的介孔外,FeHMS还原10nm左右的孔。FeHMS介孔分子筛在脱除模板剂之前,铁主要处于四面体配位状态的骨架位,经焙烧脱除模板剂之后,部分铁由骨架位迁移到孔壁表面。用酸化的乙醇溶液抽提脱除模板剂,能更有效地让铁保留在四面体配位状态的骨架位上。高温脱除模板剂后,孔壁表面的铁物种处于一种高分散的状态。此外还研究了HMS类介孔分子筛材料的水热稳定性,发现铁的引入可改善介孔分子筛材料的水热稳定性。     

氩吸附法研究多级孔分子筛的孔结构

采用不同方法分别制备了双介孔分子筛、介微孔分子筛及介孔沸石材料,利用氩吸附法并结合XRD技术表征了多级孔分子筛的孔结构。探讨了适用于多级孔分子筛的孔径分布计算方法,揭示了不同类型吸附等温线与孔径分布、孔型及孔容等之间的关系。研究表明,对于多级孔分子筛、微孔和介孔的孔径分布分别用SF法和BJH法计算较适宜,全孔分析可用NLDFT法计算。通过对TS-1介孔沸石的孔结构分析发现, TPAOH 在改性制备介孔TS-1的过程中起到了生成介孔及促进二次晶化的双重作用。     

介孔La2O3的制备及性能研究

采用SDS-PEG复合模板剂,用均相沉淀法制备了不同孔径的介孔La2O3,用XRD,BJH,TG-DSC等方法对材料的结构和性能进行了表征,用IR-2型红外发射率测量仪测定了材料在8-14μm波段的红外发射率。结果表明：通过控制复合模板剂中PEG的量,可以有效调节介孔La2O3的孔径大小,PEG的添加可以明显增大介孔La2O3的孔径,且随PEG添加量的增多而逐渐增大。PEG的添加明显提高了介孔La2O3的热稳定性和结构稳定性。PEG与孔壁间存在较强的相互协同作用,介孔La2O3在8-14μm波段具有较低的红外发射率,且其红外发射率随材料的焙烧温度、最可几孔径的减小而逐渐降低。     

以离子液体为模板剂合成MCM-41的研究——不同扩孔剂对介孔分子筛MCM-41孔径结构的影响

以离子液体为模板剂, 正硅酸乙酯为硅源, 研究了扩孔剂三甲苯, 癸烷, 以及三甲苯与癸烷1∶1的混合物对介孔分子筛MCM-41结构的影响, 采用XRD以及氮吸附-脱附分析技术对合成的介孔分子筛MCM-41进行了表征.结果表明: 三种扩孔剂中以三甲苯与癸烷1∶1的混合物效果最优, MCM-41的孔径可达到4.5 nm, 并且可以提高介孔分子筛的比表面积与结晶度.扩孔剂的最佳添加量为: 扩孔剂与模板剂之比等于1.0;最佳晶化温度120 ℃.     

Effect of Templates on the Structure and Stability of Ti-TMS

Mesoporousmaterialsareofgreatinteresttocatalysisbecauseoftheirlargeanduniformporesize(20~100A),whichallowstereo-hinderedmoleculesfacilediffusiontointernalactivesites.Althoughrecenteffectshavesuggestedthatitshouldbepossibletosynthesizemesoporousmateri...     

Probing the impact of advanced melting and advanced adsorption phenomena on the accuracy of pore size distributions from cryoporometry and adsorption using NMR relaxometry and diffusometry

The penetration of compressed CO(2) in hydrocarbon and fluorocarbon regions of concentrated surfactant mesophases are interpreted from differences in the CO(2)-processed pore expansion of mesoporous silica thin films templated by three surfactants containing varying degrees of hydrocarbon and fluorocarbon functionality. Ordered silica thin films are synthesized for the first time using the 16-carbon (C(16)) partly fluorinated surfactant, 11,11,12,12,13,13,14,14,15,15,16,16,16-tridecafluorocetyl pyridinium bromide (HFCPB), as a templating agent. Silica films templated with surfactants containing a 8-carbon (C(8)) fluorocarbon tail (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl pyridinium chloride (HFOPC)) and a 16-carbon (C(16)) hydrocarbon tail (cetyl pyridinium bromide (CPB)) and HFCPB (C(16)) are processed in compressed CO(2) (69-172 bar, 25 °C and 45 °C) during synthesis. CO(2) processing results in significant pore expansion for films templated with both fluorinated surfactants, while pore expansion is negligible for the hydrocarbon templated material suggesting that preferential CO(2) penetration occurs in the 'CO(2)-philic' fluorocarbon segments of the surfactant template. The effect of substrate surface energy on the final uniformity of the dip-coated films is studied by varying the substrate from unmodified glass to a fluorocarbon-capped substrate. The ability to create dip-coated thin films on low surface energy substrates through favorable interaction of surfactant template tail with the substrate surface functional groups is demonstrated.     

混合超分子液晶模板法合成六方介孔相含钛氧化硅

采用混合十六烷基三甲基溴化铵（CTAB）与不同碳链的脂肪胺（CnNH2n＋3, n=8,10,12,14,16）作模板,在四甲基氢氧化胺为碱源的条件下,合成了具有六方介孔结构的含钛氧化硅Ti MCM 41分子筛材料. XRD和TEM测试表明所合成材料具有高度的长程有序结构,样品的N2吸附/脱附等温线表明,高度有序的Ti MCM 41材料展示了毛细凝聚的陡峭台阶和狭窄的介孔孔径分布.对反应物配比中Ti/Si比、脂肪胺碳链长度n对六方介孔相结构的影响进行了研究,实验发现当Ti/Si< 0.15和n< 16时,均可获得具有六方介孔结构的含钛氧化硅Ti MCM 41;而当Ti/Si≥0.15或n >16时,产物将分别发生从六方向无定形态或从六方向层状介孔相结构的转移,从混合表面活性剂的堆积参数对这种相转移现象进行了分析.     

Tailoring porous silica films through supercritical carbon dioxide processing of fluorinated surfactant templates

The tailoring of porous silica thin films synthesized using perfluoroalkylpyridinium chloride surfactants as templating agents is achieved as a function of carbon dioxide processing conditions and surfactant tail length and branching. Well-ordered films with 2D hexagonal close-packed pore structure are obtained from sol-gel synthesis using the following cationic fluorinated surfactants as templates: 1-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-octyl)pyridinium chloride (HFOPC), 1-(3,3,4,4,5,5,6,6,7,8,8,8-dodecafluoro-7-trifluoromethyl -octyl)pyridinium chloride (HFDoMePC), and 1-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro-decyl)pyridinium chloride (HFDePC). Processing the sol-gel film with CO2 (69-172 bar, 25 and 45 degrees C) immediately after coating results in significant increases in pore diameter relative to the unprocessed thin films (increasing from 20% to 80% depending on surfactant template and processing conditions). Pore expansion increases with CO2 processing pressure, surfactant tail length, and surfactant branching. The varying degree of CO2 induced expansion is attributed to the solvation of the "CO2-philic" fluorinated tail and is interpreted from interfacial behavior of HFOPC, HFDoMePC, and HFDePC at the CO2-water interface.     

Surfactant Templated Silica Xerogels as Adsorbents for Rhodamine 6G

A series of silica xerogels was synthesized by using TEOS as the silica precursor and a non ionic surfactant Triton X100 (TX100) and a cationic surfactant Hexadecyltrimethylammonium Bromide (CTAB) as templates. The xerogels were synthesized through 2‐way catalysis using ultrasonic radiations for homogeneous mixing of the precursors and template. The surfactant template was later removed through calcination at 550 °C. It was found out that gels having CTAB as the template had higher surface area (612.08 m²/g) than the gels templated by TX100 (539.6 m²/g). High surface area xerogels were used in adsorption experiments for aqueous solutions of Rhodamine 6G (R6G). UV visible spectroscopy was used to find out the concentrations of dye solutions. The adsorption data of both the types of xerogels was found to follow Freundlich's adsorption model pointing towards the possibility of adsorption of the dye molecules on the heterogeneous surface of the adsorbent.     

阳离子与非离子混合表面活性剂模板合成介孔SiO2

利用各种两亲分子有序组合体构成超分子模板,合成从介观到宏观尺度不同形态的无机材料成为材料科学新崛起的研究方向[1].介孔SiO2在催化、吸附、分离介质及化学传感器等方面有广阔的应用前景.     

Effect of colloidochemical properties of template on the formation of the structure of mesoporous silica molecular sieves

A “homologous” series of mesoporous silica materials of MSM-41 type whose X-ray characteristics change in proportion to the length of hydrocarbon radical of template surfactant is synthesized using alkylpyridinium halides and sodium silicate. The correspondence principle of the state of the aggregation of micellar templates is used on synthesis for the first time. The influence of colloidochemical properties of surfactant solubilizer and solubilizate on the structuring ability of bitemplate (solubilization) composition is analyzed.     

Mesoporous Silica Materials Synthesized via Sol-Gel Methods Modified with Ionic Liquid and Surfactant Molecules

Mesoporous silica materials were synthesized via a sol-gel method employing a room temperature ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, bmimBF4) as a new solvent medium and further modified with surfactant (hexadecyl-trimethyl-ammonium bromide, CTAB) as a pore templating material. The synthesized samples were characterized by the transmission electron microscopy, X-ray diffraction, and N2 adsorption-desorption techniques. The results indicated that the mesoporous silica synthesized by using bmimBF4 and CTAB as mixed templates showed better mesostructural order and smaller pore size, compared with mesoporous silica materials synthesized by using single bmimBF4 as template under the same conditions. This indicates that the presence of surfactant can affect the microstructures of silica prepared by the present synthesis method.     

Hydrogen adsorption in transition metal carbon nano-structures

Templated microporous carbons were synthesized from metal impregnated zeolite Y templates. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were employed to characterize morphology and structure of the generated carbon materials. The surface area, micro- and meso-pore volumes, as well as the pore size distribution of all the carbon materials were determined by N₂ adsorption at 77 K and correlated to their hydrogen storage capacity. All the hydrogen adsorption isotherms were Type 1 and reversible, indicating physisorption at 77 K. Most templated carbons show good hydrogen storage with the best sample Rh-C having surface area 1817 m²/g and micropore volume 1.04 cm³/g, achieving the highest as 8.8 mmol/g hydrogen storage capacity at 77 K, 1 bar. Comparison between activated carbons and synthesized templated carbons revealed that the hydrogen adsorption in the latter carbon samples occurs mainly by pore filling and smaller pores of sizes around 6 Å to 8 Å are filled initially, followed by larger micropores. Overall, hydrogen adsorption was found to be dependent on the micropore volume as well as the pore-size, larger micropore volumes showing higher hydrogen adsorption capacity.     

Gemini Surfactants Templated Mesoporous Silica Microparticles: from Solid to Hollow Mesoporous Spheres

We synthesized a series of mesoporous silica microparticles (MSs) using cationic gemini surfactants C_14–2‐n (n = 2, 6, 10, 14) as templates. The porous structures and pore size of these MSs can be tuned by varying the length of alkyl chain in gemini surfactant templates. These MSs showed effective doxorubicin (DOX) loading and a pH‐responsive drug release characteristics. These results indicate that the MSs, especially the hollow mesoporous silica nanoparticles, have great potential for biomedical applications.