锆掺杂MCM-41介孔分子筛的水热合成与稳定性

水热条件下,以硅酸钠和硫酸锆为原料,十六烷基三甲基溴化铵(CTAB)为模板剂,按照初始的ZrO2与SiO2物质的量之比0.05、0.1、0.2和0.3合成了4种不同锆含量的含锆介孔分子筛(ZrMCM-41).采用X射线衍射(XRD)、红外光谱(FT-IR)、透射电子显微镜(TEM)和比表面积孔径测定等方法对样品的结构和形貌进行了表征.考察了不同ZrO2与SiO2物质的量之比、不同焙烧温度以及不同水热处理时间对样品孔结构的影响.结果表明:合成的样品具有典型的MCM-41介孔结构,其比表面积为448.6~891.9 m2/g.随着样品中锆含量的增加、焙烧温度的升高和水热处理时间的延长,所合成样品的介孔有序性下降,BET比表面积降低.     

模板剂对MCM-41介孔分子筛结构的影响

以微硅粉为硅源,利用水热合成法成功制备出MCM-41介孔分子筛,利用XRD、N2吸附曲线和TEM等测试方法对样品进行了表征,结果表明,模板剂的用量对样品的结构具有显著的影响,当CTAB／SiO2的摩尔比为0．15时,样品的结构有序性最高;混合模板剂可明显提高样品的比表面积和孔容,合成的MCM-41介孔分子筛比表面积从299m2／g提高到837．3m2／g,孔容从0．051cm。／g提高到0．79cm3／g。     

氢氯噻嗪／MCM-41载药体系的制备与缓释作用研究

用微波辐射法合成介孔分子筛MCM-41，采用浸渍法将利尿药物氢氯噻嗪组装到介孔分子筛MCM-41孔道中，用XRD、低温N2吸附、IR对MCM-41及药物组装体进行了表征；研究了组装体的载药量、载药时间、在体外人工胃液中的释放等。结果显示合成的分子筛MCM-41具有规则的孔径结构，比表面积为1211m^2/g；分子筛MCM-41作为药物的载体具有较短的载药时间（t=26h），较大的载药量48％（m（药物）/优（载体）），较低的释放速率，表明制得了氢氯噻嗪／MCM-41缓释释放体系。     

十八烷基三甲基溴化铵为模板合成有序介孔氧化硅及其表征

利用表面活性剂十八烷基三甲基溴化铵(STAB)为模板、正硅酸乙酯(TEOS)为硅源、盐酸为催化剂,在较低的表面活性剂浓度下(小于4%)合成了介孔氧化硅,并研究了不同的反应条件对介孔结构及有序度的影响。在热乙醇萃取或者高温煅烧除去模板剂之后,利用红外(IR)、X射线电子衍射(XRD)、高分辨透射电子显微镜(HRTEM)以及N2的吸附-脱附曲线对合成的介孔材料进行了表征。结果表明,合成的介孔氧化硅具有MCM-41型有序的孔道结构、大的孔体积(不小于1cm3/g)和BET比表面积(不小于1400m2/g),孔径均一且分布较窄。     

以间苯二酚-甲醛溶胶和MCM-48原粉制备有序介孔炭分子筛

以含有机模板的介孔纯硅分子筛MCM- 48原粉为模板,以间苯二酚(R)-甲醛溶胶为炭源制备了有序介孔炭分子筛.考察了w(R)/w(MCM- 48)和w(R)/w(H2O)对合成介孔炭分子筛的影响.产物用N2吸附/脱附、XRD、SEM、TEM和TG等手段进行了表征.结果表明,w(R)/w(MCM- 48)和w(R)/w(H2O)对所得到的介孔炭分子筛的有序性和比表面积有较大的影响.优化的w(R)/w(MCM- 48)比为0.50～0.65、w(R)/w(H2O)比为0.15～0.35,此时,能形成比表面积大于1125m2/g、平均孔径在2.2～2.4nm、具有规则介孔结构的炭分子筛,且这种炭分子筛具有高的热稳定性.     

尿素-过氧化氢混合模板法合成介孔二氧化硅

以尿素-过氧化氢为混合模板、正硅酸乙酯为硅源,在酸性条件下,通过溶胶-凝胶过程合成二氧化硅介孔材料。采用煅烧法除去模板剂,用红外光谱、XRD、N2吸附-脱附、HRTEM等分析测试手段对介孔材料的结构和形态进行了表征。结果表明:与以尿素为单一模板相比,采用混合模板剂所合成介孔材料为蠕虫状,孔径分布基本保持不变、比表面积相近(分别为445、431m2/g)、孔径(分别为7.04、8.11nm)和孔体积(分别为0.783、0.874cm3/g)明显增大。     

m-PH-SiO2/Nafion复合膜的质子导电性

为提高Nafion膜在中温段的质子导电性,用溶胶-凝胶法制备比表面积为386 m2/g掺磷中孔SiO2 (m-PH- SiO2),并与Nafion的N,N二甲基甲酰胺溶液混合,重铸法制备不同m-PH-SiO2含量的m- PH- SiO2/Nafion复合膜.用N2-吸附脱附和TEM表征m-PH- SiO2的介孔结构,S...     

稻壳灰显微结构的研究

采用SEM TEM(SAD)技术 ,首次揭示了稻壳灰的显微结构 :稻壳灰由纳米尺度的SiO2 凝胶粒子(～ 5 0nm)疏松地粘聚而成。稻壳灰结构中除了以往报道过的微米尺度的蜂窝孔 (～ 10 μm)外 ,还含有大量由SiO2凝胶粒子非紧密粘聚而形成的纳米尺度孔隙 (<5 0nm)。纳米尺度的SiO2 粒子和纳米尺度的大量孔隙是稻壳灰具有巨大的比表面积 (5 0～ 10 0m2 g)和超高火山灰活性的根本原因     

不同结构的颗粒填充对环氧树脂纳米复合材料性能的影响

通过溶液共混法制备了环氧树脂/纳米介孔MCM-41和环氧树脂/纳米SiO2复合材料,研究了结构不同的填充颗粒、不同的填充颗粒含量及其复合材料的分散性与力学性能.结果表明,由于这种具有双重纳米结构(纳米级颗粒尺寸和纳米级的介孔结构)的介孔分子筛MCM-41能与基体形成新型网络复合结构,因此在纳米介孔MCM-41的含量适当(小于10%,质量分数,下同)时,纳米介孔MCM-41能均匀地分散在环氧树脂基体中,有效地提高复合材料的拉伸强度.而含量较高(不低于5%)的实心纳米SiO2将在环氧树脂基体中产生大量团聚体,使复合材料的拉伸强度降低.     

有序介孔SiO_2分子筛的制备研究

介孔分子筛材料以其优异的物理化学性能被广泛应用于吸附分离、精细化工、化学催化、石油化工等领域。采用正交实验方法研究有序介孔SiO2的制备工艺,在CTAB与Si比值为0.14,晶化时间48h,晶化温度100℃,焙烧温度600℃条件下最终制得平均孔径为3.80nm,平均比表面积为962.78m2/g,总孔容为0.92cm3/g的有序介孔SiO2。该方法工艺简单、设备要求低、生产周期短,可应用于大规模的工业生产。     

杂原子MCM-41分子筛的合成和催化性能

采用水热合成法合成了金属原子(Zn,Ni,Fe,Al,Cu,Ce)掺杂的MCM-41介孔分子筛(简称T-MCM-41),并将其应用于邻苯二甲酸二(2-乙基已)酯(DOP)的合成反应,研究了不同原子的掺杂对T-McM-41的结构,比表面积和孔径、酸性及催化性能的影响.结果表明,所制备的T-McM-41仍然具有六方有序排列结构,比表匝f积较高(550-900 m2/g)、孔径大(3 nm左右),杂原子的引入使T-MCM-41产生了酸中心,从而使其对DOP的合成具有很好的催化活性和选择性.用T-MCM-41(T=Zn,Fe,Al,Cu)催化DOP的合成反应,在5 h的反应时间内苯酐的转化率可以达到95.5%以上,DOP的选择性可达到96.5%以上.T-MCM-41催化剂具有很好的稳定性,Al-MCM-41在重复使用5次后仍具有较好的催化活性.     

Synthesis and characterization of polyaniline/MCM-41 nanocomposites and their photocatalytic activity

The novel organic-inorganic nanocomposites were synthesized via in-situ polymerization of polyaniline (PANI) with mesoporous silica (MCM-41) for methylene blue (MB) dye degradation under visible light. The synthesized PANI/MCM-41 nanocomposites were characterized through Fourier transform infrared (FTIR), X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), and UV-visible studies. The structural and optical properties confirmed the interaction between PANI and MCM-41. The photocatalytic experiments showed that the MB dye was efficiently degraded by approximately 70% under light irradiation over the surface of the PANI/MCM-41 nanocomposites. The degradation might occur due to the efficient charge separation of the e(-)-h+ pairs at the interface of PANI and MCM-41 in the excited state under light irradiation.     

Ni and Cu incorporated mesoporous nanocomposite catalytic materials

Nickel and copper incorporated MCM-41-like mesoporous nanocomposite materials prepared by the direct hydrothermal synthesis and the impregnation procedures showed highly attractive pore structure and surface area results for catalytic applications. The XRD patterns showed that characteristic MCM-41 structure was preserved for the materials synthesized following an impregnation procedure before the calcination step. The surface area of the Cu impregnated material with a quite high Cu/Si atomic ratio (0.19) was 631 m2/g. Very narrow pore size distributions with an average pore diameter of about 2.7 nm were obtained as a result of plugging of some of the smaller pores by Cu nanoballs. For lower metal to Si ratios (for instance for Ni/Si = 0.06) much higher surface area values (1130 m2/g) were obtained. In the case of nanocomposite materials synthesized by the direct hydrothermal route, MCM-41 structure was not destroyed for samples containing metal to Si atomic ratios as high as 0.12. In the case of materials containing Cu/Si and Ni/Si ratios over 0.2 wider pore size distributions and some decrease of surface area were observed.     

The investigation of MCM-48-type and MCM-41-type mesoporous silica as oral solid dispersion carriers for water insoluble cilostazol

Objective: To explore the suitable application of MCM-41 (Mobil Composition of Matter number forty-one)-type and MCM-48-type mesoporous silica in the oral water insoluble drug delivery system.

Methods: Cilostazol (CLT) as a model drug was loaded into synthesized MCM-48 (Mobil Composition of Matter number forty-eight) and commercial MCM-41 by three common methods. The obtained MCM-41, MCM-48 and CLT-loaded samples were characterized by means of nitrogen adsorption, thermogravimetric analysis, ultraviolet-visible spectrophotometry, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry and powder X-ray diffractometer.

Results: It was found that solvent evaporation method was preferred according to the drug loading efficiency and the maximum percent cumulative drug dissolution. MCM-48 with 3D cubic pore structure and MCM-41 with 2D long tubular structure are nearly spherical particles in 300–500?nm. Nevertheless, the silica carriers with similar large specific surface areas and concentrating pore size distributions (978.66?m²/g, 3.8?nm for MCM-41 and 1108.04?m²/g, 3.6?nm for MCM-48) exhibited different adsorption behaviors for CLT. The maximum percent cumulative drug release of the two CLT/silica solid dispersion (CLT-MCM-48 and CLT-MCM-41) was 63.41% and 85.78% within 60?min, respectively; while in the subsequent 12?h release experiment, almost 100% cumulative drug release were both obtained. In the pharmacokinetics aspect, the maximum plasma concentrations of CLT-MCM-48 reached 3.63?mg/L by 0.92?h. The AUC_0–∞ values of the CLT-MCM-41 and CLT-MCM-48 were 1.14-fold and 1.73-fold, respectively, compared with the commercial preparation.

Conclusion: Our findings suggest that MCM-41-type and MCM-48-type mesoporous silica have great promise as solid dispersion carriers for sustained and immediate release separately.     

New mesoporous silica/carbon composites by in situ transformation of silica template in carbon/silica nanocomposite

Hard template-based fabrication of mesoporous carbon unavoidably goes through the removal process of the template to generate template-free carbon replica, including troublesome disposal of template waste often accompanied by toxic etchant, which not only increases the fabrication cost of materials but also raises serious environmental concerns. As a novel strategy to overcome such problem, a direct in situ synthesis approach using silica waste in carbon/silica nanocomposite as a silica source and cetyltrimethylammonium bromide as a porogen under basic condition is reported in this study for the generation of a new composite composed of mesoporous MCM-41 silica and hollow carbon capsule. The resultant MCM-41/carbon capsule composite offers a 3-D interconnected multimodal pore system, which discloses a wide pore range of ordered uniform mesopores (ca 2.3?nm) resulting from MCM-41 silica and disordered uniform mesopores (ca 3.8?nm) and macropores (ca 300?nm) from hollow mesoporous carbon, respectively. The composite has a high specific surface area (ca 909?m²/g) and large pore volume (ca 0.73?cm³/g). The in situ transformation approach of silica waste into valuable mesoporous silica is considered as a promising scalable route for efficient new multi-functional composites useful for a wide range of applications such as adsorption of volatile organic compounds and radioactive wastes produced in a nuclear facility.     

表面活性剂对纳米MCM-41分子筛分散性的影响

采用聚乙二醇为分散剂,十六烷基三甲基溴化铵为模板剂,正硅酸乙酯为硅源,在室温碱性条件下合成了粒径为40～60 nm的单分散纳米球形MCM-41分子筛.利用XRD、TEM和N2吸附脱附等手段研究了聚乙二醇用量对纳米球形MCM-41的分散性和介孔结构的影响.结果表明,表面活性剂PEG的加入,可以明显改善纳米颗粒的分散性并且对颗粒形貌影响不大;表面活性剂PEG的加入,样品的六方结构有序性和孔尺寸发生变化.PEG量在1%～20%范围内,样品仍具有较高的六方孔道有序性;PEG量过大(60%)有序性明显下降.随着PEG加入量的增加,纳米MCM-41的晶面间距增大,孔尺寸增大.适量的聚乙二醇可以得到有序性好、比表面积大、孔径均一和孔隙率大的单分散纳米球形MCM-41分子筛.     

Silica materials recovered from photonic industrial waste powder: its extraction, modification, characterization and application

This study explored the possibility of recovering waste powder from photonic industry into two useful resources, sodium fluoride (NaF) and the silica precursor solution. An alkali fusion process was utilized to effectively separate silicate supernatant and the sediment. The obtained sediment contains purified NaF (>90%), which provides further reuse possibility since NaF is widely applied in chemical industry. The supernatant is a valuable silicate source for synthesizing mesoporous silica material such as MCM-41. The MCM-41 produced from the photonic waste powder (PWP), namely MCM-41(PWP), possessed high specific surface areas (1082 m²/g), narrow pore size distributions (2.95 nm) and large pore volumes (0.99 cm³/g). The amine-modified MCM-41(PWP) was further applied as an adsorbent for the capture of CO₂ greenhouse gas. Breakthrough experiments demonstrated that the tetraethylenepentamine (TEPA) functionalized MCM-41(PWP) exhibited an adsorption capacity (82 mg CO₂/g adsorbent) of only slightly less than that of the TEPA/MCM-41 manufactured from pure chemical (97 mg CO₂/g adsorbent), and its capacity is higher than that of TEPA/ZSM-5 zeolite (43 mg CO₂/g adsorbent). The results revealed both the high potential of resource recovery from the photonic solid waste and the cost-effective application of waste-derived mesoporous adsorbent for environmental protection.     

高结晶规则大孔硅的制备和应用

ＦＳＭ－１６,ＭＣＭ－４１和ＳＢＡ－１５等具有高规则二维六角晶格的多孔硅可用不同硅源和表面活性剂合成,其孔径可达１０,１５或３０ｎｍ,可用具有不同熔基链长的表面活性剂和膨胀剂控制。其结晶规则性随孔径的增大而降低。用层状硅土Ｋａｎｅｍｉｔｅ制备的ＦＳＭ－１６和来自水玻璃的ＭＣＭ－４１,其表面阴离子度比用四甲氧基硅烷（ＴＭＯＳ）制备的ＳＢＡ－１５高得多。如将在等电点以下呈阴离子性的生物酶插入硅孔,则由于离子间的相互作用和氢键结合力,可得到结合得十分稳定的生物／无机陶瓷结合体。以此结合体为有机酸化反应的催化剂,反应的活性很高。