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本文以海泡石为原料,通过球磨、酸化脱镁后,在水热条件下合成了介孔分子筛MCM-41.考察了pH值、晶化时间、晶化温度、Si/CTAB摩尔比等因素对MCM-41合成的影响,采用XRD和BET等测试手段对合成样品进行分析表征,并用DSC和XRD考察了镁含量对分子筛的热稳定性的影响.结果表明pH值在10~12,Surf/SiO2在0.05~0.6,晶化温度在80~140℃,晶化时间在12 ~96 h,MgO含量为0~2.27%的条件下都能合成有序的介孔分子筛MCM-41,DSC和XRD实验结果表明,原料中镁含量的提高对分子筛热稳定性不利. 相似文献
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低质量分数表面活性剂作模板合成MCM-41中孔分子筛 总被引:2,自引:0,他引:2
以硅酸钠为硅源,表面活性剂十六烷基三甲基溴化铵(CTMABr)为结构模板剂,用水热晶化法在w(CTMABr)=1%~3%下制备全硅MCM-41中孔分子筛。采用染料吸附脱色实验比较了原料配比、反应体系pH值、晶化时间、晶化温度、脱模温度对MCM-41合成的影响。结果表明,合成MCM-41中孔分子筛时表面活性剂CTMABr质量分数必须达到1%以上;pH=10~12;晶化温度以125℃左右为好;前驱体脱模温度控制在600~800℃。在较优的工艺条件w(CTMABr)=1 5%、pH=11、晶化温度125℃、晶化时间24h、脱模温度640℃下得到了具有完美晶型结构、BET比表面积=1370m2/g、平均孔径3 28nm的全硅MCM-41中孔分子筛。 相似文献
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简要介绍了MCM-41介孔分子筛的特点,应用和改性原因.综述了MCM-41介孔分子筛的合成方法,主要包括水热合成法,室温合成法,微波合成法等,列出了每种合成方法的优缺点和合成过程中的影响因素,pH值、晶化时间、晶化温度、模板剂的种类及用量等都会对MCM-41介孔分子筛的结构和孔径产生很大影响.阐述了MCM-41介孔分子筛的改性方法,包括金属杂原子取代法,如主族金属、过渡金属、稀土金属等,有机修饰或功能化法,负载型改性法,如负载金属氧化物、无机酸、杂多酸、有机碱、金属的配合物等.最后就MCM-41介孔分子筛的应用前景做了展望. 相似文献
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以正硅酸乙酯为硅源、十六烷基三甲基溴化铵为模板,在氟化物存在的条件下,通过水热法在不同晶化温度和时间下进行复合分子筛Y/MCM-48的合成。利用X射线粉末衍射、Fourier变换红外光谱、N2吸附–脱附、扫描电子显微镜和透射电子显微镜对合成的样品进行表征,同时考察了样品的稳定性及不同晶化时间和温度下样品的晶相。结果表明:在120℃水热晶化36h合成的Y/MCM-48具有良好有序的MCM-48介孔相以及NaY微孔相的双重孔结构,其比表面积高达864 m2/g,平均孔径为2.4 nm。样品经800℃焙烧4 h、100℃水热处理48 h后,复合分子筛的双重孔结构仍然存在。 相似文献
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《辽宁化工》2016,(9)
采用水热法成功合成了结晶度较好的MCM-41和Co-MCM-41分子筛,并对其进行了详细的表征,研究了MCM-41及Co-MCM-41对含喹啉模拟燃料和0~#柴油的吸附脱氮性能。实验确定MCM-41和Co-MCM-41合成的适宜条件为陈化时间1 h,晶化时间2 d。采用密度泛函方法模拟的喹啉分子尺寸结果为0.7116 nm×0.5002 nm,说明其可以很容易的进入MCM-41和Co-MCM-41的介孔孔道中,但Co-MCM-41分子筛的氮脱除率明显要高于MCM-41,说明Co的加入不仅提高了分子筛酸性,而且吸附脱氮性能增强。Co/Si摩尔比为0.06时,Co-MCM-41吸附脱氮性能最好,当比值高于0.06时,Co以Co_3O_4形式堵塞分子筛孔道,造成Co-MCM-41的吸附脱氮活性降低。 相似文献
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Investigation of the Structural Characterization of Mesoporous Molecular Sieves MCM-41 from Sepiolite 总被引:1,自引:0,他引:1
Shengming Jin Guanzhou Qiu Fei Xiao Yan Chang Cuifeng Wan Min Yang 《Journal of the American Ceramic Society》2007,90(3):957-961
Mesoporous molecular sieves, MCM-41, were synthesized from sepiolite using acid leaching, followed by hydrothermal reconstruction and then calcinations at 540°C for 5 h. The structures and the porosity of MCM-41 were investigated by means of small-angle X-ray diffraction patterns, Brunaer-Emmett-Teller (BET), 29 Si MAS NMR, Fourier transform infrared (FTIR), and high resolution transmission electron microscope (HRTEM) methods. The results showed that the hexagonal MCM-41 was formed in an alkaline solution of pH 12, when crystallization was carried out at 100°C for 24 h. The specific surface area, pore diameter, and pore volumes of MCM-41 from sepiolite were 1036 m2 /g, 2.98 nm, and 1.06 cm3 /g, respectively. 29 Si MAS NMR results revealed that amorphous silica decomposed into Si–O chains consisting of two layers of Si atoms, with Q 3 configurations resulting in an increase in the fraction of Q 3 configuration during the crystallization of post-Mg-extraction sepiolite. The IR results illustrated that the complex of ≡≡SiO− –CTA+ was formed during the synthesis of MCM-41 from post-Mg-extraction sepiolite. 相似文献
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改性海泡石对亚甲基蓝的吸附性能 总被引:1,自引:0,他引:1
对海泡石进行了硫酸改性、高温改性、硫酸/高温改性,以亚甲基蓝为吸附对象,研究了改性方法对海泡石吸附性能的影响,对各改性海泡石进行了孔径、孔体积等表征. 结果表明,3种改性方法中,硫酸/高温改性对海泡石吸附性能的提高效果最好,吸附量比改性前提高47.8%,达41 mg/g,吸附等温线符合Langmuir方程. 硫酸/高温复合改性后的海泡石平均孔径达9.74 nm,孔体积达7.064′10-2 cm3/g,分别提高117%和92.6%. 对改性海泡石对亚甲基兰的吸附机理进行了探讨. 相似文献
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水热条件下CuMCM-41介孔分子筛的合成与表征 总被引:1,自引:0,他引:1
以硅酸钠(Na2SiO3·9H2O)、氯化铜(CuCl2·6H2O)等无机盐为原料,十六烷基三甲基溴化铵为模板剂,通过水热法合成CuMCM-41介孔分子筛.分别采用X射线粉末衍射、红外光谱、透射电子显微镜和N2吸附-脱附等技术,对产物的晶相、结构、形貌、比表面积和孔径分布进行了表征.同时研究金属铜添加量与比表面积、孔径之间的关系.结果表明:合成出的4种不同铜含量的CuMCM01介孔分子筛,其比表面积最高可达1032.41m2/g,平均孔径在3.4~4.0 nm之间.随着介孔分子筛中掺杂的金属铜含量的增加,介孔分子筛的比表面积变小、介孔有序性变差.当原料配比增加到n(SiO2):n(CuO)=1:0.2时,合成出的CuMCM-41介孔分子筛有序性很差. 相似文献
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Na Wang Qinghong Fang Erfan Chen Jing Zhang Yawei Shao 《Polymer Engineering and Science》2009,49(12):2459-2466
The structure, crystallization, and thermal stability of polypropylene containing nanosized MCM‐41 particle, whose pore channels were filled with polystyrene inside the pore channels with the aid of supercritical CO2, were investigated by X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analyses, respectively. The results of differential scanning calorimetry showed that the incorporation of MCM‐41 (without template) increased the melting temperature and the crystallization temperature by approximately 7 and 1.8°C, respectively. Although the incorporation of MCM‐41 (with template) and MCM‐41‐S‐PS decreased the melting temperature, the crystallization temperature and the crystallization rate increased. The result of crystallization kinetics showed dramatic increase in crystallization rate and decrease in t1/2 and tf for PP/MCM‐41 (without template) nanocomposite, whereas decrease in crystallization rate and increase in t1/2 and tf for PP/MCM‐41 (with template) and PP/MCM‐41‐S‐PS nanocomposites. The thermal results indicated that the thermal stability of the composite was enhanced by addition of all nanoparticles. At the 95% weight loss, adding 2.5 wt% nanomaterial, the decomposition temperature of PP/MCM‐41‐S‐PS was 50.71°C higher than that of PP, 13.98°C higher than that of PP/MCM‐41 (without template), and 0.39°C higher than that of PP/MCM‐41 (with template). POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers 相似文献
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《分离科学与技术》2012,47(8):1635-1643
Abstract This investigation examines metal ion adsorption on mesoporous silicate, MCM‐41, synthesized from sodium silicate solution and cethyltrimethylammonium bromide (CTAB). MCM‐41 has potential as an adsorbent material, with a regular hexagonal pore structure, large specific surface area, and large pore volume. The MCM‐41 synthesized for this investigation is characterized using powder X‐ray diffraction and nitrogen adsorption and desorption isotherms data. The adsorption behavior for cadmium(II) and lead(II) onto MCM‐41 was studied by contacting the mesoporous silicate with an aqueous solution of metal salts and acetylacetone. Both Cd2+ and Pb2+ were found to quantitatively adsorb onto MCM‐41. The results of this study suggest that MCM‐41 may have applications in the recovery of toxic metals from waste waters. 相似文献
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Mesoporous MCM-41 was prepared by leaching of sepiolite and sequent hydrothermal synthesis in NaOH solution with hexadecyltrimethylammonium bromide as template. Small-angle X-ray diffraction patterns, Scanning electron microscopy, transmission electron microscopy and Brunauer–Emmett–Teller were performed to characterize the resulting compounds. The results showed that the crystallinity and pore size of MCM-41 increased with increase of crystallization time, ratios of surfactant to SiO2 and decrease of Mg content. The experimental results of catalytic cracking of polystyrene waste showed that the MCM-41 with MgO from natural sepiolite had high catalytic activity and good selectivity to monomer styrene for the catalytic cracking of polystyrene when the ratio of waste plastics to MCM-41 was 200. The side reactions yielded ethylbenzene, isopropylbenzene, isopropenylbenzene and secondary cross-linking were suppressed by basic species MgO in MCM-41. 相似文献
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采用CTAB在碱性条件下加四乙氧基硅烷,生成白色沉淀后在550℃温度下,灼烧5 h,除去表面活性剂,获得MCM-41介孔材料。将MCM-41介孔材料装柱后,采用固相萃取的前处理方法对样品中砷进行富集,富集倍数达到20倍。建立电感耦合等离子体原子发射光谱法对水样中微量砷的测定方法,方法的检出限为0.01μg/m L,测定范围为0.5~10μg/m L,回收率为91.5%~110%。 相似文献
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Natural fibrous sepiolite with a high surface area, negative surface charge and porous structure is promising for hydroxyapatite (HAp) mineralization since the clay is naturally abundant and biocompatible. In this paper, the use of fibrous sepiolite as a template for growth of HAp nanocrystals was reported for the first time. Carbonated HAp nanorods with dimensions of 20-60 nm in length and 10-20 nm in diameter were successfully grown on the sepiolite surface with a preferred orientation to the c-axis. The critical nucleus radius of HAp in the presence of natural sepiolite was estimated as 0.296-0.312 nm. Strong acid-activation increased the specific surface area of the sepiolite by 205% and also transformed the sepiolite to silica fiber with an elastic modulus being 395% of the original value. The novel HAp/acid-activated sepiolite biocomposite has a specific surface area of 182 m2 g(-1) and an elastic modulus of over 20 GPa, considerably higher than those of the HAp synthesized without sepiolite. Such hierarchically assembled HAp/sepiolite biocomposites with controlled size and improved modulus open a new way to expand the applications of naturally abundant clays in biological load-bearing devices. 相似文献
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以碱处理的焙烧高岭土微球(CKM)为载体,采用原位合成方法成功制备了ZSM-5分子筛。考察了碱处理条件对原位合成的影响。采用XRD、FESEM、N2吸附-脱附、NH3-TPD对合成样品进行了表征。结果表明:碱处理条件对晶化产物的化学组成、形貌结构有显著影响。7.4%(质量分数)的氢氧化钠溶液在95 ℃、1.5 h条件下处理的
CKM表面合成出纯相的ZSM-5分子筛,颗粒尺寸约为0.8~1 μm,比表面积为128 m2/g,总孔容、微孔比表面积和酸量均明显增加。 相似文献