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系统地总结了介孔沸石的合成方法,包括对合成的沸石分子筛的后处理、硬模板法和软模板法;并就制备方法和产品结构的特点进行了评述。后处理法包括对沸石分子筛的脱铝处理、脱硅处理及热处理;硬模板主要包括碳纳米粒子、介孔碳黑、碳纳米管、碳纳米纤维、碳气凝胶、有序介孔碳、胶体复制碳、无机纳米粒子等;软模板主要包括高分子聚合物和有机硅烷模板剂。 相似文献
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介绍了二维多孔碳纳米片(PCNs)材料在能源领域的应用优势,综述了PCNs的制备方法以及在锂离子电池、超级电容器和电催化氧还原反应等电化学领域的应用研究进展。PCNs的制备方法为硬模板法(包括空间、盐粒表面和其他二维材料表面模板)、软模板法(包括使用两亲性小分子和两亲性块状共聚物(BCPs)制备PCNs)、无模板法(包括小分子、聚合物和生物质作为前驱体来制备PCNs)。其中软模板法相比硬模板法,其稳定性较差,还需进一步提高。指出未来应致力于开发制备PCNs的新方法和新型PCNs基材料,同时研究此类PCNs材料在分离膜、生化传感器、量子器件等方面的应用。 相似文献
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为强化SAPO-34分子筛内传质过程,增强其酸性位的可接近性,以原位碳化的蔗糖为硬模板,采用双结构导向剂(四乙基氢氧化铵、吗啡啉),通过干凝胶方法合成了多级孔道SAPO-34分子筛。使用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)及氮气物理吸附对分子筛结构进行表征,并进行了低密度聚乙烯热解性能考评。结果表明,合成的多级孔道SAPO-34晶体具有纳米尺寸,含有晶内介孔,介孔体积达0.41 cm3/g。四乙基氢氧化铵具有促进成核的作用,使晶体尺寸降低。结晶过程中纳米晶体对碳模板的包裹造成了晶内介孔的形成。该分子筛在低密度聚乙烯热解反应中T50温度显著降低,说明其具有更多可接近的酸性位。 相似文献
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BETA zeolite nanowire synthesis under non-hydrothermal conditions using carbon nanotubes as template
The properties of carbon nanotubes, used as a nanometric template and as a reactor for the synthesis of BETA zeolite, have been investigated. The confinement effect of the carbon nanotubes, induced by the high aspect ratio of the tubes could be effectively used for the synthesis of one-dimensional nanowire zeolitic materials under non-hydrothermal macroscopic conditions. Zeolite material is easily recovered by combustion of the nanotubes. The average sizes of the zeolite particles are about 20 nm. The BETA zeolite was successfully used as a catalyst for benzoylation of anisol. The zeolite catalyst exhibits a high activity compared to a commercial BETA, essentially due to its high external surface area. 相似文献
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Chularat Wattanakit Chompunuch Warakulwit Piboon Pantu Boonruen Sunpetch Metta Charoenpanich Jumras Limtrakul 《加拿大化工杂志》2012,90(4):873-880
In this work, we are reporting for the first time the synthesis of hierarchical micro‐ and mesoporous zeolite using silica–carbon (SiO2/C) composites prepared by pyrolysis of carbonaceous gases in the presence of silica gel. The pyrolysis effectively yielded carbon deposited onto the raw silica material. The obtained SiO2/C composites were utilised as a bifunctional material, mesoporous template and silica source, for the zeolite synthesis. Tetrapropylammonium hydroxide (TPAOH) was used as a microporous template. The combination of the obtained composites and the TPAOH for the hydrothermal synthesis resulted in the formation of hierarchical micro‐ and mesoporous ZSM‐5. The results from the SEM, TEM, and N2 adsorption/desorption isotherms, and 27Al MAS NMR characterisations of the synthesised samples obtained after the removal of the templates confirmed the successful formation of the micro‐ and mesoporous zeolites. The mesoporosity of the zeolites could be controlled by adjusting the carbon content in the SiO2/C composites while the carbon content could be controlled by varying the deposition time and the concentration of the carbonaceous gases used. This controllable and efficient synthesis method is considered to be a promising method for creating hierarchical micro‐ and mesoporous zeolites. © 2011 Canadian Society for Chemical Engineering 相似文献
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沸石分子筛是一种具有规则孔道结构的硅铝酸盐晶体,在气体吸附分离、工业催化、重金属离子污染治理等领域被广泛应用。传统沸石分子筛的水热合成常以含硅、铝的化工产品以及有机模板剂为原料,不仅价格昂贵,且污染环境。因此,开展以天然黏土为原料绿色合成沸石分子筛的相关研究,将廉价的天然黏土资源转化成高附加值的化工产品,具有重要的研究意义与经济效益。从天然黏土活化工艺、黏土基沸石合成工艺技术及相关机理等方面介绍了黏土基沸石分子筛的研究进展,重点综述了黏土基沸石分子筛作为工业固体酸催化剂、气体吸附分离反应器及重金属吸附剂的应用,并对黏土基沸石分子筛的未来发展趋势进行了展望。 相似文献
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以乙二胺(EDA)为模板剂,采用原位固相转化法合成了ZSM-35沸石,并通过XRD对沸石晶化过程中的影响因素和晶化机理作了详细考察。结果表明,制备ZSM-35沸石适宜的硅铝摩尔比为21n(SiO2)/n(Al2O3)37;Na+与模板剂EDA协同作用,共同对ZSM-35沸石起着结构导向作用;延长晶化时间,ZSM-35沸石容易向ZSM-5沸石转晶,合成ZSM-35沸石合适的晶化时间为14~21 h。对晶化机理的考察表明ZSM-35沸石的合成过程具有固相机理的特征,并且由于ZSM-35沸石与ZSM-5沸石具有相同的次级结构单元,在晶化过程中容易发生转晶。 相似文献
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Arnd Garsuch 《Carbon》2005,43(11):2330-2337
Ordered carbon material that preserves the structural regularity of the parent zeolite template was synthesized by using ethylene as carbon source and HY-zeolite in a batch reactor. The obtained carbons exhibit a high degree of microporosity having BET surface areas between 1400 and 2400 m2/g. The morphology and structure of the prepared carbon materials were investigated by elemental analysis, X-ray diffraction measurements, scanning electron microscopy and nitrogen adsorption. The results were compared with the parent zeolite template. The carbonization procedure of precursor-encapsulated samples was investigated by thermal analysis and it has been found that the resulting quality of the ordered carbons strongly depends on the heat treatment of the composite material. 相似文献
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Porous carbon beads were prepared from macroporous anion-exchange resin beads preliminary converted into resin-zeolite Beta composite or pure zeolite Beta spheres. Two synthesis procedures were used depending on the initial template employed. In a series of experiments, the resin from the resin-zeolite Beta composite was directly carbonized into carbon. In another series of experiments, the resin was removed by oxidation at 600 °C leaving behind self-bonded zeolite Beta beads, which were filled with carbon by chemical vapor deposition (CVD) of propylene. As a final step for both procedures, the zeolite was dissolved in hydrofluoric acid. All the carbons prepared inherited the macroscopic spherical shape of the template spheres as well as the morphology of the primary particles building up the beads. The synthesis procedure and the carbonization temperature or the temperature for CVD of carbon employed influenced the ordering and the pore structure of the produced carbons. The carbons prepared by direct carbonization showed relatively low surface areas, less than 1000 m2 g−1, and no zeolite structural regularity. The samples obtained via CVD maintained the zeolite ordering with a periodicity of 11.7 Å and had surface areas of over 2000 m2 g−1. 相似文献
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As reported in previous communications, novel porous carbons were synthesized by using zeolite Y as a template. The carbons possess a periodic ordering structure and high BET surface area with large micropore volume. In this work, the details of the synthesis methods for preparing the ordered microporous carbons were examined. It was found that the following two-step process, the filling of carbon into zeolite channels by impregnation of furfuryl alcohol and then chemical vapor deposition (CVD) of propylene, was indispensable for preparing carbon with highly periodic ordering. In addition, low-temperature CVD and the further heat treatment of zeolite/carbon composite after the CVD are key points for the appearance of both good long-range periodicity and very high BET surface area with almost no mesoporosity in the carbons. 相似文献